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Hakase
2019-09-21 00:43:47 +09:00
parent 2e57f602ae
commit 62515c7d8d
1131 changed files with 47556 additions and 24957 deletions
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crypto/dh/dh_gen.c
+36 -29
View File
@@ -1,5 +1,5 @@
/*
* Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.
* Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
@@ -30,30 +30,29 @@ int DH_generate_parameters_ex(DH *ret, int prime_len, int generator,
/*-
* We generate DH parameters as follows
* find a prime q which is prime_len/2 bits long.
* p=(2*q)+1 or (p-1)/2 = q
* For this case, g is a generator if
* g^((p-1)/q) mod p != 1 for values of q which are the factors of p-1.
* Since the factors of p-1 are q and 2, we just need to check
* g^2 mod p != 1 and g^q mod p != 1.
* find a prime p which is prime_len bits long,
* where q=(p-1)/2 is also prime.
* In the following we assume that g is not 0, 1 or p-1, since it
* would generate only trivial subgroups.
* For this case, g is a generator of the order-q subgroup if
* g^q mod p == 1.
* Or in terms of the Legendre symbol: (g/p) == 1.
*
* Having said all that,
* there is another special case method for the generators 2, 3 and 5.
* for 2, p mod 24 == 11
* for 3, p mod 12 == 5 <<<<< does not work for safe primes.
* for 5, p mod 10 == 3 or 7
* Using the quadratic reciprocity law it is possible to solve
* (g/p) == 1 for the special values 2, 3, 5:
* (2/p) == 1 if p mod 8 == 1 or 7.
* (3/p) == 1 if p mod 12 == 1 or 11.
* (5/p) == 1 if p mod 5 == 1 or 4.
* See for instance: https://en.wikipedia.org/wiki/Legendre_symbol
*
* Thanks to Phil Karn for the pointers about the
* special generators and for answering some of my questions.
*
* I've implemented the second simple method :-).
* Since DH should be using a safe prime (both p and q are prime),
* this generator function can take a very very long time to run.
*/
/*
* Actually there is no reason to insist that 'generator' be a generator.
* It's just as OK (and in some sense better) to use a generator of the
* order-q subgroup.
* Since all safe primes > 7 must satisfy p mod 12 == 11
* and all safe primes > 11 must satisfy p mod 5 != 1
* we can further improve the condition for g = 2, 3 and 5:
* for 2, p mod 24 == 23
* for 3, p mod 12 == 11
* for 5, p mod 60 == 59
*/
static int dh_builtin_genparams(DH *ret, int prime_len, int generator,
BN_GENCB *cb)
@@ -62,6 +61,16 @@ static int dh_builtin_genparams(DH *ret, int prime_len, int generator,
int g, ok = -1;
BN_CTX *ctx = NULL;
if (prime_len > OPENSSL_DH_MAX_MODULUS_BITS) {
DHerr(DH_F_DH_BUILTIN_GENPARAMS, DH_R_MODULUS_TOO_LARGE);
return 0;
}
if (prime_len < DH_MIN_MODULUS_BITS) {
DHerr(DH_F_DH_BUILTIN_GENPARAMS, DH_R_MODULUS_TOO_SMALL);
return 0;
}
ctx = BN_CTX_new();
if (ctx == NULL)
goto err;
@@ -84,17 +93,14 @@ static int dh_builtin_genparams(DH *ret, int prime_len, int generator,
if (generator == DH_GENERATOR_2) {
if (!BN_set_word(t1, 24))
goto err;
if (!BN_set_word(t2, 11))
if (!BN_set_word(t2, 23))
goto err;
g = 2;
} else if (generator == DH_GENERATOR_5) {
if (!BN_set_word(t1, 10))
if (!BN_set_word(t1, 60))
goto err;
if (!BN_set_word(t2, 3))
if (!BN_set_word(t2, 59))
goto err;
/*
* BN_set_word(t3,7); just have to miss out on these ones :-(
*/
g = 5;
} else {
/*
@@ -102,9 +108,9 @@ static int dh_builtin_genparams(DH *ret, int prime_len, int generator,
* not: since we are using safe primes, it will generate either an
* order-q or an order-2q group, which both is OK
*/
if (!BN_set_word(t1, 2))
if (!BN_set_word(t1, 12))
goto err;
if (!BN_set_word(t2, 1))
if (!BN_set_word(t2, 11))
goto err;
g = generator;
}
@@ -115,6 +121,7 @@ static int dh_builtin_genparams(DH *ret, int prime_len, int generator,
goto err;
if (!BN_set_word(ret->g, g))
goto err;
ret->dirty_cnt++;
ok = 1;
err:
if (ok == -1) {