Ephemeral Diffie-Hellman Over COSE (EDHOC)

1.1. Rationale for EDHOC

Many constrained IoT systems today do not use any security at all, and when they do, they often do not follow best practices. One reason is that many current security protocols are not designed with constrained IoT in mind. Constrained IoT systems often deal with personal information, valuable business data, and actuators interacting with the physical world. Not only do such systems need security and privacy, they often need end-to-end protection with source authentication and perfect forward secrecy. EDHOC and OSCORE [RFC8613] enables security following current best practices to devices and systems where current security protocols are impractical.¶

EDHOC is optimized for small message sizes and can therefore be sent over a small number of radio frames. The message size of a key exchange protocol may have a large impact on the performance of an IoT deployment, especially in constrained environments. For example, in a network bootstrapping setting a large number of devices turned on in a short period of time may result in large latencies caused by parallel key exchanges. Requirements on network formation time in constrained environments can be translated into key exchange overhead. In network technologies with duty cycle, each additional frame significantly increases the latency even if no other devices are transmitting.¶

Power consumption for wireless devices is highly dependent on message transmission, listening, and reception. For devices that only send a few bytes occasionally, the battery lifetime may be impacted by a heavy key exchange protocol. A key exchange may need to be executed more than once, e.g. due to a device rebooting or for security reasons such as perfect forward secrecy.¶

EDHOC is adapted to primitives and protocols designed for the Internet of Things: EDHOC is built on CBOR and COSE which enables small message overhead and efficient parsing in constrained devices. EDHOC is not bound to a particular transport layer, but it is recommended to transport the EDHOC message in CoAP payloads. EDHOC is not bound to a particular communication security protocol but works off-the-shelf with OSCORE [RFC8613] providing the necessary input parameters with required properties. Maximum code complexity (ROM/Flash) is often a constraint in many devices and by reusing already existing libraries, the additional code footprint for EDHOC + OSCORE can be kept very low.¶

1.2. Use of EDHOC

EDHOC is designed as a lightweight AKE for OSCORE, i.e. to provide authentication and session key establishment for IoT use cases such as those built on CoAP [RFC7252]. CoAP is a specialized web transfer protocol for use with constrained nodes and networks, providing a request/response interaction model between application endpoints. As such, EDHOC is targeting a large variety of use cases involving 'things' with embedded microcontrollers, sensors and actuators.¶

A typical setting is when one of the endpoints is constrained or in a constrained network, and the other endpoint is a node on the Internet (such as a mobile phone) or at the edge of the constrained network (such as a gateway). Thing-to-thing interactions over constrained networks are also relevant since both endpoints would then benefit from the lightweight properties of the protocol. EDHOC could e.g. be run when a device/device(s) connect(s) for the first time, or to establish fresh keys which are not compromised by a later compromise of the long-term keys. (Further security properties are described in Section 7.1.)¶

1.3. Terminology and Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶

Readers are expected to be familiar with the terms and concepts described in CBOR [RFC7049], CBOR Sequences [RFC8742], COSE [RFC8152], and CDDL [RFC8610]. The Concise Data Definition Language (CDDL) is used to express CBOR data structures [RFC7049]. Examples of CBOR and CDDL are provided in Appendix A.1.¶

3.1. Transport and Message Correlation

Cryptographically, EDHOC does not put requirements on the lower layers. EDHOC is not bound to a particular transport layer, and can be used in environments without IP. The transport is responsible to handle message loss, reordering, message duplication, fragmentation, and denial of service protection, where necessary. The Initiator and the Responder need to have agreed on a transport to be used for EDHOC. It is recommended to transport EDHOC in CoAP payloads, see Section 6.¶

EDHOC includes connection identifiers (C_I, C_R) to correlate messages. The connection identifiers C_I and C_R do not have any cryptographic purpose in EDHOC. They contain information facilitating retrieval of the protocol state and may therefore be very short. The connection identifier MAY be used with an application protocol (e.g. OSCORE) for which EDHOC establishes keys, in which case the connection identifiers SHALL adhere to the requirements for that protocol. Each party choses a connection identifier it desires the other party to use in outgoing messages. (For OSCORE this results in the endpoint selecting its Recipient ID, see Section 3.1 of [RFC8613]).¶

If the transport provides a mechanism for correlating messages, some of the connection identifiers may be omitted. There are four cases:¶

• corr = 0, the transport does not provide a correlation mechanism.¶
• corr = 1, the transport provides a correlation mechanism that enables the Responder to correlate message_2 and message_1.¶
• corr = 2, the transport provides a correlation mechanism that enables the Initiator to correlate message_3 and message_2.¶
• corr = 3, the transport provides a correlation mechanism that enables both parties to correlate all three messages.¶

For example, if the key exchange is transported over CoAP, the CoAP Token can be used to correlate messages, see Section 6.1.¶

3.2. Authentication Keys and Identities

The EDHOC message exchange may be authenticated using raw public keys (RPK) or public key certificates. The certificates and RPKs can contain signature keys or static Diffie-Hellman keys. In X.509 certificates, signature keys typically have key usage "digitalSignature" and Diffie-Hellman keys typically have key usage "keyAgreement".¶

EDHOC assumes the existence of mechanisms (certification authority, trusted third party, manual distribution, etc.) for specifying and distributing authentication keys and identities. Policies are set based on the identity of the other party, and parties typically only allow connections from a specific identity or a small restricted set of identities. For example, in the case of a device connecting to a network, the network may only allow connections from devices which authenticate with certificates having a particular range of serial numbers in the subject field and signed by a particular CA. On the other side, the device may only be allowed to connect to a network which authenticate with a particular public key (information of which may be provisioned, e.g., out of band or in the Auxiliary Data, see Section 3.6).¶

The EDHOC implementation must be able to receive and enforce information from the application about what is the intended peer endpoint, and in particular whether it is a specific identity or a set of identities.¶

• When a Public Key Infrastructure (PKI) is used, the trust anchor is a Certification Authority (CA) certificate, and the identity is the subject whose unique name (e.g. a domain name, NAI, or EUI) is included in the endpoint's certificate. Before running EDHOC each party needs at least one CA public key certificate, or just the public key, and a specific identity or set of identities it is allowed to communicate with. Only validated public-key certificates with an allowed subject name, as specified by the application, are to be accepted. EDHOC provides proof that the other party possesses the private authentication key corresponding to the public authentication key in its certificate. The certification path provides proof that the subject of the certificate owns the public key in the certificate.¶
• When public keys are used but not with a PKI (RPK, self-signed certificate), the trust anchor is the public authentication key of the other party. In this case, the identity is typically directly associated to the public authentication key of the other party. For example, the name of the subject may be a canonical representation of the public key. Alternatively, if identities can be expressed in the form of unique subject names assigned to public keys, then a binding to identity can be achieved by including both public key and associated subject name in the protocol message computation: CRED_I or CRED_R may be a self-signed certificate or COSE_Key containing the public authentication key and the subject name, see Figure 2. Before running EDHOC, each endpoint needs a specific public authentication key/unique associated subject name, or a set of public authentication keys/unique associated subject names, which it is allowed to communicate with. EDHOC provides proof that the other party possesses the private authentication key corresponding to the public authentication key.¶

3.3. Identifiers

One byte connection and credential identifiers are realistic in many scenarios as most constrained devices only have a few keys and connections. In cases where a node only has one connection or key, the identifiers may even be the empty byte string.¶

3.4. Cipher Suites

EDHOC cipher suites consist of an ordered set of COSE algorithms: an EDHOC AEAD algorithm, an EDHOC hash algorithm, an EDHOC ECDH curve, an EDHOC signature algorithm, an EDHOC signature algorithm curve, an application AEAD algorithm, and an application hash algorithm from the COSE Algorithms and Elliptic Curves registries. Each cipher suite is identified with a pre-defined int label. This document specifies four pre-defined cipher suites.¶

   0. ( 10, -16, 4, -8, 6, 10, -16 )
      (AES-CCM-16-64-128, SHA-256, X25519, EdDSA, Ed25519,
       AES-CCM-16-64-128, SHA-256)

   1. ( 30, -16, 4, -8, 6, 10, -16 )
      (AES-CCM-16-128-128, SHA-256, X25519, EdDSA, Ed25519,
       AES-CCM-16-64-128, SHA-256)

   2. ( 10, -16, 1, -7, 1, 10, -16 )
      (AES-CCM-16-64-128, SHA-256, P-256, ES256, P-256,
       AES-CCM-16-64-128, SHA-256)

   3. ( 30, -16, 1, -7, 1, 10, -16 )
      (AES-CCM-16-128-128, SHA-256, P-256, ES256, P-256,
       AES-CCM-16-64-128, SHA-256)

The different methods use the same cipher suites, but some algorithms are not used in some methods. The EDHOC signature algorithm and the EDHOC signature algorithm curve are not used is methods without signature authentication.¶

The Initiator need to have a list of cipher suites it supports in order of preference. The Responder need to have a list of cipher suites it supports.¶

3.5. Communication/Negotiation of Protocol Features

EDHOC allows the communication or negotiation of various protocol features during the execution of the protocol.¶

• The Initiator proposes a cipher suite (see Section 3.4), and the Responder either accepts or rejects, and may make a counter proposal.¶
• The Initiator decides on the correlation parameter corr (see Section 3.1). This is typically given by the transport which the Initiator and the Responder have agreed on beforehand. The Responder either accepts or rejects.¶
• The Initiator decides on the method parameter, see Section 8.2. The Responder either accepts or rejects.¶
• The Initiator and the Responder decide on the representation of the identifier of their respective credentials, ID_CRED_I and ID_CRED_R. The decision is reflected by the label used in the CBOR map, see for example Section 4.2.¶

3.6. Auxiliary Data

In order to reduce round trips and number of messages, and in some cases also streamline processing, certain security applications may be integrated into EDHOC by transporting auxiliary data together with the messages. One example is the transport of third-party authorization information protected outside of EDHOC [I-D.selander-ace-ake-authz]. Another example is the embedding of a certificate enrolment request or a newly issued certificate.¶

EDHOC allows opaque auxiliary data (AD) to be sent in the EDHOC messages. Unprotected Auxiliary Data (AD_1, AD_2) may be sent in message_1 and message_2, respectively. Protected Auxiliary Data (AD_3) may be sent in message_3.¶

Since data carried in AD_1 and AD_2 may not be protected, and the content of AD_3 is available to both the Initiator and the Responder, special considerations need to be made such that the availability of the data a) does not violate security and privacy requirements of the service which uses this data, and b) does not violate the security properties of EDHOC.¶

