X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=bluesky%2Fcrypto.c;h=5b2235736019c7264c5d41810918cdbd04ee3df0;hb=83fd6b61a6e092a22d4d5e59ed95f05f5e287f11;hp=6eec4643e380b13626a2da9b9b92e18cd83c0762;hpb=c83d8b650786b8e7d6a9d41c9449c203929c7215;p=bluesky.git

diff --git a/bluesky/crypto.c b/bluesky/crypto.c
index 6eec464..5b22357 100644
--- a/bluesky/crypto.c
+++ b/bluesky/crypto.c
@@ -7,20 +7,20 @@
  */
 
 #include <stdint.h>
+#include <assert.h>
 #include <errno.h>
 #include <pthread.h>
 #include <glib.h>
 #include <string.h>
 #include <gcrypt.h>
 
-#include "bluesky.h"
+#include "bluesky-private.h"
 
 /* Cryptographic operations.  The rest of the BlueSky code merely calls into
  * 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
+/* TODO: We ought to switch to an authenticated encryption mode like EAX. */
 
 GCRY_THREAD_OPTION_PTHREAD_IMPL;
 
@@ -31,8 +31,6 @@ void bluesky_crypt_init()
     if (gcry_control(GCRYCTL_INITIALIZATION_FINISHED_P))
         return;
 
-    g_print("libgcrypt not yet initialized, initializing...\n");
-
     if (!gcry_check_version(GCRYPT_VERSION))
         g_error("libgcrypt version mismatch\n");
 
@@ -46,14 +44,30 @@ void bluesky_crypt_random_bytes(guchar *buf, gint len)
     gcry_randomize(buf, len, GCRY_STRONG_RANDOM);
 }
 
+/* Hash a string down to an encryption key. */
+void bluesky_crypt_hash_key(const char *keystr, uint8_t *out)
+{
+    guint8 raw_csum[32];
+    gsize csum_len = sizeof(raw_csum);
+
+    assert(CRYPTO_KEY_SIZE == 16);
+
+    GChecksum *csum = g_checksum_new(G_CHECKSUM_SHA256);
+    g_checksum_update(csum, (const guchar *)keystr, strlen(keystr));
+    g_checksum_get_digest(csum, raw_csum, &csum_len);
+    g_checksum_free(csum);
+
+    memcpy(out, raw_csum, CRYPTO_KEY_SIZE);
+}
+
 /* Encrypt a data block. */
 BlueSkyRCStr *bluesky_crypt_encrypt(BlueSkyRCStr *in, const uint8_t *key)
 {
     gcry_error_t status;
     gcry_cipher_hd_t handle;
 
-    status = gcry_cipher_open(&handle, GCRY_CIPHER_AES, GCRY_CIPHER_MODE_CBC,
-                              GCRY_CIPHER_CBC_CTS);
+    status = gcry_cipher_open(&handle, GCRY_CIPHER_AES, GCRY_CIPHER_MODE_CTR,
+                              0);
     if (status) {
         g_error("gcrypt error setting up encryption: %s\n",
                 gcry_strerror(status));
@@ -68,14 +82,14 @@ BlueSkyRCStr *bluesky_crypt_encrypt(BlueSkyRCStr *in, const uint8_t *key)
     }
 
     bluesky_crypt_random_bytes(out, CRYPTO_BLOCK_SIZE);
-    status = gcry_cipher_setiv(handle, out, CRYPTO_BLOCK_SIZE);
+    status = gcry_cipher_setctr(handle, out, CRYPTO_BLOCK_SIZE);
     if (status) {
         g_error("gcrypt error setting IV: %s\n",
                 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 +99,45 @@ 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_CTR,
+                              0);
+    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_setctr(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);
+}