CMS DigestedData

RFC 5652 sec. 7 DigestedData, the integrity-only CMS content type. It carries the content, the digest algorithm, and the digest over the content octets. There is no signer and no key, so it establishes that content matches a digest and nothing about who produced either: its worth is the worth of the channel the message and the digest traveled over. pki.cms.sign establishes origin, pki.cms.authenticate establishes origin under a shared key.

The version follows the encapsulated type, 0 for id-data and 2 for anything else. The verifying half recomputes the digest and compares it in constant time, and its verdict carries no signer and no trust field, so it cannot be read as a signature.

pki.cms.digest(content, opts?) -> Promise<Buffer|string>

- `digestAlgorithm` (string) -- `sha256` (default), `sha384` or `sha512`.
- `contentType` (string) -- the encapsulated content type by OID name, default `data`.
- `detached` (boolean) -- omit the content, leaving the digest to travel alone.
- `pem` (boolean) -- return a PEM `CMS` block instead of DER.

async function example() {
  var der = await pki.cms.digest(Buffer.from("hello"));
  (await pki.cms.verifyDigest(der)).valid;   // -> true
}
example();

pki.cms.verifyDigest(input, opts?) -> Promise<verdict>

- `content` (BufferSource) -- the detached content the digest covers. Required when the
  message omits its own content, refused as redundant when it carries it.

async function example() {
  var der = await pki.cms.digest(Buffer.from("hello"));
  var v = await pki.cms.verifyDigest(der);
  v.valid;             // -> true
  v.digestAlgorithm;   // -> "sha256"
}
example();