* the functions in this file, so this is the only point where we interface
* with an external cryptographic library. */
+/* TODO: We ought to switch to an authenticated encryption mode like EAX. */
+
GCRY_THREAD_OPTION_PTHREAD_IMPL;
void bluesky_crypt_init()
memcpy(out, raw_csum, CRYPTO_KEY_SIZE);
}
-/* Encrypt a data block. */
-BlueSkyRCStr *bluesky_crypt_encrypt(BlueSkyRCStr *in, const uint8_t *key)
+/* Compute an HMAC of a given data block with the given key. The key and
+ * output should both as large as the hash output size. */
+#define MD_ALGO GCRY_MD_SHA256
+void bluesky_crypt_hmac(const char *buf, size_t bufsize,
+ const uint8_t key[CRYPTO_HASH_SIZE],
+ uint8_t output[CRYPTO_HASH_SIZE])
{
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);
- if (status) {
- g_error("gcrypt error setting up encryption: %s\n",
- gcry_strerror(status));
- }
+ gcry_md_hd_t handle;
- uint8_t *out = g_malloc0(in->len + CRYPTO_BLOCK_SIZE);
+ g_assert(gcry_md_get_algo_dlen(MD_ALGO) == CRYPTO_HASH_SIZE);
- gcry_cipher_setkey(handle, key, CRYPTO_KEY_SIZE);
+ status = gcry_md_open(&handle, MD_ALGO, GCRY_MD_FLAG_HMAC);
if (status) {
- g_error("gcrypt error setting key: %s\n",
+ g_error("gcrypt error setting up message digest: %s\n",
gcry_strerror(status));
+ g_assert(FALSE);
}
- bluesky_crypt_random_bytes(out, CRYPTO_BLOCK_SIZE);
- status = gcry_cipher_setiv(handle, out, CRYPTO_BLOCK_SIZE);
+ status = gcry_md_setkey(handle, key, CRYPTO_HASH_SIZE);
if (status) {
- g_error("gcrypt error setting IV: %s\n",
+ g_error("gcrypt error setting HMAC key: %s\n",
gcry_strerror(status));
+ g_assert(FALSE);
}
- 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));
- }
+ gcry_md_write(handle, buf, bufsize);
- gcry_cipher_close(handle);
+ unsigned char *digest = gcry_md_read(handle, MD_ALGO);
+ memcpy(output, digest, CRYPTO_HASH_SIZE);
+
+ gcry_md_close(handle);
+}
+
+void bluesky_crypt_derive_keys(BlueSkyCryptKeys *keys, const gchar *master)
+{
+ uint8_t outbuf[CRYPTO_HASH_SIZE];
+
+ const char *key_type = "ENCRYPT";
+ bluesky_crypt_hmac(key_type, strlen(key_type),
+ (const uint8_t *)master, outbuf);
+ memcpy(keys->encryption_key, outbuf, sizeof(keys->encryption_key));
- return bluesky_string_new(out, in->len + CRYPTO_BLOCK_SIZE);
+ key_type = "AUTH";
+ bluesky_crypt_hmac(key_type, strlen(key_type),
+ (const uint8_t *)master, outbuf);
+ memcpy(keys->authentication_key, outbuf, sizeof(keys->authentication_key));
}
-/* Decrypt a data block. */
-BlueSkyRCStr *bluesky_crypt_decrypt(BlueSkyRCStr *in, const uint8_t *key)
+/* A boolean: are blocks of the specified type encrypted in the BlueSky file
+ * system? */
+gboolean bluesky_crypt_block_needs_encryption(uint8_t type)
{
+ type -= '0';
+
+ switch (type) {
+ case LOGTYPE_DATA:
+ case LOGTYPE_INODE:
+ return TRUE;
+ case LOGTYPE_INODE_MAP:
+ case LOGTYPE_CHECKPOINT:
+ return FALSE;
+ default:
+ g_warning("Unknown log item type in crypto layer: %d!\n",
+ type);
+ return TRUE;
+ }
+}
+
+void bluesky_crypt_block_encrypt(gchar *cloud_block, size_t len,
+ BlueSkyCryptKeys *keys)
+{
+ if (bluesky_options.disable_crypto)
+ return;
+
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);
+ 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);
+ struct cloudlog_header *header = (struct cloudlog_header *)cloud_block;
