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path: root/crypto/dh/dh_check.c
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Diffstat (limited to 'crypto/dh/dh_check.c')
-rw-r--r--crypto/dh/dh_check.c46
1 files changed, 36 insertions, 10 deletions
diff --git a/crypto/dh/dh_check.c b/crypto/dh/dh_check.c
index c39ed97ba6275..347467c6a4336 100644
--- a/crypto/dh/dh_check.c
+++ b/crypto/dh/dh_check.c
@@ -76,17 +76,43 @@ int DH_check(const DH *dh, int *ret)
int ok = 0;
BN_CTX *ctx = NULL;
BN_ULONG l;
- BIGNUM *q = NULL;
+ BIGNUM *t1 = NULL, *t2 = NULL;
*ret = 0;
ctx = BN_CTX_new();
if (ctx == NULL)
goto err;
- q = BN_new();
- if (q == NULL)
+ BN_CTX_start(ctx);
+ t1 = BN_CTX_get(ctx);
+ if (t1 == NULL)
+ goto err;
+ t2 = BN_CTX_get(ctx);
+ if (t2 == NULL)
goto err;
- if (BN_is_word(dh->g, DH_GENERATOR_2)) {
+ if (dh->q) {
+ if (BN_cmp(dh->g, BN_value_one()) <= 0)
+ *ret |= DH_NOT_SUITABLE_GENERATOR;
+ else if (BN_cmp(dh->g, dh->p) >= 0)
+ *ret |= DH_NOT_SUITABLE_GENERATOR;
+ else {
+ /* Check g^q == 1 mod p */
+ if (!BN_mod_exp(t1, dh->g, dh->q, dh->p, ctx))
+ goto err;
+ if (!BN_is_one(t1))
+ *ret |= DH_NOT_SUITABLE_GENERATOR;
+ }
+ if (!BN_is_prime_ex(dh->q, BN_prime_checks, ctx, NULL))
+ *ret |= DH_CHECK_Q_NOT_PRIME;
+ /* Check p == 1 mod q i.e. q divides p - 1 */
+ if (!BN_div(t1, t2, dh->p, dh->q, ctx))
+ goto err;
+ if (!BN_is_one(t2))
+ *ret |= DH_CHECK_INVALID_Q_VALUE;
+ if (dh->j && BN_cmp(dh->j, t1))
+ *ret |= DH_CHECK_INVALID_J_VALUE;
+
+ } else if (BN_is_word(dh->g, DH_GENERATOR_2)) {
l = BN_mod_word(dh->p, 24);
if (l != 11)
*ret |= DH_NOT_SUITABLE_GENERATOR;
@@ -107,18 +133,18 @@ int DH_check(const DH *dh, int *ret)
if (!BN_is_prime_ex(dh->p, BN_prime_checks, ctx, NULL))
*ret |= DH_CHECK_P_NOT_PRIME;
- else {
- if (!BN_rshift1(q, dh->p))
+ else if (!dh->q) {
+ if (!BN_rshift1(t1, dh->p))
goto err;
- if (!BN_is_prime_ex(q, BN_prime_checks, ctx, NULL))
+ if (!BN_is_prime_ex(t1, BN_prime_checks, ctx, NULL))
*ret |= DH_CHECK_P_NOT_SAFE_PRIME;
}
ok = 1;
err:
- if (ctx != NULL)
+ if (ctx != NULL) {
+ BN_CTX_end(ctx);
BN_CTX_free(ctx);
- if (q != NULL)
- BN_free(q);
+ }
return (ok);
}