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crypto: switch poly1305 to incremental implementation
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This code is taken from poly1305-donna-32.h, poly1305-donna.h, poly1305-donna.c
from https://github.com/floodyberry/poly1305-donna, commit
e6ad6e091d30d7f4ec2d4f978be1fcfcbce72781, with the following modifications:

* Coding style (braces around one-line indented if/for loops).
* Rename unsigned long (long) to uint32_t and uint64_t.
* Rename poly1305_block_size to POLY1305_BLOCK_SIZE.
* Adding noexcept to functions.
* Merging poly1305_state_internal_t and poly1305_context types.
* Merging code from multiple files.
* Place all imported code in the poly1305_donna namespace.
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@sipa
sipa committed Jul 12, 2023
1 parent b479474 commit 50269b3
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334 changes: 212 additions & 122 deletions src/crypto/poly1305.cpp
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// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

// Based on the public domain implementation by Andrew Moon
// poly1305-donna-unrolled.c from https://github.com/floodyberry/poly1305-donna

#include <crypto/common.h>
#include <crypto/poly1305.h>

#include <string.h>

#define mul32x32_64(a,b) ((uint64_t)(a) * (b))
namespace poly1305_donna {

void poly1305_auth(unsigned char out[POLY1305_TAGLEN], const unsigned char *m, size_t inlen, const unsigned char key[POLY1305_KEYLEN]) {
uint32_t t0,t1,t2,t3;
uint32_t h0,h1,h2,h3,h4;
// Based on the public domain implementation by Andrew Moon
// poly1305-donna-32.h from https://github.com/floodyberry/poly1305-donna

void poly1305_init(poly1305_context *st, const unsigned char key[32]) noexcept {
/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
st->r[0] = (ReadLE32(&key[ 0]) ) & 0x3ffffff;
st->r[1] = (ReadLE32(&key[ 3]) >> 2) & 0x3ffff03;
st->r[2] = (ReadLE32(&key[ 6]) >> 4) & 0x3ffc0ff;
st->r[3] = (ReadLE32(&key[ 9]) >> 6) & 0x3f03fff;
st->r[4] = (ReadLE32(&key[12]) >> 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 */
st->pad[0] = ReadLE32(&key[16]);
st->pad[1] = ReadLE32(&key[20]);
st->pad[2] = ReadLE32(&key[24]);
st->pad[3] = ReadLE32(&key[28]);

st->leftover = 0;
st->final = 0;
}

static void poly1305_blocks(poly1305_context *st, const unsigned char *m, size_t bytes) noexcept {
const uint32_t hibit = (st->final) ? 0 : (1UL << 24); /* 1 << 128 */
uint32_t r0,r1,r2,r3,r4;
uint32_t s1,s2,s3,s4;
uint32_t b, nb;
size_t j;
uint64_t t[5];
uint64_t f0,f1,f2,f3;
uint64_t g0,g1,g2,g3,g4;
uint64_t c;
unsigned char mp[16];

/* clamp key */
t0 = ReadLE32(key+0);
t1 = ReadLE32(key+4);
t2 = ReadLE32(key+8);
t3 = ReadLE32(key+12);

/* precompute multipliers */
r0 = t0 & 0x3ffffff; t0 >>= 26; t0 |= t1 << 6;
r1 = t0 & 0x3ffff03; t1 >>= 20; t1 |= t2 << 12;
r2 = t1 & 0x3ffc0ff; t2 >>= 14; t2 |= t3 << 18;
r3 = t2 & 0x3f03fff; t3 >>= 8;
r4 = t3 & 0x00fffff;
uint32_t h0,h1,h2,h3,h4;
uint64_t d0,d1,d2,d3,d4;
uint32_t 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;

/* init state */
h0 = 0;
h1 = 0;
h2 = 0;
h3 = 0;
h4 = 0;

