ref: b74913235f3bd78b33f3ce37c094f4d9e9392676
dir: /libsec/salsa.c/
#include <u.h>
#include <libc.h>
#include <libsec.h>
enum{
Blockwords= SalsaBsize/sizeof(u32int)
};
/* little-endian data order */
#define GET4(p) ((((((p)[3]<<8) | (p)[2])<<8) | (p)[1])<<8 | (p)[0])
#define PUT4(p, v) (((p)[0]=v), (v>>=8), ((p)[1]=v), (v>>=8), ((p)[2]=v), (v>>=8), ((p)[3]=v))
#define ROTATE(v,c) (t = v, (u32int)(t << (c)) | (t >> (32 - (c))))
#define ENCRYPT(s, x, y, d) {\
u32int v; \
uchar *sp, *dp; \
sp = (s); \
v = GET4(sp); \
v ^= (x)+(y); \
dp = (d); \
PUT4(dp, v); \
}
static uchar sigma[16] = "expand 32-byte k";
static uchar tau[16] = "expand 16-byte k";
static void
load(u32int *d, uchar *s, int nw)
{
int i;
for(i = 0; i < nw; i++, s+=4)
d[i] = GET4(s);
}
void
setupSalsastate(Salsastate *s, uchar *key, ulong keylen, uchar *iv, ulong ivlen, int rounds)
{
if(keylen != 256/8 && keylen != 128/8)
sysfatal("invalid salsa key length");
if(ivlen != 64/8 && ivlen != 128/8 && ivlen != 192/8)
sysfatal("invalid salsa iv length");
if(rounds == 0)
rounds = 20;
s->rounds = rounds;
if(keylen == 256/8) { /* recommended */
load(&s->input[0], sigma+4*0, 1);
load(&s->input[1], key +16*0, 4);
load(&s->input[5], sigma+4*1, 1);
load(&s->input[10], sigma+4*2, 1);
load(&s->input[11], key +16*1, 4);
load(&s->input[15], sigma+4*3, 1);
}else{
load(&s->input[0], tau +4*0, 1);
load(&s->input[1], key, 4);
load(&s->input[5], tau +4*1, 1);
load(&s->input[10], tau +4*2, 1);
load(&s->input[11], key, 4);
load(&s->input[15], tau +4*3, 1);
}
s->key[0] = s->input[1];
s->key[1] = s->input[2];
s->key[2] = s->input[3];
s->key[3] = s->input[4];
s->key[4] = s->input[11];
s->key[5] = s->input[12];
s->key[6] = s->input[13];
s->key[7] = s->input[14];
s->ivwords = ivlen/4;
s->input[8] = 0;
s->input[9] = 0;
if(iv == nil){
s->input[6] = 0;
s->input[7] = 0;
}else
salsa_setiv(s, iv);
}
static void
hsalsablock(uchar h[32], Salsastate *s)
{
u32int x[Blockwords], t;
int i, rounds;
rounds = s->rounds;
x[0] = s->input[0];
x[1] = s->input[1];
x[2] = s->input[2];
x[3] = s->input[3];
x[4] = s->input[4];
x[5] = s->input[5];
x[6] = s->input[6];
x[7] = s->input[7];
x[8] = s->input[8];
x[9] = s->input[9];
x[10] = s->input[10];
x[11] = s->input[11];
x[12] = s->input[12];
x[13] = s->input[13];
x[14] = s->input[14];
x[15] = s->input[15];
for(i = rounds; i > 0; i -= 2) {
x[4] ^= ROTATE( x[0]+x[12], 7);
x[8] ^= ROTATE( x[4]+ x[0], 9);
x[12] ^= ROTATE( x[8]+ x[4],13);
x[0] ^= ROTATE(x[12]+ x[8],18);
x[9] ^= ROTATE( x[5]+ x[1], 7);
x[13] ^= ROTATE( x[9]+ x[5], 9);
