Convert cipher.hh to plain C

4 files changed, 121 insertions, 71 deletions

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);
+}
diff --git a/src/olm.cpp b/src/olm.cpp
index 56bb11f..9d84758 100644
--- a/src/olm.cpp
+++ b/src/olm.cpp
@@ -15,9 +15,9 @@
 #include "olm/olm.h"
 #include "olm/session.hh"
 #include "olm/account.hh"
+#include "olm/cipher.h"
 #include "olm/utility.hh"
 #include "olm/base64.hh"
-#include "olm/cipher.hh"
 #include "olm/memory.hh"
 
 #include <new>
@@ -59,15 +59,24 @@ static std::uint8_t const * from_c(void const * bytes) {
 
 static const std::uint8_t CIPHER_KDF_INFO[] = "Pickle";
 
-static const olm::CipherAesSha256 PICKLE_CIPHER(
-    CIPHER_KDF_INFO, sizeof(CIPHER_KDF_INFO) -1
-);
+const olm_cipher *get_pickle_cipher() {
+    static olm_cipher *cipher = NULL;
+    static olm_cipher_aes_sha_256 PICKLE_CIPHER;
+    if (!cipher) {
+        cipher = olm_cipher_aes_sha_256_init(
+            &PICKLE_CIPHER,
+            CIPHER_KDF_INFO, sizeof(CIPHER_KDF_INFO) - 1
+        );
+    }
+    return cipher;
+}
 
 std::size_t enc_output_length(
     size_t raw_length
 ) {
-    std::size_t length = PICKLE_CIPHER.encrypt_ciphertext_length(raw_length);
-    length += PICKLE_CIPHER.mac_length();
+    auto *cipher = get_pickle_cipher();
+    std::size_t length = cipher->ops->encrypt_ciphertext_length(cipher, raw_length);
+    length += cipher->ops->mac_length(cipher);
     return olm::encode_base64_length(length);
 }
 
@@ -76,8 +85,9 @@ std::uint8_t * enc_output_pos(
     std::uint8_t * output,
     size_t raw_length
 ) {
-    std::size_t length = PICKLE_CIPHER.encrypt_ciphertext_length(raw_length);
-    length += PICKLE_CIPHER.mac_length();
+    auto *cipher = get_pickle_cipher();
+    std::size_t length = cipher->ops->encrypt_ciphertext_length(cipher, raw_length);
+    length += cipher->ops->mac_length(cipher);
     return output + olm::encode_base64_length(length) - length;
 }
 
@@ -85,13 +95,15 @@ std::size_t enc_output(
     std::uint8_t const * key, std::size_t key_length,
     std::uint8_t * output, size_t raw_length
 ) {
-    std::size_t ciphertext_length = PICKLE_CIPHER.encrypt_ciphertext_length(
-        raw_length
+    auto *cipher = get_pickle_cipher();
+    std::size_t ciphertext_length = cipher->ops->encrypt_ciphertext_length(
+        cipher, raw_length
     );
-    std::size_t length = ciphertext_length + PICKLE_CIPHER.mac_length();
+    std::size_t length = ciphertext_length + cipher->ops->mac_length(cipher);
     std::size_t base64_length = olm::encode_base64_length(length);
     std::uint8_t * raw_output = output + base64_length - length;
-    PICKLE_CIPHER.encrypt(
+    cipher->ops->encrypt(
+        cipher,
         key, key_length,
         raw_output, raw_length,
         raw_output, ciphertext_length,
@@ -112,8 +124,10 @@ std::size_t enc_input(
         return std::size_t(-1);
     }
     olm::decode_base64(input, b64_length, input);
-    std::size_t raw_length = enc_length - PICKLE_CIPHER.mac_length();
-    std::size_t result = PICKLE_CIPHER.decrypt(
+    auto *cipher = get_pickle_cipher();
+    std::size_t raw_length = enc_length - cipher->ops->mac_length(cipher);
+    std::size_t result = cipher->ops->decrypt(
+        cipher,
         key, key_length,
         input, enc_length,
         input, raw_length,
diff --git a/src/ratchet.cpp b/src/ratchet.cpp
index 56ea106..de46be4 100644
--- a/src/ratchet.cpp
+++ b/src/ratchet.cpp
@@ -15,7 +15,7 @@
 #include "olm/ratchet.hh"
 #include "olm/message.hh"
 #include "olm/memory.hh"
-#include "olm/cipher.hh"
+#include "olm/cipher.h"
 #include "olm/pickle.hh"
 
 #include <cstring>
@@ -94,12 +94,13 @@ static void create_message_keys(
 
 
 static std::size_t verify_mac_and_decrypt(
-    olm::Cipher const & cipher,
+    olm_cipher const *cipher,
     olm::MessageKey const & message_key,
     olm::MessageReader const & reader,
     std::uint8_t * plaintext, std::size_t max_plaintext_length
 ) {
-    return cipher.decrypt(
+    return cipher->ops->decrypt(
+        cipher,
         message_key.key, sizeof(message_key.key),
         reader.input, reader.input_length,
         reader.ciphertext, reader.ciphertext_length,
@@ -183,7 +184,7 @@ static std::size_t verify_mac_and_decrypt_for_new_chain(
 
 olm::Ratchet::Ratchet(
     olm::KdfInfo const & kdf_info,
-    Cipher const & ratchet_cipher
+    olm_cipher const * ratchet_cipher
 ) : kdf_info(kdf_info),
     ratchet_cipher(ratchet_cipher),
     last_error(OlmErrorCode::OLM_SUCCESS) {
@@ -405,11 +406,12 @@ std::size_t olm::Ratchet::encrypt_output_length(
     if (!sender_chain.empty()) {
         counter = sender_chain[0].chain_key.index;
     }
-    std::size_t padded = ratchet_cipher.encrypt_ciphertext_length(
+    std::size_t padded = ratchet_cipher->ops->encrypt_ciphertext_length(
+        ratchet_cipher,
         plaintext_length
     );
     return olm::encode_message_length(
-        counter, olm::KEY_LENGTH, padded, ratchet_cipher.mac_length()
+        counter, olm::KEY_LENGTH, padded, ratchet_cipher->ops->mac_length(ratchet_cipher)
     );
 }
 
