HTTPsec Authentication Protocol

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Preamble

1. Introduction

1.1. Editorial Conventions

1.2. Terms

1.3. Identifiers

2. Summary

2.1. Authentication Model

2.2. Peer Identifiers

2.3. Protocol Operation

2.3.1. Initialization

2.3.2. Continuation

3. Protocol Messages

3.1. Initialization Messages

3.1.1. Initialization Request

3.1.2. Initialization Response

3.2. Continuation Messages

3.2.1. Continuation Request

3.2.2. Continuation Response

3.3. Challenge Messages

3.3.1. Challenge Response

3.4. Message Flow

4. Protocol Directives

4.1. id

4.2. dh

4.3. certificate

4.4. url

4.5. group

4.6. nonce

4.7. auth

4.8. token

4.9. signature

4.10. count

4.11. mac

4.12. digest

5. Other Headers

5.1. Content-Encoding

5.2. Cache-Control

5.3. Expires

6. Protocol Computations

6.1. Algorithms

6.1.1. Hash Algorithm

6.1.2. Public Key Algorithm

6.1.3. Encryption Scheme

6.1.4. Signature Scheme

6.1.5. Block Cipher

6.1.6. Block Cipher Mode

6.2. Header Canonicalization

6.3. Initialization Transcript

6.4. Continuation Request Transcript

6.5. Continuation Response Transcript

6.6. Shared Secret

6.7. Keys

6.7.1. MAC Keys

6.7.2. Cipher Keys

6.8. Message Body Ciphering

7. Message Validation

7.1. Initialization Request Validation

7.2. Initialization Response Validation

7.3. Continuation Request Validation

7.4. Continuation Response Validation

8. Cache Considerations

9. Security Considerations

10. References

11. Editor Address

6.7.2. Cipher Keys

The keys required for message body ciphering are computed as follows:

request-cipher-key  = H(H( shared-secret || "request cipher key"  ))

response-cipher-key = H(H( shared-secret || "response cipher key" ))

where the following apply:

String literals are ASCII without length or zero-termination.
shared-secret is computed according to the Shared Secret section.
H(H()) is the Hash Algorithm iteratively applied twice.