x[1] ^= ROTATE(x[13]+ x[9],13);
x[5] ^= ROTATE( x[1]+x[13],18);
x[14] ^= ROTATE(x[10]+ x[6], 7);
x[2] ^= ROTATE(x[14]+x[10], 9);
x[6] ^= ROTATE( x[2]+x[14],13);
x[10] ^= ROTATE( x[6]+ x[2],18);
x[3] ^= ROTATE(x[15]+x[11], 7);
x[7] ^= ROTATE( x[3]+x[15], 9);
x[11] ^= ROTATE( x[7]+ x[3],13);
x[15] ^= ROTATE(x[11]+ x[7],18);
x[1] ^= ROTATE( x[0]+ x[3], 7);
x[2] ^= ROTATE( x[1]+ x[0], 9);
x[3] ^= ROTATE( x[2]+ x[1],13);
x[0] ^= ROTATE( x[3]+ x[2],18);
x[6] ^= ROTATE( x[5]+ x[4], 7);
x[7] ^= ROTATE( x[6]+ x[5], 9);
x[4] ^= ROTATE( x[7]+ x[6],13);
x[5] ^= ROTATE( x[4]+ x[7],18);
x[11] ^= ROTATE(x[10]+ x[9], 7);
x[8] ^= ROTATE(x[11]+x[10], 9);
x[9] ^= ROTATE( x[8]+x[11],13);
x[10] ^= ROTATE( x[9]+ x[8],18);
x[12] ^= ROTATE(x[15]+x[14], 7);
x[13] ^= ROTATE(x[12]+x[15], 9);
x[14] ^= ROTATE(x[13]+x[12],13);
x[15] ^= ROTATE(x[14]+x[13],18);
}
PUT4(h+0*4, x[0]);
PUT4(h+1*4, x[5]);
PUT4(h+2*4, x[10]);
PUT4(h+3*4, x[15]);
PUT4(h+4*4, x[6]);
PUT4(h+5*4, x[7]);
PUT4(h+6*4, x[8]);
PUT4(h+7*4, x[9]);
}
void
salsa_setiv(Salsastate *s, uchar *iv)
{
if(s->ivwords == 128/32){
/* hsalsa 128-bit iv */
load(&s->input[6], iv, 4);
return;
}
if(s->ivwords == 192/32){
/* xsalsa with 192-bit iv */
u32int counter[2];
uchar h[32];
counter[0] = s->input[8];
counter[1] = s->input[9];
s->input[1] = s->key[0];
s->input[2] = s->key[1];
s->input[3] = s->key[2];
s->input[4] = s->key[3];
s->input[11] = s->key[4];
s->input[12] = s->key[5];
s->input[13] = s->key[6];
s->input[14] = s->key[7];
load(&s->input[6], iv, 4);
hsalsablock(h, s);
load(&s->input[1], h+16*0, 4);
load(&s->input[11], h+16*1, 4);
memset(h, 0, 32);
s->input[8] = counter[0];
s->input[9] = counter[1];
iv += 16;
}
/* 64-bit iv */
load(&s->input[6], iv, 2);
}
void
salsa_setblock(Salsastate *s, u64int blockno)
{
s->input[8] = blockno;
s->input[9] = blockno>>32;
}
static void
encryptblock(Salsastate *s, uchar *src, uchar *dst)
{
u32int x[Blockwords], t;
int i, rounds;
rounds = s->rounds;
x[0] = s->input[0];
x[1] = s->input[1];
x[2] = s->input[2];
x[3] = s->input[3];
x[4] = s->input[4];
x[5] = s->input[5];
x[6] = s->input[6];
x[7] = s->input[7];
x[8] = s->input[8];
x[9] = s->input[9];
x[10] = s->input[10];
x[11] = s->input[11];
x[12] = s->input[12];
x[13] = s->input[13];
x[14] = s->input[14];
x[15] = s->input[15];
for(i = rounds; i > 0; i -= 2) {
x[4] ^= ROTATE( x[0]+x[12], 7);
x[8] ^= ROTATE( x[4]+ x[0], 9);
x[12] ^= ROTATE( x[8]+ x[4],13);
x[0] ^= ROTATE(x[12]+ x[8],18);
x[9] ^= ROTATE( x[5]+ x[1], 7);
x[13] ^= ROTATE( x[9]+ x[5], 9);
