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SRP code tidy.

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Tidy up srp_Calc_k and SRP_Calc_u by making them a special case of
srp_Calc_xy which performs SHA1(PAD(x) | PAD(y)).

This addresses an OCAP Audit issue.

Reviewed-by: Rich Salz <rsalz@openssl.org>
This commit is contained in:
Dr. Stephen Henson 2016-09-29 19:24:26 +01:00
parent a00d75e1b2
commit 8f332ac962
1 changed files with 17 additions and 69 deletions
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86
crypto/srp/srp_lib.c
View file

@ -14,92 +14,40 @@
# include <openssl/evp.h>
# include "internal/bn_srp.h"
static BIGNUM *srp_Calc_k(const BIGNUM *N, const BIGNUM *g)
{
/* k = SHA1(N | PAD(g)) -- tls-srp draft 8 */
/* calculate = SHA1(PAD(x) || PAD(y)) */
static BIGNUM *srp_Calc_xy(const BIGNUM *x, const BIGNUM *y, const BIGNUM *N)
{
unsigned char digest[SHA_DIGEST_LENGTH];
unsigned char *tmp = NULL;
EVP_MD_CTX *ctxt = NULL;
int longg;
int longN = BN_num_bytes(N);
int numN = BN_num_bytes(N);
BIGNUM *res = NULL;
if (BN_ucmp(g, N) >= 0)
if (x != N && BN_ucmp(x, N) >= 0)
return NULL;
ctxt = EVP_MD_CTX_new();
if (ctxt == NULL)
if (y != N && BN_ucmp(y, N) >= 0)
return NULL;
if ((tmp = OPENSSL_malloc(longN)) == NULL)
if ((tmp = OPENSSL_malloc(numN * 2)) == NULL)
goto err;
BN_bn2bin(N, tmp);
if (!EVP_DigestInit_ex(ctxt, EVP_sha1(), NULL)
|| !EVP_DigestUpdate(ctxt, tmp, longN))
goto err;
memset(tmp, 0, longN);
longg = BN_bn2bin(g, tmp);
/* use the zeros behind to pad on left */
if (!EVP_DigestUpdate(ctxt, tmp + longg, longN - longg)
|| !EVP_DigestUpdate(ctxt, tmp, longg))
goto err;
if (!EVP_DigestFinal_ex(ctxt, digest, NULL))
if (BN_bn2binpad(x, tmp, numN) < 0
|| BN_bn2binpad(y, tmp + numN, numN) < 0
|| !EVP_Digest(tmp, numN * 2, digest, NULL, EVP_sha1(), NULL))
goto err;
res = BN_bin2bn(digest, sizeof(digest), NULL);
err:
OPENSSL_free(tmp);
EVP_MD_CTX_free(ctxt);
return res;
}
static BIGNUM *srp_Calc_k(const BIGNUM *N, const BIGNUM *g)
{
/* k = SHA1(N | PAD(g)) -- tls-srp draft 8 */
return srp_Calc_xy(N, g, N);
}
BIGNUM *SRP_Calc_u(const BIGNUM *A, const BIGNUM *B, const BIGNUM *N)
{
/* k = SHA1(PAD(A) || PAD(B) ) -- tls-srp draft 8 */
BIGNUM *u = NULL;
unsigned char cu[SHA_DIGEST_LENGTH];
unsigned char *cAB = NULL;
EVP_MD_CTX *ctxt = NULL;
int longN;
if ((A == NULL) || (B == NULL) || (N == NULL))
return NULL;
if (BN_ucmp(A, N) >= 0 || BN_ucmp(B, N) >= 0)
return NULL;
longN = BN_num_bytes(N);
ctxt = EVP_MD_CTX_new();
if (ctxt == NULL)
return NULL;
if ((cAB = OPENSSL_malloc(2 * longN)) == NULL)
goto err;
memset(cAB, 0, longN);
if (!EVP_DigestInit_ex(ctxt, EVP_sha1(), NULL)
|| !EVP_DigestUpdate(ctxt, cAB + BN_bn2bin(A, cAB + longN), longN)
|| !EVP_DigestUpdate(ctxt, cAB + BN_bn2bin(B, cAB + longN), longN))
goto err;
if (!EVP_DigestFinal_ex(ctxt, cu, NULL))
goto err;
if ((u = BN_bin2bn(cu, sizeof(cu), NULL)) == NULL)
goto err;
if (BN_is_zero(u)) {
BN_free(u);
u = NULL;
}
err:
OPENSSL_free(cAB);
EVP_MD_CTX_free(ctxt);
return u;
return srp_Calc_xy(A, B, N);
}
BIGNUM *SRP_Calc_server_key(const BIGNUM *A, const BIGNUM *v, const BIGNUM *u,