/
mod_ed25519.c
143 lines (114 loc) · 3.05 KB
/
mod_ed25519.c
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
/* $OpenBSD$ */
/*
* Public Domain, Authors: Daniel J. Bernstein, Niels Duif, Tanja Lange,
* Peter Schwabe, Bo-Yin Yang.
* Copied from supercop-20130419/crypto_sign/ed25519/ref/ed25519.c
*/
#include "crypto_api.h"
#include "ge25519.h"
static void get_hram(unsigned char *hram, const unsigned char *sm, const unsigned char *pk, unsigned char *playground, unsigned long long smlen)
{
unsigned long long i;
for (i = 0;i < 32;++i) playground[i] = sm[i];
for (i = 32;i < 64;++i) playground[i] = pk[i-32];
for (i = 64;i < smlen;++i) playground[i] = sm[i];
crypto_hash_sha512(hram,playground,smlen);
}
#ifndef VERIFYONLY
int crypto_sign_ed25519_keypair(
unsigned char *pk,
unsigned char *sk
)
{
sc25519 scsk;
ge25519 gepk;
unsigned char extsk[64];
int i;
randombytes(sk, 32);
crypto_hash_sha512(extsk, sk, 32);
extsk[0] &= 248;
extsk[31] &= 127;
extsk[31] |= 64;
sc25519_from32bytes(&scsk,extsk);
ge25519_scalarmult_base(&gepk, &scsk);
ge25519_pack(pk, &gepk);
for(i=0;i<32;i++)
sk[32 + i] = pk[i];
return 0;
}
int crypto_sign_ed25519(
unsigned char *sm,unsigned long long *smlen,
const unsigned char *m,unsigned long long mlen,
const unsigned char *sk
)
{
sc25519 sck, scs, scsk;
ge25519 ger;
unsigned char r[32];
unsigned char s[32];
unsigned char extsk[64];
unsigned long long i;
unsigned char hmg[crypto_hash_sha512_BYTES];
unsigned char hram[crypto_hash_sha512_BYTES];
crypto_hash_sha512(extsk, sk, 32);
extsk[0] &= 248;
extsk[31] &= 127;
extsk[31] |= 64;
*smlen = mlen+64;
for(i=0;i<mlen;i++)
sm[64 + i] = m[i];
for(i=0;i<32;i++)
sm[32 + i] = extsk[32+i];
crypto_hash_sha512(hmg, sm+32, mlen+32); /* Generate k as h(extsk[32],...,extsk[63],m) */
/* Computation of R */
sc25519_from64bytes(&sck, hmg);
ge25519_scalarmult_base(&ger, &sck);
ge25519_pack(r, &ger);
/* Computation of s */
for(i=0;i<32;i++)
sm[i] = r[i];
get_hram(hram, sm, sk+32, sm, mlen+64);
sc25519_from64bytes(&scs, hram);
sc25519_from32bytes(&scsk, extsk);
sc25519_mul(&scs, &scs, &scsk);
sc25519_add(&scs, &scs, &sck);
sc25519_to32bytes(s,&scs); /* cat s */
for(i=0;i<32;i++)
sm[32 + i] = s[i];
return 0;
}
#endif
int crypto_sign_ed25519_open(
unsigned char *m,unsigned long long *mlen,
const unsigned char *sm,unsigned long long smlen,
const unsigned char *pk
)
{
unsigned int i;
int ret;
unsigned char t2[32];
ge25519 get1, get2;
sc25519 schram, scs;
unsigned char hram[crypto_hash_sha512_BYTES];
*mlen = (unsigned long long) -1;
if (smlen < 64) return -1;
if (ge25519_unpackneg_vartime(&get1, pk)) return -1;
get_hram(hram,sm,pk,m,smlen);
sc25519_from64bytes(&schram, hram);
sc25519_from32bytes(&scs, sm+32);
ge25519_double_scalarmult_vartime(&get2, &get1, &schram, &ge25519_base, &scs);
ge25519_pack(t2, &get2);
ret = crypto_verify_32(sm, t2);
if (!ret)
{
for(i=0;i<smlen-64;i++)
m[i] = sm[i + 64];
*mlen = smlen-64;
}
else
{
for(i=0;i<smlen-64;i++)
m[i] = 0;
}
return ret;
}