RFC 7516, "JSON Web Encryption (JWE)", May 2015

Errata ID: 8676
Status: Reported
Type: Technical
Publication Format(s) : TEXT
Reported By: Burak Can Kus
Date Reported: 2025-12-12

Section 5.2 says:

14.  Compute the Encoded Protected Header value BASE64URL(UTF8(JWE
     Protected Header)).  If the JWE Protected Header is not present
     (which can only happen when using the JWE JSON Serialization and
     no "protected" member is present), let this value be the empty
     string.

It should say:

14.  Compute the Encoded Protected Header value BASE64URL(UTF8(JWE
     Protected Header)).  If the JWE Protected Header is not present
     (which can only happen when using the JWE JSON Serialization and
     no "protected" member is present), let this value be the empty
     string. Instead of serializing the JWE Protected Header JSON
     object, use the Base64url decoded representation of JWE
     Protected Header.

Notes:

Step 3 says:

3. Verify that the octet sequence resulting from decoding the
encoded JWE Protected Header is a UTF-8-encoded representation
of a completely valid JSON object conforming to RFC 7159
[RFC7159]; let the JWE Protected Header be this JSON object.

Since JWE Protected Header is the JSON object, the serialized value might often end up different than the Base64url representation of the input value, this is because JSON is not canonical. So in step 14, instead of serializing the JSON object of the JWE Protected Header, the Base64url decoded value must be used to obtain the same value.

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