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authorRichard van der Hoff <richard@matrix.org>2016-05-24 13:33:33 +0100
committerRichard van der Hoff <richard@matrix.org>2016-05-24 13:33:33 +0100
commit2e7800cf650197f4b8998ef8ac24d08daa316a2f (patch)
tree1f9e5e06b755f929c7bad363b77eaafdd21d706c /include/olm/cipher.h
parentb1c5732fc8c89ee9217d0f54408f860565fa01f4 (diff)
parent2fd28a66824bda7b86c08b065736009c39761987 (diff)
Merge branch 'rav/c_bindings'
Diffstat (limited to 'include/olm/cipher.h')
-rw-r--r--include/olm/cipher.h138
1 files changed, 138 insertions, 0 deletions
diff --git a/include/olm/cipher.h b/include/olm/cipher.h
new file mode 100644
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+++ b/include/olm/cipher.h
@@ -0,0 +1,138 @@
+/* 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 _olm_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
+ );
+};
+
+struct _olm_cipher {
+ const struct _olm_cipher_ops *ops;
+ /* cipher-specific fields follow */
+};
+
+struct _olm_cipher_aes_sha_256 {
+ struct _olm_cipher base_cipher;
+
+ /** context string for the HKDF used for deriving the AES256 key, HMAC key,
+ * and AES IV, from the key material passed to encrypt/decrypt.
+ */
+ uint8_t const * kdf_info;
+
+ /** length of context string kdf_info */
+ size_t kdf_info_length;
+};
+
+extern const struct _olm_cipher_ops _olm_cipher_aes_sha_256_ops;
+
+/**
+ * get an initializer for an instance of struct _olm_cipher_aes_sha_256.
+ *
+ * To use it, declare:
+ *
+ * struct _olm_cipher_aes_sha_256 MY_CIPHER =
+ * OLM_CIPHER_INIT_AES_SHA_256("MY_KDF");
+ * struct _olm_cipher *cipher = OLM_CIPHER_BASE(&MY_CIPHER);
+ */
+#define OLM_CIPHER_INIT_AES_SHA_256(KDF_INFO) { \
+ .base_cipher = { &_olm_cipher_aes_sha_256_ops },\
+ .kdf_info = (uint8_t *)(KDF_INFO), \
+ .kdf_info_length = sizeof(KDF_INFO) - 1 \
+}
+#define OLM_CIPHER_BASE(CIPHER) \
+ (&((CIPHER)->base_cipher))
+
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* OLM_CIPHER_H_ */