Size the hash staging buffer to the input and cache the HMAC pads - #103
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Both hot paths allocated more than the work required. TransformUntyped and TransformStream sized their staging buffer to the full 64 KB default regardless of input, so hashing a one-byte message (as HKDF does, byte by byte) still cleared a 64 KB buffer; a shared StagingSize helper now clamps the buffer to the actual input length, honouring a user-set BufferSize as the chunk maximum. THMACNotBuildInAdapter recomputed ipad/opad and copied the key on every Initialize — and HKDF re-inits the HMAC for every Extract and Expand block — so an FPadsValid flag now caches the pads and rebuilds them only when the key changes, invalidated on both SetKey and Clear.
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Both hot paths allocated more than the work required. TransformUntyped and TransformStream sized their staging buffer to the full 64 KB default regardless of input, so hashing a one-byte message (as HKDF does, byte by byte) still cleared a 64 KB buffer; a shared StagingSize helper now clamps the buffer to the actual input length, honouring a user-set BufferSize as the chunk maximum. THMACNotBuildInAdapter recomputed ipad/opad and copied the key on every Initialize — and HKDF re-inits the HMAC for every Extract and Expand block — so an FPadsValid flag now caches the pads and rebuilds them only when the key changes, invalidated on both SetKey and Clear.