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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*/
/* The implementation is based on:
* Public Domain poly1305 from Andrew Moon
* https://github.com/floodyberry/poly1305-donna
*/
#include "tomcrypt.h"
#ifdef LTC_POLY1305
/* internal only */
static void _poly1305_block(poly1305_state *st, const unsigned char *in, unsigned long inlen)
{
const unsigned long hibit = (st->final) ? 0 : (1UL << 24); /* 1 << 128 */
ulong32 r0,r1,r2,r3,r4;
ulong32 s1,s2,s3,s4;
ulong32 h0,h1,h2,h3,h4;
ulong32 tmp;
ulong64 d0,d1,d2,d3,d4;
ulong32 c;
r0 = st->r[0];
r1 = st->r[1];
r2 = st->r[2];
r3 = st->r[3];
r4 = st->r[4];
s1 = r1 * 5;
s2 = r2 * 5;
s3 = r3 * 5;
s4 = r4 * 5;
h0 = st->h[0];
h1 = st->h[1];
h2 = st->h[2];
h3 = st->h[3];
h4 = st->h[4];
while (inlen >= 16) {
/* h += in[i] */
LOAD32L(tmp, in+ 0); h0 += (tmp ) & 0x3ffffff;
LOAD32L(tmp, in+ 3); h1 += (tmp >> 2) & 0x3ffffff;
LOAD32L(tmp, in+ 6); h2 += (tmp >> 4) & 0x3ffffff;
LOAD32L(tmp, in+ 9); h3 += (tmp >> 6) & 0x3ffffff;
LOAD32L(tmp, in+12); h4 += (tmp >> 8) | hibit;
/* h *= r */
d0 = ((ulong64)h0 * r0) + ((ulong64)h1 * s4) + ((ulong64)h2 * s3) + ((ulong64)h3 * s2) + ((ulong64)h4 * s1);
d1 = ((ulong64)h0 * r1) + ((ulong64)h1 * r0) + ((ulong64)h2 * s4) + ((ulong64)h3 * s3) + ((ulong64)h4 * s2);
d2 = ((ulong64)h0 * r2) + ((ulong64)h1 * r1) + ((ulong64)h2 * r0) + ((ulong64)h3 * s4) + ((ulong64)h4 * s3);
d3 = ((ulong64)h0 * r3) + ((ulong64)h1 * r2) + ((ulong64)h2 * r1) + ((ulong64)h3 * r0) + ((ulong64)h4 * s4);
d4 = ((ulong64)h0 * r4) + ((ulong64)h1 * r3) + ((ulong64)h2 * r2) + ((ulong64)h3 * r1) + ((ulong64)h4 * r0);
/* (partial) h %= p */
c = (ulong32)(d0 >> 26); h0 = (ulong32)d0 & 0x3ffffff;
d1 += c; c = (ulong32)(d1 >> 26); h1 = (ulong32)d1 & 0x3ffffff;
d2 += c; c = (ulong32)(d2 >> 26); h2 = (ulong32)d2 & 0x3ffffff;
d3 += c; c = (ulong32)(d3 >> 26); h3 = (ulong32)d3 & 0x3ffffff;
d4 += c; c = (ulong32)(d4 >> 26); h4 = (ulong32)d4 & 0x3ffffff;
h0 += c * 5; c = (h0 >> 26); h0 = h0 & 0x3ffffff;
h1 += c;
in += 16;
inlen -= 16;
}
st->h[0] = h0;
st->h[1] = h1;
st->h[2] = h2;
st->h[3] = h3;
st->h[4] = h4;
}
/**
Initialize an POLY1305 context.
