1 /* $OpenBSD: poly1305.c,v 1.4 2023/07/17 05:26:38 djm Exp $ */
2 /*
3 * Public Domain poly1305 from Andrew Moon
4 * poly1305-donna-unrolled.c from https://github.com/floodyberry/poly1305-donna
5 */
6
7 #include "includes.h"
8
9 #include <sys/types.h>
10 #ifdef HAVE_STDINT_H
11 # include <stdint.h>
12 #endif
13
14 #include "poly1305.h"
15
16 #define mul32x32_64(a,b) ((uint64_t)(a) * (b))
17
18 #define U8TO32_LE(p) \
19 (((uint32_t)((p)[0])) | \
20 ((uint32_t)((p)[1]) << 8) | \
21 ((uint32_t)((p)[2]) << 16) | \
22 ((uint32_t)((p)[3]) << 24))
23
24 #define U32TO8_LE(p, v) \
25 do { \
26 (p)[0] = (uint8_t)((v)); \
27 (p)[1] = (uint8_t)((v) >> 8); \
28 (p)[2] = (uint8_t)((v) >> 16); \
29 (p)[3] = (uint8_t)((v) >> 24); \
30 } while (0)
31
32 void
poly1305_auth(unsigned char out[POLY1305_TAGLEN],const unsigned char * m,size_t inlen,const unsigned char key[POLY1305_KEYLEN])33 poly1305_auth(unsigned char out[POLY1305_TAGLEN], const unsigned char *m, size_t inlen, const unsigned char key[POLY1305_KEYLEN]) {
34 uint32_t t0,t1,t2,t3;
35 uint32_t h0,h1,h2,h3,h4;
36 uint32_t r0,r1,r2,r3,r4;
37 uint32_t s1,s2,s3,s4;
38 uint32_t b, nb;
39 size_t j;
40 uint64_t t[5];
41 uint64_t f0,f1,f2,f3;
42 uint32_t g0,g1,g2,g3,g4;
43 uint64_t c;
44 unsigned char mp[16];
45
46 /* clamp key */
47 t0 = U8TO32_LE(key+0);
48 t1 = U8TO32_LE(key+4);
49 t2 = U8TO32_LE(key+8);
50 t3 = U8TO32_LE(key+12);
51
52 /* precompute multipliers */
53 r0 = t0 & 0x3ffffff; t0 >>= 26; t0 |= t1 << 6;
54 r1 = t0 & 0x3ffff03; t1 >>= 20; t1 |= t2 << 12;
55 r2 = t1 & 0x3ffc0ff; t2 >>= 14; t2 |= t3 << 18;
56 r3 = t2 & 0x3f03fff; t3 >>= 8;
57 r4 = t3 & 0x00fffff;
58
59 s1 = r1 * 5;
60 s2 = r2 * 5;
61 s3 = r3 * 5;
62 s4 = r4 * 5;
63
64 /* init state */
65 h0 = 0;
66 h1 = 0;
67 h2 = 0;
68 h3 = 0;
69 h4 = 0;
70
71 /* full blocks */
72 if (inlen < 16) goto poly1305_donna_atmost15bytes;
73 poly1305_donna_16bytes:
74 m += 16;
75 inlen -= 16;
76
77 t0 = U8TO32_LE(m-16);
78 t1 = U8TO32_LE(m-12);
79 t2 = U8TO32_LE(m-8);
80 t3 = U8TO32_LE(m-4);
81
82 h0 += t0 & 0x3ffffff;
83 h1 += ((((uint64_t)t1 << 32) | t0) >> 26) & 0x3ffffff;
84 h2 += ((((uint64_t)t2 << 32) | t1) >> 20) & 0x3ffffff;
85 h3 += ((((uint64_t)t3 << 32) | t2) >> 14) & 0x3ffffff;
86 h4 += (t3 >> 8) | (1 << 24);
87
88
89 poly1305_donna_mul:
90 t[0] = mul32x32_64(h0,r0) + mul32x32_64(h1,s4) + mul32x32_64(h2,s3) + mul32x32_64(h3,s2) + mul32x32_64(h4,s1);
91 t[1] = mul32x32_64(h0,r1) + mul32x32_64(h1,r0) + mul32x32_64(h2,s4) + mul32x32_64(h3,s3) + mul32x32_64(h4,s2);
