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diff --git a/libs/libtox/src/toxcore/crypto_core.h b/libs/libtox/src/toxcore/crypto_core.h
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+/*
+ * Functions for the core crypto.
+ */
+
+/*
+ * Copyright © 2016-2017 The TokTok team.
+ * Copyright © 2013 Tox project.
+ *
+ * This file is part of Tox, the free peer to peer instant messenger.
+ *
+ * Tox is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Tox is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Tox.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef CRYPTO_CORE_H
+#define CRYPTO_CORE_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+/**
+ * The number of bytes in a Tox public key.
+ */
+#define CRYPTO_PUBLIC_KEY_SIZE         32
+
+uint32_t crypto_public_key_size(void);
+
+/**
+ * The number of bytes in a Tox secret key.
+ */
+#define CRYPTO_SECRET_KEY_SIZE         32
+
+uint32_t crypto_secret_key_size(void);
+
+/**
+ * The number of bytes in a shared key computed from public and secret keys.
+ */
+#define CRYPTO_SHARED_KEY_SIZE         32
+
+uint32_t crypto_shared_key_size(void);
+
+/**
+ * The number of bytes in a symmetric key.
+ */
+#define CRYPTO_SYMMETRIC_KEY_SIZE      CRYPTO_SHARED_KEY_SIZE
+
+uint32_t crypto_symmetric_key_size(void);
+
+/**
+ * The number of bytes needed for the MAC (message authentication code) in an
+ * encrypted message.
+ */
+#define CRYPTO_MAC_SIZE                16
+
+uint32_t crypto_mac_size(void);
+
+/**
+ * The number of bytes in a nonce used for encryption/decryption.
+ */
+#define CRYPTO_NONCE_SIZE              24
+
+uint32_t crypto_nonce_size(void);
+
+/**
+ * The number of bytes in a SHA256 hash.
+ */
+#define CRYPTO_SHA256_SIZE             32
+
+uint32_t crypto_sha256_size(void);
+
+/**
+ * The number of bytes in a SHA512 hash.
+ */
+#define CRYPTO_SHA512_SIZE             64
+
+uint32_t crypto_sha512_size(void);
+
+/**
+ * A `memcmp`-like function whose running time does not depend on the input
+ * bytes, only on the input length. Useful to compare sensitive data where
+ * timing attacks could reveal that data.
+ *
+ * This means for instance that comparing "aaaa" and "aaaa" takes 4 time, and
+ * "aaaa" and "baaa" also takes 4 time. With a regular `memcmp`, the latter may
+ * take 1 time, because it immediately knows that the two strings are not equal.
+ */
+int32_t crypto_memcmp(const void *p1, const void *p2, size_t length);
+
+/**
+ * A `bzero`-like function which won't be optimised away by the compiler. Some
+ * compilers will inline `bzero` or `memset` if they can prove that there will
+ * be no reads to the written data. Use this function if you want to be sure the
+ * memory is indeed zeroed.
+ */
+void crypto_memzero(void *data, size_t length);
+
+/**
+ * Compute a SHA256 hash (32 bytes).
+ */
+void crypto_sha256(uint8_t *hash, const uint8_t *data, size_t length);
+
+/**
+ * Compute a SHA512 hash (64 bytes).
+ */
+void crypto_sha512(uint8_t *hash, const uint8_t *data, size_t length);
+
+/**
+ * Compare 2 public keys of length CRYPTO_PUBLIC_KEY_SIZE, not vulnerable to
+ * timing attacks.
+ *
+ * @return 0 if both mem locations of length are equal, -1 if they are not.
+ */
+int32_t public_key_cmp(const uint8_t *pk1, const uint8_t *pk2);
+
+/**
+ * Return a random 32 bit integer.
+ */
+uint32_t random_int(void);
+
+/**
+ * Return a random 64 bit integer.
+ */
+uint64_t random_64b(void);
+
+/**
+ * Check if a Tox public key CRYPTO_PUBLIC_KEY_SIZE is valid or not. This
+ * should only be used for input validation.
