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[oweals/openssl.git] / crypto / rsa / rsa_oaep.c

diff --git a/crypto/rsa/rsa_oaep.c b/crypto/rsa/rsa_oaep.c
index 5637a31ce86ede3bee9799b2db4d4ce2cec1bc77..1849e55cd5de0980afabbccc828f47e24105e4ef 100644 (file)
--- a/crypto/rsa/rsa_oaep.c
+++ b/crypto/rsa/rsa_oaep.c
@@ -34,7 +34,7 @@ int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
        return (0);
        }
     
-    dbmask = Malloc(emlen - 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);
@@ -50,7 +50,8 @@ int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
           emlen - flen - 2 * SHA_DIGEST_LENGTH - 1);
     db[emlen - flen - SHA_DIGEST_LENGTH - 1] = 0x01;
     memcpy(db + emlen - flen - SHA_DIGEST_LENGTH, from, (unsigned int) flen);
-    RAND_bytes(seed, SHA_DIGEST_LENGTH);
+    if (RAND_bytes(seed, SHA_DIGEST_LENGTH) <= 0)
+       return (0);
 #ifdef PKCS_TESTVECT
     memcpy(seed,
           "\xaa\xfd\x12\xf6\x59\xca\xe6\x34\x89\xb4\x79\xe5\x07\x6d\xde\xc2\xf0\x6c\xb5\x8f",
@@ -65,7 +66,7 @@ int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
     for (i = 0; i < SHA_DIGEST_LENGTH; i++)
        seed[i] ^= seedmask[i];
 
-    Free(dbmask);
+    OPENSSL_free(dbmask);
     return (1);
     }
 
@@ -75,27 +76,28 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
     {
     int i, dblen, mlen = -1;
     unsigned char *maskeddb;
-    unsigned char *db, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
+    int lzero;
+    unsigned char *db = NULL, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
 
-    if (flen < 2 * SHA_DIGEST_LENGTH + 1)
-       {
-       RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
-       return (-1);
-       }
+    if (--num < 2 * SHA_DIGEST_LENGTH + 1)
+       goto decoding_err;
 
-    dblen = flen - SHA_DIGEST_LENGTH;
-    db = Malloc(dblen);
+    lzero = num - flen;
+    if (lzero < 0)
+       goto decoding_err;
+    maskeddb = from - lzero + SHA_DIGEST_LENGTH;
+    
+    dblen = num - SHA_DIGEST_LENGTH;
+    db = OPENSSL_malloc(dblen);
     if (db == NULL)
        {
        RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
        return (-1);
        }
 
-    maskeddb = from + SHA_DIGEST_LENGTH;
-    
     MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen);
-    for (i = 0; i < SHA_DIGEST_LENGTH; i++)
-       seed[i] ^= from[i];
+    for (i = lzero; i < SHA_DIGEST_LENGTH; i++)
+       seed[i] ^= from[i - lzero];
   
     MGF1(db, dblen, seed, SHA_DIGEST_LENGTH);
     for (i = 0; i < dblen; i++)
@@ -104,29 +106,35 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
     SHA1(param, plen, phash);
 
     if (memcmp(db, phash, SHA_DIGEST_LENGTH) != 0)
-       RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
+       goto decoding_err;
     else
        {
        for (i = SHA_DIGEST_LENGTH; i < dblen; i++)
            if (db[i] != 0x00)
                break;
        if (db[i] != 0x01 || i++ >= dblen)
-           RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP,
-                  RSA_R_OAEP_DECODING_ERROR);
+         goto decoding_err;
        else
            {
            mlen = dblen - i;
            if (tlen < mlen)
                {
-               RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE);
+               RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE);
                mlen = -1;
                }
            else
                memcpy(to, db + i, mlen);
            }
        }
-    Free(db);
+    OPENSSL_free(db);
     return (mlen);
+
+decoding_err:
+    /* to avoid chosen ciphertext attacks, the error message should not reveal
+     * which kind of decoding error happened */
+    RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
+    if (db != NULL) OPENSSL_free(db);
+    return -1;
     }
 
 int MGF1(unsigned char *mask, long len, unsigned char *seed, long seedlen)