80 lines
3.4 KiB
Markdown
80 lines
3.4 KiB
Markdown
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[](https://godoc.org/github.com/aead/chacha20)
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## The ChaCha20 stream cipher
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ChaCha is a stream cipher family created by Daniel J. Bernstein.
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The most common ChaCha cipher is ChaCha20 (20 rounds). ChaCha20 is standardized in [RFC 7539](https://tools.ietf.org/html/rfc7539 "RFC 7539").
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This package provides implementations of three ChaCha versions:
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- ChaCha20 with a 64 bit nonce (can en/decrypt up to 2^64 * 64 bytes for one key-nonce combination)
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- ChaCha20 with a 96 bit nonce (can en/decrypt up to 2^32 * 64 bytes ~ 256 GB for one key-nonce combination)
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- XChaCha20 with a 192 bit nonce (can en/decrypt up to 2^64 * 64 bytes for one key-nonce combination)
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Furthermore the chacha subpackage implements ChaCha20/12 and ChaCha20/8.
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These versions use 12 or 8 rounds instead of 20.
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But it's recommended to use ChaCha20 (with 20 rounds) - it will be fast enough for almost all purposes.
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### Installation
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Install in your GOPATH: `go get -u github.com/aead/chacha20`
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### Requirements
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All go versions >= 1.5.3 are supported.
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Please notice, that the amd64 AVX2 asm implementation requires go1.7 or newer.
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### Performance
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#### AMD64
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Hardware: Intel i7-6500U 2.50GHz x 2
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System: Linux Ubuntu 16.04 - kernel: 4.4.0-62-generic
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Go version: 1.8.0
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```
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AVX2
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name speed cpb
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ChaCha20_64-4 573MB/s ± 0% 4.16
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ChaCha20_1K-4 2.19GB/s ± 0% 1.06
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XChaCha20_64-4 261MB/s ± 0% 9.13
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XChaCha20_1K-4 1.69GB/s ± 4% 1.37
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XORKeyStream64-4 474MB/s ± 2% 5.02
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XORKeyStream1K-4 2.09GB/s ± 1% 1.11
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XChaCha20_XORKeyStream64-4 262MB/s ± 0% 9.09
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XChaCha20_XORKeyStream1K-4 1.71GB/s ± 1% 1.36
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SSSE3
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name speed cpb
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ChaCha20_64-4 583MB/s ± 0% 4.08
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ChaCha20_1K-4 1.15GB/s ± 1% 2.02
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XChaCha20_64-4 267MB/s ± 0% 8.92
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XChaCha20_1K-4 984MB/s ± 5% 2.42
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XORKeyStream64-4 492MB/s ± 1% 4.84
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XORKeyStream1K-4 1.10GB/s ± 5% 2.11
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XChaCha20_XORKeyStream64-4 266MB/s ± 0% 8.96
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XChaCha20_XORKeyStream1K-4 1.00GB/s ± 2% 2.32
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```
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#### 386
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Hardware: Intel i7-6500U 2.50GHz x 2
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System: Linux Ubuntu 16.04 - kernel: 4.4.0-62-generic
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Go version: 1.8.0
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```
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SSSE3
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name speed cpb
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ChaCha20_64-4 570MB/s ± 0% 4.18
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ChaCha20_1K-4 650MB/s ± 0% 3.66
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XChaCha20_64-4 223MB/s ± 0% 10.69
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XChaCha20_1K-4 584MB/s ± 1% 4.08
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XORKeyStream64-4 392MB/s ± 1% 6.08
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XORKeyStream1K-4 629MB/s ± 1% 3.79
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XChaCha20_XORKeyStream64-4 222MB/s ± 0% 10.73
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XChaCha20_XORKeyStream1K-4 585MB/s ± 0% 4.07
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SSE2
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name speed cpb
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ChaCha20_64-4 509MB/s ± 0% 4.68
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ChaCha20_1K-4 553MB/s ± 2% 4.31
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XChaCha20_64-4 201MB/s ± 0% 11.86
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XChaCha20_1K-4 498MB/s ± 4% 4.78
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XORKeyStream64-4 359MB/s ± 1% 6.64
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XORKeyStream1K-4 545MB/s ± 0% 4.37
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XChaCha20_XORKeyStream64-4 201MB/s ± 1% 11.86
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XChaCha20_XORKeyStream1K-4 507MB/s ± 0% 4.70
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```
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