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Clean up |ECDH_compute_key|.

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1. Check for the presence of the private key before allocating or
   computing anything.
2. Check the return value of |BN_CTX_get|.
3. Don't bother computing the Y coordinate since it is not used.
4. |OPENSSL_cleanse| the temporary buffer.
5. Remove conditional logic in cleanup section.
This commit is contained in:
Brian Smith 2015-10-08 11:52:56 -10:00
parent a347436e9e
commit 18093e10b9
1 changed files with 26 additions and 30 deletions
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56
crypto/ecdh/ecdh.c
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@ -78,29 +78,24 @@
int ECDH_compute_key(void *out, size_t outlen, const EC_POINT *pub_key,
EC_KEY *priv_key, void *(*KDF)(const void *in, size_t inlen,
void *out, size_t *outlen)) {
BN_CTX *ctx;
EC_POINT *tmp = NULL;
BIGNUM *x = NULL, *y = NULL;
const BIGNUM *priv;
const EC_GROUP *group;
int ret = -1;
size_t buflen;
uint8_t *buf = NULL;
if ((ctx = BN_CTX_new()) == NULL) {
goto err;
}
BN_CTX_start(ctx);
x = BN_CTX_get(ctx);
y = BN_CTX_get(ctx);
priv = EC_KEY_get0_private_key(priv_key);
const BIGNUM *priv = EC_KEY_get0_private_key(priv_key);
if (priv == NULL) {
OPENSSL_PUT_ERROR(ECDH, ECDH_R_NO_PRIVATE_VALUE);
goto err;
return -1;
}
group = EC_KEY_get0_group(priv_key);
BN_CTX *ctx = BN_CTX_new();
if (ctx == NULL) {
return -1;
}
BN_CTX_start(ctx);
int ret = -1;
EC_POINT *tmp = NULL;
size_t buflen = 0;
uint8_t *buf = NULL;
const EC_GROUP *group = EC_KEY_get0_group(priv_key);
tmp = EC_POINT_new(group);
if (tmp == NULL) {
@ -113,7 +108,13 @@ int ECDH_compute_key(void *out, size_t outlen, const EC_POINT *pub_key,
goto err;
}
if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) {
BIGNUM *x = BN_CTX_get(ctx);
if (!x) {
OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE);
goto err;
}
if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, NULL, ctx)) {
OPENSSL_PUT_ERROR(ECDH, ECDH_R_POINT_ARITHMETIC_FAILURE);
goto err;
}
@ -146,18 +147,13 @@ int ECDH_compute_key(void *out, size_t outlen, const EC_POINT *pub_key,
}
err:
if (tmp) {
EC_POINT_free(tmp);
}
if (ctx) {
BN_CTX_end(ctx);
}
if (ctx) {
BN_CTX_free(ctx);
}
if (buf) {
OPENSSL_free(buf);
OPENSSL_cleanse(buf, buflen);
}
OPENSSL_free(buf);
EC_POINT_free(tmp);
BN_CTX_end(ctx);
BN_CTX_free(ctx);
return ret;
}