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Diffstat (limited to 'crypto/rsa/rsa_oaep.c')
-rw-r--r--crypto/rsa/rsa_oaep.c97
1 files changed, 63 insertions, 34 deletions
diff --git a/crypto/rsa/rsa_oaep.c b/crypto/rsa/rsa_oaep.c
index e3f7c608ec..553d212ebe 100644
--- a/crypto/rsa/rsa_oaep.c
+++ b/crypto/rsa/rsa_oaep.c
@@ -28,7 +28,7 @@
#include <openssl/rand.h>
#include <openssl/sha.h>
-int MGF1(unsigned char *mask, long len,
+static int MGF1(unsigned char *mask, long len,
const unsigned char *seed, long seedlen);
int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
@@ -52,18 +52,12 @@ int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
return 0;
}
- dbmask = OPENSSL_malloc(emlen - SHA_DIGEST_LENGTH);
- if (dbmask == NULL)
- {
- RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
- return 0;
- }
-
to[0] = 0;
seed = to + 1;
db = to + SHA_DIGEST_LENGTH + 1;
- EVP_Digest((void *)param, plen, db, NULL, EVP_sha1(), NULL);
+ if (!EVP_Digest((void *)param, plen, db, NULL, EVP_sha1(), NULL))
+ return 0;
memset(db + SHA_DIGEST_LENGTH, 0,
emlen - flen - 2 * SHA_DIGEST_LENGTH - 1);
db[emlen - flen - SHA_DIGEST_LENGTH - 1] = 0x01;
@@ -76,11 +70,20 @@ int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
20);
#endif
- MGF1(dbmask, emlen - SHA_DIGEST_LENGTH, seed, SHA_DIGEST_LENGTH);
+ dbmask = OPENSSL_malloc(emlen - SHA_DIGEST_LENGTH);
+ if (dbmask == NULL)
+ {
+ RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+
+ if (MGF1(dbmask, emlen - SHA_DIGEST_LENGTH, seed, SHA_DIGEST_LENGTH) < 0)
+ return 0;
for (i = 0; i < emlen - SHA_DIGEST_LENGTH; i++)
db[i] ^= dbmask[i];
- MGF1(seedmask, SHA_DIGEST_LENGTH, db, emlen - SHA_DIGEST_LENGTH);
+ if (MGF1(seedmask, SHA_DIGEST_LENGTH, db, emlen - SHA_DIGEST_LENGTH) < 0)
+ return 0;
for (i = 0; i < SHA_DIGEST_LENGTH; i++)
seed[i] ^= seedmask[i];
@@ -96,6 +99,7 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
const unsigned char *maskeddb;
int lzero;
unsigned char *db = NULL, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
+ unsigned char *padded_from;
int bad = 0;
if (--num < 2 * SHA_DIGEST_LENGTH + 1)
@@ -106,8 +110,6 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
lzero = num - flen;
if (lzero < 0)
{
- /* lzero == -1 */
-
/* signalling this error immediately after detection might allow
* for side-channel attacks (e.g. timing if 'plen' is huge
* -- cf. James H. Manger, "A Chosen Ciphertext Attack on RSA Optimal
@@ -115,26 +117,37 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
* so we use a 'bad' flag */
bad = 1;
lzero = 0;
+ flen = num; /* don't overflow the memcpy to padded_from */
}
- maskeddb = from - lzero + SHA_DIGEST_LENGTH;
dblen = num - SHA_DIGEST_LENGTH;
- db = OPENSSL_malloc(dblen);
+ db = OPENSSL_malloc(dblen + num);
if (db == NULL)
{
- RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
+ RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
return -1;
}
- MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen);
- for (i = lzero; i < SHA_DIGEST_LENGTH; i++)
- seed[i] ^= from[i - lzero];
+ /* Always do this zero-padding copy (even when lzero == 0)
+ * to avoid leaking timing info about the value of lzero. */
+ padded_from = db + dblen;
+ memset(padded_from, 0, lzero);
+ memcpy(padded_from + lzero, from, flen);
+
+ maskeddb = padded_from + SHA_DIGEST_LENGTH;
+
+ if (MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen))
+ return -1;
+ for (i = 0; i < SHA_DIGEST_LENGTH; i++)
+ seed[i] ^= padded_from[i];
- MGF1(db, dblen, seed, SHA_DIGEST_LENGTH);
+ if (MGF1(db, dblen, seed, SHA_DIGEST_LENGTH))
+ return -1;
for (i = 0; i < dblen; i++)
db[i] ^= maskeddb[i];
- EVP_Digest((void *)param, plen, phash, NULL, EVP_sha1(), NULL);
+ if (!EVP_Digest((void *)param, plen, phash, NULL, EVP_sha1(), NULL))
+ return -1;
if (memcmp(db, phash, SHA_DIGEST_LENGTH) != 0 || bad)
goto decoding_err;
@@ -143,13 +156,13 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
for (i = SHA_DIGEST_LENGTH; i < dblen; i++)
if (db[i] != 0x00)
break;
- if (db[i] != 0x01 || i++ >= dblen)
+ if (i == dblen || db[i] != 0x01)
goto decoding_err;
else
{
/* everything looks OK */
- mlen = dblen - i;
+ mlen = dblen - ++i;
if (tlen < mlen)
{
RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE);
@@ -170,37 +183,53 @@ decoding_err:
return -1;
}
-int MGF1(unsigned char *mask, long len,
- const unsigned char *seed, long seedlen)
+int PKCS1_MGF1(unsigned char *mask, long len,
+ const unsigned char *seed, long seedlen, const EVP_MD *dgst)
{
long i, outlen = 0;
unsigned char cnt[4];
EVP_MD_CTX c;
- unsigned char md[SHA_DIGEST_LENGTH];
+ unsigned char md[EVP_MAX_MD_SIZE];
+ int mdlen;
+ int rv = -1;
EVP_MD_CTX_init(&c);
+ mdlen = EVP_MD_size(dgst);
+ if (mdlen < 0)
+ goto err;
for (i = 0; outlen < len; i++)
{
cnt[0] = (unsigned char)((i >> 24) & 255);
cnt[1] = (unsigned char)((i >> 16) & 255);
cnt[2] = (unsigned char)((i >> 8)) & 255;
cnt[3] = (unsigned char)(i & 255);
- EVP_DigestInit_ex(&c,EVP_sha1(), NULL);
- EVP_DigestUpdate(&c, seed, seedlen);
- EVP_DigestUpdate(&c, cnt, 4);
- if (outlen + SHA_DIGEST_LENGTH <= len)
+ if (!EVP_DigestInit_ex(&c,dgst, NULL)
+ || !EVP_DigestUpdate(&c, seed, seedlen)
+ || !EVP_DigestUpdate(&c, cnt, 4))
+ goto err;
+ if (outlen + mdlen <= len)
{
- EVP_DigestFinal_ex(&c, mask + outlen, NULL);
- outlen += SHA_DIGEST_LENGTH;
+ if (!EVP_DigestFinal_ex(&c, mask + outlen, NULL))
+ goto err;
+ outlen += mdlen;
}
else
{
- EVP_DigestFinal_ex(&c, md, NULL);
+ if (!EVP_DigestFinal_ex(&c, md, NULL))
+ goto err;
memcpy(mask + outlen, md, len - outlen);
outlen = len;
}
}
+ rv = 0;
+ err:
EVP_MD_CTX_cleanup(&c);
- return 0;
+ return rv;
+ }
+
+static int MGF1(unsigned char *mask, long len, const unsigned char *seed,
+ long seedlen)
+ {
+ return PKCS1_MGF1(mask, len, seed, seedlen, EVP_sha1());
}
#endif
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