3.7. Ephemeral Public Keys

The ECDH ephemeral public keys are formatted as a COSE_Key of type EC2 or OKP according to Sections 13.1 and 13.2 of [RFC8152], but only the 'x' parameter is included in the EDHOC messages. For Elliptic Curve Keys of type EC2, compact representation as per [RFC6090] MAY be used also in the COSE_Key. If the COSE implementation requires an 'y' parameter, any of the possible values of the y-coordinate can be used, see Appendix C of [RFC6090]. COSE [RFC8152] always use compact output for Elliptic Curve Keys of type EC2.¶

3.8. Key Derivation

EDHOC uses HKDF [RFC5869] with the EDHOC hash algorithm in the selected cipher suite to derive keys. HKDF-Extract is used to derive fixed-length uniformly pseudorandom keys (PRK) from ECDH shared secrets. HKDF-Expand is used to derive additional output keying material (OKM) from the PRKs. The PRKs are derived using HKDF-Extract [RFC5869].¶

   PRK = HKDF-Extract( salt, IKM )

PRK_2e is used to derive key and IV to encrypt message_2. PRK_3e2m is used to derive keys and IVs produce a MAC in message_2 and to encrypt message_3. PRK_4x3m is used to derive keys and IVs produce a MAC in message_3 and to derive application specific data.¶

PRK_2e is derived with the following input:¶

• The salt SHALL be the empty byte string. Note that [RFC5869] specifies that if the salt is not provided, it is set to a string of zeros (see Section 2.2 of [RFC5869]). For implementation purposes, not providing the salt is the same as setting the salt to the empty byte string.¶
• The input keying material (IKM) SHALL be the ECDH shared secret G_XY (calculated from G_X and Y or G_Y and X) as defined in Section 12.4.1 of [RFC8152].¶

Example: Assuming the use of SHA-256 the extract phase of HKDF produces PRK_2e as follows:¶

   PRK_2e = HMAC-SHA-256( salt, G_XY )

where salt = 0x (the empty byte string).¶

The pseudorandom keys PRK_3e2m and PRK_4x3m are defined as follow:¶

• If the Reponder authenticates with a static Diffie-Hellman key, then PRK_3e2m = HKDF-Extract( PRK_2e, G_RX ), where G_RX is the ECDH shared secret calculated from G_R and X, or G_X and R, else PRK_3e2m = PRK_2e.¶
• If the Initiator authenticates with a static Diffie-Hellman key, then PRK_4x3m = HKDF-Extract( PRK_3e2m, G_IY ), where G_IY is the ECDH shared secret calculated from G_I and Y, or G_Y and I, else PRK_4x3m = PRK_3e2m.¶

Example: Assuming the use of curve25519, the ECDH shared secrets G_XY, G_RX, and G_IY are the outputs of the X25519 function [RFC7748]:¶

   G_XY = X25519( Y, G_X ) = X25519( X, G_Y )

The keys and IVs used in EDHOC are derived from PRK using HKDF-Expand [RFC5869] where the EDHOC-KDF is instantiated with the EDHOC AEAD algorithm in the selected cipher suite.¶

   OKM = EDHOC-KDF( PRK, transcript_hash, label, length )
       = HKDF-Expand( PRK, info, length )

where info is the CBOR encoding of¶

info = [
   edhoc_aead_id : int / tstr,
   transcript_hash : bstr,
   label : tstr,
   length : uint
]

where¶

• edhoc_aead_id is an int or tstr containing the algorithm identifier of the EDHOC AEAD algorithm in the selected cipher suite encoded as defined in [RFC8152]. Note that a single fixed edhoc_aead_id is used in all invocations of EDHOC-KDF, including the derivation of K_2e and invocations of the EDHOC-Exporter.¶
• transcript_hash is a bstr set to one of the transcript hashes TH_2, TH_3, or TH_4 as defined in Sections 4.5.1, 4.6.1, and 3.8.1.¶
• label is a tstr set to the name of the derived key or IV, i.e. "K_2m", "IV_2m", "K_2e", "K_3m", "IV_3m", "K_3ae", or "IV_3ae".¶
• length is the length of output keying material (OKM) in bytes¶

K_2m and IV_2m are derived using the transcript hash TH_2 and the pseudorandom key PRK_3e2m. K_3ae and IV_3ae are derived using the transcript hash TH_3 and the pseudorandom key PRK_3e2m. K_3m and IV_3m are derived using the transcript hash TH_3 and the pseudorandom key PRK_4x3m. IVs are only used if the EDHOC AEAD algorithm uses IVs.¶

   EDHOC-Exporter(label, length)
     = EDHOC-KDF(PRK_4x3m, TH_4, label, length)

   TH_4 = H( TH_3, CIPHERTEXT_3 )

4.1. Overview

This section specifies authentication method = 0, 1, 2, and 3, see Section 8.2. EDHOC supports authentication with signature or static Diffie-Hellman keys in the form of raw public keys (RPK) and public key certificates with the requirements that:¶

• Only the Responder SHALL have access to the Responder's private authentication key,¶
• Only the Initiator SHALL have access to the Initiator's private authentication key,¶
• The Initiator is able to retrieve the Responder's public authentication key using ID_CRED_R,¶
• The Responder is able to retrieve the Initiator's public authentication key using ID_CRED_I,¶

where ID_CRED_I and ID_CRED_R are the identifiers of the public authentication keys. Their encoding is specified in Section 4.2.¶

Initiator                                                   Responder
|               METHOD_CORR, SUITES_I, G_X, C_I, AD_1               |
+------------------------------------------------------------------>|
|                             message_1                             |
|                                                                   |
|   C_I, G_Y, C_R, Enc(K_2e; ID_CRED_R, Signature_or_MAC_2, AD_2)   |
|<------------------------------------------------------------------+
|                             message_2                             |
|                                                                   |
|       C_R, AEAD(K_3ae; ID_CRED_I, Signature_or_MAC_3, AD_3)       |
+------------------------------------------------------------------>|
|                             message_3                             |

4.2. Encoding of Public Authentication Key Identifiers

The identifiers ID_CRED_I and ID_CRED_R are COSE header_maps, i.e. CBOR maps containing COSE Common Header Parameters, see Section 3.1 of [RFC8152]). ID_CRED_I and ID_CRED_R need to contain parameters that can identify a public authentication key. In the following paragraph we give some examples of possible COSE header parameters used.¶

Raw public keys are most optimally stored as COSE_Key objects and identified with a 'kid' parameter:¶

• ID_CRED_x = { 4 : kid_x }, where kid_x : bstr, for x = I or R.¶

Public key certificates can be identified in different ways. Header parameters for identifying X.509 certificates are defined in [I-D.ietf-cose-x509], for example:¶

• by a hash value with the 'x5t' parameter;¶

  • ID_CRED_x = { 34 : COSE_CertHash }, for x = I or R,¶

• by a URL with the 'x5u' parameter;¶

  • ID_CRED_x = { 35 : uri }, for x = I or R,¶

The purpose of ID_CRED_I and ID_CRED_R is to facilitate retrieval of a public authentication key and when they do not contain the actual credential, they may be very short. ID_CRED_I and ID_CRED_R MAY contain the actual credential used for authentication. It is RECOMMENDED that they uniquely identify the public authentication key as the recipient may otherwise have to try several keys. ID_CRED_I and ID_CRED_R are transported in the ciphertext, see Section 4.5.2 and Section 4.6.2.¶

The authentication key MUST be a signature key or static Diffie-Hellman key. The Initiator and the Responder MAY use different types of authentication keys, e.g. one uses a signature key and the other uses a static Diffie-Hellman key. When using a signature key, the authentication is provided by a signature. When using a static Diffie-Hellman key the authentication is provided by a Message Authentication Code (MAC) computed from an ephemeral-static ECDH shared secret which enables significant reductions in message sizes. The MAC is implemented with an AEAD algorithm. When using a static Diffie-Hellman keys the Initiator's and Responder's private authentication keys are called I and R, respectively, and the public authentication keys are called G_I and G_R, respectively.¶

The actual credentials CRED_I and CRED_R are signed or MAC:ed by the Initiator and the Responder respectively, see Section 4.6.1 and Section 4.5.1. The Initiator and the Responder MAY use different types of credentials, e.g. one uses RPK and the other uses certificate. When the credential is a certificate, CRED_x is end-entity certificate (i.e. not the certificate chain) encoded as a CBOR bstr. When the credential is a COSE_Key, CRED_x is a CBOR map only contains specific fields from the COSE_Key. For COSE_Keys of type OKP the CBOR map SHALL only include the parameters 1 (kty), -1 (crv), and -2 (x-coordinate). For COSE_Keys of type EC2 the CBOR map SHALL only include the parameters 1 (kty), -1 (crv), -2 (x-coordinate), and -3 (y-coordinate). If the parties have agreed on an identity besides the public key, the indentity is included in the CBOR map with the label "subject name", otherwise the subject name is the empty text string. The parameters SHALL be encoded in decreasing order with int labels first and text string labels last. An example of CRED_x when the RPK contains an X25519 static Diffie-Hellman key and the parties have agreed on an EUI-64 identity is shown below:¶

CRED_x = {
  1:  1,
 -1:  4,
 -2:  h'b1a3e89460e88d3a8d54211dc95f0b90
        3ff205eb71912d6db8f4af980d2db83a',
 "subject name" : "42-50-31-FF-EF-37-32-39"
}

4.3. Encoding of bstr_identifier

A bstr_identifier is a special encoding for byte strings, used throughout the protocol.¶

Byte strings of length greater than one are encoded as CBOR byte strings. Byte strings of length one are encoded as the corresponding integer - 24.¶

For example, the byte string h'59e9' encoded as a bstr_identifier is equal to h'59e9', while the byte string h'2a' is encoded as the integer 18.¶

The CDDL definition of the bstr_identifier is given below:¶

bstr_identifier = bstr / int

Note that, despite what could be interpreted by the CDDL definition only, bstr_identifier once decoded are always byte strings.¶

4.4. EDHOC Message 1

message_1 = (
  METHOD_CORR : int,
  SUITES_I : [ selected : suite, supported : 2* suite ] / suite,
  G_X : bstr,
  C_I : bstr_identifier,
  ? AD_1 : bstr,
)

suite = int

4.5. EDHOC Message 2

message_2 = (
  data_2,
  CIPHERTEXT_2 : bstr,
)

data_2 = (
  ? C_I : bstr_identifier,
  G_Y : bstr,
  C_R : bstr_identifier,
)

4.6. EDHOC Message 3

message_3 = (
  data_3,
  CIPHERTEXT_3 : bstr,
)

data_3 = (
  ? C_R : bstr_identifier,
)