@@ -452,7 +454,8 @@ std::size_t olm::Ratchet::encrypt(
     create_message_keys(chain_index, sender_chain[0].chain_key, kdf_info, keys);
     advance_chain_key(chain_index, sender_chain[0].chain_key, sender_chain[0].chain_key);
 
-    std::size_t ciphertext_length = ratchet_cipher.encrypt_ciphertext_length(
+    std::size_t ciphertext_length = ratchet_cipher->ops->encrypt_ciphertext_length(
+        ratchet_cipher,
         plaintext_length
     );
     std::uint32_t counter = keys.index;
@@ -467,7 +470,8 @@ std::size_t olm::Ratchet::encrypt(
 
     olm::store_array(writer.ratchet_key, ratchet_key.public_key);
 
-    ratchet_cipher.encrypt(
+    ratchet_cipher->ops->encrypt(
+        ratchet_cipher,
         keys.key, sizeof(keys.key),
         plaintext, plaintext_length,
         writer.ciphertext, ciphertext_length,
@@ -484,7 +488,8 @@ std::size_t olm::Ratchet::decrypt_max_plaintext_length(
 ) {
     olm::MessageReader reader;
     olm::decode_message(
-        reader, input, input_length, ratchet_cipher.mac_length()
+        reader, input, input_length,
+        ratchet_cipher->ops->mac_length(ratchet_cipher)
     );
 
     if (!reader.ciphertext) {
@@ -492,7 +497,8 @@ std::size_t olm::Ratchet::decrypt_max_plaintext_length(
         return std::size_t(-1);
     }
 
-    return ratchet_cipher.decrypt_max_plaintext_length(reader.ciphertext_length);
+    return ratchet_cipher->ops->decrypt_max_plaintext_length(
+        ratchet_cipher, reader.ciphertext_length);
 }
 
 
@@ -502,7 +508,8 @@ std::size_t olm::Ratchet::decrypt(
 ) {
     olm::MessageReader reader;
     olm::decode_message(
-        reader, input, input_length, ratchet_cipher.mac_length()
+        reader, input, input_length,
+        ratchet_cipher->ops->mac_length(ratchet_cipher)
     );
 
     if (reader.version != PROTOCOL_VERSION) {
@@ -515,7 +522,8 @@ std::size_t olm::Ratchet::decrypt(
         return std::size_t(-1);
     }
 
-    std::size_t max_length = ratchet_cipher.decrypt_max_plaintext_length(
+    std::size_t max_length = ratchet_cipher->ops->decrypt_max_plaintext_length(
+        ratchet_cipher,
         reader.ciphertext_length
     );
 
diff --git a/src/session.cpp b/src/session.cpp
index c0b6cf4..0d9b58a 100644
--- a/src/session.cpp
+++ b/src/session.cpp
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 #include "olm/session.hh"
-#include "olm/cipher.hh"
+#include "olm/cipher.h"
 #include "olm/crypto.hh"
 #include "olm/account.hh"
 #include "olm/memory.hh"
@@ -30,19 +30,27 @@ static const std::uint8_t ROOT_KDF_INFO[] = "OLM_ROOT";
 static const std::uint8_t RATCHET_KDF_INFO[] = "OLM_RATCHET";
 static const std::uint8_t CIPHER_KDF_INFO[] = "OLM_KEYS";
 
-static const olm::CipherAesSha256 OLM_CIPHER(
-    CIPHER_KDF_INFO, sizeof(CIPHER_KDF_INFO) -1
-);
-
 static const olm::KdfInfo OLM_KDF_INFO = {
     ROOT_KDF_INFO, sizeof(ROOT_KDF_INFO) - 1,
     RATCHET_KDF_INFO, sizeof(RATCHET_KDF_INFO) - 1
 };
 
+const olm_cipher *get_cipher() {
+    static olm_cipher *cipher;
+    static olm_cipher_aes_sha_256 OLM_CIPHER;
+    if (!cipher) {
+        cipher = olm_cipher_aes_sha_256_init(
+            &OLM_CIPHER,
+            CIPHER_KDF_INFO, sizeof(CIPHER_KDF_INFO) - 1
+        );
+    }
+    return cipher;
+}
+
 } // namespace
 
 olm::Session::Session(
-) : ratchet(OLM_KDF_INFO, OLM_CIPHER),
+) : ratchet(OLM_KDF_INFO, get_cipher()),
     last_error(OlmErrorCode::OLM_SUCCESS),
     received_message(false) {
 
@@ -149,7 +157,7 @@ std::size_t olm::Session::new_inbound_session(
     olm::MessageReader message_reader;
     decode_message(
         message_reader, reader.message, reader.message_length,
-        ratchet.ratchet_cipher.mac_length()
+        ratchet.ratchet_cipher->ops->mac_length(ratchet.ratchet_cipher)
     );
 
     if (!message_reader.ratchet_key