add initial implementation of basic private key encryption functionality

1 files changed, 148 insertions, 0 deletions

diff --git a/include/olm/pk.h b/include/olm/pk.h
new file mode 100644
index 0000000..a91a80d
--- /dev/null
+++ b/include/olm/pk.h
@@ -0,0 +1,148 @@
+/* Copyright 2018 New Vector 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_PK_H_
+#define OLM_PK_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct OlmPkEncryption OlmPkEncryption;
+
+/* The size of an encryption object in bytes */
+size_t olm_pk_encryption_size();
+
+/** Initialise an encryption object using the supplied memory
+ *  The supplied memory must be at least olm_pk_encryption_size() bytes */
+OlmPkEncryption *olm_pk_encryption(
+    void * memory
+);
+
+/** A null terminated string describing the most recent error to happen to an
+ * encryption object */
+const char * olm_pk_encryption_last_error(
+    OlmPkEncryption * encryption
+);
+
+/** Clears the memory used to back this encryption object */
+size_t olm_clear_pk_encryption(
+    OlmPkEncryption *encryption
+);
+
+/** Set the recipient's public key for encrypting to */
+size_t olm_pk_encryption_set_recipient_key(
+    OlmPkEncryption *encryption,
+    void const *public_key, size_t public_key_length
+);
+
+/** Get the length of the ciphertext that will correspond to a plaintext of the
+ * given length. */
+size_t olm_pk_ciphertext_length(
+    OlmPkEncryption *encryption,
+    size_t plaintext_length
+);
+
+/** Get the length of the message authentication code. */
+size_t olm_pk_mac_length(
+    OlmPkEncryption *encryption
+);
+
+/** Get the length of a public or ephemeral key */
+size_t olm_pk_key_length();
+
+/** The number of random bytes needed to encrypt a message. */
+size_t olm_pk_encrypt_random_length(
+    OlmPkEncryption *encryption
+);
+
+/** Encrypt a plaintext for the recipient set using
+ * olm_pk_encryption_set_recipient_key. Returns olm_error() on failure. If the
+ * ciphertext, mac, or ephemeral_key buffers were too small then
+ * olm_pk_encryption_last_error() will be "OUTPUT_BUFFER_TOO_SMALL". If there
+ * weren't enough random bytes then olm_pk_encryption_last_error() will be
+ * "NOT_ENOUGH_RANDOM". */
+size_t olm_pk_encrypt(
+    OlmPkEncryption *encryption,
+    void const * plaintext, size_t plaintext_length,
+    void * ciphertext, size_t ciphertext_length,
+    void * mac, size_t mac_length,
+    void * ephemeral_key, size_t ephemeral_key_size,
+    void * random, size_t random_length
+);
+
+typedef struct OlmPkDecryption OlmPkDecryption;
+
+/* The size of a decryption object in bytes */
+size_t olm_pk_decryption_size();
+
+/** Initialise a decryption object using the supplied memory
+ *  The supplied memory must be at least olm_pk_decryption_size() bytes */
+OlmPkDecryption *olm_pk_decryption(
+    void * memory
+);
+
+/** A null terminated string describing the most recent error to happen to a
+ * decription object */
+const char * olm_pk_decryption_last_error(
+    OlmPkDecryption * decryption
+);
+
+/** Clears the memory used to back this decryption object */
+size_t olm_clear_pk_decryption(
+    OlmPkDecryption *decryption
+);
+
+/** The number of random bytes needed to generate a new key. */
+size_t olm_pk_generate_key_random_length();
+
+/** Generate a new key to use for decrypting messages. The associated public
+ * key will be written to the pubkey buffer. Returns olm_error() on failure. If
+ * the pubkey buffer is too small then olm_pk_decryption_last_error() will be
+ * "OUTPUT_BUFFER_TOO_SMALL". If there weren't enough random bytes then
+ * olm_pk_decryption_last_error() will be "NOT_ENOUGH_RANDOM". */
+size_t olm_pk_generate_key(
+    OlmPkDecryption * decryption,
+    void * pubkey, size_t pubkey_length,
+    void * random, size_t random_length
+);
+
+/** Get the length of the plaintext that will correspond to a ciphertext of the
+ * given length. */
+size_t olm_pk_max_plaintext_length(
+    OlmPkDecryption * decryption,
+    size_t ciphertext_length
+);
+
+/** Decrypt a ciphertext.  The input ciphertext buffer is destroyed.  Returns
+ * the length of the plaintext on success. Returns olm_error() on failure. If
+ * the plaintext buffer is too small then olm_pk_encryption_last_error() will
+ * be "OUTPUT_BUFFER_TOO_SMALL". */
+size_t olm_pk_decrypt(
+    OlmPkDecryption * decrytion,
+    void const * ephemeral_key, size_t ephemeral_key_length,
+    void const * mac, size_t mac_length,
+    void * ciphertext, size_t ciphertext_length,
+    void * plaintext, size_t max_plaintext_length
+);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OLM_PK_H_ */