encrypt: add get_symmetric_algorithm

Implement function to map yaca algorithm enums to EVP_CIPHER.

It is currently not very fast, and doesn't handle all algorithms/modes
supported by yaca.

Change-Id: I34c9a78044561b7fdcdc9e23632e45ff745e7f34
Signed-off-by: Mateusz Kulikowski <m.kulikowski@samsung.com>

diff --git a/src/encrypt.c b/src/encrypt.c
index ca8fa1d..596a1a4 100644 (file)
--- a/src/encrypt.c
+++ b/src/encrypt.c
@@ -20,12 +20,90 @@
 
 #include <openssl/crypto.h>
 #include <openssl/rand.h>
+#include <openssl/evp.h>
 
 #include <yaca/crypto.h>
 #include <yaca/error.h>
 
 #include "internal.h"
 
+static const char *symmetric_algo_to_str(yaca_enc_algo_e algo)
+{
+       switch(algo)
+       {
+       case YACA_ENC_AES:
+               return "aes";
+       case YACA_ENC_UNSAFE_DES:
+               return "des";
+       case YACA_ENC_UNSAFE_RC2:
+               return "rc2";
+       case YACA_ENC_UNSAFE_RC4:
+               return "rc4";
+       case YACA_ENC_CAST5:
+               return "cast5";
+
+       case YACA_ENC_UNSAFE_3DES_2TDEA: // TODO: add 3des/2tdea support
+       case YACA_ENC_3DES_3TDEA:  // TODO: add 3des/3tdea support
+       case YACA_ENC_UNSAFE_SKIPJACK:  // TODO: add skipjack implementation
+       default:
+               return NULL;
+       }
+}
+
+static const char *bcm_to_str(yaca_block_cipher_mode_e bcm)
+{
+       switch (bcm) {
+       case YACA_BCM_ECB:
+               return "ecb";
+       case YACA_BCM_CBC:
+               return "cbc";
+       case YACA_BCM_CTR:
+               return "ctr";
+       case YACA_BCM_GCM:
+               return "gcm";
+       case YACA_BCM_CFB:
+               return "cfb";
+       case YACA_BCM_OFB:
+               return "ofb";
+       case YACA_BCM_OCB:
+               return "ocb";
+       case YACA_BCM_CCM:
+               return "ccm";
+       default:
+               return NULL;
+       }
+}
+
+int get_symmetric_algorithm(yaca_enc_algo_e algo,
+                           yaca_block_cipher_mode_e bcm,
+                           unsigned key_bits,
+                           const EVP_CIPHER **cipher)
+{
+       char cipher_name[32];
+       const char *algo_name = symmetric_algo_to_str(algo);
+       const char *bcm_name = bcm_to_str(bcm);
+       const EVP_CIPHER *lcipher;
+       int ret;
+
+       if (algo_name == NULL || bcm_name == NULL || key_bits == 0 ||
+           cipher == NULL)
+               return YACA_ERROR_INVALID_ARGUMENT;
+
+       ret = snprintf(cipher_name, sizeof(cipher_name), "%s-%d-%s", algo_name,
+                      key_bits, bcm_name);
+       if (ret < 0)
+               return YACA_ERROR_INVALID_ARGUMENT;
+       if ((unsigned)ret >= sizeof(cipher_name)) // output was truncated
+               return YACA_ERROR_INVALID_ARGUMENT;
+
+       lcipher = EVP_get_cipherbyname(cipher_name);
+       if (lcipher == NULL)
+               return YACA_ERROR_OPENSSL_FAILURE; // TODO: yaca_get_error_code_from_openssl(ret);
+
+       *cipher = lcipher;
+       return 0;
+}
+
 API int yaca_encrypt_init(yaca_ctx_h *ctx,
                          yaca_enc_algo_e algo,
                          yaca_block_cipher_mode_e bcm,