5.1. EDHOC Error Message

This section defines a message format for the EDHOC error message, used during the protocol. An EDHOC error message can be sent by both parties as a reply to any non-error EDHOC message. After sending an error message, the protocol MUST be discontinued. Errors at the EDHOC layer are sent as normal successful messages in the lower layers (e.g. CoAP POST and 2.04 Changed). An advantage of using such a construction is to avoid issues created by usage of cross protocol proxies (e.g. UDP to TCP).¶

error SHALL be a CBOR Sequence (see Appendix A.1) as defined below¶

error = (
  ? C_x : bstr_identifier,
  ERR_MSG : tstr,
  ? SUITES_R : [ supported : 2* suite ] / suite,
)

where:¶

• C_x - variable length connection identifier, encoded as a bstr_identifier (see Section 4.3). If error is sent by the Responder and corr (METHOD_CORR mod 4) equals 0 or 2 then C_x is set to C_I, else if error is sent by the Initiator and corr (METHOD_CORR mod 4) equals 0 or 1 then C_x is set to C_R, else C_x is omitted.¶
• ERR_MSG - text string containing the diagnostic payload, defined in the same way as in Section 5.5.2 of [RFC7252]. ERR_MSG MAY be a 0-length text string.¶
• SUITES_R - cipher suites from SUITES_I or the EDHOC cipher suites registry that the Responder supports. SUITES_R MUST only be included in replies to message_1. If a single supported cipher suite is conveyed then the supported cipher suite is encoded as an int instead of an array.¶

After receiving SUITES_R, the Initiator can determine which selected cipher suite to use for the next EDHOC run with the Responder. If the Initiator intends to contact the Responder in the future, the Initiator SHOULD remember which selected cipher suite to use until the next message_1 has been sent, otherwise the Initiator and Responder will likely run into an infinite loop. After a successful run of EDHOC, the Initiator MAY remember the selected cipher suite to use in future EDHOC runs. Note that if the Initiator or Responder is updated with new cipher suite policies, any cached information may be outdated.¶

Initiator                                                   Responder
|        METHOD_CORR, SUITES_I = [5, 5, 6, 7], G_X, C_I, AD_1       |
+------------------------------------------------------------------>|
|                             message_1                             |
|                                                                   |
|                     C_I, ERR_MSG, SUITES_R = 6                    |
|<------------------------------------------------------------------+
|                               error                               |
|                                                                   |
|         METHOD_CORR, SUITES_I = [6, 5, 6], G_X, C_I, AD_1         |
+------------------------------------------------------------------>|
|                             message_1                             |

Initiator                                                   Responder
|         METHOD_CORR, SUITES_I = [5, 5, 6], G_X, C_I, AD_1         |
+------------------------------------------------------------------>|
|                             message_1                             |
|                                                                   |
|                  C_I, ERR_MSG, SUITES_R = [7, 9]                  |
|<------------------------------------------------------------------+
|                               error                               |
|                                                                   |
|        METHOD_CORR, SUITES_I = [7, 5, 6, 7], G_X, C_I, AD_1       |
+------------------------------------------------------------------>|
|                             message_1                             |

6.1. Transferring EDHOC in CoAP

It is recommended to transport EDHOC as an exchange of CoAP [RFC7252] messages. CoAP is a reliable transport that can preserve packet ordering and handle message duplication. CoAP can also perform fragmentation and protect against denial of service attacks. It is recommended to carry the EDHOC messages in Confirmable messages, especially if fragmentation is used.¶

By default, the CoAP client is the Initiator and the CoAP server is the Responder, but the roles SHOULD be chosen to protect the most sensitive identity, see Section 7. By default, EDHOC is transferred in POST requests and 2.04 (Changed) responses to the Uri-Path: "/.well-known/edhoc", but an application may define its own path that can be discovered e.g. using resource directory [I-D.ietf-core-resource-directory].¶

By default, the message flow is as follows: EDHOC message_1 is sent in the payload of a POST request from the client to the server's resource for EDHOC. EDHOC message_2 or the EDHOC error message is sent from the server to the client in the payload of a 2.04 (Changed) response. EDHOC message_3 or the EDHOC error message is sent from the client to the server's resource in the payload of a POST request. If needed, an EDHOC error message is sent from the server to the client in the payload of a 2.04 (Changed) response.¶

An example of a successful EDHOC exchange using CoAP is shown in Figure 7. In this case the CoAP Token enables the Initiator to correlate message_1 and message_2 so the correlation parameter corr = 1.¶

Client    Server
  |          |
  +--------->| Header: POST (Code=0.02)
  |   POST   | Uri-Path: "/.well-known/edhoc"
  |          | Content-Format: application/edhoc
  |          | Payload: EDHOC message_1
  |          |
  |<---------+ Header: 2.04 Changed
  |   2.04   | Content-Format: application/edhoc
  |          | Payload: EDHOC message_2
  |          |
  +--------->| Header: POST (Code=0.02)
  |   POST   | Uri-Path: "/.well-known/edhoc"
  |          | Content-Format: application/edhoc
  |          | Payload: EDHOC message_3
  |          |
  |<---------+ Header: 2.04 Changed
  |   2.04   |
  |          |

The exchange in Figure 7 protects the client identity against active attackers and the server identity against passive attackers. An alternative exchange that protects the server identity against active attackers and the client identity against passive attackers is shown in Figure 8. In this case the CoAP Token enables the Responder to correlate message_2 and message_3 so the correlation parameter corr = 2.¶

Client    Server
  |          |
  +--------->| Header: POST (Code=0.02)
  |   POST   | Uri-Path: "/.well-known/edhoc"
  |          |
  |<---------+ Header: 2.04 Changed
  |   2.04   | Content-Format: application/edhoc
  |          | Payload: EDHOC message_1
  |          |
  +--------->| Header: POST (Code=0.02)
  |   POST   | Uri-Path: "/.well-known/edhoc"
  |          | Content-Format: application/edhoc
  |          | Payload: EDHOC message_2
  |          |
  |<---------+ Header: 2.04 Changed
  |   2.04   | Content-Format: application/edhoc
  |          | Payload: EDHOC message_3
  |          |

To protect against denial-of-service attacks, the CoAP server MAY respond to the first POST request with a 4.01 (Unauthorized) containing an Echo option [I-D.ietf-core-echo-request-tag]. This forces the initiator to demonstrate its reachability at its apparent network address. If message fragmentation is needed, the EDHOC messages may be fragmented using the CoAP Block-Wise Transfer mechanism [RFC7959].¶

   Master Secret = EDHOC-Exporter( "OSCORE Master Secret", length )
   Master Salt   = EDHOC-Exporter( "OSCORE Master Salt", 8 )

7.1. Security Properties

EDHOC inherits its security properties from the theoretical SIGMA-I protocol [SIGMA]. Using the terminology from [SIGMA], EDHOC provides perfect forward secrecy, mutual authentication with aliveness, consistency, peer awareness. As described in [SIGMA], peer awareness is provided to the Responder, but not to the Initiator.¶

EDHOC protects the credential identifier of the Initiator against active attacks and the credential identifier of the Responder against passive attacks. The roles should be assigned to protect the most sensitive identity/identifier, typically that which is not possible to infer from routing information in the lower layers.¶

Compared to [SIGMA], EDHOC adds an explicit method type and expands the message authentication coverage to additional elements such as algorithms, auxiliary data, and previous messages. This protects against an attacker replaying messages or injecting messages from another session.¶

EDHOC also adds negotiation of connection identifiers and downgrade protected negotiation of cryptographic parameters, i.e. an attacker cannot affect the negotiated parameters. A single session of EDHOC does not include negotiation of cipher suites, but it enables the Responder to verify that the selected cipher suite is the most preferred cipher suite by the Initiator which is supported by both the Initiator and the Responder.¶

As required by [RFC7258], IETF protocols need to mitigate pervasive monitoring when possible. One way to mitigate pervasive monitoring is to use a key exchange that provides perfect forward secrecy. EDHOC therefore only supports methods with perfect forward secrecy. To limit the effect of breaches, it is important to limit the use of symmetrical group keys for bootstrapping. EDHOC therefore strives to make the additional cost of using raw public keys and self-signed certificates as small as possible. Raw public keys and self-signed certificates are not a replacement for a public key infrastructure, but SHOULD be used instead of symmetrical group keys for bootstrapping.¶

Compromise of the long-term keys (private signature or static DH keys) does not compromise the security of completed EDHOC exchanges. Compromising the private authentication keys of one party lets an active attacker impersonate that compromised party in EDHOC exchanges with other parties, but does not let the attacker impersonate other parties in EDHOC exchanges with the compromised party. Compromise of the long-term keys does not enable a passive attacker to compromise future session keys. Compromise of the HDKF input parameters (ECDH shared secret) leads to compromise of all session keys derived from that compromised shared secret. Compromise of one session key does not compromise other session keys.¶

If supported by the device, it is RECOMMENDED that at least the long-term private keys is stored in a Trusted Execution Environment (TEE) and that sensitive operations using these keys are performed inside the TEE. To achieve even higher security additional operation such as ephemeral key generation, all computations of shared secrets, and storage of the PRK keys can be done inside the TEE. Optimally, the whole EDHOC protocol can be implemented inside the TEE. Typically an adversary with physical access to a device can be assumed to gain access to all information outside of the TEE, but none of the information inside the TEE.¶

Key compromise impersonation (KCI): In EDHOC authenticated with signature keys, EDHOC provides KCI protection against an attacker having access to the long term key or the ephemeral secret key. With static Diffie-Hellman key authentication, KCI protection would be provided against an attacker having access to the long-term Diffie-Hellman key, but not to an attacker having access to the ephemeral secret key. Note that the term KCI has typically been used for compromise of long-term keys, and that an attacker with access to the ephemeral secret key can only attack that specific protocol run.¶

Repudiation: In EDHOC authenticated with signature keys, the Initiator could theoretically prove that the Responder performed a run of the protocol by presenting the private ephemeral key, and vice versa. Note that storing the private ephemeral keys violates the protocol requirements. With static Diffie-Hellman key authentication, both parties can always deny having participated in the protocol.¶

7.2. Cryptographic Considerations

The security of the SIGMA protocol requires the MAC to be bound to the identity of the signer. Hence the message authenticating functionality of the authenticated encryption in EDHOC is critical: authenticated encryption MUST NOT be replaced by plain encryption only, even if authentication is provided at another level or through a different mechanism. EDHOC implements SIGMA-I using the same Sign-then-MAC approach as TLS 1.3.¶

To reduce message overhead EDHOC does not use explicit nonces and instead rely on the ephemeral public keys to provide randomness to each session. A good amount of randomness is important for the key generation, to provide liveness, and to protect against interleaving attacks. For this reason, the ephemeral keys MUST NOT be reused, and both parties SHALL generate fresh random ephemeral key pairs.¶