x[1] ^= ROTATE(x[13]+ x[9],13);
x[5] ^= ROTATE( x[1]+x[13],18);
x[14] ^= ROTATE(x[10]+ x[6], 7);
x[2] ^= ROTATE(x[14]+x[10], 9);
x[6] ^= ROTATE( x[2]+x[14],13);
x[10] ^= ROTATE( x[6]+ x[2],18);
x[3] ^= ROTATE(x[15]+x[11], 7);
x[7] ^= ROTATE( x[3]+x[15], 9);
x[11] ^= ROTATE( x[7]+ x[3],13);
x[15] ^= ROTATE(x[11]+ x[7],18);
x[1] ^= ROTATE( x[0]+ x[3], 7);
x[2] ^= ROTATE( x[1]+ x[0], 9);
x[3] ^= ROTATE( x[2]+ x[1],13);
x[0] ^= ROTATE( x[3]+ x[2],18);
x[6] ^= ROTATE( x[5]+ x[4], 7);
x[7] ^= ROTATE( x[6]+ x[5], 9);
x[4] ^= ROTATE( x[7]+ x[6],13);
x[5] ^= ROTATE( x[4]+ x[7],18);
x[11] ^= ROTATE(x[10]+ x[9], 7);
x[8] ^= ROTATE(x[11]+x[10], 9);
x[9] ^= ROTATE( x[8]+x[11],13);
x[10] ^= ROTATE( x[9]+ x[8],18);
x[12] ^= ROTATE(x[15]+x[14], 7);
x[13] ^= ROTATE(x[12]+x[15], 9);
x[14] ^= ROTATE(x[13]+x[12],13);
x[15] ^= ROTATE(x[14]+x[13],18);
}
#ifdef FULL_UNROLL
ENCRYPT(src+0*4, x[0], s->input[0], dst+0*4);
ENCRYPT(src+1*4, x[1], s->input[1], dst+1*4);
ENCRYPT(src+2*4, x[2], s->input[2], dst+2*4);
ENCRYPT(src+3*4, x[3], s->input[3], dst+3*4);
ENCRYPT(src+4*4, x[4], s->input[4], dst+4*4);
ENCRYPT(src+5*4, x[5], s->input[5], dst+5*4);
ENCRYPT(src+6*4, x[6], s->input[6], dst+6*4);
ENCRYPT(src+7*4, x[7], s->input[7], dst+7*4);
ENCRYPT(src+8*4, x[8], s->input[8], dst+8*4);
ENCRYPT(src+9*4, x[9], s->input[9], dst+9*4);
ENCRYPT(src+10*4, x[10], s->input[10], dst+10*4);
ENCRYPT(src+11*4, x[11], s->input[11], dst+11*4);
ENCRYPT(src+12*4, x[12], s->input[12], dst+12*4);
ENCRYPT(src+13*4, x[13], s->input[13], dst+13*4);
ENCRYPT(src+14*4, x[14], s->input[14], dst+14*4);
ENCRYPT(src+15*4, x[15], s->input[15], dst+15*4);
#else
for(i=0; i<nelem(x); i+=4){
ENCRYPT(src, x[i], s->input[i], dst);
ENCRYPT(src+4, x[i+1], s->input[i+1], dst+4);
ENCRYPT(src+8, x[i+2], s->input[i+2], dst+8);
ENCRYPT(src+12, x[i+3], s->input[i+3], dst+12);
src += 16;
dst += 16;
}
#endif
if(++s->input[8] == 0)
s->input[9]++;
}
void
salsa_encrypt2(uchar *src, uchar *dst, ulong bytes, Salsastate *s)
{
uchar tmp[SalsaBsize];
for(; bytes >= SalsaBsize; bytes -= SalsaBsize){
encryptblock(s, src, dst);
src += SalsaBsize;
dst += SalsaBsize;
}
if(bytes > 0){
memmove(tmp, src, bytes);
encryptblock(s, tmp, tmp);
memmove(dst, tmp, bytes);
}
}
void
salsa_encrypt(uchar *buf, ulong bytes, Salsastate *s)
{
salsa_encrypt2(buf, buf, bytes, s);
}
void
hsalsa(uchar h[32], uchar *key, ulong keylen, uchar nonce[16], int rounds)
{
Salsastate s[1];
setupSalsastate(s, key, keylen, nonce, 16, rounds);
hsalsablock(h, s);
memset(s, 0, sizeof(s));
}