/* Copyright 2018, 2019 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.
 */

import libolm.error;
extern (C):

struct 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 (const(OlmPkEncryption)* encryption);

/** An error code describing the most recent error to happen to an encryption
 * object */
OlmErrorCode olm_pk_encryption_last_error_code (const(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, const(void)* 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 (const(OlmPkEncryption)* encryption, size_t plaintext_length);

/** Get the length of the message authentication code. */
size_t olm_pk_mac_length (const(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 (const(OlmPkEncryption)* encryption);

/** Encrypt a plaintext for the recipient set using
 * olm_pk_encryption_set_recipient_key. Writes to the ciphertext, mac, and
 * ephemeral_key buffers, whose values should be sent to the recipient. mac is
 * a Message Authentication Code to ensure that the data is received and
 * decrypted properly. ephemeral_key is the public part of the ephemeral key
 * used (together with the recipient's key) to generate a symmetric encryption
 * 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 "OLM_INPUT_BUFFER_TOO_SMALL". */
size_t olm_pk_encrypt (OlmPkEncryption* encryption, const(void)* 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, const(void)* random, size_t random_length);

struct 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 (const(OlmPkDecryption)* decryption);

/** An error code describing the most recent error to happen to a decription
 * object */
OlmErrorCode olm_pk_decryption_last_error_code (const(OlmPkDecryption)* decryption);

/** Clears the memory used to back this decryption object */
size_t olm_clear_pk_decryption (OlmPkDecryption* decryption);

/** Get the number of bytes required to store an olm private key
 */
size_t olm_pk_private_key_length ();

/** DEPRECATED: Use olm_pk_private_key_length()
 */
size_t olm_pk_generate_key_random_length ();

/** Initialise the key from the private part of a key as returned by
 * olm_pk_get_private_key(). 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 the private key was not long enough then olm_pk_decryption_last_error()
 * will be "OLM_INPUT_BUFFER_TOO_SMALL".
 *
 * Note that the pubkey is a base64 encoded string, but the private key is
 * an unencoded byte array
 */
size_t olm_pk_key_from_private (OlmPkDecryption* decryption, void* pubkey, size_t pubkey_length, const(void)* privkey, size_t privkey_length);

/** DEPRECATED: Use olm_pk_key_from_private
 */
size_t olm_pk_generate_key (OlmPkDecryption* decryption, void* pubkey, size_t pubkey_length, const(void)* privkey, size_t privkey_length);

/** Returns the number of bytes needed to store a decryption object. */
size_t olm_pickle_pk_decryption_length (const(OlmPkDecryption)* decryption);

/** Stores decryption object as a base64 string. Encrypts the object using the
 * supplied key. Returns the length of the pickled object on success.
 * Returns olm_error() on failure. If the pickle output buffer
 * is smaller than olm_pickle_pk_decryption_length() then
 * olm_pk_decryption_last_error() will be "OUTPUT_BUFFER_TOO_SMALL" */
size_t olm_pickle_pk_decryption (OlmPkDecryption* decryption, const(void)* key, size_t key_length, void* pickled, size_t pickled_length);

/** Loads a decryption object from a pickled base64 string. The associated
 * public key will be written to the pubkey buffer. Decrypts the object using
 * the supplied key. Returns olm_error() on failure. If the key doesn't
 * match the one used to encrypt the account then olm_pk_decryption_last_error()
 * will be "BAD_ACCOUNT_KEY". If the base64 couldn't be decoded then
 * olm_pk_decryption_last_error() will be "INVALID_BASE64". The input pickled
 * buffer is destroyed */
size_t olm_unpickle_pk_decryption (OlmPkDecryption* decryption, const(void)* key, size_t key_length, void* pickled, size_t pickled_length, void* pubkey, size_t pubkey_length);

/** Get the length of the plaintext that will correspond to a ciphertext of the
 * given length. */
size_t olm_pk_max_plaintext_length (const(OlmPkDecryption)* decryption, size_t ciphertext_length);

/** Decrypt a ciphertext. The input ciphertext buffer is destroyed. See the
 * olm_pk_encrypt function for descriptions of the ephemeral_key and mac
 * arguments. 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* decryption, const(void)* ephemeral_key, size_t ephemeral_key_length, const(void)* mac, size_t mac_length, void* ciphertext, size_t ciphertext_length, void* plaintext, size_t max_plaintext_length);

/**
 * Get the private key for an OlmDecryption object as an unencoded byte array
 * private_key must be a pointer to a buffer of at least
 * olm_pk_private_key_length() bytes and this length must be passed in
 * private_key_length. If the given buffer is too small, returns olm_error()
 * and olm_pk_encryption_last_error() will be "OUTPUT_BUFFER_TOO_SMALL".
 * Returns the number of bytes written.
 */
size_t olm_pk_get_private_key (OlmPkDecryption* decryption, void* private_key, size_t private_key_length);

struct OlmPkSigning;

/* The size of a signing object in bytes */
size_t olm_pk_signing_size ();

/** Initialise a signing object using the supplied memory
 *  The supplied memory must be at least olm_pk_signing_size() bytes */
OlmPkSigning* olm_pk_signing (void* memory);

/** A null terminated string describing the most recent error to happen to a
 * signing object */
const(char)* olm_pk_signing_last_error (const(OlmPkSigning)* sign);

/** A null terminated string describing the most recent error to happen to a
 * signing object */
OlmErrorCode olm_pk_signing_last_error_code (const(OlmPkSigning)* sign);

/** Clears the memory used to back this signing object */
size_t olm_clear_pk_signing (OlmPkSigning* sign);

/**
 * Initialise the signing object with a public/private keypair from a seed. The
 * associated public key will be written to the pubkey buffer. Returns
 * olm_error() on failure. If the public key buffer is too small then
 * olm_pk_signing_last_error() will be "OUTPUT_BUFFER_TOO_SMALL".  If the seed
 * buffer is too small then olm_pk_signing_last_error() will be
 * "INPUT_BUFFER_TOO_SMALL".
 */
size_t olm_pk_signing_key_from_seed (OlmPkSigning* sign, void* pubkey, size_t pubkey_length, const(void)* seed, size_t seed_length);

/**
 * The size required for the seed for initialising a signing object.
 */
size_t olm_pk_signing_seed_length ();

/**
 * The size of the public key of a signing object.
 */
size_t olm_pk_signing_public_key_length ();

/**
 * The size of a signature created by a signing object.
 */
size_t olm_pk_signature_length ();

/**
 * Sign a message. The signature will be written to the signature
 * buffer. Returns olm_error() on failure. If the signature buffer is too
 * small, olm_pk_signing_last_error() will be "OUTPUT_BUFFER_TOO_SMALL".
 */
size_t olm_pk_sign (OlmPkSigning* sign, const(ubyte)* message, size_t message_length, ubyte* signature, size_t signature_length);

/* OLM_PK_H_ */