92 t[2] = mul32x32_64(h0,r2) + mul32x32_64(h1,r1) + mul32x32_64(h2,r0) + mul32x32_64(h3,s4) + mul32x32_64(h4,s3);
93 t[3] = mul32x32_64(h0,r3) + mul32x32_64(h1,r2) + mul32x32_64(h2,r1) + mul32x32_64(h3,r0) + mul32x32_64(h4,s4);
94 t[4] = mul32x32_64(h0,r4) + mul32x32_64(h1,r3) + mul32x32_64(h2,r2) + mul32x32_64(h3,r1) + mul32x32_64(h4,r0);
95
96 h0 = (uint32_t)t[0] & 0x3ffffff; c = (t[0] >> 26);
97 t[1] += c; h1 = (uint32_t)t[1] & 0x3ffffff; b = (uint32_t)(t[1] >> 26);
98 t[2] += b; h2 = (uint32_t)t[2] & 0x3ffffff; b = (uint32_t)(t[2] >> 26);
99 t[3] += b; h3 = (uint32_t)t[3] & 0x3ffffff; b = (uint32_t)(t[3] >> 26);
100 t[4] += b; h4 = (uint32_t)t[4] & 0x3ffffff; b = (uint32_t)(t[4] >> 26);
101 h0 += b * 5;
102
103 if (inlen >= 16) goto poly1305_donna_16bytes;
104
105 /* final bytes */
106 poly1305_donna_atmost15bytes:
107 if (!inlen) goto poly1305_donna_finish;
108
109 for (j = 0; j < inlen; j++) mp[j] = m[j];
110 mp[j++] = 1;
111 for (; j < 16; j++) mp[j] = 0;
112 inlen = 0;
113
114 t0 = U8TO32_LE(mp+0);
115 t1 = U8TO32_LE(mp+4);
116 t2 = U8TO32_LE(mp+8);
117 t3 = U8TO32_LE(mp+12);
118
119 h0 += t0 & 0x3ffffff;
120 h1 += ((((uint64_t)t1 << 32) | t0) >> 26) & 0x3ffffff;
121 h2 += ((((uint64_t)t2 << 32) | t1) >> 20) & 0x3ffffff;
122 h3 += ((((uint64_t)t3 << 32) | t2) >> 14) & 0x3ffffff;
123 h4 += (t3 >> 8);
124
125 goto poly1305_donna_mul;
126
127 poly1305_donna_finish:
128 b = h0 >> 26; h0 = h0 & 0x3ffffff;
129 h1 += b; b = h1 >> 26; h1 = h1 & 0x3ffffff;
130 h2 += b; b = h2 >> 26; h2 = h2 & 0x3ffffff;
131 h3 += b; b = h3 >> 26; h3 = h3 & 0x3ffffff;
132 h4 += b; b = h4 >> 26; h4 = h4 & 0x3ffffff;
133 h0 += b * 5; b = h0 >> 26; h0 = h0 & 0x3ffffff;
134 h1 += b;
135
136 g0 = h0 + 5; b = g0 >> 26; g0 &= 0x3ffffff;
137 g1 = h1 + b; b = g1 >> 26; g1 &= 0x3ffffff;
138 g2 = h2 + b; b = g2 >> 26; g2 &= 0x3ffffff;
139 g3 = h3 + b; b = g3 >> 26; g3 &= 0x3ffffff;
140 g4 = h4 + b - (1 << 26);
141
142 b = (g4 >> 31) - 1;
143 nb = ~b;
144 h0 = (h0 & nb) | (g0 & b);
145 h1 = (h1 & nb) | (g1 & b);
146 h2 = (h2 & nb) | (g2 & b);
147 h3 = (h3 & nb) | (g3 & b);
148 h4 = (h4 & nb) | (g4 & b);
149
150 f0 = ((h0 ) | (h1 << 26)) + (uint64_t)U8TO32_LE(&key[16]);
151 f1 = ((h1 >> 6) | (h2 << 20)) + (uint64_t)U8TO32_LE(&key[20]);
152 f2 = ((h2 >> 12) | (h3 << 14)) + (uint64_t)U8TO32_LE(&key[24]);
153 f3 = ((h3 >> 18) | (h4 << 8)) + (uint64_t)U8TO32_LE(&key[28]);
154
155 U32TO8_LE(&out[ 0], f0); f1 += (f0 >> 32);
156 U32TO8_LE(&out[ 4], f1); f2 += (f1 >> 32);
157 U32TO8_LE(&out[ 8], f2); f3 += (f2 >> 32);
158 U32TO8_LE(&out[12], f3);
159 }
160