Fix for CMS/PKCS7 MMA. If RSA decryption fails use a random key and

[openssl.git] / crypto / cms / cms_enc.c

diff --git a/crypto/cms/cms_enc.c b/crypto/cms/cms_enc.c
index bab26235bdc4674d1997b46aa512dba02719f0e0..580083b45f870aebd3e21680cfe70d6d15260dfd 100644 (file)
--- a/crypto/cms/cms_enc.c
+++ b/crypto/cms/cms_enc.c
@@ -73,6 +73,8 @@ BIO *cms_EncryptedContent_init_bio(CMS_EncryptedContentInfo *ec)
        const EVP_CIPHER *ciph;
        X509_ALGOR *calg = ec->contentEncryptionAlgorithm;
        unsigned char iv[EVP_MAX_IV_LENGTH], *piv = NULL;
+       unsigned char *tkey = NULL;
+       size_t tkeylen;
 
        int ok = 0;
 
@@ -137,32 +139,57 @@ BIO *cms_EncryptedContent_init_bio(CMS_EncryptedContentInfo *ec)
                                CMS_R_CIPHER_PARAMETER_INITIALISATION_ERROR);
                goto err;
                }
-
-
-       if (enc && !ec->key)
+       /* Generate random session key */
+       if (!enc || !ec->key)
                {
-               /* Generate random key */
-               if (!ec->keylen)
-                       ec->keylen = EVP_CIPHER_CTX_key_length(ctx);
-               ec->key = OPENSSL_malloc(ec->keylen);
-               if (!ec->key)
+               tkeylen = EVP_CIPHER_CTX_key_length(ctx);
+               tkey = OPENSSL_malloc(tkeylen);
+               if (!tkey)
                        {
                        CMSerr(CMS_F_CMS_ENCRYPTEDCONTENT_INIT_BIO,
                                                        ERR_R_MALLOC_FAILURE);
                        goto err;
                        }
-               if (EVP_CIPHER_CTX_rand_key(ctx, ec->key) <= 0)
+               if (EVP_CIPHER_CTX_rand_key(ctx, tkey) <= 0)
                        goto err;
-               keep_key = 1;
                }
-       else if (ec->keylen != (unsigned int)EVP_CIPHER_CTX_key_length(ctx))
+
+       if (!ec->key)
+               {
+               ec->key = tkey;
+               ec->keylen = tkeylen;
+               tkey = NULL;
+               if (enc)
+                       keep_key = 1;
+               else
+                       ERR_clear_error();
+               
+               }
+
+       if (ec->keylen != tkeylen)
                {
                /* If necessary set key length */
                if (EVP_CIPHER_CTX_set_key_length(ctx, ec->keylen) <= 0)
                        {
-                       CMSerr(CMS_F_CMS_ENCRYPTEDCONTENT_INIT_BIO,
-                               CMS_R_INVALID_KEY_LENGTH);
-                       goto err;
+                       /* Only reveal failure if debugging so we don't
+                        * leak information which may be useful in MMA.
+                        */
+                       if (ec->debug)
+                               {
+                               CMSerr(CMS_F_CMS_ENCRYPTEDCONTENT_INIT_BIO,
+                                               CMS_R_INVALID_KEY_LENGTH);
+                               goto err;
+                               }
+                       else
+                               {
+                               /* Use random key */
+                               OPENSSL_cleanse(ec->key, ec->keylen);
+                               OPENSSL_free(ec->key);
+                               ec->key = tkey;
+                               ec->keylen = tkeylen;
+                               tkey = NULL;
+                               ERR_clear_error();
+                               }
                        }
                }
 
@@ -198,6 +225,11 @@ BIO *cms_EncryptedContent_init_bio(CMS_EncryptedContentInfo *ec)
                OPENSSL_free(ec->key);
                ec->key = NULL;
                }
+       if (tkey)
+               {
+               OPENSSL_cleanse(tkey, tkeylen);
+               OPENSSL_free(tkey);
+               }
        if (ok)
                return b;
        BIO_free(b);