/* full blocks */
if (inlen < 16) goto poly1305_donna_atmost15bytes;
poly1305_donna_16bytes:
m += 16;
inlen -= 16;

t0 = ReadLE32(m-16);
t1 = ReadLE32(m-12);
t2 = ReadLE32(m-8);
t3 = ReadLE32(m-4);

h0 += t0 & 0x3ffffff;
h1 += ((((uint64_t)t1 << 32) | t0) >> 26) & 0x3ffffff;
h2 += ((((uint64_t)t2 << 32) | t1) >> 20) & 0x3ffffff;
h3 += ((((uint64_t)t3 << 32) | t2) >> 14) & 0x3ffffff;
h4 += (t3 >> 8) | (1 << 24);


poly1305_donna_mul:
t[0] = mul32x32_64(h0,r0) + mul32x32_64(h1,s4) + mul32x32_64(h2,s3) + mul32x32_64(h3,s2) + mul32x32_64(h4,s1);
t[1] = mul32x32_64(h0,r1) + mul32x32_64(h1,r0) + mul32x32_64(h2,s4) + mul32x32_64(h3,s3) + mul32x32_64(h4,s2);
t[2] = mul32x32_64(h0,r2) + mul32x32_64(h1,r1) + mul32x32_64(h2,r0) + mul32x32_64(h3,s4) + mul32x32_64(h4,s3);
t[3] = mul32x32_64(h0,r3) + mul32x32_64(h1,r2) + mul32x32_64(h2,r1) + mul32x32_64(h3,r0) + mul32x32_64(h4,s4);
t[4] = mul32x32_64(h0,r4) + mul32x32_64(h1,r3) + mul32x32_64(h2,r2) + mul32x32_64(h3,r1) + mul32x32_64(h4,r0);

h0 = (uint32_t)t[0] & 0x3ffffff; c = (t[0] >> 26);
t[1] += c; h1 = (uint32_t)t[1] & 0x3ffffff; b = (uint32_t)(t[1] >> 26);
t[2] += b; h2 = (uint32_t)t[2] & 0x3ffffff; b = (uint32_t)(t[2] >> 26);
t[3] += b; h3 = (uint32_t)t[3] & 0x3ffffff; b = (uint32_t)(t[3] >> 26);
t[4] += b; h4 = (uint32_t)t[4] & 0x3ffffff; b = (uint32_t)(t[4] >> 26);
h0 += b * 5;

if (inlen >= 16) goto poly1305_donna_16bytes;

/* final bytes */
poly1305_donna_atmost15bytes:
if (!inlen) goto poly1305_donna_finish;

for (j = 0; j < inlen; j++) mp[j] = m[j];
mp[j++] = 1;
for (; j < 16; j++) mp[j] = 0;
inlen = 0;

t0 = ReadLE32(mp+0);
t1 = ReadLE32(mp+4);
t2 = ReadLE32(mp+8);
t3 = ReadLE32(mp+12);

h0 += t0 & 0x3ffffff;
h1 += ((((uint64_t)t1 << 32) | t0) >> 26) & 0x3ffffff;
h2 += ((((uint64_t)t2 << 32) | t1) >> 20) & 0x3ffffff;
h3 += ((((uint64_t)t3 << 32) | t2) >> 14) & 0x3ffffff;
h4 += (t3 >> 8);

goto poly1305_donna_mul;

poly1305_donna_finish:
b = h0 >> 26; h0 = h0 & 0x3ffffff;
h1 += b; b = h1 >> 26; h1 = h1 & 0x3ffffff;
h2 += b; b = h2 >> 26; h2 = h2 & 0x3ffffff;
h3 += b; b = h3 >> 26; h3 = h3 & 0x3ffffff;
h4 += b; b = h4 >> 26; h4 = h4 & 0x3ffffff;
h0 += b * 5; b = h0 >> 26; h0 = h0 & 0x3ffffff;
h1 += b;