The choice of key length used in the different algorithms needs to be harmonized, so that a sufficient security level is maintained for certificates, EDHOC, and the protection of application data. The Initiator and the Responder should enforce a minimum security level.¶

The data rates in many IoT deployments are very limited. Given that the application keys are protected as well as the long-term authentication keys they can often be used for years or even decades before the cryptographic limits are reached. If the application keys established through EDHOC need to be renewed, the communicating parties can derive application keys with other labels or run EDHOC again.¶

7.3. Cipher Suites

Cipher suite number 0 (AES-CCM-16-64-128, SHA-256, X25519, EdDSA, Ed25519, AES-CCM-16-64-128, SHA-256) is mandatory to implement. Implementations only need to implement the algorithms needed for their supported methods. For many constrained IoT devices it is problematic to support more than one cipher suites, so some deployments with P-256 may not support the mandatory cipher suite. This is not a problem for local deployments.¶

The HMAC algorithm HMAC 256/64 (HMAC w/ SHA-256 truncated to 64 bits) SHALL NOT be supported for use in EDHOC.¶

7.4. Unprotected Data

The Initiator and the Responder must make sure that unprotected data and metadata do not reveal any sensitive information. This also applies for encrypted data sent to an unauthenticated party. In particular, it applies to AD_1, ID_CRED_R, AD_2, and ERR_MSG. Using the same AD_1 in several EDHOC sessions allows passive eavesdroppers to correlate the different sessions. Another consideration is that the list of supported cipher suites may potentially be used to identify the application.¶

The Initiator and the Responder must also make sure that unauthenticated data does not trigger any harmful actions. In particular, this applies to AD_1 and ERR_MSG.¶

7.5. Denial-of-Service

EDHOC itself does not provide countermeasures against Denial-of-Service attacks. By sending a number of new or replayed message_1 an attacker may cause the Responder to allocate state, perform cryptographic operations, and amplify messages. To mitigate such attacks, an implementation SHOULD rely on lower layer mechanisms such as the Echo option in CoAP [I-D.ietf-core-echo-request-tag] that forces the initiator to demonstrate reachability at its apparent network address.¶

7.6. Implementation Considerations

The availability of a secure pseudorandom number generator and truly random seeds are essential for the security of EDHOC. If no true random number generator is available, a truly random seed must be provided from an external source. As each pseudorandom number must only be used once, an implementation need to get a new truly random seed after reboot, or continuously store state in nonvolatile memory, see ([RFC8613], Appendix B.1.1) for issues and solution approaches for writing to nonvolatile memory. If ECDSA is supported, "deterministic ECDSA" as specified in [RFC6979] is RECOMMENDED.¶

The referenced processing instructions in [SP-800-56A] must be complied with, including deleting the intermediate computed values along with any ephemeral ECDH secrets after the key derivation is completed. The ECDH shared secret, keys, and IVs MUST be secret. Implementations should provide countermeasures to side-channel attacks such as timing attacks. Depending on the selected curve, the parties should perform various validations of each other's public keys, see e.g. Section 5 of [SP-800-56A].¶

The Initiator and the Responder are responsible for verifying the integrity of certificates. The selection of trusted CAs should be done very carefully and certificate revocation should be supported. The private authentication keys MUST be kept secret.¶

The Initiator and the Responder are allowed to select the connection identifiers C_I and C_R, respectively, for the other party to use in the ongoing EDHOC protocol as well as in a subsequent application protocol (e.g. OSCORE [RFC8613]). The choice of connection identifier is not security critical in EDHOC but intended to simplify the retrieval of the right security context in combination with using short identifiers. If the wrong connection identifier of the other party is used in a protocol message it will result in the receiving party not being able to retrieve a security context (which will terminate the protocol) or retrieve the wrong security context (which also terminates the protocol as the message cannot be verified).¶

The Responder MUST finish the verification step of message_3 before passing AD_3 to the application.¶

If two nodes unintentionally initiate two simultaneous EDHOC message exchanges with each other even if they only want to complete a single EDHOC message exchange, they MAY terminate the exchange with the lexicographically smallest G_X. If the two G_X values are equal, the received message_1 MUST be discarded to mitigate reflection attacks. Note that in the case of two simultaneous EDHOC exchanges where the nodes only complete one and where the nodes have different preferred cipher suites, an attacker can affect which of the two nodes' preferred cipher suites will be used by blocking the other exchange.¶

7.7. Other Documents Referencing EDHOC

EDHOC has been analyzed in several other documents. A formal verification of EDHOC was done in [SSR18], an analysis of EDHOC for certificate enrollment was done in [Kron18], the use of EDHOC in LoRaWAN is analyzed in [LoRa1] and [LoRa2], the use of EDHOC in IoT bootstrapping is analyzed in [Perez18], and the use of EDHOC in 6TiSCH is described in [I-D.ietf-6tisch-dtsecurity-zerotouch-join].¶

8.1. EDHOC Cipher Suites Registry

IANA has created a new registry titled "EDHOC Cipher Suites" under the new heading "EDHOC". The registration procedure is "Expert Review". The columns of the registry are Value, Array, Description, and Reference, where Value is an integer and the other columns are text strings. The initial contents of the registry are:¶

Value: -24
Algorithms: N/A
Desc: Reserved for Private Use
Reference: [[this document]]

Value: -23
Algorithms: N/A
Desc: Reserved for Private Use
Reference: [[this document]]

Value: 0
Array: 10, 5, 4, -8, 6, 10, 5
Desc: AES-CCM-16-64-128, SHA-256, X25519, EdDSA, Ed25519,
      AES-CCM-16-64-128, SHA-256
Reference: [[this document]]

Value: 1
Array: 30, 5, 4, -8, 6, 10, 5
Desc: AES-CCM-16-128-128, SHA-256, X25519, EdDSA, Ed25519,
      AES-CCM-16-64-128, SHA-256
Reference: [[this document]]

Value: 2
Array: 10, 5, 1, -7, 1, 10, 5
Desc: AES-CCM-16-64-128, SHA-256, P-256, ES256, P-256,
      AES-CCM-16-64-128, SHA-256
Reference: [[this document]]

Value: 3
Array: 30, 5, 1, -7, 1, 10, 5
Desc: AES-CCM-16-128-128, SHA-256, P-256, ES256, P-256,
      AES-CCM-16-64-128, SHA-256
Reference: [[this document]]

8.2. EDHOC Method Type Registry

IANA has created a new registry titled "EDHOC Method Type" under the new heading "EDHOC". The registration procedure is "Expert Review". The columns of the registry are Value, Description, and Reference, where Value is an integer and the other columns are text strings. The initial contents of the registry are:¶

+-------+-------------------+-------------------+-------------------+
| Value | Initiator         | Responder         | Reference         |
+-------+-------------------+-------------------+-------------------+
|     0 | Signature Key     | Signature Key     | [[this document]] |
|     1 | Signature Key     | Static DH Key     | [[this document]] |
|     2 | Static DH Key     | Signature Key     | [[this document]] |
|     3 | Static DH Key     | Static DH Key     | [[this document]] |
+-------+-------------------+-------------------+-------------------+

8.3. The Well-Known URI Registry

IANA has added the well-known URI 'edhoc' to the Well-Known URIs registry.¶

• URI suffix: edhoc¶
• Change controller: IETF¶
• Specification document(s): [[this document]]¶
• Related information: None¶

8.4. Media Types Registry

IANA has added the media type 'application/edhoc' to the Media Types registry.¶

• Type name: application¶
• Subtype name: edhoc¶
• Required parameters: N/A¶
• Optional parameters: N/A¶
• Encoding considerations: binary¶
• Security considerations: See Section 7 of this document.¶
• Interoperability considerations: N/A¶
• Published specification: [[this document]] (this document)¶
• Applications that use this media type: To be identified¶
• Fragment identifier considerations: N/A¶

• Additional information:¶

  • Magic number(s): N/A¶
  • File extension(s): N/A¶
  • Macintosh file type code(s): N/A¶
• Person & email address to contact for further information: See "Authors' Addresses" section.¶
• Intended usage: COMMON¶
• Restrictions on usage: N/A¶
• Author: See "Authors' Addresses" section.¶
• Change Controller: IESG¶

8.5. CoAP Content-Formats Registry

IANA has added the media type 'application/edhoc' to the CoAP Content-Formats registry.¶

• Media Type: application/edhoc¶
• Encoding:¶
• ID: TBD42¶
• Reference: [[this document]]¶

8.6. Expert Review Instructions

The IANA Registries established in this document is defined as "Expert Review". This section gives some general guidelines for what the experts should be looking for, but they are being designated as experts for a reason so they should be given substantial latitude.¶

Expert reviewers should take into consideration the following points:¶

• Clarity and correctness of registrations. Experts are expected to check the clarity of purpose and use of the requested entries. Expert needs to make sure the values of algorithms are taken from the right registry, when that's required. Expert should consider requesting an opinion on the correctness of registered parameters from relevant IETF working groups. Encodings that do not meet these objective of clarity and completeness should not be registered.¶
• Experts should take into account the expected usage of fields when approving point assignment. The length of the encoded value should be weighed against how many code points of that length are left, the size of device it will be used on, and the number of code points left that encode to that size.¶
• Specifications are recommended. When specifications are not provided, the description provided needs to have sufficient information to verify the points above.¶

A.1. CBOR and CDDL

The Concise Binary Object Representation (CBOR) [RFC7049] is a data format designed for small code size and small message size. CBOR builds on the JSON data model but extends it by e.g. encoding binary data directly without base64 conversion. In addition to the binary CBOR encoding, CBOR also has a diagnostic notation that is readable and editable by humans. The Concise Data Definition Language (CDDL) [RFC8610] provides a way to express structures for protocol messages and APIs that use CBOR. [RFC8610] also extends the diagnostic notation.¶

CBOR data items are encoded to or decoded from byte strings using a type-length-value encoding scheme, where the three highest order bits of the initial byte contain information about the major type. CBOR supports several different types of data items, in addition to integers (int, uint), simple values (e.g. null), byte strings (bstr), and text strings (tstr), CBOR also supports arrays [] of data items, maps {} of pairs of data items, and sequences [RFC8742] of data items. Some examples are given below. For a complete specification and more examples, see [RFC7049] and [RFC8610]. We recommend implementors to get used to CBOR by using the CBOR playground [CborMe].¶

Diagnostic          Encoded              Type
------------------------------------------------------------------
1                   0x01                 unsigned integer
24                  0x1818               unsigned integer
-24                 0x37                 negative integer
-25                 0x3818               negative integer
null                0xf6                 simple value
h'12cd'             0x4212cd             byte string
'12cd'              0x4431326364         byte string
"12cd"              0x6431326364         text string
{ 4 : h'cd' }       0xa10441cd           map
<< 1, 2, null >>    0x430102f6           byte string
[ 1, 2, null ]      0x830102f6           array
( 1, 2, null )      0x0102f6             sequence
1, 2, null          0x0102f6             sequence
------------------------------------------------------------------