+ *
+ * @return false if it isn't, true if it is.
+ */
+bool public_key_valid(const uint8_t *public_key);
+
+/**
+ * Generate a new random keypair. Every call to this function is likely to
+ * generate a different keypair.
+ */
+int32_t crypto_new_keypair(uint8_t *public_key, uint8_t *secret_key);
+
+/**
+ * Derive the public key from a given secret key.
+ */
+void crypto_derive_public_key(uint8_t *public_key, const uint8_t *secret_key);
+
+/**
+ * Encrypt plain text of the given length to encrypted of length +
+ * CRYPTO_MAC_SIZE using the public key (CRYPTO_PUBLIC_KEY_SIZE bytes) of the
+ * receiver and the secret key of the sender and a CRYPTO_NONCE_SIZE byte
+ * nonce.
+ *
+ * @return -1 if there was a problem, length of encrypted data if everything
+ * was fine.
+ */
+int32_t encrypt_data(const uint8_t *public_key, const uint8_t *secret_key, const uint8_t *nonce, const uint8_t *plain,
+                     size_t length, uint8_t *encrypted);
+
+/**
+ * Decrypt encrypted text of the given length to plain text of the given length
+ * - CRYPTO_MAC_SIZE using the public key (CRYPTO_PUBLIC_KEY_SIZE bytes) of
+ * the sender, the secret key of the receiver and a CRYPTO_NONCE_SIZE byte
+ * nonce.
+ *
+ * @return -1 if there was a problem (decryption failed), length of plain text
+ * data if everything was fine.
+ */
+int32_t decrypt_data(const uint8_t *public_key, const uint8_t *secret_key, const uint8_t *nonce,
+                     const uint8_t *encrypted, size_t length, uint8_t *plain);
+
+/**
+ * Fast encrypt/decrypt operations. Use if this is not a one-time communication.
+ * encrypt_precompute does the shared-key generation once so it does not have
+ * to be preformed on every encrypt/decrypt.
+ */
+int32_t encrypt_precompute(const uint8_t *public_key, const uint8_t *secret_key, uint8_t *shared_key);
+
+/**
+ * Encrypts plain of length length to encrypted of length + CRYPTO_MAC_SIZE
+ * using a shared key CRYPTO_SYMMETRIC_KEY_SIZE big and a CRYPTO_NONCE_SIZE
+ * byte nonce.
+ *
+ * @return -1 if there was a problem, length of encrypted data if everything
+ * was fine.
+ */
+int32_t encrypt_data_symmetric(const uint8_t *shared_key, const uint8_t *nonce, const uint8_t *plain, size_t length,
+                               uint8_t *encrypted);
+
+/**
+ * Decrypts encrypted of length length to plain of length length -
+ * CRYPTO_MAC_SIZE using a shared key CRYPTO_SHARED_KEY_SIZE big and a
+ * CRYPTO_NONCE_SIZE byte nonce.
+ *
+ * @return -1 if there was a problem (decryption failed), length of plain data
+ * if everything was fine.
+ */
+int32_t decrypt_data_symmetric(const uint8_t *shared_key, const uint8_t *nonce, const uint8_t *encrypted, size_t length,
+                               uint8_t *plain);
+
+/**
+ * Increment the given nonce by 1 in big endian (rightmost byte incremented
+ * first).
+ */
+void increment_nonce(uint8_t *nonce);
+
+/**
+ * Increment the given nonce by a given number. The number should be in host
+ * byte order.
+ */
+void increment_nonce_number(uint8_t *nonce, uint32_t host_order_num);
+
+/**
+ * Fill the given nonce with random bytes.
+ */
+void random_nonce(uint8_t *nonce);
+
+/**
+ * Fill a key CRYPTO_SYMMETRIC_KEY_SIZE big with random bytes.
+ */
+void new_symmetric_key(uint8_t *key);
+
+/**
+ * Fill an array of bytes with random values.
+ */
+void random_bytes(uint8_t *bytes, size_t length);
+
+#endif /* CRYPTO_CORE_H */