g0 = h0 + 5; b = g0 >> 26; g0 &= 0x3ffffff;
g1 = h1 + b; b = g1 >> 26; g1 &= 0x3ffffff;
g2 = h2 + b; b = g2 >> 26; g2 &= 0x3ffffff;
g3 = h3 + b; b = g3 >> 26; g3 &= 0x3ffffff;
g4 = h4 + b - (1 << 26);

b = (g4 >> 31) - 1;
nb = ~b;
h0 = (h0 & nb) | (g0 & b);
h1 = (h1 & nb) | (g1 & b);
h2 = (h2 & nb) | (g2 & b);
h3 = (h3 & nb) | (g3 & b);
h4 = (h4 & nb) | (g4 & b);

f0 = ((h0 ) | (h1 << 26)) + (uint64_t)ReadLE32(&key[16]);
f1 = ((h1 >> 6) | (h2 << 20)) + (uint64_t)ReadLE32(&key[20]);
f2 = ((h2 >> 12) | (h3 << 14)) + (uint64_t)ReadLE32(&key[24]);
f3 = ((h3 >> 18) | (h4 << 8)) + (uint64_t)ReadLE32(&key[28]);

WriteLE32(&out[ 0], f0); f1 += (f0 >> 32);
WriteLE32(&out[ 4], f1); f2 += (f1 >> 32);
WriteLE32(&out[ 8], f2); f3 += (f2 >> 32);
WriteLE32(&out[12], f3);
h0 = st->h[0];
h1 = st->h[1];
h2 = st->h[2];
h3 = st->h[3];
h4 = st->h[4];

while (bytes >= POLY1305_BLOCK_SIZE) {
/* h += m[i] */
h0 += (ReadLE32(m+ 0) ) & 0x3ffffff;
h1 += (ReadLE32(m+ 3) >> 2) & 0x3ffffff;
h2 += (ReadLE32(m+ 6) >> 4) & 0x3ffffff;
h3 += (ReadLE32(m+ 9) >> 6) & 0x3ffffff;
h4 += (ReadLE32(m+12) >> 8) | hibit;

/* h *= r */
d0 = ((uint64_t)h0 * r0) + ((uint64_t)h1 * s4) + ((uint64_t)h2 * s3) + ((uint64_t)h3 * s2) + ((uint64_t)h4 * s1);
d1 = ((uint64_t)h0 * r1) + ((uint64_t)h1 * r0) + ((uint64_t)h2 * s4) + ((uint64_t)h3 * s3) + ((uint64_t)h4 * s2);
d2 = ((uint64_t)h0 * r2) + ((uint64_t)h1 * r1) + ((uint64_t)h2 * r0) + ((uint64_t)h3 * s4) + ((uint64_t)h4 * s3);
d3 = ((uint64_t)h0 * r3) + ((uint64_t)h1 * r2) + ((uint64_t)h2 * r1) + ((uint64_t)h3 * r0) + ((uint64_t)h4 * s4);
d4 = ((uint64_t)h0 * r4) + ((uint64_t)h1 * r3) + ((uint64_t)h2 * r2) + ((uint64_t)h3 * r1) + ((uint64_t)h4 * r0);

/* (partial) h %= p */
c = (uint32_t)(d0 >> 26); h0 = (uint32_t)d0 & 0x3ffffff;
d1 += c; c = (uint32_t)(d1 >> 26); h1 = (uint32_t)d1 & 0x3ffffff;
d2 += c; c = (uint32_t)(d2 >> 26); h2 = (uint32_t)d2 & 0x3ffffff;
d3 += c; c = (uint32_t)(d3 >> 26); h3 = (uint32_t)d3 & 0x3ffffff;
d4 += c; c = (uint32_t)(d4 >> 26); h4 = (uint32_t)d4 & 0x3ffffff;
h0 += c * 5; c = (h0 >> 26); h0 = h0 & 0x3ffffff;
h1 += c;

m += POLY1305_BLOCK_SIZE;
bytes -= POLY1305_BLOCK_SIZE;
}

st->h[0] = h0;
st->h[1] = h1;
st->h[2] = h2;
st->h[3] = h3;
st->h[4] = h4;
}

void poly1305_finish(poly1305_context *st, unsigned char mac[16]) noexcept {
uint32_t h0,h1,h2,h3,h4,c;
uint32_t g0,g1,g2,g3,g4;
uint64_t f;
uint32_t mask;

