diff options
Diffstat (limited to 'src/crypto/dh/dh.c')
| -rw-r--r-- | src/crypto/dh/dh.c | 66 |
1 files changed, 32 insertions, 34 deletions
diff --git a/src/crypto/dh/dh.c b/src/crypto/dh/dh.c index c884ae34..3356776f 100644 --- a/src/crypto/dh/dh.c +++ b/src/crypto/dh/dh.c @@ -138,32 +138,30 @@ void DH_get0_pqg(const DH *dh, const BIGNUM **out_p, const BIGNUM **out_q, } int DH_generate_parameters_ex(DH *dh, int prime_bits, int generator, BN_GENCB *cb) { - /* We generate DH parameters as follows - * find a prime q which is prime_bits/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. - * - * 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 - * - * Thanks to Phil Karn <karn@qualcomm.com> 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. - */ + // We generate DH parameters as follows + // find a prime q which is prime_bits/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. + // + // 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 + // + // Thanks to Phil Karn <karn@qualcomm.com> 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. BIGNUM *t1, *t2; int g, ok = 0; @@ -180,7 +178,7 @@ int DH_generate_parameters_ex(DH *dh, int prime_bits, int generator, BN_GENCB *c goto err; } - /* Make sure |dh| has the necessary elements */ + // Make sure |dh| has the necessary elements if (dh->p == NULL) { dh->p = BN_new(); if (dh->p == NULL) { @@ -213,14 +211,14 @@ int DH_generate_parameters_ex(DH *dh, int prime_bits, int generator, BN_GENCB *c if (!BN_set_word(t2, 3)) { goto err; } - /* BN_set_word(t3,7); just have to miss - * out on these ones :-( */ + // BN_set_word(t3,7); just have to miss + // out on these ones :-( g = 5; } else { - /* in the general case, don't worry if 'generator' is a - * generator or not: since we are using safe primes, - * it will generate either an order-q or an order-2q group, - * which both is OK */ + // in the general case, don't worry if 'generator' is a + // generator or 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)) { goto err; } @@ -299,7 +297,7 @@ int DH_generate_key(DH *dh) { goto err; } } else { - /* secret exponent length */ + // secret exponent length unsigned priv_bits = dh->priv_length; if (priv_bits == 0) { const unsigned p_bits = BN_num_bits(dh->p); |