@param st The POLY1305 state
@param key The secret key
@param keylen The length of the secret key (octets)
@return CRYPT_OK if successful
*/
int poly1305_init(poly1305_state *st, const unsigned char *key, unsigned long keylen)
{
LTC_ARGCHK(st != NULL);
LTC_ARGCHK(key != NULL);
LTC_ARGCHK(keylen == 32);
/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
LOAD32L(st->r[0], key + 0); st->r[0] = (st->r[0] ) & 0x3ffffff;
LOAD32L(st->r[1], key + 3); st->r[1] = (st->r[1] >> 2) & 0x3ffff03;
LOAD32L(st->r[2], key + 6); st->r[2] = (st->r[2] >> 4) & 0x3ffc0ff;
LOAD32L(st->r[3], key + 9); st->r[3] = (st->r[3] >> 6) & 0x3f03fff;
LOAD32L(st->r[4], key + 12); st->r[4] = (st->r[4] >> 8) & 0x00fffff;
/* h = 0 */
st->h[0] = 0;
st->h[1] = 0;
st->h[2] = 0;
st->h[3] = 0;
st->h[4] = 0;
/* save pad for later */
LOAD32L(st->pad[0], key + 16);
LOAD32L(st->pad[1], key + 20);
LOAD32L(st->pad[2], key + 24);
LOAD32L(st->pad[3], key + 28);
st->leftover = 0;
st->final = 0;
return CRYPT_OK;
}
/**
Process data through POLY1305
@param st The POLY1305 state
@param in The data to send through HMAC
@param inlen The length of the data to HMAC (octets)
@return CRYPT_OK if successful
*/
int poly1305_process(poly1305_state *st, const unsigned char *in, unsigned long inlen)
{
unsigned long i;
if (inlen == 0) return CRYPT_OK; /* nothing to do */
LTC_ARGCHK(st != NULL);
LTC_ARGCHK(in != NULL);
/* handle leftover */
if (st->leftover) {
unsigned long want = (16 - st->leftover);
if (want > inlen) want = inlen;
for (i = 0; i < want; i++) st->buffer[st->leftover + i] = in[i];
inlen -= want;
in += want;
st->leftover += want;
if (st->leftover < 16) return CRYPT_OK;
_poly1305_block(st, st->buffer, 16);
st->leftover = 0;
}
/* process full blocks */
if (inlen >= 16) {
unsigned long want = (inlen & ~(16 - 1));
_poly1305_block(st, in, want);
in += want;
inlen -= want;
}
/* store leftover */
if (inlen) {
for (i = 0; i < inlen; i++) st->buffer[st->leftover + i] = in[i];
st->leftover += inlen;
}
return CRYPT_OK;
}
/**
Terminate a POLY1305 session
@param st The POLY1305 state
@param mac [out] The destination of the POLY1305 authentication tag
@param maclen [in/out] The max size and resulting size of the POLY1305 authentication tag
@return CRYPT_OK if successful
*/
int poly1305_done(poly1305_state *st, unsigned char *mac, unsigned long *maclen)
{
ulong32 h0,h1,h2,h3,h4,c;
ulong32 g0,g1,g2,g3,g4;
ulong64 f;
ulong32 mask;
LTC_ARGCHK(st != NULL);
LTC_ARGCHK(mac != NULL);
LTC_ARGCHK(maclen != NULL);
LTC_ARGCHK(*maclen >= 16);
/* process the remaining block */
if (st->leftover) {
unsigned long i = st->leftover;
st->buffer[i++] = 1;
for (; i < 16; i++) st->buffer[i] = 0;
st->final = 1;
_poly1305_block(st, st->buffer, 16);
}
/* fully carry h */
h0 = st->h[0];
h1 = st->h[1];
h2 = st->h[2];
h3 = st->h[3];
h4 = st->h[4];
c = h1 >> 26; h1 = h1 & 0x3ffffff;
h2 += c; c = h2 >> 26; h2 = h2 & 0x3ffffff;
h3 += c; c = h3 >> 26; h3 = h3 & 0x3ffffff;
h4 += c; c = h4 >> 26; h4 = h4 & 0x3ffffff;
h0 += c * 5; c = h0 >> 26; h0 = h0 & 0x3ffffff;
h1 += c;
/* compute h + -p */
g0 = h0 + 5; c = g0 >> 26; g0 &= 0x3ffffff;
g1 = h1 + c; c = g1 >> 26; g1 &= 0x3ffffff;
g2 = h2 + c; c = g2 >> 26; g2 &= 0x3ffffff;
g3 = h3 + c; c = g3 >> 26; g3 &= 0x3ffffff;
g4 = h4 + c - (1UL << 26);
/* select h if h < p, or h + -p if h >= p */
mask = (g4 >> 31) - 1;
g0 &= mask;
g1 &= mask;
g2 &= mask;
g3 &= mask;
g4 &= mask;
mask = ~mask;
h0 = (h0 & mask) | g0;
h1 = (h1 & mask) | g1;
h2 = (h2 & mask) | g2;
h3 = (h3 & mask) | g3;
h4 = (h4 & mask) | g4;
/* h = h % (2^128) */
h0 = ((h0 ) | (h1 << 26)) & 0xffffffff;
h1 = ((h1 >> 6) | (h2 << 20)) & 0xffffffff;
h2 = ((h2 >> 12) | (h3 << 14)) & 0xffffffff;
h3 = ((h3 >> 18) | (h4 << 8)) & 0xffffffff;
/* mac = (h + pad) % (2^128) */
f = (ulong64)h0 + st->pad[0] ; h0 = (ulong32)f;
f = (ulong64)h1 + st->pad[1] + (f >> 32); h1 = (ulong32)f;
f = (ulong64)h2 + st->pad[2] + (f >> 32); h2 = (ulong32)f;
f = (ulong64)h3 + st->pad[3] + (f >> 32); h3 = (ulong32)f;
STORE32L(h0, mac + 0);
STORE32L(h1, mac + 4);
STORE32L(h2, mac + 8);
STORE32L(h3, mac + 12);
/* zero out the state */
st->h[0] = 0;
st->h[1] = 0;
st->h[2] = 0;
st->h[3] = 0;
st->h[4] = 0;
st->r[0] = 0;
st->r[1] = 0;
st->r[2] = 0;
st->r[3] = 0;
st->r[4] = 0;
st->pad[0] = 0;
st->pad[1] = 0;
st->pad[2] = 0;
st->pad[3] = 0;
*maclen = 16;
return CRYPT_OK;
}
#endif
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */
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