/* process the remaining block */
if (st->leftover) {
size_t i = st->leftover;
st->buffer[i++] = 1;
for (; i < POLY1305_BLOCK_SIZE; i++) {
st->buffer[i] = 0;
}
st->final = 1;
poly1305_blocks(st, st->buffer, POLY1305_BLOCK_SIZE);
}

/* 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 >> ((sizeof(uint32_t) * 8) - 1)) - 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 = (uint64_t)h0 + st->pad[0] ; h0 = (uint32_t)f;
f = (uint64_t)h1 + st->pad[1] + (f >> 32); h1 = (uint32_t)f;
f = (uint64_t)h2 + st->pad[2] + (f >> 32); h2 = (uint32_t)f;
f = (uint64_t)h3 + st->pad[3] + (f >> 32); h3 = (uint32_t)f;

WriteLE32(mac + 0, h0);
WriteLE32(mac + 4, h1);
WriteLE32(mac + 8, h2);
WriteLE32(mac + 12, h3);

/* 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;
}

void poly1305_update(poly1305_context *st, const unsigned char *m, size_t bytes) noexcept {
size_t i;

/* handle leftover */
if (st->leftover) {
size_t want = (POLY1305_BLOCK_SIZE - st->leftover);
if (want > bytes) {
want = bytes;
}
for (i = 0; i < want; i++) {
st->buffer[st->leftover + i] = m[i];
}
bytes -= want;
m += want;
st->leftover += want;
if (st->leftover < POLY1305_BLOCK_SIZE) return;
poly1305_blocks(st, st->buffer, POLY1305_BLOCK_SIZE);
st->leftover = 0;
}

/* process full blocks */
if (bytes >= POLY1305_BLOCK_SIZE) {
size_t want = (bytes & ~(POLY1305_BLOCK_SIZE - 1));
poly1305_blocks(st, m, want);
m += want;
bytes -= want;
}

/* store leftover */
if (bytes) {
for (i = 0; i < bytes; i++) {
st->buffer[st->leftover + i] = m[i];
}
st->leftover += bytes;
}
}

} // namespace poly1305_donna

void poly1305_auth(unsigned char mac[16], const unsigned char *m, size_t bytes, const unsigned char key[32]) {
using namespace poly1305_donna;
poly1305_context ctx;
poly1305_init(&ctx, key);
poly1305_update(&ctx, m, bytes);
poly1305_finish(&ctx, mac);
}
21 changes: 21 additions & 0 deletions src/crypto/poly1305.h
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Expand Up @@ -10,6 +10,27 @@

#define POLY1305_KEYLEN 32
#define POLY1305_TAGLEN 16
#define POLY1305_BLOCK_SIZE 16

namespace poly1305_donna {

// Based on the public domain implementation by Andrew Moon
// poly1305-donna-32.h from https://github.com/floodyberry/poly1305-donna

typedef struct {
uint32_t r[5];
uint32_t h[5];
uint32_t pad[4];
size_t leftover;
unsigned char buffer[POLY1305_BLOCK_SIZE];
unsigned char final;
} poly1305_context;

void poly1305_init(poly1305_context *st, const unsigned char key[32]) noexcept;
void poly1305_update(poly1305_context *st, const unsigned char *m, size_t bytes) noexcept;
void poly1305_finish(poly1305_context *st, unsigned char mac[16]) noexcept;

} // namespace poly1305_donna

void poly1305_auth(unsigned char out[POLY1305_TAGLEN], const unsigned char *m, size_t inlen,
const unsigned char key[POLY1305_KEYLEN]);
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