A.2. COSE

CBOR Object Signing and Encryption (COSE) [RFC8152] describes how to create and process signatures, message authentication codes, and encryption using CBOR. COSE builds on JOSE, but is adapted to allow more efficient processing in constrained devices. EDHOC makes use of COSE_Key, COSE_Encrypt0, and COSE_Sign1 objects.¶

B.1. Test Vectors for EDHOC Authenticated with Signature Keys (x5t)

EDHOC with signature authentication and X.509 certificates is used. In this test vector, the hash value 'x5t' is used to identify the certificate.¶

method (Signature Authentication)
0

CoAP is used as transport and the Initiator acts as CoAP client:¶

corr (the Initiator can correlate message_1 and message_2)
1

From there, METHOD_CORR has the following value:¶

METHOD_CORR (4 * method + corr) (int)
1

No unprotected opaque auxiliary data is sent in the message exchanges.¶

The list of supported cipher suites of the Initiator in order of preference is the following:¶

Supported Cipher Suites (4 bytes)
00 01 02 03

The cipher suite selected by the Initiator is the most preferred:¶

Selected Cipher Suite (int)
0

The mandatory-to-implement cipher suite 0 is supported by both the Initiator and the Responder, see Section 7.3.¶

X (Initiator's ephemeral private key) (32 bytes)
8f 78 1a 09 53 72 f8 5b 6d 9f 61 09 ae 42 26 11 73 4d 7d bf a0 06 9a 2d
f2 93 5b b2 e0 53 bf 35

G_X (Initiator's ephemeral public key) (32 bytes)
89 8f f7 9a 02 06 7a 16 ea 1e cc b9 0f a5 22 46 f5 aa 4d d6 ec 07 6b ba
02 59 d9 04 b7 ec 8b 0c

Connection identifier chosen by Initiator (0 bytes)

AD_1 (0 bytes)

SUITES_I (int)
0

message_1 =
(
  1,
  0,
  h'898ff79a02067a16ea1eccb90fa52246f5aa4dd6ec076bba0259d904b7ec8b0c',
  h''
)

message_1 (CBOR Sequence) (37 bytes)
01 00 58 20 89 8f f7 9a 02 06 7a 16 ea 1e cc b9 0f a5 22 46 f5 aa 4d d6
ec 07 6b ba 02 59 d9 04 b7 ec 8b 0c 40

Y (Responder's ephemeral private key) (32 bytes)
fd 8c d8 77 c9 ea 38 6e 6a f3 4f f7 e6 06 c4 b6 4c a8 31 c8 ba 33 13 4f
d4 cd 71 67 ca ba ec da

G_Y (Responder's ephemeral public key) (32 bytes)
71 a3 d5 99 c2 1d a1 89 02 a1 ae a8 10 b2 b6 38 2c cd 8d 5f 9b f0 19 52
81 75 4c 5e bc af 30 1e

G_XY (ECDH shared secret) (32 bytes)
2b b7 fa 6e 13 5b c3 35 d0 22 d6 34 cb fb 14 b3 f5 82 f3 e2 e3 af b2 b3
15 04 91 49 5c 61 78 2b

salt (0 bytes)

PRK_2e (32 bytes)
ec 62 92 a0 67 f1 37 fc 7f 59 62 9d 22 6f bf c4 e0 68 89 49 f6 62 a9 7f
d8 2f be b7 99 71 39 4a

SK_R (Responders's private authentication key) (32 bytes)
df 69 27 4d 71 32 96 e2 46 30 63 65 37 2b 46 83 ce d5 38 1b fc ad cd 44
0a 24 c3 91 d2 fe db 94

PRK_3e2m (32 bytes)
ec 62 92 a0 67 f1 37 fc 7f 59 62 9d 22 6f bf c4 e0 68 89 49 f6 62 a9 7f
d8 2f be b7 99 71 39 4a

Connection identifier chosen by Responder (1 byte)
2b

C_R (1 byte)
13

data_2 =
(
  h'71a3d599c21da18902a1aea810b2b6382ccd8d5f9bf0195281754c5ebcaf301e',
  h'13'
)

data_2 (CBOR Sequence) (35 bytes)
58 20 71 a3 d5 99 c2 1d a1 89 02 a1 ae a8 10 b2 b6 38 2c cd 8d 5f 9b f0
19 52 81 75 4c 5e bc af 30 1e 13

Input to calculate TH_2 (CBOR Sequence) (72 bytes)
01 00 58 20 89 8f f7 9a 02 06 7a 16 ea 1e cc b9 0f a5 22 46 f5 aa 4d d6
ec 07 6b ba 02 59 d9 04 b7 ec 8b 0c 40 58 20 71 a3 d5 99 c2 1d a1 89 02
a1 ae a8 10 b2 b6 38 2c cd 8d 5f 9b f0 19 52 81 75 4c 5e bc af 30 1e 13

TH_2 (32 bytes)
b0 dc 6c 1b a0 ba e6 e2 88 86 10 fa 0b 27 bf c5 2e 31 1a 47 b9 ca fb 60
9d e4 f6 a1 76 0d 6c f7

Responders's subject name (text string)
""

X509_R (110 bytes)
47 62 4d c9 cd c6 82 4b 2a 4c 52 e9 5e c9 d6 b0 53 4b 71 c2 b4 9e 4b f9
03 15 00 ce e6 86 99 79 c2 97 bb 5a 8b 38 1e 98 db 71 41 08 41 5e 5c 50
db 78 97 4c 27 15 79 b0 16 33 a3 ef 62 71 be 5c 22 5e b2 8f 9c f6 18 0b
5a 6a f3 1e 80 20 9a 08 5c fb f9 5f 3f dc f9 b1 8b 69 3d 6c 0e 0d 0f fb
8e 3f 9a 32 a5 08 59 ec d0 bf cf f2 c2 18

CRED_R (112 bytes)
58 6e 47 62 4d c9 cd c6 82 4b 2a 4c 52 e9 5e c9 d6 b0 53 4b 71 c2 b4 9e
4b f9 03 15 00 ce e6 86 99 79 c2 97 bb 5a 8b 38 1e 98 db 71 41 08 41 5e
5c 50 db 78 97 4c 27 15 79 b0 16 33 a3 ef 62 71 be 5c 22 5e b2 8f 9c f6
18 0b 5a 6a f3 1e 80 20 9a 08 5c fb f9 5f 3f dc f9 b1 8b 69 3d 6c 0e 0d
0f fb 8e 3f 9a 32 a5 08 59 ec d0 bf cf f2 c2 18

ID_CRED_R =
{
  34: [-15, h'FC79990F2431A3F5']
}

ID_CRED_R (14 bytes)
a1 18 22 82 2e 48 fc 79 99 0f 24 31 a3 f5

AD_2  (0 bytes)

P_2m (0 bytes)

A_2m =
[
  "Encrypt0",
  h'A11822822E48FC79990F2431A3F5',
  h'5820B0DC6C1BA0BAE6E2888610FA0B27BFC52E311A47B9CAFB609DE4F6A1760D6CF
  7586E47624DC9CDC6824B2A4C52E95EC9D6B0534B71C2B49E4BF9031500CEE6869979
  C297BB5A8B381E98DB714108415E5C50DB78974C271579B01633A3EF6271BE5C225EB
  28F9CF6180B5A6AF31E80209A085CFBF95F3FDCF9B18B693D6C0E0D0FFB8E3F9A32A5
  0859ECD0BFCFF2C218'
  ]

A_2m (CBOR-encoded) (173 bytes)
83 68 45 6e 63 72 79 70 74 30 4e a1 18 22 82 2e 48 fc 79 99 0f 24 31 a3
f5 58 92 58 20 b0 dc 6c 1b a0 ba e6 e2 88 86 10 fa 0b 27 bf c5 2e 31 1a
47 b9 ca fb 60 9d e4 f6 a1 76 0d 6c f7 58 6e 47 62 4d c9 cd c6 82 4b 2a
4c 52 e9 5e c9 d6 b0 53 4b 71 c2 b4 9e 4b f9 03 15 00 ce e6 86 99 79 c2
97 bb 5a 8b 38 1e 98 db 71 41 08 41 5e 5c 50 db 78 97 4c 27 15 79 b0 16
33 a3 ef 62 71 be 5c 22 5e b2 8f 9c f6 18 0b 5a 6a f3 1e 80 20 9a 08 5c
fb f9 5f 3f dc f9 b1 8b 69 3d 6c 0e 0d 0f fb 8e 3f 9a 32 a5 08 59 ec d0
bf cf f2 c2 18

info for K_2m =
[
  10,
  h'B0DC6C1BA0BAE6E2888610FA0B27BFC52E311A47B9CAFB609DE4F6A1760D6CF7',
  "K_2m",
  16
]

info for K_2m (CBOR-encoded) (42 bytes)
84 0a 58 20 b0 dc 6c 1b a0 ba e6 e2 88 86 10 fa 0b 27 bf c5 2e 31 1a 47
b9 ca fb 60 9d e4 f6 a1 76 0d 6c f7 64 4b 5f 32 6d 10

K_2m (16 bytes)
b7 48 6a 94 a3 6c f6 9e 67 3f c4 57 55 ee 6b 95

info for IV_2m =
[
  10,
  h'B0DC6C1BA0BAE6E2888610FA0B27BFC52E311A47B9CAFB609DE4F6A1760D6CF7',
  "IV_2m",
  13
]

info for IV_2m (CBOR-encoded) (43 bytes)
84 0a 58 20 b0 dc 6c 1b a0 ba e6 e2 88 86 10 fa 0b 27 bf c5 2e 31 1a 47
b9 ca fb 60 9d e4 f6 a1 76 0d 6c f7 65 49 56 5f 32 6d 0d

IV_2m (13 bytes)
c5 b7 17 0e 65 d5 4f 1a e0 5d 10 af 56

MAC_2 (8 bytes)
cf 99 99 ae 75 9e c0 d8

M_2 =
[
  "Signature1",
  h'A11822822E48FC79990F2431A3F5',
  h'5820B0DC6C1BA0BAE6E2888610FA0B27BFC52E311A47B9CAFB609DE4F6A1760D6CF
  7586E47624DC9CDC6824B2A4C52E95EC9D6B0534B71C2B49E4BF9031500CEE6869979
  C297BB5A8B381E98DB714108415E5C50DB78974C271579B01633A3EF6271BE5C225EB
  28F9CF6180B5A6AF31E80209A085CFBF95F3FDCF9B18B693D6C0E0D0FFB8E3F9A32A5
  0859ECD0BFCFF2C218',
  h'CF9999AE759EC0D8'
]