+ g_assert(memcmp(header->magic, CLOUDLOG_MAGIC, sizeof(header->magic)) == 0);
- gcry_cipher_setkey(handle, key, CRYPTO_KEY_SIZE);
+ gcry_cipher_setkey(handle, keys->encryption_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));
- }
+ gboolean encrypted = bluesky_crypt_block_needs_encryption(header->type);
- 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));
+ if (encrypted) {
+ header->magic[3] ^= 0x10;
+
+ bluesky_crypt_random_bytes(header->crypt_iv, sizeof(header->crypt_iv));
+ status = gcry_cipher_setctr(handle, header->crypt_iv,
+ sizeof(header->crypt_iv));
+ if (status) {
+ g_error("gcrypt error setting IV: %s\n",
+ gcry_strerror(status));
+ }
+
+ status = gcry_cipher_encrypt(handle,
+ cloud_block + sizeof(struct cloudlog_header),
+ GUINT32_FROM_LE(header->size1),
+ NULL, 0);
+ if (status) {
+ g_error("gcrypt error encrypting: %s\n",
+ gcry_strerror(status));
+ }
+ } else {
+ memset(header->crypt_iv, 0, sizeof(header->crypt_iv));
}
+ bluesky_crypt_hmac((char *)&header->crypt_iv,
+ cloud_block + len - (char *)&header->crypt_iv - GUINT32_FROM_LE(header->size3),
+ keys->authentication_key,
+ header->crypt_auth);
+
gcry_cipher_close(handle);
+}
+
+gboolean bluesky_crypt_block_decrypt(gchar *cloud_block, size_t len,
+ BlueSkyCryptKeys *keys,
+ gboolean allow_unauth)
+{
+ gcry_error_t status;
+ uint8_t hmac_check[CRYPTO_HASH_SIZE];
+
+ gboolean encrypted = TRUE;
+
+ struct cloudlog_header *header = (struct cloudlog_header *)cloud_block;
+ if (memcmp(header->magic, CLOUDLOG_MAGIC,
+ sizeof(header->magic)) == 0)
+ encrypted = FALSE;
+ else
+ g_assert(memcmp(header->magic, CLOUDLOG_MAGIC_ENCRYPTED,
+ sizeof(header->magic)) == 0);
+
+ if (bluesky_options.disable_crypto) {
+ g_assert(encrypted == FALSE);
+ return TRUE;
+ }
+
+ if (encrypted != bluesky_crypt_block_needs_encryption(header->type)) {
+ g_warning("Encrypted status of item does not match expected!\n");
+ }
+
+ bluesky_crypt_hmac((char *)&header->crypt_iv,
+ cloud_block + len - (char *)&header->crypt_iv - GUINT32_FROM_LE(header->size3),
+ keys->authentication_key,
+ hmac_check);
+ if (memcmp(hmac_check, header->crypt_auth, CRYPTO_HASH_SIZE) != 0) {
+ g_warning("Cloud block HMAC does not match!");
+ if (allow_unauth
+ && (header->type == LOGTYPE_INODE_MAP + '0'
+ || header->type == LOGTYPE_CHECKPOINT + '0'))
+ {
+ g_warning("Allowing unauthenticated data from cleaner");
+ } else {
+ return FALSE;
+ }
+ }
+
+ if (encrypted) {
+ gcry_cipher_hd_t handle;
+ 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));
+ }
+
+ gcry_cipher_setkey(handle, keys->encryption_key, CRYPTO_KEY_SIZE);
+ if (status) {
+ g_error("gcrypt error setting key: %s\n",
+ gcry_strerror(status));
+ }
+
+ status = gcry_cipher_setctr(handle, header->crypt_iv,
+ sizeof(header->crypt_iv));
+ if (status) {
+ g_error("gcrypt error setting IV: %s\n",
+ gcry_strerror(status));
+ }
+
+ status = gcry_cipher_decrypt(handle,
+ cloud_block + sizeof(struct cloudlog_header),
+ GUINT32_FROM_LE(header->size1),
+ NULL, 0);
+ if (status) {
+ g_error("gcrypt error decrypting: %s\n",
+ gcry_strerror(status));
+ }
+ header->magic[3] ^= 0x10;
+ memset(header->crypt_iv, 0, sizeof(header->crypt_iv));
+
+ gcry_cipher_close(handle);
+ }
- return bluesky_string_new(out, in->len + CRYPTO_BLOCK_SIZE);
+ return TRUE;
}
projects / bluesky.git / blobdiff