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/*
* Based on public domain code available at: http://cr.yp.to/snuffle.html
*
* This therefore is public domain.
*/
#include "Salsa20.hpp"
#include "Constants.hpp"
#define ROTATE(v,c) (((v) << (c)) | ((v) >> (32 - (c))))
#define XOR(v,w) ((v) ^ (w))
#define PLUS(v,w) ((uint32_t)((v) + (w)))
#define PLUSONE(v) ((uint32_t)((v) + 1))
#if __BYTE_ORDER == __LITTLE_ENDIAN
#define U8TO32_LITTLE(p) (*((const uint32_t *)((const void *)(p))))
#define U32TO8_LITTLE(c,v) *((uint32_t *)((void *)(c))) = (v)
#else
#ifdef __GNUC__
#define U8TO32_LITTLE(p) __builtin_bswap32(*((const uint32_t *)((const void *)(p))))
#define U32TO8_LITTLE(c,v) *((uint32_t *)((void *)(c))) = __builtin_bswap32((v))
#else
error need be;
#endif
#endif
namespace ZeroTier {
static const char *sigma = "expand 32-byte k";
static const char *tau = "expand 16-byte k";
void Salsa20::init(const void *key,unsigned int kbits,const void *iv)
throw()
{
const char *constants;
const uint8_t *k = (const uint8_t *)key;
_state[1] = U8TO32_LITTLE(k + 0);
_state[2] = U8TO32_LITTLE(k + 4);
_state[3] = U8TO32_LITTLE(k + 8);
_state[4] = U8TO32_LITTLE(k + 12);
if (kbits == 256) { /* recommended */
k += 16;
constants = sigma;
} else { /* kbits == 128 */
constants = tau;
}
_state[11] = U8TO32_LITTLE(k + 0);
_state[12] = U8TO32_LITTLE(k + 4);
_state[13] = U8TO32_LITTLE(k + 8);
_state[14] = U8TO32_LITTLE(k + 12);
_state[6] = U8TO32_LITTLE(((const uint8_t *)iv) + 0);
_state[7] = U8TO32_LITTLE(((const uint8_t *)iv) + 4);
_state[8] = 0;
_state[9] = 0;
_state[0] = U8TO32_LITTLE(constants + 0);
_state[5] = U8TO32_LITTLE(constants + 4);
_state[10] = U8TO32_LITTLE(constants + 8);
_state[15] = U8TO32_LITTLE(constants + 12);
}
void Salsa20::encrypt(const void *in,void *out,unsigned int bytes)
throw()
{
uint32_t x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
uint32_t j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
uint8_t tmp[64];
const uint8_t *m = (const uint8_t *)in;
uint8_t *c = (uint8_t *)out;
uint8_t *ctarget = c;
unsigned int i;
if (!bytes) return;
j0 = _state[0];
j1 = _state[1];
j2 = _state[2];
j3 = _state[3];
j4 = _state[4];
j5 = _state[5];
j6 = _state[6];
j7 = _state[7];
j8 = _state[8];
j9 = _state[9];
j10 = _state[10];
j11 = _state[11];
j12 = _state[12];
j13 = _state[13];
j14 = _state[14];
j15 = _state[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) {
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,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));
j8 = PLUSONE(j8);
if (!j8) {
j9 = PLUSONE(j9);
/* 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];
}
_state[8] = j8;
_state[9] = j9;
return;
}
bytes -= 64;
c += 64;
m += 64;
}
}
} // namespace ZeroTier
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