RFC 8224, "Authenticated Identity Management in the Session Initiation Protocol (SIP)", February 2018

Note: This RFC has been updated by RFC 8946

Errata ID: 6499
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Marc Petit-Huguenin
Date Reported: 2021-03-27
Verifier Name: Orie Steele
Date Verified: 2024-11-15

Section 4 says:

Identity = "Identity" HCOLON signed-identity-digest SEMI
          ident-info *( SEMI ident-info-params )
signed-identity-digest = 1*(base64-char / ".")
ident-info = "info" EQUAL ident-info-uri
ident-info-uri = LAQUOT absoluteURI RAQUOT
ident-info-params = ident-info-alg / ident-type /
    ident-info-extension
ident-info-alg = "alg" EQUAL token
ident-type = "ppt" EQUAL token
ident-info-extension = generic-param

base64-char = ALPHA / DIGIT / "/" / "+"

It should say:

Identity = "Identity" HCOLON signed-identity-digest SEMI
          ident-info *( SEMI ident-info-params )
signed-identity-digest = 1*(base64url-char / ".")
ident-info = "info" EQUAL ident-info-uri
ident-info-uri = LAQUOT absoluteURI RAQUOT
ident-info-params = ident-info-alg / ident-type /
    ident-info-extension
ident-info-alg = "alg" EQUAL token
ident-type = "ppt" EQUAL token
ident-info-extension = generic-param

base64url-char = ALPHA / DIGIT / "-" / "_"

Notes:

RFC 8225 makes it clear that the encoding is BASE4URL, not the standard BASE64 encoding.

See also:
- https://datatracker.ietf.org/doc/html/rfc8224#section-4.1.1
- https://datatracker.ietf.org/doc/html/rfc7515#appendix-F
- https://datatracker.ietf.org/doc/html/rfc7515#appendix-C
- https://datatracker.ietf.org/doc/html/rfc4648#section-5

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