From 9b3d768ceec9e8f051f6f140361a82c231b6a063 Mon Sep 17 00:00:00 2001
From: Mateusz Kulikowski <m.kulikowski@samsung.com>
Date: Mon, 11 Apr 2016 15:31:50 +0200
Subject: [PATCH] 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>
---
 src/encrypt.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/src/encrypt.c b/src/encrypt.c
index ca8fa1d..596a1a4 100644
--- 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,
-- 
2.7.4