Support digest structured value.

CHANGELOG.md

@@ -1,5 +1,12 @@
 # @digitalbazaar/http-digest-header Changelog
 
+## 2.3.0 - 2025-10-dd
+
+### Added
+- Support parsing a digest from structured field value, i.e., expressed as
+  a base64-encoded byte array that is wrapped in colons;
+  see: https://datatracker.ietf.org/doc/html/rfc9651#name-byte-sequences.
+
 ## 2.2.1 - 2025-10-08
 
 ### Fixed

lib/httpDigest.js

@@ -76,10 +76,13 @@ function _createMultihash({digest}) {
 }
 
 function _parseHeaderValue(headerValue) {
-  const [key, encodedDigest] = headerValue.split(/=(.+)/);
+  const [key, digestValue] = headerValue.split(/=(.+)/);
 
+  let encodedDigest;
   let algorithm;
   if(key === 'mh') {
+    encodedDigest = digestValue;
+
     // if `encodedDigest` starts with `uEi`, then it is a base64url-encoded
     // sha-256 multihash
     if(encodedDigest.startsWith('uEi')) {
@@ -89,6 +92,10 @@ function _parseHeaderValue(headerValue) {
         `Only base64url-encoded, sha-256 multihash is supported.`);
     }
   } else {
+    // per RFC 9651, the digest value could be a structured field value,
+    // expressed as a base64-encoded byte array wrapped in colons
+    encodedDigest = digestValue?.replace(/^:(.*):$/, '$1');
+
     algorithm = key.replace('-', '').toLowerCase();
     if(algorithm !== 'sha256') {
       throw new Error(`Algorithm "${algorithm}" is not supported.`);

test/unit/httpDigest.spec.js

@@ -143,6 +143,37 @@ describe('http-signature-digest', () => {
       should.exist(verifyResult);
       verifyResult.verified.should.equal(true);
     });
+    it('should verify a digest wrapped in colons', async () => {
+      const data = `{"hello": "world"}`;
+      const headerValue =
+        `sha-256=:X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=:`;
+      let verifyResult;
+      let err;
+      try {
+        verifyResult = await verifyHeaderValue({data, headerValue});
+      } catch(e) {
+        err = e;
+      }
+      should.not.exist(err);
+      should.exist(verifyResult);
+      verifyResult.verified.should.equal(true);
+    });
+    it('should verify false if a multihash digest is wrapped in colons',
+      async () => {
+        const data = '{"hello":"world"}';
+        const headerValue =
+          `mh=:uEiCTojlxqRTl6svwqNJRVM2jCcPBxy-7mRTUfGDzy2gViA:`;
+        let verifyResult;
+        let err;
+        try {
+          verifyResult = await verifyHeaderValue({data, headerValue});
+        } catch(e) {
+          err = e;
+        }
+        should.not.exist(err);
+        should.exist(verifyResult);
+        verifyResult.verified.should.equal(false);
+      });
     it('should verify false if verifying bad data object', async () => {
       const data = {hello: 'world'};
       const headerValue = await createHeaderValue(