HTTPsec Authentication Protocol

7.2. Initialization Response Validation

A initialization response message MUST meet all the following conditions to be considered valid by the requester that receives it:

1. The header is well-formed according to the Initialization Response section.
2. The dh directive meets these conditions:
   • dh > 1
   • dh < p
   • dh ^ q MOD p = 1
   where p and q are from the Diffie-Hellman group indicated by the group directive in the initialization request.
3. The certificate directive, if present and if considered by the requester, provides a public key that is valid according to the Public Key Algorithm specification, notably regarding minimum key size.
4. The certificate directive, if present and if considered by the requester, satisfies locally determined validation constraints, typically with respect to installed certification authority root certificates.
5. The signature directive value is valid. See signature section for details of the validation procedure.