deriveBits: document deriveBits limitation, and explicitly return an

error
grafana · Apr 25, 2024 · 3f7b1d5 · 3f7b1d5
1 parent cf71dba
commit 3f7b1d5
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Showing 3 changed files with 19 additions and 9 deletions.
diff --git a/README.md b/README.md
@@ -50,6 +50,8 @@ The current state of the project is that it is an experimental module of the Web
 | `crypto.subtle.deriveKey()`  | ❌   | ❌   | ❌     |
 | `crypto.subtle.deriveBits()` | ✅   | ❌   | ❌     |
 
+Note: `deriveBits` currently doesn't support length parameter non-multiple of 8.
+
 ##### Key wrapping
 
 | API                         | AES-CBC | AES-GCM | AES-CTR | AES-KW | RSA-OAEP |

diff --git a/webcrypto/subtle_crypto.go b/webcrypto/subtle_crypto.go
@@ -703,6 +703,12 @@ func (sc *SubtleCrypto) DeriveBits( //nolint:funlen,gocognit // we have a lot of
 			return NewError(InvalidAccessError, err.Error())
 		}
 
+		// currently we don't support lengths that are not multiples of 8
+		// https://github.com/grafana/xk6-webcrypto/issues/80
+		if length%8 != 0 {
+			return NewError(NotSupportedError, "currently only multiples of 8 are supported for length")
+		}
+
 		deriver, err = newBitsDeriver(normalizeAlgorithmName)
 		if err != nil {
 			return err

diff --git a/webcrypto/tests/derive_bits_keys/ecdh_bits.js b/webcrypto/tests/derive_bits_keys/ecdh_bits.js
@@ -87,15 +87,17 @@ function define_tests() {
                });
            }, namedCurve + " short result");
 
-           // Non-multiple of 8
-           promise_test(function(test) {
-               return subtle.deriveBits({name: "ECDH", public: publicKeys[namedCurve]}, privateKeys[namedCurve], 8 * sizes[namedCurve] - 11)
-               .then(function(derivation) {
-                   assert_true(equalBuffers(derivation, derivations[namedCurve], 8 * sizes[namedCurve] - 11), "Derived correct bits " + namedCurve + " size: " + 8 * sizes[namedCurve] + " derivation: " + JSON.stringify(derivation) + " expected: " + JSON.stringify(derivations[namedCurve]) );
-               }, function(err) {
-                   assert_unreached("deriveBits failed with error " + err.name + ": " + err.message);
-               });
-           }, namedCurve + " non-multiple of 8 bits");
+        // TODO: once we have support of lengths that are not a multiple of 8 bits, uncomment this test
+        // https://github.com/grafana/xk6-webcrypto/issues/80
+        //   // Non-multiple of 8
+        //    promise_test(function(test) {
+        //        return subtle.deriveBits({name: "ECDH", public: publicKeys[namedCurve]}, privateKeys[namedCurve], 8 * sizes[namedCurve] - 11)
+        //        .then(function(derivation) {
+        //            assert_true(equalBuffers(derivation, derivations[namedCurve], 8 * sizes[namedCurve] - 11), "Derived correct bits " + namedCurve + " size: " + 8 * sizes[namedCurve] + " derivation: " + JSON.stringify(derivation) + " expected: " + JSON.stringify(derivations[namedCurve]) );
+        //        }, function(err) {
+        //            assert_unreached("deriveBits failed with error " + err.name + ": " + err.message);
+        //        });
+        //    }, namedCurve + " non-multiple of 8 bits");
 
            // Errors to test: