KCCM partial AEAD block - #2350
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Merged with one small revision - the authLen value has the blockSize subtracted from it at the end of the loop so the (authLen - assocOff) in the PR was doubling up. It's now up on https://www.bouncycastle.org/betas if you want to try the revision. |
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Thanks, no idea how that crept in. All works. |
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I know that feeling. Cheers, marking this as closed then. It's the last fix for this release. |
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Jul 14, 2026
…Cipher (DSTU 7624 CCM), incorporating github PR #2350: init zero-extends a short nonce to the block size and processAssociatedText zero-pads a trailing partial AAD block instead of throwing "padding not supported". Corrects the PR's AAD MAC loop, whose bound byteIndex < authLen - assocOff double-subtracted the offset (authLen already equals aadLen - assocOff) and skipped every AAD block after the first, silently changing the MAC for multi-block associated data; the bound is byteIndex < authLen. Adds DSTU7624Test cases locking the multi-block AAD MAC to its pre-PR value and round-tripping partial AAD and short nonces; relates to github #2350.
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Following the fixes for github #287, the KCCM mode still rejects AEAD data that is not a multiple of the engine blockSize.
In addition, the nonce is required to be at least as long as the engine blockSize. It should probably be required to be exactly the blockSize, since it is simply processed as a block by the underlying engine, and subsequent bytes are ignored.