M_2 (184 bytes)
84 6a 53 69 67 6e 61 74 75 72 65 31 4e a1 18 22 82 2e 48 fc 79 99 0f 24
31 a3 f5 58 92 58 20 b0 dc 6c 1b a0 ba e6 e2 88 86 10 fa 0b 27 bf c5 2e
31 1a 47 b9 ca fb 60 9d e4 f6 a1 76 0d 6c f7 58 6e 47 62 4d c9 cd c6 82
4b 2a 4c 52 e9 5e c9 d6 b0 53 4b 71 c2 b4 9e 4b f9 03 15 00 ce e6 86 99
79 c2 97 bb 5a 8b 38 1e 98 db 71 41 08 41 5e 5c 50 db 78 97 4c 27 15 79
b0 16 33 a3 ef 62 71 be 5c 22 5e b2 8f 9c f6 18 0b 5a 6a f3 1e 80 20 9a
08 5c fb f9 5f 3f dc f9 b1 8b 69 3d 6c 0e 0d 0f fb 8e 3f 9a 32 a5 08 59
ec d0 bf cf f2 c2 18 48 cf 99 99 ae 75 9e c0 d8

Signature_or_MAC_2 (64 bytes)
45 47 81 ec ef eb b4 83 e6 90 83 9d 57 83 8d fe 24 a8 cf 3f 66 42 8a a0
16 20 4a 22 61 84 4a f8 4f 98 b8 c6 83 4f 38 7f dd 60 6a 29 41 3a dd e3
a2 07 74 02 13 74 01 19 6f 6a 50 24 06 6f ac 0e

P_2e (CBOR Sequence) (80 bytes)
a1 18 22 82 2e 48 fc 79 99 0f 24 31 a3 f5 58 40 45 47 81 ec ef eb b4 83
e6 90 83 9d 57 83 8d fe 24 a8 cf 3f 66 42 8a a0 16 20 4a 22 61 84 4a f8
4f 98 b8 c6 83 4f 38 7f dd 60 6a 29 41 3a dd e3 a2 07 74 02 13 74 01 19
6f 6a 50 24 06 6f ac 0e

info for K_2e =
[
  10,
  h'B0DC6C1BA0BAE6E2888610FA0B27BFC52E311A47B9CAFB609DE4F6A1760D6CF7',
  "K_2e",
  80
]

info for K_2e (CBOR-encoded) (43 bytes)
84 0a 58 20 b0 dc 6c 1b a0 ba e6 e2 88 86 10 fa 0b 27 bf c5 2e 31 1a 47
b9 ca fb 60 9d e4 f6 a1 76 0d 6c f7 64 4b 5f 32 65 18 50

K_2e (80 bytes)
38 cd 1a 83 89 6d 43 af 3d e8 39 35 27 42 0d ac 7d 7a 76 96 7e 85 74 58
26 bb 39 e1 76 21 8d 7e 5f e7 97 60 14 c9 ed ba c0 58 ee 18 cd 57 71 80
a4 4d de 0b 83 00 fe 8e 09 66 9a 34 d6 3e 3a e6 10 12 26 ab f8 5c eb 28
05 dc 00 13 d1 78 2a 20

CIPHERTEXT_2 (80 bytes)
99 d5 38 01 a7 25 bf d6 a4 e7 1d 04 84 b7 55 ec 38 3d f7 7a 91 6e c0 db
c0 2b ba 7c 21 a2 00 80 7b 4f 58 5f 72 8b 67 1a d6 78 a4 3a ac d3 3b 78
eb d5 66 cd 00 4f c6 f1 d4 06 f0 1d 97 04 e7 05 b2 15 52 a9 eb 28 ea 31
6a b6 50 37 d7 17 86 2e

message_2 =
(
 data_2,
 h'99d53801a725bfd6a4e71d0484b755ec383df77a916ec0dbc02bba7c21a200807b4f
585f728b671ad678a43aacd33b78ebd566cd004fc6f1d406f01d9704e705b21552a9eb
28ea316ab65037d717862e'
)

message_2 (CBOR Sequence) (117 bytes)
58 20 71 a3 d5 99 c2 1d a1 89 02 a1 ae a8 10 b2 b6 38 2c cd 8d 5f 9b f0
19 52 81 75 4c 5e bc af 30 1e 13 58 50 99 d5 38 01 a7 25 bf d6 a4 e7 1d
04 84 b7 55 ec 38 3d f7 7a 91 6e c0 db c0 2b ba 7c 21 a2 00 80 7b 4f 58
5f 72 8b 67 1a d6 78 a4 3a ac d3 3b 78 eb d5 66 cd 00 4f c6 f1 d4 06 f0
1d 97 04 e7 05 b2 15 52 a9 eb 28 ea 31 6a b6 50 37 d7 17 86 2e

SK_I (Initiator's private authentication key) (32 bytes)
2f fc e7 a0 b2 b8 25 d3 97 d0 cb 54 f7 46 e3 da 3f 27 59 6e e0 6b 53 71
48 1d c0 e0 12 bc 34 d7

PRK_4x3m (32 bytes)
ec 62 92 a0 67 f1 37 fc 7f 59 62 9d 22 6f bf c4 e0 68 89 49 f6 62 a9 7f
d8 2f be b7 99 71 39 4a

data_3 (CBOR Sequence) (1 bytes)
13

Input to calculate TH_3 (CBOR Sequence) (117 bytes)
58 20 b0 dc 6c 1b a0 ba e6 e2 88 86 10 fa 0b 27 bf c5 2e 31 1a 47 b9 ca
fb 60 9d e4 f6 a1 76 0d 6c f7 58 50 99 d5 38 01 a7 25 bf d6 a4 e7 1d 04
84 b7 55 ec 38 3d f7 7a 91 6e c0 db c0 2b ba 7c 21 a2 00 80 7b 4f 58 5f
72 8b 67 1a d6 78 a4 3a ac d3 3b 78 eb d5 66 cd 00 4f c6 f1 d4 06 f0 1d
97 04 e7 05 b2 15 52 a9 eb 28 ea 31 6a b6 50 37 d7 17 86 2e 13

TH_3 (32 bytes)
a2 39 a6 27 ad a3 80 2d b8 da e5 1e c3 92 bf eb 92 6d 39 3e f6 ee e4 dd
b3 2e 4a 27 ce 93 58 da

Initiator's subject name (text string)
""

X509_I (101 bytes)
fa 34 b2 2a 9c a4 a1 e1 29 24 ea e1 d1 76 60 88 09 84 49 cb 84 8f fc 79
5f 88 af c4 9c be 8a fd d1 ba 00 9f 21 67 5e 8f 6c 77 a4 a2 c3 01 95 60
1f 6f 0a 08 52 97 8b d4 3d 28 20 7d 44 48 65 02 ff 7b dd a6 32 c7 88 37
00 16 b8 96 5b db 20 74 bf f8 2e 5a 20 e0 9b ec 21 f8 40 6e 86 44 2b 87
ec 3f f2 45 b7

CRED_I (103 bytes)
58 65 fa 34 b2 2a 9c a4 a1 e1 29 24 ea e1 d1 76 60 88 09 84 49 cb 84 8f
fc 79 5f 88 af c4 9c be 8a fd d1 ba 00 9f 21 67 5e 8f 6c 77 a4 a2 c3 01
95 60 1f 6f 0a 08 52 97 8b d4 3d 28 20 7d 44 48 65 02 ff 7b dd a6 32 c7
88 37 00 16 b8 96 5b db 20 74 bf f8 2e 5a 20 e0 9b ec 21 f8 40 6e 86 44
2b 87 ec 3f f2 45 b7

ID_CRED_I =
{
  34: [-15, h'FC79990F2431A3F5']
}

ID_CRED_I (14 bytes)
a1 18 22 82 2e 48 5b 78 69 88 43 9e bc f2

AD_3 (0 bytes)

P_3m (0 bytes)

A_3m (CBOR-encoded) (164 bytes)
83 68 45 6e 63 72 79 70 74 30 4e a1 18 22 82 2e 48 5b 78 69 88 43 9e bc
f2 58 89 58 20 a2 39 a6 27 ad a3 80 2d b8 da e5 1e c3 92 bf eb 92 6d 39
3e f6 ee e4 dd b3 2e 4a 27 ce 93 58 da 58 65 fa 34 b2 2a 9c a4 a1 e1 29
24 ea e1 d1 76 60 88 09 84 49 cb 84 8f fc 79 5f 88 af c4 9c be 8a fd d1
ba 00 9f 21 67 5e 8f 6c 77 a4 a2 c3 01 95 60 1f 6f 0a 08 52 97 8b d4 3d
28 20 7d 44 48 65 02 ff 7b dd a6 32 c7 88 37 00 16 b8 96 5b db 20 74 bf
f8 2e 5a 20 e0 9b ec 21 f8 40 6e 86 44 2b 87 ec 3f f2 45 b7

info for K_3m =
[
  10,
  h'A239A627ADA3802DB8DAE51EC392BFEB926D393EF6EEE4DDB32E4A27CE9358DA',
  "K_3m",
  16
]

info for K_3m (CBOR-encoded) (42 bytes)
84 0a 58 20 a2 39 a6 27 ad a3 80 2d b8 da e5 1e c3 92 bf eb 92 6d 39 3e
f6 ee e4 dd b3 2e 4a 27 ce 93 58 da 64 4b 5f 33 6d 10

K_3m (16 bytes)
3d bb f0 d6 01 03 26 e8 27 3f c6 c6 c3 b0 de cd

info for IV_3m =
[
  10,
  h'A239A627ADA3802DB8DAE51EC392BFEB926D393EF6EEE4DDB32E4A27CE9358DA',
  "IV_3m",
  13
]

info for IV_3m (CBOR-encoded) (43 bytes)
84 0a 58 20 a2 39 a6 27 ad a3 80 2d b8 da e5 1e c3 92 bf eb 92 6d 39 3e
f6 ee e4 dd b3 2e 4a 27 ce 93 58 da 65 49 56 5f 33 6d 0d

IV_3m (13 bytes)
10 b6 f4 41 4a 2c 91 3c cd a1 96 42 e3

MAC_3 (8 bytes)
5e ef b8 85 98 3c 22 d9

M_3 =
[
  "Signature1",
  h'A11822822E485B786988439EBCF2',
  h'5820A239A627ADA3802DB8DAE51EC392BFEB926D393EF6EEE4DDB32E4A27CE9358D
  A5865FA34B22A9CA4A1E12924EAE1D1766088098449CB848FFC795F88AFC49CBE8AFD
  D1BA009F21675E8F6C77A4A2C30195601F6F0A0852978BD43D28207D44486502FF7BD
  DA632C788370016B8965BDB2074BFF82E5A20E09BEC21F8406E86442B87EC3FF245
  B7',
  h'5EEFB885983C22D9']

