Internet DRAFT - draft-haiyangjiang-i2bgp
draft-haiyangjiang-i2bgp
Network Working Group H. Jiang, Ed.
Internet-Draft P. Cong
Intended status: Informational L. Wang
Expires: 21 May 2023 Y. Zhang
W. Wang
Beijing University of Posts and Telecommunications
17 November 2022
Desensitize Intra-domain Information for Inter-domain Routing
draft-haiyangjiang-i2bgp-01
Abstract
Border Gateway Protocol (BGP) is a routing protocol for autonomous
systems running on TCP. It is currently the only protocol capable of
handling multiple connections between unrelated routing domains, such
as the size of the Internet. BGP is built on the experience of EGP.
The main function of BGP system is to exchange network access
information with other BGP systems. However, it cannot fully
utilizethe complete information in the domain to achieve the optimal
decision. This document proposes I2BGP, which describes how to
obtain desensitization information in the domain to optimize routing
decisions.
Status of This Memo
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This Internet-Draft will expire on 21 May 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Requirements and Use Case Scenario . . . . . . . . . . . . . 3
3.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 3
3.1.1. Supporting Information Export . . . . . . . . . . . . 3
3.1.2. Privacy Protection Requirement . . . . . . . . . . . 4
3.2. Use Case Scenario . . . . . . . . . . . . . . . . . . . . 4
4. Overview of I2BGP . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Homomorphic Encryption . . . . . . . . . . . . . . . . . 5
4.2. DIT Overview . . . . . . . . . . . . . . . . . . . . . . 5
4.3. Delta Trap . . . . . . . . . . . . . . . . . . . . . . . 7
4.4. Enhanced DIT . . . . . . . . . . . . . . . . . . . . . . 7
5. Manageability Considerations . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
9. Normative References . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Border Gate way Protocol (BGP) early used to solve the problem of the
interconnection between a large number of Internet ASs (autonomous
systems). Compared with the traditional dual-IP dual-wire
technology, it is more efficient. At present, the BGP protocol is
widely deployed on the Internet, and there are many important
enhancements to improve BGP performance in terms of refifining
scheduling granularity, accelerating convergence time, anomalous
behavior detection and so on.
However, current BGP-like protocols follow the basic principle of
taking hops - the number of Autonomous Systems (AS) on a path - as
the metric for routing: the less hops, the higher the priority of the
path, such as [RFC4271]. Such strategy regards all domains as
indiscriminate blackbox and thus can not achieve the optimal inter-
domain routing decisions due to the lack of intra-domain information.
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This document proposes I2BGP which developed based on BGP-4. It use
a Desensitized Intra-domain information-aware Tactic (DIT) to assist
inter-domain routing decisions, which can be embedded in BGP or
applied independently as a control-plane strategy. DIT can make use
of intra-domain information while protecting data privacy at the same
time, thus solving the contradiction between data sharing and privacy
protection.
2. Conventions
DIT: The frame that the document proposed, which makes near-optimal
inter-domain routing decisions with desensitized intra-domain
information that the document proposed.
AS/ASes:Autonomous Systems in the internet.
I2BGP: The special protocol which based on BGP and owned the ability
that extract the message from intra-domain and make the optimal
decision.
DRT: It represents uppercase mathematical symbol of delta.
drt: It represents lower mathematical symbols of delta.
o: The article uses it for the same OR operation, mainly in the
formula of encryption and decryption.
o+: The article uses it for the XOR operation, mainly in the formula
of encryption and decryption.
3. Requirements and Use Case Scenario
This section describes some essential requirements for I2GBP and the
scenario about the problem hidden in BGP.
3.1. Requirements
3.1.1. Supporting Information Export
Data within a domain could be exported, mainly referring to the link
performance status, e.g., delay, bandwidth, packet loss rate, hops,
etc. The performance of an inter-domain transmission is jointly
determined by the link performance of all passed domains, then, for
different attributes, which can be summarized as bottleneck type
(bandwidth) and cumulative type (delay, packet loss rate, hops), the
calculation of combination will be different. In this document,
I2BGP takes the number of hops as a typical example that ought to be
calculated by addition.
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3.1.2. Privacy Protection Requirement
Private information of domains should not be deduced from the
exported information, because information like hops may involve
intra-domain topology, which requires that the information cannot be
directly disclosed to other ASes.
3.2. Use Case Scenario
BGP cannot use the information in the domain to make routing
decisions, which often makes the final routing decision not optimal.
Take the forwarding hops as an example, Figure 1 shows two paths
between server s and client c: Path A with 4 As hops (s -> a1 -> a2
-> a3 -> c ) and Path B with 2 As hops(s -> b -> c ). For client c,
Path B will be selected as actually routing path according the
principle of BGP, and Path A will be discarded. But in fact, there
are additional hops in each domain, shown as the numbers in Figure 1,
which makes path A the real better path.
