Allocation audit from Android benchmark showed 19 allocs in signSchnorr
and 4 in verifySchnorr. Most were intermediate ByteArray/LongArray that
can be replaced with pre-allocated scratch buffers.
Changes:
- Add sha256Into() (expect/actual) that writes digest into existing buffer
instead of allocating a new ByteArray(32) per call. Uses
MessageDigest.digest(buf,off,len) on JVM/Android, CC_SHA256 on Apple.
- Add scratch byte buffers to PointScratch: hashBuf(256), bytesTmp1/2(32),
scalarTmp1/2/3 for intermediate scalar results.
- Add ScalarN.reduceTo() allocation-free variant.
- Rewrite signSchnorrInternal to reuse scratch buffers for:
- dBytes serialization (bytesTmp1 instead of U256.toBytes alloc)
- AUX_PREFIX+auxrand hash (hashBuf instead of array concatenation)
- auxHash XOR (scalarTmp1/2/3 instead of U256.fromBytes allocs)
- nonce/challenge hash inputs (hashBuf instead of ByteArray alloc)
- nonce scalar (scalarTmp1 instead of ScalarN.reduce alloc)
- challenge scalar (scalarTmp3 instead of allocs)
- e*d and k+e*d (splitK1/entryTmp2 instead of ScalarN.mul/add allocs)
- Rewrite verifySchnorr to use hashBuf and sha256Into for challenge hash.
Only the 64-byte output signature is allocated per sign call.
Verify allocates nothing for 32-byte messages (hashBuf is large enough).
https://claude.ai/code/session_01EMY5RnXb9rnsyU2KbXrSaY
Claude
c915c2b883