/* $OpenBSD: chacha.c,v 1.2 2023/07/17 05:26:38 djm Exp $ */ /* chacha-merged.c version 20080118 D. J. Bernstein Public domain. */ #include "includes.h" __RCSID("$NetBSD: chacha.c,v 1.5.28.1 2023/11/02 22:15:21 sborrill Exp $"); #include /* for NULL */ #include "chacha.h" typedef unsigned char u8; typedef unsigned int u32; typedef struct chacha_ctx chacha_ctx; #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 const char tau[16] = "expand 16-byte k"; void chacha_keysetup(chacha_ctx *x,const u8 *k,u32 kbits) { const char *constants; x->input[4] = U8TO32_LITTLE(k + 0); x->input[5] = U8TO32_LITTLE(k + 4); x->input[6] = U8TO32_LITTLE(k + 8); x->input[7] = U8TO32_LITTLE(k + 12); if (kbits == 256) { /* recommended */ k += 16; constants = sigma; } else { /* kbits == 128 */ constants = tau; } x->input[8] = U8TO32_LITTLE(k + 0); x->input[9] = U8TO32_LITTLE(k + 4); x->input[10] = U8TO32_LITTLE(k + 8); x->input[11] = U8TO32_LITTLE(k + 12); x->input[0] = U8TO32_LITTLE(constants + 0); x->input[1] = U8TO32_LITTLE(constants + 4); x->input[2] = U8TO32_LITTLE(constants + 8); x->input[3] = U8TO32_LITTLE(constants + 12); } void chacha_ivsetup(chacha_ctx *x, const u8 *iv, const u8 *counter) { x->input[12] = counter == NULL ? 0 : U8TO32_LITTLE(counter + 0); x->input[13] = counter == NULL ? 0 : U8TO32_LITTLE(counter + 4); x->input[14] = U8TO32_LITTLE(iv + 0); x->input[15] = U8TO32_LITTLE(iv + 4); } void chacha_encrypt_bytes(chacha_ctx *x,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 = x->input[0]; j1 = x->input[1]; j2 = x->input[2]; j3 = x->input[3]; j4 = x->input[4]; j5 = x->input[5]; j6 = x->input[6]; j7 = x->input[7]; j8 = x->input[8]; j9 = x->input[9]; j10 = x->input[10]; j11 = x->input[11]; j12 = x->input[12]; j13 = x->input[13]; j14 = x->input[14]; j15 = x->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); x0 = XOR(x0,U8TO32_LITTLE(m + 0)); x1 = XOR(x1,U8TO32_LITTLE(m + 4)); x2 = XOR(x2,U8TO32_LITTLE(m + 8)); x3 = XOR(x3,U8TO32_LITTLE(m + 12)); x4 = XOR(x4,U8TO32_LITTLE(m + 16)); x5 = XOR(x5,U8TO32_LITTLE(m + 20)); x6 = XOR(x6,U8TO32_LITTLE(m + 24)); x7 = XOR(x7,U8TO32_LITTLE(m + 28)); x8 = XOR(x8,U8TO32_LITTLE(m + 32)); x9 = XOR(x9,U8TO32_LITTLE(m + 36)); x10 = XOR(x10,U8TO32_LITTLE(m + 40)); x11 = XOR(x11,U8TO32_LITTLE(m + 44)); x12 = XOR(x12,U8TO32_LITTLE(m + 48)); x13 = XOR(x13,U8TO32_LITTLE(m + 52)); x14 = XOR(x14,U8TO32_LITTLE(m + 56)); x15 = XOR(x15,U8TO32_LITTLE(m + 60)); 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]; } x->input[12] = j12; x->input[13] = j13; return; } bytes -= 64; c += 64; m += 64; } }