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Backport _crypto_sign_ed25519_small_order() changes

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This commit is contained in:
Frank Denis 2017-10-23 00:15:52 +02:00
parent 3e6e734605
commit 2cee8ae850
1 changed files with 7 additions and 28 deletions
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35
src/libsodium/crypto_sign/ed25519/ref10/open.c
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@ -34,7 +34,7 @@ crypto_sign_check_S_lt_L(const unsigned char *S)
}
int
_crypto_sign_ed25519_small_order(const unsigned char p[32])
_crypto_sign_ed25519_small_order(const unsigned char s[32])
{
CRYPTO_ALIGN(16)
static const unsigned char blacklist[][32] = {
@ -57,48 +57,27 @@ _crypto_sign_ed25519_small_order(const unsigned char p[32])
0x76, 0x0d, 0x10, 0x67, 0x0f, 0x2a, 0x20, 0x53, 0xfa, 0x2c, 0x39,
0xcc, 0xc6, 0x4e, 0xc7, 0xfd, 0x77, 0x92, 0xac, 0x03, 0x7a },
/* p-1 (order 2) */
{ 0x13, 0xe8, 0x95, 0x8f, 0xc2, 0xb2, 0x27, 0xb0, 0x45, 0xc3, 0xf4,
0x89, 0xf2, 0xef, 0x98, 0xf0, 0xd5, 0xdf, 0xac, 0x05, 0xd3, 0xc6,
0x33, 0x39, 0xb1, 0x38, 0x02, 0x88, 0x6d, 0x53, 0xfc, 0x85 },
/* p (order 4) */
{ 0xb4, 0x17, 0x6a, 0x70, 0x3d, 0x4d, 0xd8, 0x4f, 0xba, 0x3c, 0x0b,
0x76, 0x0d, 0x10, 0x67, 0x0f, 0x2a, 0x20, 0x53, 0xfa, 0x2c, 0x39,
0xcc, 0xc6, 0x4e, 0xc7, 0xfd, 0x77, 0x92, 0xac, 0x03, 0xfa },
/* p+1 (order 1) */
{ 0xec, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f },
/* p+2707385501144840649318225287225658788936804267575313519463743609750303402022
(order 8) */
/* p (=0, order 4) */
{ 0xed, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f },
/* p+55188659117513257062467267217118295137698188065244968500265048394206261417927
(order 8) */
/* p+1 (=1, order 1) */
{ 0xee, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f },
/* 2p-1 (order 2) */
{ 0xd9, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
/* 2p (order 4) */
{ 0xda, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
/* 2p+1 (order 1) */
{ 0xdb, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f }
};
size_t i, j;
unsigned char c;
for (i = 0; i < sizeof blacklist / sizeof blacklist[0]; i++) {
c = 0;
for (j = 0; j < 32; j++) {
c |= p[j] ^ blacklist[i][j];
for (j = 0; j < 31; j++) {
c |= s[j] ^ blacklist[i][j];
}
c |= (s[j] & 0x7f) ^ blacklist[i][j];
if (c == 0) {
return 1;
}