PBKDF2 allows zero length and returns and empty string

This CL adapts our implementation to the spec change described in the PR#380 [1]. Instead of trowing an OperationError exception, we allow now zero as value for the 'length' parameter. Given that the deriveBits operation must result in an empty string, this change early returns to avoid the unnecessary computation of the bits derivation. The specific WTP defined for this case are modified in this CL as well, so no additional test cases are needed. [1] w3c/webcrypto#380 Bug: 376493194 Change-Id: If685c349a0a9d134a8e8f7c902e8aac342945226
web-platform-tests · Nov 7, 2024 · 7669912 · 7669912
1 parent 1b37e8e
commit 7669912
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Showing 2 changed files with 2 additions and 12 deletions.
diff --git a/WebCryptoAPI/derive_bits_keys/derived_bits_length_testcases.js b/WebCryptoAPI/derive_bits_keys/derived_bits_length_testcases.js
@@ -3,7 +3,7 @@ var testCases = {
         {length: 256, expected: algorithms["HKDF"].derivation},
         {length: 384, expected: algorithms["HKDF"].derivation384},
         {length: 230, expected: undefined}, // should throw an exception, not multiple of 8
-        {length: 0, expected: undefined}, // explicitly disallowed, so should throw
+        {length: 0, expected: emptyArray},
         {length: null, expected: undefined }, // should throw an exception
         {length: undefined, expected: undefined }, // should throw an exception
         {length: "omitted", expected: undefined }, // default value is null, so should throw
@@ -12,7 +12,7 @@ var testCases = {
         {length: 256, expected: algorithms["PBKDF2"].derivation},
         {length: 384, expected: algorithms["PBKDF2"].derivation384},
         {length: 230, expected: undefined}, // should throw an exception, not multiple of 8
-        {length: 0, expected: undefined}, // explicitly disallowed, so should throw
+        {length: 0, expected: emptyArray},
         {length: null, expected: undefined }, // should throw an exception
         {length: undefined, expected: undefined }, // should throw an exception
         {length: "omitted", expected: undefined }, // default value is null, so should throw

diff --git a/WebCryptoAPI/derive_bits_keys/pbkdf2.js b/WebCryptoAPI/derive_bits_keys/pbkdf2.js
@@ -103,16 +103,6 @@ function define_tests() {
 
                         });
 
-                        // 0 length (OperationError)
-                        subsetTest(promise_test, function(test) {
-                            return subtle.deriveBits({name: "PBKDF2", salt: salts[saltSize], hash: hashName, iterations: parseInt(iterations)}, baseKeys[passwordSize], 0)
-                            .then(function(derivation) {
-                                assert_unreached("0 length should have thrown an OperationError");
-                            }, function(err) {
-                                assert_equals(err.name, "OperationError", "deriveBits with 0 length correctly threw OperationError: " + err.message);
-                            });
-                        }, testName + " with 0 length");
-
                         // length not multiple of 8 (OperationError)
                         subsetTest(promise_test, function(test) {
                             return subtle.deriveBits({name: "PBKDF2", salt: salts[saltSize], hash: hashName, iterations: parseInt(iterations)}, baseKeys[passwordSize], 44)