On Fri, 30 Aug 2024 23:26:12 GMT, Kevin Driver <kdri...@openjdk.org> wrote:
>> Introduce an API for Key Derivation Functions (KDFs), which are >> cryptographic algorithms for deriving additional keys from a secret key and >> other data. See [JEP 478](https://openjdk.org/jeps/478). >> >> Work was begun in [another PR](https://github.com/openjdk/jdk/pull/18924). > > Kevin Driver has updated the pull request incrementally with one additional > commit since the last revision: > > change impl class to use byte arrays rather than SecretKey objects where > possible src/java.base/share/classes/com/sun/crypto/provider/HkdfKeyDerivation.java line 358: > 356: } > 357: > 358: return Arrays.copyOf(kdfOutput, outLen); Here is an alternative solution which does not need `Arrays.copyOf()` call: Suggestion: kdfOutput = new byte[outLen]; int i = 0; int offset = 0; try { while (i < rounds) { if (i > 0) { hmacObj.update(kdfOutput, offset - hmacLen, hmacLen); // add T(i-1) } hmacObj.update(info); // Add info hmacObj.update((byte) ++i); // Add round number if (i == rounds && (outLen - offset < hmacLen)) { // special handling for last chunk byte[] tmp = hmacObj.doFinal(); System.arraycopy(tmp, 0, kdfOutput, offset, outLen - offset); offset = outLen; } else { hmacObj.doFinal(kdfOutput, offset); offset += hmacLen; } } } catch (ShortBufferException sbe) { // This really shouldn't happen given that we've // sized the buffers to their largest possible size up-front, // but just in case... throw new RuntimeException(sbe); } return kdfOutput; ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/20301#discussion_r1744602889
