Awesome

chacha20 - ChaCha20

Yawning Angel (yawning at schwanenlied dot me)

Yet another Go ChaCha20 implementation. Everything else I found was slow, didn't support all the variants I need to use, or relied on cgo to go fast.

Features:

• 20 round, 256 bit key only. Everything else is pointless and stupid.
• IETF 96 bit nonce variant.
• XChaCha 24 byte nonce variant.
• SSSE3 and AVX2 support on amd64 targets.
• Incremental encrypt/decrypt support, unlike golang.org/x/crypto/salsa20.