Internet DRAFT - draft-nsri-avtcore-aria-srtp
draft-nsri-avtcore-aria-srtp
AVTCore W. Kim
Internet-Draft J. Lee
Intended status: Standards Track D. Kim
Expires: August 25, 2012 J. Park
D. Kwon
NSRI
February 22, 2012
The ARIA Algorithm and Its Use with the Secure Real-time Transport
Protocol(SRTP)
draft-nsri-avtcore-aria-srtp-00
Abstract
This document describes the use of the ARIA block cipher algorithm
within the Secure Real-time Transport Protocol (SRTP) for providing
confidentiality for the Real-time Transport Protocol (RTP) traffic
and for the control traffic for RTP, the Real-time Transport Control
Protocol (RTCP). It details three modes of operation (CTR, CCM, GCM)
and a SRTP Key Derivation Function for ARIA.
Status of This Memo
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This Internet-Draft will expire on August 25, 2012.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. ARIA . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Cryptographic Transforms . . . . . . . . . . . . . . . . . . . 3
2.1. ARIA-CTR . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. ARIA-CCM and ARIA-GCM . . . . . . . . . . . . . . . . . . . 4
3. ARIA-CTR PRF . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. Normative References . . . . . . . . . . . . . . . . . . . 7
6.2. Informative References . . . . . . . . . . . . . . . . . . 8
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1. Introduction
This document describes the use of the ARIA [RFC5794] block cipher
algorithm in the Secure Real-time Transport Protocol (SRTP) [RFC3711]
for providing confidentiality for the Real-time Transport Protocol
(RTP) [RFC3550] traffic and for the control traffic for RTP, the
Real-time Transport Control Protocol (RTCP) [RFC3550].
1.1. ARIA
ARIA is a general-purpose block cipher algorithm developed by Korean
cryptographers in 2003. It is an iterated block cipher with 128-,
192-, and 256-bit keys and encrypts 128-bit blocks in 12, 14, and 16
rounds, depending on the key size. It is secure and suitable for
most software and hardware implementations on 32-bit and 8-bit
processors. It was established as a Korean standard block cipher
algorithm in 2004 [ARIAKS] and has been widely used in Korea,
especially for government-to-public services. It was included in
PKCS #11 in 2007 [ARIAPKCS]. The algorithm specification and object
identifiers are described in [RFC5794].
1.2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. Cryptographic Transforms
Block ciphers ARIA and AES share common characteristics including
mode, key size, and block size. ARIA does not have any restrictions
for modes of operation that are used with this block cipher. We
define three modes of running ARIA within the SRTP protocol, (1) ARIA
in Counter Mode, (2) ARIA in Counter with CBC-MAC (CCM) Mode and (3)
ARIA in Galois/Counter Mode (GCM).
2.1. ARIA-CTR
Section 4.1.1 of [RFC3711] defines AES-128 counter mode encryption,
which it refers to as "AES_CM". Section 2 of [RFC6188] defines
"AES_192_CM" and "AES_256_CM" in SRTP. ARIA counter modes are
defined in a similar manner, and are denoted by ARIA_128_CTR,
ARIA_192_CTR and ARIA_256_CTR respectively, according to the key
lengths. The plaintext inputs to the block cipher are formed as in
AES-CTR(AES_CM, AES_192_CM, AES_256_CM) and the block cipher outputs
are processed as in AES-CTR. The only difference in the processing
is that ARIA-CTR uses ARIA as the underlying encryption primitive.
When ARIA-CTR is used, it MUST be used only in conjunction with an
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authentication function.
The ARIA-CTR ciphersuites with HMAC-SHA1 as an authentication
function are listed below. For each ciphersuites, the authentication
key size is 20 octets.
Name Enc. Key Size Auth. Tag Size
=========================================================
ARIA_128_CTR_HMAC_SHA1_80 16 octets 10 octets
ARIA_128_CTR_HMAC_SHA1_32 16 octets 4 octets
ARIA_192_CTR_HMAC_SHA1_80 24 octets 10 octets
ARIA_192_CTR_HMAC_SHA1_32 24 octets 4 octets
ARIA_256_CTR_HMAC_SHA1_80 32 octets 10 octets
ARIA_256_CTR_HMAC_SHA1_32 32 octets 4 octets
Figure 1: ARIA-CTR algorithms for SRTP/SRTCP
2.2. ARIA-CCM and ARIA-GCM
CCM(Counter with CBC-MAC) [RFC3610] and GCM(Galois Counter Mode)
[GCM] are AEAD(authenticated encryption with associated data) block
cipher modes. ARIA-CCM and ARIA-GCM are defined similarly as AES-CCM
and AES-GCM.
The internet draft [I-D.mcgrew-tls-aes-ccm] describes the use of AES-
GCM and AES-CCM with SRTP. The use of ARIA-CCM and ARIA-GCM with
SRTP is defined the same as that of AES-CCM and AES-GCM.
