X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=bluesky%2Fcrypto.c;h=8aeba3aebc2e7c4ae124959033442bea1962ddc1;hb=fe2b07cf3f79430f9b4d16a8d567ea9b6178d9d2;hp=6eec4643e380b13626a2da9b9b92e18cd83c0762;hpb=c83d8b650786b8e7d6a9d41c9449c203929c7215;p=bluesky.git

diff --git a/bluesky/crypto.c b/bluesky/crypto.c
index 6eec464..8aeba3a 100644
--- a/bluesky/crypto.c
+++ b/bluesky/crypto.c
@@ -19,9 +19,6 @@
  * the functions in this file, so this is the only point where we interface
  * with an external cryptographic library. */
 
-#define CRYPTO_BLOCK_SIZE 16        /* 128-bit AES */
-#define CRYPTO_KEY_SIZE   16
-
 GCRY_THREAD_OPTION_PTHREAD_IMPL;
 
 void bluesky_crypt_init()
@@ -74,8 +71,8 @@ BlueSkyRCStr *bluesky_crypt_encrypt(BlueSkyRCStr *in, const uint8_t *key)
                 gcry_strerror(status));
     }
 
-    gcry_cipher_encrypt(handle, out + CRYPTO_BLOCK_SIZE, in->len,
-                        in->data, in->len);
+    status = gcry_cipher_encrypt(handle, out + CRYPTO_BLOCK_SIZE, in->len,
+                                 in->data, in->len);
     if (status) {
         g_error("gcrypt error encrypting: %s\n",
                 gcry_strerror(status));
@@ -85,3 +82,45 @@ BlueSkyRCStr *bluesky_crypt_encrypt(BlueSkyRCStr *in, const uint8_t *key)
 
     return bluesky_string_new(out, in->len + CRYPTO_BLOCK_SIZE);
 }
+
+/* Decrypt a data block. */
+BlueSkyRCStr *bluesky_crypt_decrypt(BlueSkyRCStr *in, const uint8_t *key)
+{
+    gcry_error_t status;
+    gcry_cipher_hd_t handle;
+
+    g_return_val_if_fail(in->len > CRYPTO_BLOCK_SIZE, NULL);
+
+    status = gcry_cipher_open(&handle, GCRY_CIPHER_AES, GCRY_CIPHER_MODE_CBC,
+                              GCRY_CIPHER_CBC_CTS);
+    if (status) {
+        g_error("gcrypt error setting up encryption: %s\n",
+                gcry_strerror(status));
+    }
+
+    uint8_t *out = g_malloc0(in->len - CRYPTO_BLOCK_SIZE);
+
+    gcry_cipher_setkey(handle, key, CRYPTO_KEY_SIZE);
+    if (status) {
+        g_error("gcrypt error setting key: %s\n",
+                gcry_strerror(status));
+    }
+
+    status = gcry_cipher_setiv(handle, in->data, CRYPTO_BLOCK_SIZE);
+    if (status) {
+        g_error("gcrypt error setting IV: %s\n",
+                gcry_strerror(status));
+    }
+
+    status = gcry_cipher_decrypt(handle, out, in->len - CRYPTO_BLOCK_SIZE,
+                                 in->data + CRYPTO_BLOCK_SIZE,
+                                 in->len - CRYPTO_BLOCK_SIZE);
+    if (status) {
+        g_error("gcrypt error decrypting: %s\n",
+                gcry_strerror(status));
+    }
+
+    gcry_cipher_close(handle);
+
+    return bluesky_string_new(out, in->len + CRYPTO_BLOCK_SIZE);
+}