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authorMark Haines <mark.haines@matrix.org>2015-06-11 14:20:35 +0100
committerMark Haines <mark.haines@matrix.org>2015-06-11 14:20:35 +0100
commit816435a86097a6609cb6e5ad422083bc49b19632 (patch)
tree60be06f84b4fe6ee404b3cbce9b0ca1256bab1cb /include/axolotl/cipher.hh
parent8161b56ff050b81a20002e9d8addf947625d17be (diff)
Move AES specific details behind a cipher interface
Diffstat (limited to 'include/axolotl/cipher.hh')
-rw-r--r--include/axolotl/cipher.hh127
1 files changed, 127 insertions, 0 deletions
diff --git a/include/axolotl/cipher.hh b/include/axolotl/cipher.hh
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+++ b/include/axolotl/cipher.hh
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+/* 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 AXOLOTL_CIPHER_HH_
+#define AXOLOTL_CIPHER_HH_
+
+#include <cstdint>
+
+namespace axolotl {
+
+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
+ *
+ * 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
+ *
+ * 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 /* AXOLOTL_CIPHER_HH_ */