The following members of the ARIA-GCM family may be used with SRTP/
SRTCP:
Name Key Size Auth. Tag Size
====================================================
AEAD_ARIA_128_GCM 16 octets 16 octets
AEAD_ARIA_256_GCM 32 octets 16 octets
AEAD_ARIA_128_GCM_8 16 octets 8 octets
AEAD_ARIA_256_GCM_8 32 octets 8 octets
AEAD_ARIA_128_GCM_12 16 octets 12 octets
AEAD_ARIA_256_GCM_12 32 octets 12 octets
Figure 2: ARIA-GCM algorithms for SRTP/SRTCP
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The following members of the ARIA-CCM family may be used with SRTP/
SRTCP:
Name Key Size Auth. Tag Size
====================================================
AEAD_ARIA_128_CCM 16 octets 16 octets
AEAD_ARIA_256_CCM 32 octets 16 octets
Figure 3: ARIA-CCM algorithms for SRTP/SRTCP
3. ARIA-CTR PRF
Section 4.3.3 of [RFC3711] defines the AES-128 counter mode key
derivation function, which it refers to as "AES-CM PRF". Section 3
of [RFC6188] defines the AES-192 counter mode key derivation function
and the AES-256 counter mode key derivation function, which it refers
to as "AES_192_CM_PRF" and "AES_256_CM_PRF" respectively. The ARIA-
CTR PRF is defined in a similar manner, but with each invocation of
AES replaced with an invocation of ARIA. According to the key
lengths of underlying encryption algorithm, ARIA-CTR PRFs are denoted
by "ARIA_128_CTR_PRF", "ARIA_192_CTR_PRF" and "ARIA_256_CTR_PRF".
The usage requirements of [RFC6188] regarding the AES-CM PRF apply to
the ARIA-CTR PRF as well. The PRFs for ARIA ciphersuites with SRTP
are defined by ARIA-CTR PRF of the equal key length with the
encryption algorithm.
4. Security Considerations
At the time of writing this document no security problem has been
found on ARIA (see [TSL]).
The security considerations in [RFC3610] [GCM] [RFC3711] [RFC6188]
[I-D.mcgrew-tls-aes-ccm] apply to this document as well.
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5. IANA Considerations
[RFC4568] defines SRTP "crypto suites". In order to allow SDP to
signal the use of the algorithms defined in this document, IANA is
requested to register the following crypto suites into the sub-
registry for SRTP crypto suites under the SRTP transport of the SDP
Security Descriptions:
srtp-crypto-suite-ext = "ARIA_128_CTR_HMAC_SHA1_80"/
"ARIA_128_CTR_HMAC_SHA1_32"/
"ARIA_192_CTR_HMAC_SHA1_80"/
"ARIA_192_CTR_HMAC_SHA1_32"/
"ARIA_256_CTR_HMAC_SHA1_80"/
"ARIA_256_CTR_HMAC_SHA1_32"/
"AEAD_ARIA_128_GCM" /
"AEAD_ARIA_256_GCM" /
"AEAD_ARIA_128_GCM_8" /
"AEAD_ARIA_256_GCM_8" /
"AEAD_ARIA_128_GCM_12" /
"AEAD_ARIA_256_GCM_12" /
"AEAD_ARIA_128_CCM" /
"AEAD_ARIA_256_CCM" /
srtp-crypto-suite-ext
DTLS-SRTP[RFC5764] defines a DTLS-SRTP "SRTP Protection Profile". In
order to allow the use of the algorithms defined in this document in
DTLS-SRTP, IANA will also register the following SRTP Protection
Profiles:
SRTP_ARIA_128_CTR_HMAC_SHA1_80 = {TBD,TBD};
SRTP_ARIA_128_CTR_HMAC_SHA1_32 = {TBD,TBD};
SRTP_ARIA_192_CTR_HMAC_SHA1_80 = {TBD,TBD};
SRTP_ARIA_192_CTR_HMAC_SHA1_32 = {TBD,TBD};
SRTP_ARIA_256_CTR_HMAC_SHA1_80 = {TBD,TBD};
SRTP_ARIA_256_CTR_HMAC_SHA1_32 = {TBD,TBD};
SRTP_AEAD_ARIA_128_GCM = {TBD,TBD};
SRTP_AEAD_ARIA_256_GCM = {TBD,TBD};
SRTP_AEAD_ARIA_128_GCM_8 = {TBD,TBD};
SRTP_AEAD_ARIA_256_GCM_8 = {TBD,TBD};
SRTP_AEAD_ARIA_128_GCM_12 = {TBD,TBD};
SRTP_AEAD_ARIA_256_GCM_12 = {TBD,TBD};
SRTP_AEAD_ARIA_128_CCM = {TBD,TBD};
SRTP_AEAD_ARIA_256_CCM = {TBD,TBD};
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[RFC3830] and [RFC5748] define encryption algorithms and PRFs for the
SRTP policy in MIKEY. In order to allow the use of the algorithms
defined in this document in MIKEY, IANA is requested to allocate the
following numbers in the MIKEY sub-registries.