M_3 (175 bytes)
84 6a 53 69 67 6e 61 74 75 72 65 31 4e a1 18 22 82 2e 48 5b 78 69 88 43
9e bc f2 58 89 58 20 a2 39 a6 27 ad a3 80 2d b8 da e5 1e c3 92 bf eb 92
6d 39 3e f6 ee e4 dd b3 2e 4a 27 ce 93 58 da 58 65 fa 34 b2 2a 9c a4 a1
e1 29 24 ea e1 d1 76 60 88 09 84 49 cb 84 8f fc 79 5f 88 af c4 9c be 8a
fd d1 ba 00 9f 21 67 5e 8f 6c 77 a4 a2 c3 01 95 60 1f 6f 0a 08 52 97 8b
d4 3d 28 20 7d 44 48 65 02 ff 7b dd a6 32 c7 88 37 00 16 b8 96 5b db 20
74 bf f8 2e 5a 20 e0 9b ec 21 f8 40 6e 86 44 2b 87 ec 3f f2 45 b7 48 5e
ef b8 85 98 3c 22 d9

Signature_or_MAC_3 (64 bytes)
b3 31 76 33 fa eb c7 f4 24 9c f3 ab 95 96 fd ae 2b eb c8 e7 27 5d 39 9f
42 00 04 f3 76 7b 88 d6 0f fe 37 dc f3 90 a0 00 d8 5a b0 ad b0 d7 24 e3
a5 7c 4d fe 24 14 a4 1e 79 78 91 b9 55 35 89 06

P_3ae (CBOR Sequence) (80 bytes)
a1 18 22 82 2e 48 5b 78 69 88 43 9e bc f2 58 40 b3 31 76 33 fa eb c7 f4
24 9c f3 ab 95 96 fd ae 2b eb c8 e7 27 5d 39 9f 42 00 04 f3 76 7b 88 d6
0f fe 37 dc f3 90 a0 00 d8 5a b0 ad b0 d7 24 e3 a5 7c 4d fe 24 14 a4 1e
79 78 91 b9 55 35 89 06

A_3ae (CBOR-encoded) (45 bytes)
83 68 45 6e 63 72 79 70 74 30 40 58 20 a2 39 a6 27 ad a3 80 2d b8 da e5
1e c3 92 bf eb 92 6d 39 3e f6 ee e4 dd b3 2e 4a 27 ce 93 58 da

info for K_3ae =
[
  10,
  h'A239A627ADA3802DB8DAE51EC392BFEB926D393EF6EEE4DDB32E4A27CE9358DA',
  "K_3ae",
  16
]

info for K_3ae (CBOR-encoded) (43 bytes)
84 0a 58 20 a2 39 a6 27 ad a3 80 2d b8 da e5 1e c3 92 bf eb 92 6d 39 3e
f6 ee e4 dd b3 2e 4a 27 ce 93 58 da 65 4b 5f 33 61 65 10

K_3ae (16 bytes)
58 b5 2f 94 5b 30 9d 85 4c a7 36 cd 06 a9 62 95

info for IV_3ae =
[
  10,
  h'A239A627ADA3802DB8DAE51EC392BFEB926D393EF6EEE4DDB32E4A27CE9358DA',
  "IV_3ae",
  13
]

info for IV_3ae (CBOR-encoded) (44 bytes)
84 0a 58 20 a2 39 a6 27 ad a3 80 2d b8 da e5 1e c3 92 bf eb 92 6d 39 3e
f6 ee e4 dd b3 2e 4a 27 ce 93 58 da 66 49 56 5f 33 61 65 0d

IV_3ae (13 bytes)
cf a9 a5 85 58 10 d6 dc e9 74 3c 3b c3

CIPHERTEXT_3 (88 bytes)
2d 88 ff 86 da 47 48 2c 0d fa 55 9a c8 24 a4 a7 83 d8 70 c9 db a4 78 05
e8 aa fb ad 69 74 c4 96 46 58 65 03 fa 9b bf 3e 00 01 2c 03 7e af 56 e4
5e 30 19 20 83 9b 81 3a 53 f6 d4 c5 57 48 0f 6c 79 7d 5b 76 f0 e4 62 f5
f5 7a 3d b6 d2 b5 0c 32 31 9f 34 0f 4a c5 af 9a

message_3 =
(
  h'13',
  h''
)

message_3 (CBOR Sequence) (91 bytes)
13 58 58 2d 88 ff 86 da 47 48 2c 0d fa 55 9a c8 24 a4 a7 83 d8 70 c9 db
a4 78 05 e8 aa fb ad 69 74 c4 96 46 58 65 03 fa 9b bf 3e 00 01 2c 03 7e
af 56 e4 5e 30 19 20 83 9b 81 3a 53 f6 d4 c5 57 48 0f 6c 79 7d 5b 76 f0
e4 62 f5 f5 7a 3d b6 d2 b5 0c 32 31 9f 34 0f 4a c5 af 9a

B.2. Test Vectors for EDHOC Authenticated with Static Diffie-Hellman Keys

EDHOC with static Diffie-Hellman keys is used.¶

method (Static DH Based Authentication)
3

CoAP is used as transport and the Initiator acts as CoAP client:¶

corr (the Initiator can correlate message_1 and message_2)
1

From there, METHOD_CORR has the following value:¶

METHOD_CORR (4 * method + corr) (int)
13

No unprotected opaque auxiliary data is sent in the message exchanges.¶

The list of supported cipher suites of the Initiator in order of preference is the following:¶

Supported Cipher Suites (4 bytes)
00 01 02 03

The cipher suite selected by the Initiator is the most preferred:¶

Selected Cipher Suite (int)
0

The mandatory-to-implement cipher suite 0 is supported by both the Initiator and the Responder, see Section 7.3.¶

X (Initiator's ephemeral private key) (32 bytes)
ae 11 a0 db 86 3c 02 27 e5 39 92 fe b8 f5 92 4c 50 d0 a7 ba 6e ea b4 ad
1f f2 45 72 f4 f5 7c fa

G_X (Initiator's ephemeral public key) (32 bytes)
8d 3e f5 6d 1b 75 0a 43 51 d6 8a c2 50 a0 e8 83 79 0e fc 80 a5 38 a4 44
ee 9e 2b 57 e2 44 1a 7c

Connection identifier chosen by Initiator (1 bytes)
16

C_I (1 byte)
21

AD_1 (0 bytes)

SUITES_I (int)
0

message_1 =
(
  13,
  0,
  h'8D3EF56D1B750A4351D68AC250A0E883790EFC80A538A444EE9E2B57E2441A7C',
  -2
)

message_1 (CBOR Sequence) (37 bytes)
0d 00 58 20 8d 3e f5 6d 1b 75 0a 43 51 d6 8a c2 50 a0 e8 83 79 0e fc 80
a5 38 a4 44 ee 9e 2b 57 e2 44 1a 7c 21

Y (Responder's ephemeral private key) (32 bytes)
c6 46 cd dc 58 12 6e 18 10 5f 01 ce 35 05 6e 5e bc 35 f4 d4 cc 51 07 49
a3 a5 e0 69 c1 16 16 9a

G_Y (Responder's ephemeral public key) (32 bytes)
52 fb a0 bd c8 d9 53 dd 86 ce 1a b2 fd 7c 05 a4 65 8c 7c 30 af db fc 33
01 04 70 69 45 1b af 35

G_XY (ECDH shared secret) (32 bytes)
de fc 2f 35 69 10 9b 3d 1f a4 a7 3d c5 e2 fe b9 e1 15 0d 90 c2 5e e2 f0
66 c2 d8 85 f4 f8 ac 4e

salt (0 bytes)

PRK_2e (32 bytes)
93 9f cb 05 6d 2e 41 4f 1b ec 61 04 61 99 c2 c7 63 d2 7f 0c 3d 15 fa 16
71 fa 13 4e 0d c5 a0 4d

SK_R (Responders's private authentication key) (32 bytes)
bb 50 1a ac 67 b9 a9 5f 97 e0 ed ed 6b 82 a6 62 93 4f bb fc 7a d1 b7 4c
1f ca d6 6a 07 94 22 d0

R (Responder's private authentication key) (32 bytes)
bb 50 1a ac 67 b9 a9 5f 97 e0 ed ed 6b 82 a6 62 93 4f bb fc 7a d1 b7 4c
1f ca d6 6a 07 94 22 d0

G_R (Responder's public authentication key) (32 bytes)
a3 ff 26 35 95 be b3 77 d1 a0 ce 1d 04 da d2 d4 09 66 ac 6b cb 62 20 51
b8 46 59 18 4d 5d 9a 32

G_RX (ECDH shared secret) (32 bytes)
21 c7 ef f4 fb 69 fa 4b 67 97 d0 58 84 31 5d 84 11 a3 fd a5 4f 6d ad a6
1d 4f cd 85 e7 90 66 68

PRK_3e2m (32 bytes)
75 07 7c 69 1e 35 01 2d 48 bc 24 c8 4f 2b ab 89 f5 2f ac 03 fe dd 81 3e
43 8c 93 b1 0b 39 93 07

Connection identifier chosen by Responder (1 byte)
20

C_R (1 byte)
08

data_2 =
(
  h'52FBA0BDC8D953DD86CE1AB2FD7C05A4658C7C30AFDBFC3301047069451BAF35',
  08
)

data_2 (CBOR Sequence) (35 bytes)
58 20 52 fb a0 bd c8 d9 53 dd 86 ce 1a b2 fd 7c 05 a4 65 8c 7c 30 af db
fc 33 01 04 70 69 45 1b af 35 08

Input to calculate TH_2 (CBOR Sequence) (72 bytes)
0d 00 58 20 8d 3e f5 6d 1b 75 0a 43 51 d6 8a c2 50 a0 e8 83 79 0e fc 80
a5 38 a4 44 ee 9e 2b 57 e2 44 1a 7c 21 58 20 52 fb a0 bd c8 d9 53 dd 86
ce 1a b2 fd 7c 05 a4 65 8c 7c 30 af db fc 33 01 04 70 69 45 1b af 35 08

TH_2 (32 bytes)
6a 28 78 e8 4b 2c c0 21 cc 1a eb a2 96 52 53 ef 42 f7 fa 30 0c af 9c 49
1a 52 e6 83 6a 25 64 ff

Responders's subject name (text string)
""

ID_CRED_R =
{
  4: h'07'
}

ID_CRED_R (4 bytes)
a1 04 41 07

{
  1: 1,
  -1: 4,
  -2: h'A3FF263595BEB377D1A0CE1D04DAD2D40966AC6BCB622051B84659184D5D9A32',
  "subject name": ""
}

