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salsa_private.h
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/*
salsa20-regs.c version 20051118
D. J. Bernstein
Public domain.
*/
typedef unsigned char u8;
typedef unsigned int u32;
typedef struct
{
u32 input[16]; /* could be compressed */
} salsa_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))
static inline void
salsa20_wordtobyte(u8 output[64],const u32 input[16])
{
u32 x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
int i;
x0 = input[0];
x1 = input[1];
x2 = input[2];
x3 = input[3];
x4 = input[4];
x5 = input[5];
x6 = input[6];
x7 = input[7];
x8 = input[8];
x9 = input[9];
x10 = input[10];
x11 = input[11];
x12 = input[12];
x13 = input[13];
x14 = input[14];
x15 = input[15];
for (i = 20;i > 0;i -= 2) {
x4 = XOR( x4,ROTATE(PLUS( x0,x12), 7));
x8 = XOR( x8,ROTATE(PLUS( x4, x0), 9));
x12 = XOR(x12,ROTATE(PLUS( x8, x4),13));
x0 = XOR( x0,ROTATE(PLUS(x12, x8),18));
x9 = XOR( x9,ROTATE(PLUS( x5, x1), 7));
x13 = XOR(x13,ROTATE(PLUS( x9, x5), 9));
x1 = XOR( x1,ROTATE(PLUS(x13, x9),13));
x5 = XOR( x5,ROTATE(PLUS( x1,x13),18));
x14 = XOR(x14,ROTATE(PLUS(x10, x6), 7));
x2 = XOR( x2,ROTATE(PLUS(x14,x10), 9));
x6 = XOR( x6,ROTATE(PLUS( x2,x14),13));
x10 = XOR(x10,ROTATE(PLUS( x6, x2),18));
x3 = XOR( x3,ROTATE(PLUS(x15,x11), 7));
x7 = XOR( x7,ROTATE(PLUS( x3,x15), 9));
x11 = XOR(x11,ROTATE(PLUS( x7, x3),13));
x15 = XOR(x15,ROTATE(PLUS(x11, x7),18));
x1 = XOR( x1,ROTATE(PLUS( x0, x3), 7));
x2 = XOR( x2,ROTATE(PLUS( x1, x0), 9));
x3 = XOR( x3,ROTATE(PLUS( x2, x1),13));
x0 = XOR( x0,ROTATE(PLUS( x3, x2),18));
x6 = XOR( x6,ROTATE(PLUS( x5, x4), 7));
x7 = XOR( x7,ROTATE(PLUS( x6, x5), 9));
x4 = XOR( x4,ROTATE(PLUS( x7, x6),13));
x5 = XOR( x5,ROTATE(PLUS( x4, x7),18));
x11 = XOR(x11,ROTATE(PLUS(x10, x9), 7));
x8 = XOR( x8,ROTATE(PLUS(x11,x10), 9));
x9 = XOR( x9,ROTATE(PLUS( x8,x11),13));
x10 = XOR(x10,ROTATE(PLUS( x9, x8),18));
x12 = XOR(x12,ROTATE(PLUS(x15,x14), 7));
x13 = XOR(x13,ROTATE(PLUS(x12,x15), 9));
x14 = XOR(x14,ROTATE(PLUS(x13,x12),13));
x15 = XOR(x15,ROTATE(PLUS(x14,x13),18));
}
x0 = PLUS(x0,input[0]);
x1 = PLUS(x1,input[1]);
x2 = PLUS(x2,input[2]);
x3 = PLUS(x3,input[3]);
x4 = PLUS(x4,input[4]);
x5 = PLUS(x5,input[5]);
x6 = PLUS(x6,input[6]);
x7 = PLUS(x7,input[7]);
x8 = PLUS(x8,input[8]);
x9 = PLUS(x9,input[9]);
x10 = PLUS(x10,input[10]);
x11 = PLUS(x11,input[11]);
x12 = PLUS(x12,input[12]);
x13 = PLUS(x13,input[13]);
x14 = PLUS(x14,input[14]);
x15 = PLUS(x15,input[15]);
U32TO8_LITTLE(output + 0,x0);
U32TO8_LITTLE(output + 4,x1);
U32TO8_LITTLE(output + 8,x2);
U32TO8_LITTLE(output + 12,x3);
U32TO8_LITTLE(output + 16,x4);
U32TO8_LITTLE(output + 20,x5);
U32TO8_LITTLE(output + 24,x6);
U32TO8_LITTLE(output + 28,x7);
U32TO8_LITTLE(output + 32,x8);
U32TO8_LITTLE(output + 36,x9);
U32TO8_LITTLE(output + 40,x10);
U32TO8_LITTLE(output + 44,x11);
U32TO8_LITTLE(output + 48,x12);
U32TO8_LITTLE(output + 52,x13);
U32TO8_LITTLE(output + 56,x14);
U32TO8_LITTLE(output + 60,x15);
}
static const char sigma[16] = "expand 32-byte k";
static const char tau[16] = "expand 16-byte k";
static void
salsa_keysetup(salsa_ctx *x,const u8 *k,u32 kbits,u32 ivbits)
{
const char *constants;
x->input[1] = U8TO32_LITTLE(k + 0);
x->input[2] = U8TO32_LITTLE(k + 4);
x->input[3] = U8TO32_LITTLE(k + 8);
x->input[4] = U8TO32_LITTLE(k + 12);
if (kbits == 256) { /* recommended */
k += 16;
constants = sigma;
} else { /* kbits == 128 */
constants = tau;
}
x->input[11] = U8TO32_LITTLE(k + 0);
x->input[12] = U8TO32_LITTLE(k + 4);
x->input[13] = U8TO32_LITTLE(k + 8);
x->input[14] = U8TO32_LITTLE(k + 12);
x->input[0] = U8TO32_LITTLE(constants + 0);
x->input[5] = U8TO32_LITTLE(constants + 4);
x->input[10] = U8TO32_LITTLE(constants + 8);
x->input[15] = U8TO32_LITTLE(constants + 12);
}
static void
salsa_ivsetup(salsa_ctx *x,const u8 *iv)
{
x->input[6] = U8TO32_LITTLE(iv + 0);
x->input[7] = U8TO32_LITTLE(iv + 4);
x->input[8] = 0;
x->input[9] = 0;
}
static void
salsa_encrypt_bytes(salsa_ctx *x,const u8 *m,u8 *c,u32 bytes)
{
u8 output[64];
int i;
if (!bytes) return;
for (;;) {
salsa20_wordtobyte(output,x->input);
x->input[8] = PLUSONE(x->input[8]);
if (!x->input[8]) {
x->input[9] = PLUSONE(x->input[9]);
/* stopping at 2^70 bytes per nonce is user's responsibility */
}
if (bytes <= 64) {
for (i = 0;i < bytes;++i) c[i] = m[i] ^ output[i];
return;
}
for (i = 0;i < 64;++i) c[i] = m[i] ^ output[i];
bytes -= 64;
c += 64;
m += 64;
}
}