+------+ +------+ +------+
-------------| 2 |-----| 3 |-----| 2 |--------------|
| +------+ +------+ +------+ |
| As a1 As a2 As a3 |
+---------+ +---------+
|Server s | |Cilent c |
+---------+ +---------+
| +------+ |
|----------------------- | 15 |---------------------------|
+------+
As b
Figure 1: Example of BGP-based inter-domain routing
4. Overview of I2BGP
This section describes the model of I2BGP and how it exports the
information from intra-domain without revealing data and make the
final route decision. The judgment attributes of traditional BGP
path selection do not include the impact of intra-domain performance.
The document introduces an additional attribute, Attr, for BGP to
accomplish data carrying and spreading.
Due to each domain is a confidential system with complete
independence and autonomy and BGP runs at border routers of each
domain and specifies the next hop when forwarding across domains
according to the RFC4271. In order to fetch messages from the
domain, I2BGP proposes the DIT technique. It masks the intra-domain
topology and abstract each domain into a characteristic topology
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graph with its border routers exclusively. Because there are direct
or indirect connections between all border routers (nodes) of a
domain, and we abstract these connections as edges between nodes.
After taking the information out of the domain, in order to prevent
the information in the domain from being leaked, DIT proposes a
random obfuscation technology to ensure data security, which can
ensure that information in the domain can be obtained while imitating
information security issues. Finally, we spread the retrieved
information to other domains through the new field Attr, and obtain
the optimal route by comparing this field.
4.1. Homomorphic Encryption
This document introduces homomorphic cryptography to export
information without revealing data, and to ensure the validity of the
final calculation results. Homomorphic Cryptography provide a
potential solution to the contradiction of information exportation
and privacy, it is a kind of cryptographic technique that performs
arithmetic operations on the encrypted data and yields a result
equivalent to the cyphertext result of some computation on the
unencrypted original data. Its principle can be explained as follow:
De(En(a)oEn(b)) = ao+b,
where En() is the encryption operation, De() is the decryption
operation, o and o+are correspond to the operations on the plaintext
and cyphertext domains, respectively. When o+ represents addition,
this encryption is an additive homomorphic encryption, and when o+
represents multiplication, this encryption is a multiplicative
homomorphic encryption. The encryption function that satisfifies
both additive homomorphism and multiplicative homomorphism properties
and can perform any times of additive and multiplicative operations
is called fully homomorphic encryption.
Homomorphic encryption algorithms usually have high computational
complexity. I2BGP select a algorithm which encrypt simple numbers
and satisfy homomorphic additivity to avoid this problem.
4.2. DIT Overview
Firstly, we mask the intra-domain topology and abstract each domain
into a characteristic topology graphwith its border routers
exclusively. Because of the reachability between routes within a
domain, there are direct or indirect connections between all border
routers (nodes) of a domain, and we abstract these connections as
edges between nodes.
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Assuming intra-domain information is directly embedded in BGP header
and transmitted to the neighbors. Then, during the route convergence
process, cumulative calculations (e.g., addition, min() or max())
over multiple domains can inherently protect the privacy of all
upstream domains data, i.e., mathematically speaking, on the basis of
c = a + b, it couldnot infer the values of a and b when only c is
known. This is one of the foundations for the privacy protection in
DIT. However, the inherent data privacy protection brought by
cumulative calculations is effective only after at least one such
operation has already been conducted. In other words, the cumulative
calculations can only achieve non-destination domain data protection.
For example, as shown in the Figure 2, for As 3, the value of As 1or
As 2 cannot be inferred from the cumulative summation sent from As 2.
However, As 2 is directly connected to the destination domain of the
route (As 1), the value of As 1 is directly exposed to As 2 due to
the lack of protection from cumulative calculation. That is, for the
destination domain of each route, information leakage risk still
exists, which is caused by directly connected neighbordomains, we
name it the Direct Connection issue.
To solve Direct Connection issue, we propose a basicmethod named
Random Number Confusion. In the path selection process, it is only
necessary to select the optimal pathby basic comparisons. Just like
giving random offsets to all nodes in the coordinate system will not
change the relative positions. Therefore, for target D, DIT adds a
random number to the data in the domain when initially spreading the
data to the adjacent domain, that is, D will export the data in the
domain, which will not affect the comparison of the final results.
After fetching the data, to carry the above intra-domain data, we add
a new filed, Attr, to the BGP packet header, although which is not
strictly required because we can also reuse existing fields, provided
the re-definition of the field function is approved. And the
quantifified value of the destination-based cumulative path
performance is embedded into this fifield and diffused to neighbor
domains with the route update message. Then the optimal route is
obtained by comparing.
