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/*
20250126
*/
/*
Based on poly1305-donna (https://github.com/floodyberry/poly1305-donna)
- modified for NaCl API
- switched to cryptoint
*/
#include "crypto_onetimeauth_poly1305.h"
#include "haslib1305.h"
#ifndef HASLIB1305
#include "crypto_int16.h"
#include "crypto_uint32.h"
#include "crypto_uint64.h"
/* clang-format off */
int crypto_onetimeauth_poly1305_tinyssh(unsigned char *o,
const unsigned char *m,
unsigned long long n,
const unsigned char *k) {
crypto_uint32 h0, h1, h2, h3, h4;
crypto_uint32 r0, r1, r2, r3, r4;
crypto_uint32 s1, s2, s3, s4;
crypto_uint64 d0, d1, d2, d3, d4;
crypto_uint32 c, mask;
crypto_uint64 f;
crypto_uint64 i;
/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
r0 = (crypto_uint32_load(k + 0) ) & 0x3ffffff;
r1 = (crypto_uint32_load(k + 3) >> 2) & 0x3ffff03;
r2 = (crypto_uint32_load(k + 6) >> 4) & 0x3ffc0ff;
r3 = (crypto_uint32_load(k + 9) >> 6) & 0x3f03fff;
r4 = (crypto_uint32_load(k + 12) >> 8) & 0x00fffff;
s1 = r1 * 5;
s2 = r2 * 5;
s3 = r3 * 5;
s4 = r4 * 5;
/* h = 0 */
h0 = h1 = h2 = h3 = h4 = 0;
while (n > 0) {
/* h += m[i] */
if (n >= 16) {
h0 += (crypto_uint32_load(m ) ) & 0x3ffffff;
h1 += (crypto_uint32_load(m + 3) >> 2) & 0x3ffffff;
h2 += (crypto_uint32_load(m + 6) >> 4) & 0x3ffffff;
h3 += (crypto_uint32_load(m + 9) >> 6) & 0x3ffffff;
h4 += (crypto_uint32_load(m + 12) >> 8) | 16777216;
m += 16;
n -= 16;
}
else {
unsigned char mm[16];
for (i = 0; i < 16; ++i) mm[i] = 0;
for (i = 0; i < n; ++i) mm[i] = m[i];
mm[i] = 1;
h0 += (crypto_uint32_load(mm ) ) & 0x3ffffff;
h1 += (crypto_uint32_load(mm + 3) >> 2) & 0x3ffffff;
h2 += (crypto_uint32_load(mm + 6) >> 4) & 0x3ffffff;
h3 += (crypto_uint32_load(mm + 9) >> 6) & 0x3ffffff;
h4 += (crypto_uint32_load(mm + 12) >> 8);
n = 0;
}
/* h *= r */
d0 = ((crypto_uint64)h0 * r0) + ((crypto_uint64)h1 * s4) + ((crypto_uint64)h2 * s3) + ((crypto_uint64)h3 * s2) + ((crypto_uint64)h4 * s1);
d1 = ((crypto_uint64)h0 * r1) + ((crypto_uint64)h1 * r0) + ((crypto_uint64)h2 * s4) + ((crypto_uint64)h3 * s3) + ((crypto_uint64)h4 * s2);
d2 = ((crypto_uint64)h0 * r2) + ((crypto_uint64)h1 * r1) + ((crypto_uint64)h2 * r0) + ((crypto_uint64)h3 * s4) + ((crypto_uint64)h4 * s3);
d3 = ((crypto_uint64)h0 * r3) + ((crypto_uint64)h1 * r2) + ((crypto_uint64)h2 * r1) + ((crypto_uint64)h3 * r0) + ((crypto_uint64)h4 * s4);
d4 = ((crypto_uint64)h0 * r4) + ((crypto_uint64)h1 * r3) + ((crypto_uint64)h2 * r2) + ((crypto_uint64)h3 * r1) + ((crypto_uint64)h4 * r0);
/* (partial) h %= p */
c = (crypto_uint32)(d0 >> 26); h0 = (crypto_uint32)d0 & 0x3ffffff;
d1 += c; c = (crypto_uint32)(d1 >> 26); h1 = (crypto_uint32)d1 & 0x3ffffff;
d2 += c; c = (crypto_uint32)(d2 >> 26); h2 = (crypto_uint32)d2 & 0x3ffffff;
d3 += c; c = (crypto_uint32)(d3 >> 26); h3 = (crypto_uint32)d3 & 0x3ffffff;
d4 += c; c = (crypto_uint32)(d4 >> 26); h4 = (crypto_uint32)d4 & 0x3ffffff;
h0 += c * 5; c = (h0 >> 26); h0 = h0 & 0x3ffffff;
h1 += c;
}
/* fully carry h */
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 */
r0 = h0 + 5; c = r0 >> 26; r0 &= 0x3ffffff;
r1 = h1 + c; c = r1 >> 26; r1 &= 0x3ffffff;
r2 = h2 + c; c = r2 >> 26; r2 &= 0x3ffffff;
r3 = h3 + c; c = r3 >> 26; r3 &= 0x3ffffff;
r4 = h4 + c - (1 << 26);
/* select h if h < p, or h + -p if h >= p */
mask = crypto_uint32_topbit_01(r4);
mask -= 1;
r0 ^= h0;
r1 ^= h1;
r2 ^= h2;
r3 ^= h3;
r4 ^= h4;
h0 ^= mask & r0;
h1 ^= mask & r1;
h2 ^= mask & r2;
h3 ^= mask & r3;
h4 ^= mask & r4;
/* 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 = (crypto_uint64)h0 + crypto_uint32_load(k + 16) ; h0 = (crypto_uint32)f;
f = (crypto_uint64)h1 + crypto_uint32_load(k + 20) + (f >> 32); h1 = (crypto_uint32)f;
f = (crypto_uint64)h2 + crypto_uint32_load(k + 24) + (f >> 32); h2 = (crypto_uint32)f;
f = (crypto_uint64)h3 + crypto_uint32_load(k + 28) + (f >> 32); h3 = (crypto_uint32)f;
crypto_uint32_store(o + 0, h0);
crypto_uint32_store(o + 4, h1);
crypto_uint32_store(o + 8, h2);
crypto_uint32_store(o + 12, h3);
return 0;
}
int crypto_onetimeauth_poly1305_tinyssh_verify(const unsigned char *h,
const unsigned char *in,
unsigned long long l,
const unsigned char *k) {
unsigned char correct[16];
crypto_int16 d = 0;
long long i;
crypto_onetimeauth_poly1305(correct, in, l, k);
for (i = 0; i < 16; ++i) d |= correct[i] ^ h[i];
return crypto_int16_nonzero_mask(d);
}
/* clang-format on */
#endif
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