ref: 23d5a950c92dfbcf26b069059712fa282255a8ac
dir: /sys/src/libsec/port/salsa.c/
#include "os.h"
#include <libsec.h>
/* little-endian data order */
#define GET4(p) ((p)[0]|((p)[1]<<8)|((p)[2]<<16)|((p)[3]<<24))
#define PUT4(p,v) (p)[0]=(v);(p)[1]=(v)>>8;(p)[2]=(v)>>16;(p)[3]=(v)>>24
#define ROTATE(v,c) (t = v, (u32int)(t << (c)) | (t >> (32 - (c))))
#define ENCRYPT(s, x, y, d) {\
u32int v; \
v = GET4(s); \
v ^= (x)+(y); \
PUT4(d, 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) /* hsalsa, xsalsa */
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->xkey[0] = s->input[1];
s->xkey[1] = s->input[2];
s->xkey[2] = s->input[3];
s->xkey[3] = s->input[4];
s->xkey[4] = s->input[11];
s->xkey[5] = s->input[12];
s->xkey[6] = s->input[13];
s->xkey[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
dorounds(u32int x[16], int rounds)
{
u32int t;
for(; rounds > 0; rounds -= 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);
}
}
static void
hsalsablock(uchar h[32], Salsastate *s)
{
u32int x[16];
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];
dorounds(x, s->rounds);
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 with 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->xkey[0];
s->input[2] = s->xkey[1];
s->input[3] = s->xkey[2];
s->input[4] = s->xkey[3];
s->input[11] = s->xkey[4];
s->input[12] = s->xkey[5];
s->input[13] = s->xkey[6];
s->input[14] = s->xkey[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[16];
int i;
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];
dorounds(x, s->rounds);
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;
}
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
salsa_core(u32int in[16], u32int out[16], int rounds)
{
u32int x[16];
x[0] = in[0];
x[1] = in[1];
x[2] = in[2];
x[3] = in[3];
x[4] = in[4];
x[5] = in[5];
x[6] = in[6];
x[7] = in[7];
x[8] = in[8];
x[9] = in[9];
x[10] = in[10];
x[11] = in[11];
x[12] = in[12];
x[13] = in[13];
x[14] = in[14];
x[15] = in[15];
dorounds(x, rounds);
out[0] = x[0] + in[0];
out[1] = x[1] + in[1];
out[2] = x[2] + in[2];
out[3] = x[3] + in[3];
out[4] = x[4] + in[4];
out[5] = x[5] + in[5];
out[6] = x[6] + in[6];
out[7] = x[7] + in[7];
out[8] = x[8] + in[8];
out[9] = x[9] + in[9];
out[10] = x[10] + in[10];
out[11] = x[11] + in[11];
out[12] = x[12] + in[12];
out[13] = x[13] + in[13];
out[14] = x[14] + in[14];
out[15] = x[15] + in[15];
}
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));
}