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+------------+ +------------+ +------------+
| | | | | |
| As 1 |--------| As 2 |------| As 3 |
| | | | | |
+------------+ +------------+ +------------+
| |
| |
+------------+
| |
| As 4 |
| |
+------------+
Figure 2: Inter-domain information security scenarios
4.3. Delta Trap
While Random Number Confusion solves the destination direct
connection issue, there is still a trap of information leakage. It
can be drawed from a mathematical perspective. Suppose it is known
that x1 + x2 = y1 and x1 + x2 + x3 = y2. Even if x1 and x2 are
unknown, x3 can also be calculated by using the difference value drt
between y1 and y2, i.e., x3 = y2 - y1. As shown in the Figure 2, the
value of As 3 can be obtained using the aforementioned difference
value drt method by As 4. To solve the problem, the document
proposed Enhanced DIT.
4.4. Enhanced DIT
Delta Trap drt is triggered by one path has one more hop (itself)
than the other of same destination. From perspective of connection
topology, triangular structure is at risk of data leakage. Based on
this, the document design a private number comparison algorithm
leveraged by homomorphic encryption, which iscapable of comparing
paths in a triangle topology under guarantee of data security. The
comparison result could guide the logical removal of non-shortest
paths. It includes classic homomorphic encryption algorithm Paillier
and a private number comparison algorithm.
Paillier algorithm randomly selecting two large prime to generate
key. Then it can process the corresponding value by encrypting and
decrypting. Based on Paillier, the private number comparison which
is used as an independent module of DIT is patch the leakage caused
by Delta Trap drt.
Private Number Comparison firstly detectes the triangle structures
from the network topology. Then it will compare paths, comparison
and path selection would be accomplished by communicating with each
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other As. As shown in Figure 3, suppose A, B and C, each of which is
responsible for local values, N_A, N_B, N_C , respectively. First, A
sends encrypted N_A by private key of A, En^A(N_A), to B and C.
After receiving the message from A, B sends En^A(N_A)oEn^A(N_B) to C,
where o represents homomorphic addition calculation, which means
En(x)oEn(y) = En(x+y). After receiving the message from A and B, C
sends En^A(N_A + N_B)oEn^A(drt_C ) and En^A(N_A)oEn_A(N_C + drt_C )
to A in the specifified order. After receiving the message from C, A
decrypts and subtracts the two values,De^A (En_A(N_A + N_B + drt_C ))
- De^A(En^A(N_A + N_C + drt_C )), and get the signed delta value
DRT_C, which will be sent back to C. Finally, according to DRT_C, C
and A can determine the priority of the two paths, Path_(C->A) and
Path_(C->B->A).
+---------------------+
| |
|----------------| a=En(Na) |-------------|
| | DRTc=De(c1)-De(c2) | |
(1)a| | | | (1)a
| +---------NA----------+ | (3)c1,c2
| | (4)DRTc
| |
| |
| |
+---------------------+ +----------------------+
| | | |
| b=aoEn(Nb) |-----------------------------| c1=aoEn(Nc+drtc) |
| | (2)b | c2=boEn(drtc) |
| | | |
+---------NB----------+ +----------NC----------+
Figure 3: Comparison example: communication and computation
process of homomorphic encryption-based private number comparison
5. Manageability Considerations
I2BGP introduces a new field Attr based on BGP to obtain the message
of link in domain. The transmission and use of this field is similar
to med and local-pref in the BGP header.
6. IANA Considerations
There are no IANA considerations related to this document.
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7. Security Considerations
Due to I2BGP is based on BGP, I2BGP faces the following security
risks like BGP:
1.TCP/IP protocol vulnerabilities: I2BGP runs on top of TCP, and no
special encryption and authentication mechanisms are designed. All
attacks against TCP/IP vulnerabilities can cause harm to the
operation of I2BGP.
2.Communication mechanism loopholes: There are many loopholes in the
operation mechanism of I2BGP itself. If an external attacker
maliciously modifies the message content and the order of sending
messages, the I2BGP peers will not be able to exchange routing
information normally through BGP.
3.Information verification vulnerability: I2BGP does not have a
corresponding mechanism to ensure the authenticity of router routing
information. If a router announces false, wrong or suboptimal
routing information to its neighbors, the existing mechanism cannot
identify it.
8. Acknowledgements
Acknowledgements to Yuchao Zhang, Peizhuang Cong, Haiyang Jiang, Lei
Wang, Wendong Wang, Xiangyang Gong, Dan Li for their review and
contributions.
9. Normative References
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
Authors' Addresses
Haiyang Jiang (editor)
Beijing University of Posts and Telecommunications
China
Email: jianghaiyang@bupt.edu.cn
Peizhuang Cong
Beijing University of Posts and Telecommunications
Email: congpeizhuang@bupt.edu.cn
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Lei Wang
Beijing University of Posts and Telecommunications
Email: lwang@bupt.edu.cn
Yuchao Zhang
Beijing University of Posts and Telecommunications
Email: yczhang@bupt.edu.cn
Wendong Wang
Beijing University of Posts and Telecommunications
Email: wdwang@bupt.edu.cn
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