From 9047d936bd8bbf6acc6799e559c2766d4c487263 Mon Sep 17 00:00:00 2001
From: Michael Vrable <mvrable@cs.ucsd.edu>
Date: Tue, 1 Sep 2009 21:23:26 -0700
Subject: [PATCH] Implement data decryption as well.

---
 bluesky/bluesky.h |  1 +
 bluesky/crypto.c  | 46 ++++++++++++++++++++++++++++++++++++++++++++--
 bluesky/inode.c   |  3 ++-
 3 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/bluesky/bluesky.h b/bluesky/bluesky.h
index afb2304..831d850 100644
--- a/bluesky/bluesky.h
+++ b/bluesky/bluesky.h
@@ -35,6 +35,7 @@ BlueSkyRCStr *bluesky_string_dup(BlueSkyRCStr *string);
 void bluesky_crypt_init();
 void bluesky_crypt_random_bytes(guchar *buf, gint len);
 BlueSkyRCStr *bluesky_crypt_encrypt(BlueSkyRCStr *in, const uint8_t *key);
+BlueSkyRCStr *bluesky_crypt_decrypt(BlueSkyRCStr *in, const uint8_t *key);
 
 /* File types.  The numeric values are chosen to match with those used in
  * NFSv3. */
diff --git a/bluesky/crypto.c b/bluesky/crypto.c
index 6eec464..defe1b3 100644
--- a/bluesky/crypto.c
+++ b/bluesky/crypto.c
@@ -74,8 +74,8 @@ 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 +85,45 @@ 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);
+}
diff --git a/bluesky/inode.c b/bluesky/inode.c
index 42b045c..e4902cd 100644
--- a/bluesky/inode.c
+++ b/bluesky/inode.c
@@ -342,8 +342,9 @@ void bluesky_block_fetch(BlueSkyFS *fs, BlueSkyBlock *block)
     BlueSkyRCStr *string = s3store_get(fs->store, block->ref);
 
     bluesky_string_unref(block->data);
-    block->data = string;
+    block->data = bluesky_crypt_decrypt(string, fs->encryption_key);
     block->type = BLUESKY_BLOCK_CACHED;
+    bluesky_string_unref(string);
 }
 
 /* Write the given block to cloud-backed storage and mark it clean. */
-- 
2.20.1