diff options
| author | Pieter Wuille <pieter@wuille.net> | 2022-04-22 12:28:28 -0400 |
|---|---|---|
| committer | Pieter Wuille <pieter@wuille.net> | 2022-05-04 14:53:46 -0400 |
| commit | 81c09ee45caecf8d9daf6766b94cebf54f3f08cd (patch) | |
| tree | a369e53ad3d26375c5cc601b74cf3ddd8dfa845e | |
| parent | 33aaf434af2740d33abc0f45f613a666092630c3 (diff) | |
Unroll the ChaCha20 inner loop for performance
| -rw-r--r-- | src/crypto/chacha20.cpp | 48 |
1 files changed, 28 insertions, 20 deletions
diff --git a/src/crypto/chacha20.cpp b/src/crypto/chacha20.cpp index f3ff4268ee..c7e12b0612 100644 --- a/src/crypto/chacha20.cpp +++ b/src/crypto/chacha20.cpp @@ -18,6 +18,8 @@ constexpr static inline uint32_t rotl32(uint32_t v, int c) { return (v << c) | ( a += b; d = rotl32(d ^ a, 8); \ c += d; b = rotl32(b ^ c, 7); +#define REPEAT10(a) do { {a}; {a}; {a}; {a}; {a}; {a}; {a}; {a}; {a}; {a}; } while(0) + static const unsigned char sigma[] = "expand 32-byte k"; static const unsigned char tau[] = "expand 16-byte k"; @@ -119,16 +121,19 @@ void ChaCha20::Keystream(unsigned char* c, size_t bytes) x13 = j13; x14 = j14; x15 = j15; - for (i = 20;i > 0;i -= 2) { - QUARTERROUND( x0, x4, x8,x12) - QUARTERROUND( x1, x5, x9,x13) - QUARTERROUND( x2, x6,x10,x14) - QUARTERROUND( x3, x7,x11,x15) - QUARTERROUND( x0, x5,x10,x15) - QUARTERROUND( x1, x6,x11,x12) - QUARTERROUND( x2, x7, x8,x13) - QUARTERROUND( x3, x4, x9,x14) - } + + // The 20 inner ChaCha20 rounds are unrolled here for performance. + REPEAT10( + QUARTERROUND( x0, x4, x8,x12); + QUARTERROUND( x1, x5, x9,x13); + QUARTERROUND( x2, x6,x10,x14); + QUARTERROUND( x3, x7,x11,x15); + QUARTERROUND( x0, x5,x10,x15); + QUARTERROUND( x1, x6,x11,x12); + QUARTERROUND( x2, x7, x8,x13); + QUARTERROUND( x3, x4, x9,x14); + ); + x0 += j0; x1 += j1; x2 += j2; @@ -231,16 +236,19 @@ void ChaCha20::Crypt(const unsigned char* m, unsigned char* c, size_t bytes) x13 = j13; x14 = j14; x15 = j15; - for (i = 20;i > 0;i -= 2) { - QUARTERROUND( x0, x4, x8,x12) - QUARTERROUND( x1, x5, x9,x13) - QUARTERROUND( x2, x6,x10,x14) - QUARTERROUND( x3, x7,x11,x15) - QUARTERROUND( x0, x5,x10,x15) - QUARTERROUND( x1, x6,x11,x12) - QUARTERROUND( x2, x7, x8,x13) - QUARTERROUND( x3, x4, x9,x14) - } + + // The 20 inner ChaCha20 rounds are unrolled here for performance. + REPEAT10( + QUARTERROUND( x0, x4, x8,x12); + QUARTERROUND( x1, x5, x9,x13); + QUARTERROUND( x2, x6,x10,x14); + QUARTERROUND( x3, x7,x11,x15); + QUARTERROUND( x0, x5,x10,x15); + QUARTERROUND( x1, x6,x11,x12); + QUARTERROUND( x2, x7, x8,x13); + QUARTERROUND( x3, x4, x9,x14); + ); + x0 += j0; x1 += j1; x2 += j2; |