HTTP Problem Types for Digest Fields

3.1. Unsupported Hashing Algorithm

This section defines the "https://iana.org/assignments/http-problem-types#digest-unsupported-algorithm" problem type. A server MAY use this problem type if it wants to communicate to the client that one of the hashing algorithms referenced in the integrity or integrity preference fields present in the request is not supported.¶

For this problem type, unsupported-algorithm is defined as the only extension member. It SHOULD be populated in a response using this problem type, with its value being the algorithm key of the unsupported algorithm from the request. The response can include the corresponding integrity preference field to indicate the server's algorithm support and preference.¶

Example:¶

POST /books HTTP/1.1
Host: foo.example
Content-Type: application/json
Accept: application/json
Accept-Encoding: identity
Repr-Digest: sha-256=:mEkdbO7Srd9LIOegftO0aBX+VPTVz7/CSHes2Z27gc4=:

{"title": "New Title"}

HTTP/1.1 400 Bad Request
Content-Type: application/problem+json
Want-Repr-Digest: sha-512=10, sha-256=0

{
  "type": "https://iana.org/assignments/http-problem-types#digest-unsupported-algorithm",
  "title": "Unsupported hashing algorithm",
  "unsupported-algorithm": "sha-256"
}

This problem type is a hint to the client about algorithm support, which the client could use to retry the request with a different, supported, algorithm. Note that a request may contain more than one integrity field.¶

This problem type can also be used when a request contains an integrity preference field. For example:¶

GET /items/123 HTTP/1.1
Host: foo.example
Want-Repr-Digest: sha=10

HTTP/1.1 400 Bad Request
Content-Type: application/problem+json

{
  "type": "https://iana.org/assignments/http-problem-types#digest-unsupported-algorithm",
  "title": "Unsupported hashing algorithm",
  "unsupported-algorithm": "sha"
}

3.2. Invalid Digest Value

This section defines the "https://iana.org/assignments/http-problem-types#digest-invalid-value" problem type. A server MAY use this problem type when responding to a request, whose integrity fields include a digest value, that cannot be generated by the corresponding hashing algorithm. For example, if the digest value of the sha-512 hashing algorithm is not 64 bytes long, it cannot be a valid digest value and the server can skip computing the digest value. This problem type MUST NOT be used if the server is not able to parse the integrity fields according to Section 4.5 of [STRUCTURED-FIELDS], for example because of a syntax error in the field value.¶

The server SHOULD include a human-readable description why the value is considered invalid in the title member.¶

The following example shows a request with the content {"hello": "world"} (plus LF), but the digest has been truncated. The subsequent response indicates the invalid SHA-512 digest.¶

PUT /items/123 HTTP/1.1
Host: foo.example
Content-Type: application/json
Repr-Digest: sha-512=:YMAam51Jz/jOATT6/zvHrLVgOYTGFy1d6GJiOHTohq4:

{"hello": "world"}

HTTP/1.1 400 Bad Request
Content-Type: application/problem+json

{
  "type": "https://iana.org/assignments/http-problem-types#digest-invalid-value",
  "title": "digest value for sha-512 is not 64 bytes long"
}

This problem type indicates a fault in the sender's calculation or encoding of the digest value. A retry of the same request without modification will likely not yield a successful response.¶

3.3. Mismatching Digest Value

This section defines the "https://iana.org/assignments/http-problem-types#digest-mismatching-value" problem type. A server MAY use this problem type when responding to a request, whose integrity fields include a digest value that does not match the digest value that the server calculated for the request content or representation.¶

Three problem type extension members are defined: the algorithm, provided-digest, and calculated-digest members. A response using this problem type SHOULD populate all members, with the value of algorithm being the algorithm key of the used hashing algorithm, with the value of provided-digest being the digest value taken from the request's integrity fields, and the value of calculated-digest being the calculated digest. The digest values MUST BE serialized as byte sequences as described in Section 4.1.8 of [STRUCTURED-FIELDS].¶

The following example shows a request with the content {"hello": "woXYZ"} (plus LF), but the representation digest for {"hello": "world"} (plus LF). The subsequent response indicates the mismatching SHA-256 digest values.¶

PUT /items/123 HTTP/1.1
Host: foo.example
Content-Type: application/json
Repr-Digest: sha-256=:RK/0qy18MlBSVnWgjwz6lZEWjP/lF5HF9bvEF8FabDg=:

{"hello": "woXYZ"}

HTTP/1.1 400 Bad Request
Content-Type: application/problem+json

{
  "type": "https://iana.org/assignments/http-problem-types#digest-mismatching-value",
  "title": "digest value fromr request does not match expected value",
  "algorithm": "sha-256",
  "provided-digest": ":RK/0qy18MlBSVnWgjwz6lZEWjP/lF5HF9bvEF8FabDg=:",
  "calculated-digest": ":8vXo+0QVwf2woEblm4hTAftp0/K5fWSMZG4CKtplwjc=:"
}

If the sender receives this problem type, the request might be modified unintentionally by an intermediary. The sender could use this information to retry the request without modification to address temporary transmission issues.¶

5.1. Registration of "digest-unsupported-algorithm" Problem Type

Type URI:

https://iana.org/assignments/http-problem-types#digest-unsupported-algorithm¶

Title:

Unsupported Hashing Algorithm¶

Recommended HTTP status code:

400¶

Reference:

Section 3.1 of this document¶

5.2. Registration of "digest-invalid-value" Problem Type

Type URI:

https://iana.org/assignments/http-problem-types#digest-invalid-value¶

Title:

Invalid Digest Value¶

Recommended HTTP status code:

400¶

Reference:

Section 3.2 of this document¶

5.3. Registration of "digest-mismatching-value" Problem Type

Type URI:

https://iana.org/assignments/http-problem-types#digest-mismatching-value¶

Title:

Mismatching Digest Value¶

Recommended HTTP status code:

400¶

Reference:

Section 3.3 of this document¶