CRED_R (54 bytes)
a4 01 01 20 04 21 58 20 a3 ff 26 35 95 be b3 77 d1 a0 ce 1d 04 da d2 d4
09 66 ac 6b cb 62 20 51 b8 46 59 18 4d 5d 9a 32 6c 73 75 62 6a 65 63 74
20 6e 61 6d 65 60

AD_2  (0 bytes)

P_2m (0 bytes)

A_2m =
[
  "Encrypt0",
  h'A1044107',
  h'58206A2878E84B2CC021CC1AEBA2965253EF42F7FA300CAF9C491A52E6836A2564FFA401012004215820A3FF263595BEB377D1A0CE1D04DAD2D40966AC6BCB622051B84659184D5D9A326C7375626A656374206E616D6560'
]

A_2m (CBOR-encoded) (105 bytes)
83 68 45 6e 63 72 79 70 74 30 44 a1 04 41 07 58 58 58 20 6a 28 78 e8 4b
2c c0 21 cc 1a eb a2 96 52 53 ef 42 f7 fa 30 0c af 9c 49 1a 52 e6 83 6a
25 64 ff a4 01 01 20 04 21 58 20 a3 ff 26 35 95 be b3 77 d1 a0 ce 1d 04
da d2 d4 09 66 ac 6b cb 62 20 51 b8 46 59 18 4d 5d 9a 32 6c 73 75 62 6a
65 63 74 20 6e 61 6d 65 60

info for K_2m =
[
  10,
  h'6A2878E84B2CC021CC1AEBA2965253EF42F7FA300CAF9C491A52E6836A2564FF',
  "K_2m",
  16
]

info for K_2m (CBOR-encoded) (42 bytes)
84 0a 58 20 6a 28 78 e8 4b 2c c0 21 cc 1a eb a2 96 52 53 ef 42 f7 fa 30
0c af 9c 49 1a 52 e6 83 6a 25 64 ff 64 4b 5f 32 6d 10

K_2m (16 bytes)
81 2a 48 87 d1 90 ff ed 2b 10 0b a7 a5 c2 5e 67

info for IV_2m =
[
  10,
  h'6A2878E84B2CC021CC1AEBA2965253EF42F7FA300CAF9C491A52E6836A2564FF',
  "IV_2m",
  13
]

info for IV_2m (CBOR-encoded) (43 bytes)
84 0a 58 20 6a 28 78 e8 4b 2c c0 21 cc 1a eb a2 96 52 53 ef 42 f7 fa 30
0c af 9c 49 1a 52 e6 83 6a 25 64 ff 65 49 56 5f 32 6d 0d

IV_2m (13 bytes)
92 3c 0f 94 31 51 5b 69 21 30 49 2b 7f

MAC_2 (8 bytes)
64 21 0d 2e 18 b9 28 cd

Signature_or_MAC_2 (8 bytes)
64 21 0d 2e 18 b9 28 cd

P_2e (CBOR Sequence) (10 bytes)
30 48 64 21 0d 2e 18 b9 28 cd

info for K_2e =
[
  10,
  h'6A2878E84B2CC021CC1AEBA2965253EF42F7FA300CAF9C491A52E6836A2564FF',
  "K_2e",
  10
]

info for K_2e (CBOR-encoded) (42 bytes)
84 0a 58 20 6a 28 78 e8 4b 2c c0 21 cc 1a eb a2 96 52 53 ef 42 f7 fa 30
0c af 9c 49 1a 52 e6 83 6a 25 64 ff 64 4b 5f 32 65 0a

K_2e (10 bytes)
ec be 9a bd 5f 62 3a fc 65 26

CIPHERTEXT_2 (10 bytes)
dc f6 fe 9c 52 4c 22 45 4d eb

message_2 =
(
 data_2,
 h'DCF6FE9C524C22454DEB'
)

message_2 (CBOR Sequence) (46 bytes)
58 20 52 fb a0 bd c8 d9 53 dd 86 ce 1a b2 fd 7c 05 a4 65 8c 7c 30 af db
fc 33 01 04 70 69 45 1b af 35 08 4a dc f6 fe 9c 52 4c 22 45 4d eb

SK_I (Initiator's private authentication key) (32 bytes)
2b be a6 55 c2 33 71 c3 29 cf bd 3b 1f 02 c6 c0 62 03 38 37 b8 b5 90 99
a4 43 6f 66 60 81 b0 8e

G_I (Initiator's public authentication key) (32 bytes)
2c 44 0c c1 21 f8 d7 f2 4c 3b 0e 41 ae da fe 9c aa 4f 4e 7a bb 83 5e c3
0f 1d e8 8a db 96 ff 71

G_IY (ECDH shared secret) (32 bytes)
cb ff 8c d3 4a 81 df ec 4c b6 5d 9a 57 2e bd 09 64 45 0c 78 56 3d a4 98
1d 80 d3 6c 8b 1a 75 2a

PRK_4x3m (32 bytes)
ec 62 92 a0 67 f1 37 fc 7f 59 62 9d 22 6f bf c4 e0 68 89 49 f6 62 a9 7f
d8 2f be b7 99 71 39 4a

data_3 (CBOR Sequence) (1 bytes)
08

Input to calculate TH_3 (CBOR Sequence) (46 bytes)
58 20 6a 28 78 e8 4b 2c c0 21 cc 1a eb a2 96 52 53 ef 42 f7 fa 30 0c af
9c 49 1a 52 e6 83 6a 25 64 ff 4a dc f6 fe 9c 52 4c 22 45 4d eb 08

TH_3 (32 bytes)
51 dd 22 43 a6 b8 3f 13 16 dc 53 29 1a e1 91 cd 93 b4 44 cc e4 80 16 07
03 ee d9 c4 a1 bc b6 11

Initiator's subject name (text string)
""

ID_CRED_I =
{
  4: h'24'
}

ID_CRED_I (4 bytes)
a1 04 41 24

{
  1: 1,
  -1: 4,
   -2: h'2C440CC121F8D7F24C3B0E41AEDAFE9CAA4F4E7ABB835EC30F1DE88ADB96FF71',
   "subject name": ""
 }

CRED_I (54 bytes)
a4 01 01 20 04 21 58 20 2c 44 0c c1 21 f8 d7 f2 4c 3b 0e 41 ae da fe 9c
aa 4f 4e 7a bb 83 5e c3 0f 1d e8 8a db 96 ff 71 6c 73 75 62 6a 65 63 74
20 6e 61 6d 65 60

AD_3 (0 bytes)

P_3m (0 bytes)

A_3m (CBOR-encoded) (105 bytes)
83 68 45 6e 63 72 79 70 74 30 44 a1 04 41 24 58 58 58 20 51 dd 22 43 a6
b8 3f 13 16 dc 53 29 1a e1 91 cd 93 b4 44 cc e4 80 16 07 03 ee d9 c4 a1
bc b6 11 a4 01 01 20 04 21 58 20 2c 44 0c c1 21 f8 d7 f2 4c 3b 0e 41 ae
da fe 9c aa 4f 4e 7a bb 83 5e c3 0f 1d e8 8a db 96 ff 71 6c 73 75 62 6a
65 63 74 20 6e 61 6d 65 60

info for K_3m =
[
  10,
  h'51DD2243A6B83F1316DC53291AE191CD93B444CCE480160703EED9C4A1BCB611',
  "K_3m",
  16
]

info for K_3m (CBOR-encoded) (42 bytes)
84 0a 58 20 51 dd 22 43 a6 b8 3f 13 16 dc 53 29 1a e1 91 cd 93 b4 44 cc
e4 80 16 07 03 ee d9 c4 a1 bc b6 11 64 4b 5f 33 6d 10

K_3m (16 bytes)
84 85 31 8a a3 08 6f d5 86 7a 02 8e 99 e2 40 30

info for IV_3m =
[
  10,
  h'51DD2243A6B83F1316DC53291AE191CD93B444CCE480160703EED9C4A1BCB611',
  "IV_3m",
  13
]

info for IV_3m (CBOR-encoded) (43 bytes)
84 0a 58 20 51 dd 22 43 a6 b8 3f 13 16 dc 53 29 1a e1 91 cd 93 b4 44 cc
e4 80 16 07 03 ee d9 c4 a1 bc b6 11 65 49 56 5f 33 6d 0d

IV_3m (13 bytes)
1e 10 5b 88 50 0e d5 ae b0 5d 00 6b ea

MAC_3 (8 bytes)
1f b7 5a c1 aa d2 34 25

Signature_or_MAC_3 (8 bytes)
1f b7 5a c1 aa d2 34 25

P_3ae (CBOR Sequence) (10 bytes)
0c 48 1f b7 5a c1 aa d2 34 25

A_3ae (CBOR-encoded) (45 bytes)
83 68 45 6e 63 72 79 70 74 30 40 58 20 51 dd 22 43 a6 b8 3f 13 16 dc 53
29 1a e1 91 cd 93 b4 44 cc e4 80 16 07 03 ee d9 c4 a1 bc b6 11

info for K_3ae =
[
  10,
  h'51DD2243A6B83F1316DC53291AE191CD93B444CCE480160703EED9C4A1BCB611',
  "K_3ae",
  16
]

info for K_3ae (CBOR-encoded) (43 bytes)
84 0a 58 20 51 dd 22 43 a6 b8 3f 13 16 dc 53 29 1a e1 91 cd 93 b4 44 cc
e4 80 16 07 03 ee d9 c4 a1 bc b6 11 65 4b 5f 33 61 65 10

K_3ae (16 bytes)
bf 29 0b 7e e0 4b 86 5d e1 01 0a 81 1b 36 00 64

info for IV_3ae =
[
  10,
  h'51DD2243A6B83F1316DC53291AE191CD93B444CCE480160703EED9C4A1BCB611',
  "IV_3ae",
  13
]

info for IV_3ae (CBOR-encoded) (44 bytes)
84 0a 58 20 51 dd 22 43 a6 b8 3f 13 16 dc 53 29 1a e1 91 cd 93 b4 44 cc
e4 80 16 07 03 ee d9 c4 a1 bc b6 11 66 49 56 5f 33 61 65 0d

IV_3ae (13 bytes)
0e 74 45 0a fc ec e9 73 af 64 e9 4d 46

CIPHERTEXT_3 (18 bytes)
53 c3 99 19 99 a5 ff b8 69 21 e9 9b 60 7c 06 77 70 e0

message_3 =
(
  h'08',
  h'53C3991999A5FFB86921E99B607C067770E0'
)

message_3 (CBOR Sequence) (20 bytes)
08 52 53 c3 99 19 99 a5 ff b8 69 21 e9 9b 60 7c 06 77 70 e0