1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
|
/*
* Derived from poly1305-donna-64.h by Andrew Moon <liquidsun@gmail.com>
* in https://github.com/floodyberry/poly1305-donna
*
* (C) 2014 Andrew Moon
* (C) 2014 Jack Lloyd
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_POLY1305_DONNA_H__
#define BOTAN_POLY1305_DONNA_H__
#include <botan/loadstor.h>
#include <botan/mul128.h>
#if !defined(BOTAN_TARGET_HAS_NATIVE_UINT128)
#include <botan/internal/donna128.h>
#endif
namespace Botan {
namespace {
#if !defined(BOTAN_TARGET_HAS_NATIVE_UINT128)
typedef donna128 uint128_t;
#else
inline u64bit carry_shift(const uint128_t a, size_t shift)
{
return static_cast<u64bit>(a >> shift);
}
#endif
void poly1305_init(secure_vector<u64bit>& X, const byte key[32])
{
/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
const u64bit t0 = load_le<u64bit>(key, 0);
const u64bit t1 = load_le<u64bit>(key, 1);
X[0] = ( t0 ) & 0xffc0fffffff;
X[1] = ((t0 >> 44) | (t1 << 20)) & 0xfffffc0ffff;
X[2] = ((t1 >> 24) ) & 0x00ffffffc0f;
/* h = 0 */
X[3] = 0;
X[4] = 0;
X[5] = 0;
/* save pad for later */
X[6] = load_le<u64bit>(key, 2);
X[7] = load_le<u64bit>(key, 3);
}
void poly1305_blocks(secure_vector<u64bit>& X, const byte *m, size_t blocks, bool is_final = false)
{
const u64bit hibit = is_final ? 0 : (static_cast<u64bit>(1) << 40); /* 1 << 128 */
//u64bit c;
const u64bit r0 = X[0];
const u64bit r1 = X[1];
const u64bit r2 = X[2];
u64bit h0 = X[3+0];
u64bit h1 = X[3+1];
u64bit h2 = X[3+2];
const u64bit s1 = r1 * (5 << 2);
const u64bit s2 = r2 * (5 << 2);
while(blocks--)
{
/* h += m[i] */
const u64bit t0 = load_le<u64bit>(m, 0);
const u64bit t1 = load_le<u64bit>(m, 1);
h0 += (( t0 ) & 0xfffffffffff);
h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffff);
h2 += (((t1 >> 24) ) & 0x3ffffffffff) | hibit;
/* h *= r */
uint128_t d0 = uint128_t(h0) * r0 + uint128_t(h1) * s2 + uint128_t(h2) * s1;
uint128_t d1 = uint128_t(h0) * r1 + uint128_t(h1) * r0 + uint128_t(h2) * s2;
uint128_t d2 = uint128_t(h0) * r2 + uint128_t(h1) * r1 + uint128_t(h2) * r0;
/* (partial) h %= p */
u64bit c = carry_shift(d0, 44); h0 = d0 & 0xfffffffffff;
d1 += c; c = carry_shift(d1, 44); h1 = d1 & 0xfffffffffff;
d2 += c; c = carry_shift(d2, 42); h2 = d2 & 0x3ffffffffff;
h0 += c * 5; c = carry_shift(h0, 44); h0 = h0 & 0xfffffffffff;
h1 += c;
m += 16;
}
X[3+0] = h0;
X[3+1] = h1;
X[3+2] = h2;
}
void poly1305_finish(secure_vector<u64bit>& X, byte mac[16])
{
/* fully carry h */
u64bit h0 = X[3+0];
u64bit h1 = X[3+1];
u64bit h2 = X[3+2];
u64bit c;
c = (h1 >> 44); h1 &= 0xfffffffffff;
h2 += c; c = (h2 >> 42); h2 &= 0x3ffffffffff;
h0 += c * 5; c = (h0 >> 44); h0 &= 0xfffffffffff;
h1 += c; c = (h1 >> 44); h1 &= 0xfffffffffff;
h2 += c; c = (h2 >> 42); h2 &= 0x3ffffffffff;
h0 += c * 5; c = (h0 >> 44); h0 &= 0xfffffffffff;
h1 += c;
/* compute h + -p */
u64bit g0 = h0 + 5; c = (g0 >> 44); g0 &= 0xfffffffffff;
u64bit g1 = h1 + c; c = (g1 >> 44); g1 &= 0xfffffffffff;
u64bit g2 = h2 + c - ((u64bit)1 << 42);
/* select h if h < p, or h + -p if h >= p */
c = (g2 >> ((sizeof(u64bit) * 8) - 1)) - 1;
g0 &= c;
g1 &= c;
g2 &= c;
c = ~c;
h0 = (h0 & c) | g0;
h1 = (h1 & c) | g1;
h2 = (h2 & c) | g2;
/* h = (h + pad) */
const u64bit t0 = X[6];
const u64bit t1 = X[7];
h0 += (( t0 ) & 0xfffffffffff) ; c = (h0 >> 44); h0 &= 0xfffffffffff;
h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffff) + c; c = (h1 >> 44); h1 &= 0xfffffffffff;
h2 += (((t1 >> 24) ) & 0x3ffffffffff) + c; h2 &= 0x3ffffffffff;
/* mac = h % (2^128) */
h0 = ((h0 ) | (h1 << 44));
h1 = ((h1 >> 20) | (h2 << 24));
store_le(&mac[0], h0, h1);
/* zero out the state */
zero_mem(&X[0], X.size());
}
}
}
#endif
|
