P1 (header protection — eliminate remaining HP allocations):
Add HeaderProtection.maskInto(hpKey, src, srcOffset, scratch16, dstMask)
that writes the 5-byte mask into a caller-owned buffer using a
caller-owned 16-byte AES scratch. Add `hpScratch` (16 bytes) and
`hpMask` (5 bytes) to PacketProtection — same per-direction
single-threaded analysis as nonceScratch from the prior commit. Thread
both buffers through Short/LongHeaderPacket build / parseAndDecrypt /
peekKeyPhase as optional parameters paired with nonceScratch; production
call sites in QuicConnectionWriter / QuicConnectionParser pass
`proto.hpScratch` + `proto.hpMask`. With both this commit and 09b28b8d
the AES-128-GCM hot path now allocates ZERO bytes for HP + nonce per
packet (down from 16-byte sample slice + 16-byte AES output + 5-byte
mask + 12-byte nonce = 49 bytes/pkt).
ChaCha20HeaderProtection.maskInto routes through the same shape but
still allocates a fresh 5-byte ciphertext + 12-byte nonce slice
internally — Quartz's `ChaCha20Core.chaCha20Xor` SPI takes a
standalone nonce ByteArray. Documented as a future cleanup; AES is
the dominant path in production.
A2 (TlsRunningSha256 — lazy fallback accumulator):
Probe `digest.clone()` ONCE at construction. Conscrypt's clone
support is a build-time property (native bridge presence), not state-
dependent, so a single probe is a reliable signal. Devices where the
probe succeeds skip the byte accumulator entirely (zero overhead);
devices where it fails get the byte-accumulator path from the very
first update so the first snapshot already has the complete
transcript. Replaces the previous "always accumulate" shape that
wasted a few KB per handshake on every device, including the
overwhelming majority that support clone.
All quic JVM unit tests pass; spotless applied.
https://claude.ai/code/session_01EBHtGLy5o7FUR5qfcpHUUx
Claude
8a3bd52631