diff options
Diffstat (limited to 'examples/random/chacha.h')
| -rw-r--r-- | examples/random/chacha.h | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/examples/random/chacha.h b/examples/random/chacha.h new file mode 100644 index 00000000..7df352f9 --- /dev/null +++ b/examples/random/chacha.h @@ -0,0 +1,196 @@ +#pragma once +/* +chacha-merged.c version 20080118 +D. J. Bernstein +Public domain. +*/ + +/* $OpenBSD: chacha_private.h,v 1.3 2022/02/28 21:56:29 dtucker Exp $ */ +/* Tomo: chacha.h,v 1.0 2024/11/03 Bruce Hill */ + +typedef unsigned char u8; +typedef unsigned int u32; + +typedef struct +{ + u32 input[16]; /* could be compressed */ +} chacha_ctx; + +#define KEYSZ 32 +#define IVSZ 8 + +#define U8C(v) (v##U) +#define U32C(v) (v##U) + +#define U8V(v) ((u8)(v) & U8C(0xFF)) +#define U32V(v) ((u32)(v) & U32C(0xFFFFFFFF)) + +#define ROTL32(v, n) \ + (U32V((v) << (n)) | ((v) >> (32 - (n)))) + +#define U8TO32_LITTLE(p) \ + (((u32)((p)[0]) ) | \ + ((u32)((p)[1]) << 8) | \ + ((u32)((p)[2]) << 16) | \ + ((u32)((p)[3]) << 24)) + +#define U32TO8_LITTLE(p, v) \ + do { \ + (p)[0] = U8V((v) ); \ + (p)[1] = U8V((v) >> 8); \ + (p)[2] = U8V((v) >> 16); \ + (p)[3] = U8V((v) >> 24); \ + } while (0) + +#define ROTATE(v, c) (ROTL32(v, c)) +#define XOR(v, w) ((v) ^ (w)) +#define PLUS(v, w) (U32V((v) + (w))) +#define PLUSONE(v) (PLUS((v), 1)) + +#define QUARTERROUND(a, b, c, d) \ + a = PLUS(a, b); d = ROTATE(XOR(d, a), 16); \ + c = PLUS(c, d); b = ROTATE(XOR(b, c), 12); \ + a = PLUS(a, b); d = ROTATE(XOR(d, a), 8); \ + c = PLUS(c, d); b = ROTATE(XOR(b, c), 7); + +static const char sigma[16] = "expand 32-byte k"; + +static void +chacha_keysetup(chacha_ctx *chacha, const u8 *k) +{ + chacha->input[0] = U8TO32_LITTLE(sigma + 0); + chacha->input[1] = U8TO32_LITTLE(sigma + 4); + chacha->input[2] = U8TO32_LITTLE(sigma + 8); + chacha->input[3] = U8TO32_LITTLE(sigma + 12); + chacha->input[4] = U8TO32_LITTLE(k + 0); + chacha->input[5] = U8TO32_LITTLE(k + 4); + chacha->input[6] = U8TO32_LITTLE(k + 8); + chacha->input[7] = U8TO32_LITTLE(k + 12); + chacha->input[8] = U8TO32_LITTLE(k + 16); + chacha->input[9] = U8TO32_LITTLE(k + 20); + chacha->input[10] = U8TO32_LITTLE(k + 24); + chacha->input[11] = U8TO32_LITTLE(k + 28); +} + +static void +chacha_ivsetup(chacha_ctx *chacha, const u8 *iv) +{ + chacha->input[12] = 0; + chacha->input[13] = 0; + chacha->input[14] = U8TO32_LITTLE(iv + 0); + chacha->input[15] = U8TO32_LITTLE(iv + 4); +} + +static void +chacha_encrypt_bytes(chacha_ctx *chacha, const u8 *m, u8 *c, u32 bytes) +{ + u32 x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15; + u32 j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15; + u8 *ctarget = NULL; + u8 tmp[64]; + u_int i; + + if (!bytes) return; + + j0 = chacha->input[0]; + j1 = chacha->input[1]; + j2 = chacha->input[2]; + j3 = chacha->input[3]; + j4 = chacha->input[4]; + j5 = chacha->input[5]; + j6 = chacha->input[6]; + j7 = chacha->input[7]; + j8 = chacha->input[8]; + j9 = chacha->input[9]; + j10 = chacha->input[10]; + j11 = chacha->input[11]; + j12 = chacha->input[12]; + j13 = chacha->input[13]; + j14 = chacha->input[14]; + j15 = chacha->input[15]; + + for (;;) { + if (bytes < 64) { + for (i = 0;i < bytes;++i) tmp[i] = m[i]; + m = tmp; + ctarget = c; + c = tmp; + } + x0 = j0; + x1 = j1; + x2 = j2; + x3 = j3; + x4 = j4; + x5 = j5; + x6 = j6; + x7 = j7; + x8 = j8; + x9 = j9; + x10 = j10; + x11 = j11; + x12 = j12; + 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) + } + x0 = PLUS(x0, j0); + x1 = PLUS(x1, j1); + x2 = PLUS(x2, j2); + x3 = PLUS(x3, j3); + x4 = PLUS(x4, j4); + x5 = PLUS(x5, j5); + x6 = PLUS(x6, j6); + x7 = PLUS(x7, j7); + x8 = PLUS(x8, j8); + x9 = PLUS(x9, j9); + x10 = PLUS(x10, j10); + x11 = PLUS(x11, j11); + x12 = PLUS(x12, j12); + x13 = PLUS(x13, j13); + x14 = PLUS(x14, j14); + x15 = PLUS(x15, j15); + + j12 = PLUSONE(j12); + if (!j12) { + j13 = PLUSONE(j13); + /* stopping at 2^70 bytes per nonce is user's responsibility */ + } + + U32TO8_LITTLE(c + 0, x0); + U32TO8_LITTLE(c + 4, x1); + U32TO8_LITTLE(c + 8, x2); + U32TO8_LITTLE(c + 12, x3); + U32TO8_LITTLE(c + 16, x4); + U32TO8_LITTLE(c + 20, x5); + U32TO8_LITTLE(c + 24, x6); + U32TO8_LITTLE(c + 28, x7); + U32TO8_LITTLE(c + 32, x8); + U32TO8_LITTLE(c + 36, x9); + U32TO8_LITTLE(c + 40, x10); + U32TO8_LITTLE(c + 44, x11); + U32TO8_LITTLE(c + 48, x12); + U32TO8_LITTLE(c + 52, x13); + U32TO8_LITTLE(c + 56, x14); + U32TO8_LITTLE(c + 60, x15); + + if (bytes <= 64) { + if (bytes < 64) { + for (i = 0;i < bytes;++i) ctarget[i] = c[i]; + } + chacha->input[12] = j12; + chacha->input[13] = j13; + return; + } + bytes -= 64; + c += 64; + } +} |