From 294cf482ea49f690ac9eaad52f2574a90b2e51e6 Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <richard@matrix.org>
Date: Mon, 16 May 2016 16:25:09 +0100
Subject: Convert cipher.hh to plain C

---
 src/cipher.cpp | 96 +++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 58 insertions(+), 38 deletions(-)

(limited to 'src/cipher.cpp')

diff --git a/src/cipher.cpp b/src/cipher.cpp
index a550312..8c56efa 100644
--- a/src/cipher.cpp
+++ b/src/cipher.cpp
@@ -12,15 +12,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-#include "olm/cipher.hh"
+#include "olm/cipher.h"
 #include "olm/crypto.hh"
 #include "olm/memory.hh"
 #include <cstring>
 
-olm::Cipher::~Cipher() {
-
-}
-
 namespace {
 
 struct DerivedKeys {
@@ -51,41 +47,34 @@ static void derive_keys(
 
 static const std::size_t MAC_LENGTH = 8;
 
-} // namespace
-
-
-olm::CipherAesSha256::CipherAesSha256(
-    std::uint8_t const * kdf_info, std::size_t kdf_info_length
-) : kdf_info(kdf_info), kdf_info_length(kdf_info_length) {
-
-}
-
-
-std::size_t olm::CipherAesSha256::mac_length() const {
+size_t aes_sha_256_cipher_mac_length(const struct olm_cipher *cipher) {
     return MAC_LENGTH;
 }
 
-
-std::size_t olm::CipherAesSha256::encrypt_ciphertext_length(
-    std::size_t plaintext_length
-) const {
+size_t aes_sha_256_cipher_encrypt_ciphertext_length(
+        const struct olm_cipher *cipher, size_t plaintext_length
+) {
     return olm::aes_encrypt_cbc_length(plaintext_length);
 }
 
+size_t aes_sha_256_cipher_encrypt(
+    const struct olm_cipher *cipher,
+    uint8_t const * key, size_t key_length,
+    uint8_t const * plaintext, size_t plaintext_length,
+    uint8_t * ciphertext, size_t ciphertext_length,
+    uint8_t * output, size_t output_length
+) {
+    auto *c = reinterpret_cast<const olm_cipher_aes_sha_256 *>(cipher);
 
-std::size_t olm::CipherAesSha256::encrypt(
-    std::uint8_t const * key, std::size_t key_length,
-    std::uint8_t const * plaintext, std::size_t plaintext_length,
-    std::uint8_t * ciphertext, std::size_t ciphertext_length,
-    std::uint8_t * output, std::size_t output_length
-) const {
-    if (encrypt_ciphertext_length(plaintext_length) < ciphertext_length) {
+    if (aes_sha_256_cipher_encrypt_ciphertext_length(cipher, plaintext_length)
+            < ciphertext_length) {
         return std::size_t(-1);
     }
+
     struct DerivedKeys keys;
     std::uint8_t mac[SHA256_OUTPUT_LENGTH];
 
-    derive_keys(kdf_info, kdf_info_length, key, key_length, keys);
+    derive_keys(c->kdf_info, c->kdf_info_length, key, key_length, keys);
 
     olm::aes_encrypt_cbc(
         keys.aes_key, keys.aes_iv, plaintext, plaintext_length, ciphertext
@@ -102,22 +91,26 @@ std::size_t olm::CipherAesSha256::encrypt(
 }
 
 
-std::size_t olm::CipherAesSha256::decrypt_max_plaintext_length(
-    std::size_t ciphertext_length
-) const {
+size_t aes_sha_256_cipher_decrypt_max_plaintext_length(
+    const struct olm_cipher *cipher,
+    size_t ciphertext_length
+) {
     return ciphertext_length;
 }
 
-std::size_t olm::CipherAesSha256::decrypt(
-     std::uint8_t const * key, std::size_t key_length,
-     std::uint8_t const * input, std::size_t input_length,
-     std::uint8_t const * ciphertext, std::size_t ciphertext_length,
-     std::uint8_t * plaintext, std::size_t max_plaintext_length
-) const {
+size_t aes_sha_256_cipher_decrypt(
+    const struct olm_cipher *cipher,
+    uint8_t const * key, size_t key_length,
+    uint8_t const * input, size_t input_length,
+    uint8_t const * ciphertext, size_t ciphertext_length,
+    uint8_t * plaintext, size_t max_plaintext_length
+) {
+    auto *c = reinterpret_cast<const olm_cipher_aes_sha_256 *>(cipher);
+
     DerivedKeys keys;
     std::uint8_t mac[SHA256_OUTPUT_LENGTH];
 
-    derive_keys(kdf_info, kdf_info_length, key, key_length, keys);
+    derive_keys(c->kdf_info, c->kdf_info_length, key, key_length, keys);
 
     crypto_hmac_sha256(
         keys.mac_key, olm::KEY_LENGTH, input, input_length - MAC_LENGTH, mac
@@ -136,3 +129,30 @@ std::size_t olm::CipherAesSha256::decrypt(
     olm::unset(keys);
     return plaintext_length;
 }
+
+
+void aes_sha_256_cipher_destruct(struct olm_cipher *cipher) {
+}
+
+
+const cipher_ops aes_sha_256_cipher_ops = {
+  aes_sha_256_cipher_mac_length,
+  aes_sha_256_cipher_encrypt_ciphertext_length,
+  aes_sha_256_cipher_encrypt,
+  aes_sha_256_cipher_decrypt_max_plaintext_length,
+  aes_sha_256_cipher_decrypt,
+  aes_sha_256_cipher_destruct
+};
+
+} // namespace
+
+
+olm_cipher *olm_cipher_aes_sha_256_init(struct olm_cipher_aes_sha_256 *cipher,
+                                        uint8_t const * kdf_info,
+                                        size_t kdf_info_length)
+{
+    cipher->base_cipher.ops = &aes_sha_256_cipher_ops;
+    cipher->kdf_info = kdf_info;
+    cipher->kdf_info_length = kdf_info_length;
+    return &(cipher->base_cipher);
+}
-- 
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