diff options
| author | Dr. Stephen Henson <steve@openssl.org> | 2011-12-01 17:27:36 +0000 |
|---|---|---|
| committer | Dr. Stephen Henson <steve@openssl.org> | 2011-12-01 17:27:36 +0000 |
| commit | 07981709667191ae61595a6f40530ccc4e41386f (patch) | |
| tree | e58577826cea242bf32547703d97b83a667f76fc | |
| parent | 28ff14779e7ab3baf0f0c59b5e51380a8d881ad8 (diff) | |
Update DH_check() to peform sensible checks when q parameter is present.
| -rw-r--r-- | crypto/dh/dh.h | 3 | ||||
| -rw-r--r-- | crypto/dh/dh_check.c | 48 |
2 files changed, 42 insertions, 9 deletions
diff --git a/crypto/dh/dh.h b/crypto/dh/dh.h index 2929ebe21f..9b90197acf 100644 --- a/crypto/dh/dh.h +++ b/crypto/dh/dh.h @@ -165,6 +165,9 @@ struct dh_st #define DH_CHECK_P_NOT_SAFE_PRIME 0x02 #define DH_UNABLE_TO_CHECK_GENERATOR 0x04 #define DH_NOT_SUITABLE_GENERATOR 0x08 +#define DH_CHECK_Q_NOT_PRIME 0x10 +#define DH_CHECK_INVALID_Q_VALUE 0x20 +#define DH_CHECK_INVALID_J_VALUE 0x40 /* DH_check_pub_key error codes */ #define DH_CHECK_PUBKEY_TOO_SMALL 0x01 diff --git a/crypto/dh/dh_check.c b/crypto/dh/dh_check.c index 066898174e..fa1df0efc0 100644 --- a/crypto/dh/dh_check.c +++ b/crypto/dh/dh_check.c @@ -75,15 +75,42 @@ 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) goto err; + BN_CTX_start(ctx); + t1=BN_CTX_get(ctx); + 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; @@ -106,16 +133,19 @@ 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 + else if (!dh->q) { - if (!BN_rshift1(q,dh->p)) goto err; - if (!BN_is_prime_ex(q,BN_prime_checks,ctx,NULL)) + if (!BN_rshift1(t1,dh->p)) goto err; + if (!BN_is_prime_ex(t1,BN_prime_checks,ctx,NULL)) *ret|=DH_CHECK_P_NOT_SAFE_PRIME; } ok=1; err: - if (ctx != NULL) BN_CTX_free(ctx); - if (q != NULL) BN_free(q); + if (ctx != NULL) + { + BN_CTX_end(ctx); + BN_CTX_free(ctx); + } return(ok); } |