chacha20 0.5.0

The ChaCha20 stream cipher (RFC 8439) implemented in pure Rust using traits from the RustCrypto stream-cipher crate, with optional architecture-specific hardware acceleration (AVX2, SSE2). Additionally provides the ChaCha8, ChaCha12, and XChaCha20 stream ciphers, and also optional rand_core-compatible RNGs based on those ciphers.