SRTP Enc. alg | Value
----------------------
NULL | 0
AES-CM | 1
AES-F8 | 2
SEED-CTR | 3
SEED-CCM | 4
SEED-GCM | 5
ARIA-128-CTR | 6 (NEW)
ARIA-128-CCM | 7 (NEW)
ARIA-128-GCM | 8 (NEW)
ARIA-128-GCM-8 | 9 (NEW)
ARIA-128-GCM-12| 10 (NEW)
Figure 4: Figure 1 from RFC 5748 (revised)
SRTP PRF | Value
---------------------
AES-CM | 0
SEED-CTR | 1
ARIA-128-CTR | 2 (NEW)
Figure 5: Figure 2 from RFC 5748 (revised)
6. References
6.1. Normative References
[GCM] Dworkin, M., "Recommendation for Block
Cipher Modes of Operation: Galois/Counter
Mode (GCM) and GMAC", NIST SP 800-38D,
November 2007.
[RFC2119] Bradner, S., "Key words for use in RFCs to
Indicate Requirement Levels", BCP 14,
RFC 2119, March 1997.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R.,
and V. Jacobson, "RTP: A Transport Protocol
for Real-Time Applications", STD 64,
RFC 3550, July 2003.
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[RFC3711] Baugher, M., McGrew, D., Naslund, M.,
Carrara, E., and K. Norrman, "The Secure
Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004.
[RFC3830] Arkko, J., Carrara, E., Lindholm, F.,
Naslund, M., and K. Norrman, "MIKEY:
Multimedia Internet KEYing", RFC 3830,
August 2004.
[RFC4568] Andreasen, F., Baugher, M., and D. Wing,
"Session Description Protocol (SDP)
Security Descriptions for Media Streams",
RFC 4568, July 2006.
[RFC5764] McGrew, D. and E. Rescorla, "Datagram
Transport Layer Security (DTLS) Extension
to Establish Keys for the Secure Real-time
Transport Protocol (SRTP)", RFC 5764,
May 2010.
[RFC6188] McGrew, D., "The Use of AES-192 and AES-256
in Secure RTP", RFC 6188, March 2011.
6.2. Informative References
[ARIAKS] Korean Agency for Technology and Standards,
"128 bit block encryption algorithm ARIA -
Part 1: General (in Korean)", KS X 1213-
1:2009, December 2009.
[ARIAPKCS] RSA Laboratories, "Additional PKCS #11
Mechanisms", PKCS #11 v2.20 Amendment 3
Revision 1, January 2007.
[I-D.mcgrew-tls-aes-ccm] McGrew, D. and D. Bailey, "AES-CCM Cipher
Suites for TLS",
draft-mcgrew-tls-aes-ccm-03 (work in
progress), February 2012.
[RFC3610] Whiting, D., Housley, R., and N. Ferguson,
"Counter with CBC-MAC (CCM)", RFC 3610,
September 2003.
[RFC5748] Yoon, S., Jeong, J., Kim, H., Jeong, H.,
and Y. Won, "IANA Registry Update for
Support of the SEED Cipher Algorithm in
Multimedia Internet KEYing (MIKEY)",
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RFC 5748, August 2010.
[RFC5794] Lee, J., Lee, J., Kim, J., Kwon, D., and C.
Kim, "A Description of the ARIA Encryption
Algorithm", RFC 5794, March 2010.
[TSL] Tang, X., Sun, B., Li, R., Li, C., and J.
Yin, "A meet-in-the-middle attack on
reduced-round ARIA", The Journal of Systems
and Software Vol.84(10), pp. 1685-1692,
October 2011.
Authors' Addresses
Woo-Hwan Kim
National Security Research Institute
P.O.Box 1, Yuseong
Daejeon 305-350
Korea
EMail: whkim5@ensec.re.kr
Jungkeun Lee
National Security Research Institute
P.O.Box 1, Yuseong
Daejeon 305-350
Korea
EMail: jklee@ensec.re.kr
Dong-Chan Kim
National Security Research Institute
P.O.Box 1, Yuseong
Daejeon 305-350
Korea
EMail: dongchan@ensec.re.kr
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Je-Hong Park
National Security Research Institute
P.O.Box 1, Yuseong
Daejeon 305-350
Korea
EMail: jhpark@ensec.re.kr
Daesung Kwon
National Security Research Institute
P.O.Box 1, Yuseong
Daejeon 305-350
Korea
EMail: ds_kwon@ensec.re.kr
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