Convert cipher.hh to plain C

3 files changed, 138 insertions, 136 deletions

diff --git a/include/olm/cipher.h b/include/olm/cipher.h
new file mode 100644
index 0000000..0d6fd5b
--- /dev/null
+++ b/include/olm/cipher.h
@@ -0,0 +1,134 @@
+/* Copyright 2015 OpenMarket Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef OLM_CIPHER_H_
+#define OLM_CIPHER_H_
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct olm_cipher;
+
+struct cipher_ops {
+    /**
+     * Returns the length of the message authentication code that will be
+     * appended to the output.
+     */
+    size_t (*mac_length)(const struct olm_cipher *cipher);
+
+    /**
+     * Returns the length of cipher-text for a given length of plain-text.
+     */
+    size_t (*encrypt_ciphertext_length)(const struct olm_cipher *cipher,
+                                        size_t plaintext_length);
+
+    /*
+     * Encrypts the plain-text into the output buffer and authenticates the
+     * contents of the output buffer covering both cipher-text and any other
+     * associated data in the output buffer.
+     *
+     *  |---------------------------------------output_length-->|
+     *  output  |--ciphertext_length-->|       |---mac_length-->|
+     *          ciphertext
+     *
+     * The plain-text pointers and cipher-text pointers may be the same.
+     *
+     * Returns size_t(-1) if the length of the cipher-text or the output
+     * buffer is too small. Otherwise returns the length of the output buffer.
+     */
+    size_t (*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
+    );
+
+    /**
+     * Returns the maximum length of plain-text that a given length of
+     * cipher-text can contain.
+     */
+    size_t (*decrypt_max_plaintext_length)(
+        const struct olm_cipher *cipher,
+        size_t ciphertext_length
+    );
+
+    /**
+     * Authenticates the input and decrypts the cipher-text into the plain-text
+     * buffer.
+     *
+     *  |----------------------------------------input_length-->|
+     *  input   |--ciphertext_length-->|       |---mac_length-->|
+     *          ciphertext
+     *
+     * The plain-text pointers and cipher-text pointers may be the same.
+     *
+     *  Returns size_t(-1) if the length of the plain-text buffer is too
+     *  small or if the authentication check fails. Otherwise returns the length
+     *  of the plain text.
+     */
+    size_t (*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
+    );
+
+    /** destroy any private data associated with this cipher */
+    void (*destruct)(struct olm_cipher *cipher);
+};
+
+struct olm_cipher {
+    const struct cipher_ops *ops;
+    /* cipher-specific fields follow */
+};
+
+struct olm_cipher_aes_sha_256 {
+    struct olm_cipher base_cipher;
+
+    uint8_t const * kdf_info;
+    size_t kdf_info_length;
+};
+
+
+/**
+ * initialises a cipher type which uses AES256 for encryption and SHA256 for
+ * authentication.
+ *
+ * cipher: structure to be initialised
+ *
+ * kdf_info: context string for the HKDF used for deriving the AES256 key, HMAC
+ * key, and AES IV, from the key material passed to encrypt/decrypt. Note that
+ * this is NOT copied so must have a lifetime at least as long as the cipher
+ * instance.
+ *
+ * kdf_info_length: length of context string kdf_info
+ */
+struct 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);
+
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* OLM_CIPHER_H_ */
diff --git a/include/olm/cipher.hh b/include/olm/cipher.hh
deleted file mode 100644
index c561972..0000000
--- a/include/olm/cipher.hh
+++ /dev/null
@@ -1,132 +0,0 @@
-/* Copyright 2015 OpenMarket Ltd
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef OLM_CIPHER_HH_
-#define OLM_CIPHER_HH_
-
-#include <cstdint>
-#include <cstddef>
-
-namespace olm {
-
-class Cipher {
-public:
-    virtual ~Cipher();
-
-    /**
-     * Returns the length of the message authentication code that will be
-     * appended to the output.
-     */
-    virtual std::size_t mac_length() const = 0;
-
-    /**
-     * Returns the length of cipher-text for a given length of plain-text.
-     */
-    virtual std::size_t encrypt_ciphertext_length(
-        std::size_t plaintext_length
-    ) const = 0;
-
-    /*
-     * Encrypts the plain-text into the output buffer and authenticates the
-     * contents of the output buffer covering both cipher-text and any other
-     * associated data in the output buffer.
-     *
-     *  |---------------------------------------output_length-->|
-     *  output  |--ciphertext_length-->|       |---mac_length-->|
-     *          ciphertext
-     *
-     * The plain-text pointers and cipher-text pointers may be the same.
-     *
-     * Returns std::size_t(-1) if the length of the cipher-text or the output
-     * buffer is too small. Otherwise returns the length of the output buffer.
-     */
-    virtual std::size_t 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 = 0;
-
-    /**
-     * Returns the maximum length of plain-text that a given length of
-     * cipher-text can contain.
-     */
-    virtual std::size_t decrypt_max_plaintext_length(
-        std::size_t ciphertext_length
-    ) const = 0;
-
-    /**
-     * Authenticates the input and decrypts the cipher-text into the plain-text
-     * buffer.
-     *
-     *  |----------------------------------------input_length-->|
-     *  input   |--ciphertext_length-->|       |---mac_length-->|
-     *          ciphertext
-     *
-     * The plain-text pointers and cipher-text pointers may be the same.
-     *
-     *  Returns std::size_t(-1) if the length of the plain-text buffer is too
-     *  small or if the authentication check fails. Otherwise returns the length
-     *  of the plain text.
-     */
-    virtual std::size_t 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 = 0;
-};
-
-
-class CipherAesSha256 : public Cipher {
-public:
-    CipherAesSha256(
-        std::uint8_t const * kdf_info, std::size_t kdf_info_length
-    );
-
-    virtual std::size_t mac_length() const;
-
-    virtual std::size_t encrypt_ciphertext_length(
-        std::size_t plaintext_length
-    ) const;
-
-    virtual std::size_t 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;
-
-    virtual std::size_t decrypt_max_plaintext_length(
-        std::size_t ciphertext_length
-    ) const;
-
-    virtual std::size_t 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;
-
-private:
-    std::uint8_t const * kdf_info;
-    std::size_t kdf_info_length;
-};
-
-
-} // namespace
-
-
-#endif /* OLM_CIPHER_HH_ */
diff --git a/include/olm/ratchet.hh b/include/olm/ratchet.hh
index b2787c7..e1d462d 100644
--- a/include/olm/ratchet.hh
+++ b/include/olm/ratchet.hh
@@ -17,9 +17,9 @@
 #include "olm/list.hh"
 #include "olm/error.h"
 
-namespace olm {
+struct olm_cipher;
 
-class Cipher;
+namespace olm {
 
 typedef std::uint8_t SharedKey[olm::KEY_LENGTH];
 
@@ -69,14 +69,14 @@ struct Ratchet {
 
     Ratchet(
         KdfInfo const & kdf_info,
-        Cipher const & ratchet_cipher
+        olm_cipher const *ratchet_cipher
     );
 
     /** A some strings identifying the application to feed into the KDF. */
     KdfInfo const & kdf_info;
 
     /** The AEAD cipher to use for encrypting messages. */
-    Cipher const & ratchet_cipher;
+    olm_cipher const *ratchet_cipher;
 
     /** The last error that happened encrypting or decrypting a message. */
     OlmErrorCode last_error;