toxcore/crypto_core.h
Rama master · réplica de lectura del repositorio original.
/* SPDX-License-Identifier: GPL-3.0-or-later
* Copyright © 2016-2026 The TokTok team.
* Copyright © 2013 Tox project.
*/
/** @file
* @brief Functions for the core crypto.
*
* @note This code has to be perfect. We don't mess around with encryption.
*/
#ifndef C_TOXCORE_TOXCORE_CRYPTO_CORE_H
#define C_TOXCORE_TOXCORE_CRYPTO_CORE_H
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include "attributes.h"
#include "mem.h"
#include "rng.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief The number of bytes in a signature.
*/
#define CRYPTO_SIGNATURE_SIZE 64
/**
* @brief The number of bytes in a Tox public key used for signatures.
*/
#define CRYPTO_SIGN_PUBLIC_KEY_SIZE 32
/**
* @brief The number of bytes in a Tox secret key used for signatures.
*/
#define CRYPTO_SIGN_SECRET_KEY_SIZE 64
/**
* @brief The number of bytes in a Tox public key used for encryption.
*/
#define CRYPTO_PUBLIC_KEY_SIZE 32
/**
* @brief The number of bytes in a Tox secret key used for encryption.
*/
#define CRYPTO_SECRET_KEY_SIZE 32
/**
* @brief The number of bytes in a shared key computed from public and secret keys.
*/
#define CRYPTO_SHARED_KEY_SIZE 32
/**
* @brief The number of bytes in a symmetric key.
*/
#define CRYPTO_SYMMETRIC_KEY_SIZE CRYPTO_SHARED_KEY_SIZE
/**
* @brief The number of bytes needed for the MAC (message authentication code) in an
* encrypted message.
*/
#define CRYPTO_MAC_SIZE 16
/**
* @brief The number of bytes in a nonce used for encryption/decryption.
*/
#define CRYPTO_NONCE_SIZE 24
/**
* @brief The number of bytes in a SHA256 hash.
*/
#define CRYPTO_SHA256_SIZE 32
/**
* @brief The number of bytes in a SHA512 hash.
*/
#define CRYPTO_SHA512_SIZE 64
/**
* @brief The number of bytes in an encryption public key used by DHT group chats.
*/
#define ENC_PUBLIC_KEY_SIZE CRYPTO_PUBLIC_KEY_SIZE
/**
* @brief The number of bytes in an encryption secret key used by DHT group chats.
*/
#define ENC_SECRET_KEY_SIZE CRYPTO_SECRET_KEY_SIZE
/**
* @brief The number of bytes in a signature public key.
*/
#define SIG_PUBLIC_KEY_SIZE CRYPTO_SIGN_PUBLIC_KEY_SIZE
/**
* @brief The number of bytes in a signature secret key.
*/
#define SIG_SECRET_KEY_SIZE CRYPTO_SIGN_SECRET_KEY_SIZE
/**
* @brief The number of bytes in a DHT group chat public key identifier.
*/
#define CHAT_ID_SIZE SIG_PUBLIC_KEY_SIZE
/**
* @brief The number of bytes in an extended public key used by DHT group chats.
*/
#define EXT_PUBLIC_KEY_SIZE (ENC_PUBLIC_KEY_SIZE + SIG_PUBLIC_KEY_SIZE)
/**
* @brief The number of bytes in an extended secret key used by DHT group chats.
*/
#define EXT_SECRET_KEY_SIZE (ENC_SECRET_KEY_SIZE + SIG_SECRET_KEY_SIZE)
/**
* @brief The number of bytes in an HMAC authenticator.
*/
#define CRYPTO_HMAC_SIZE 32
/**
* @brief The number of bytes in an HMAC secret key.
*/
#define CRYPTO_HMAC_KEY_SIZE 32
/**
* @brief 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 *_Nonnull data, size_t length);
/**
* @brief Compute a SHA256 hash (32 bytes).
*
* @param[out] hash The SHA256 hash of @p data will be written to this byte array.
*/
void crypto_sha256(uint8_t hash[_Nonnull CRYPTO_SHA256_SIZE], const uint8_t *_Nonnull data, size_t length);
/**
* @brief Compute a SHA512 hash (64 bytes).
*
* @param[out] hash The SHA512 hash of @p data will be written to this byte array.
*/
void crypto_sha512(uint8_t hash[_Nonnull CRYPTO_SHA512_SIZE], const uint8_t *_Nonnull data, size_t length);
/**
* @brief Compute an HMAC authenticator (32 bytes).
*
* @param[out] auth Resulting authenticator.
* @param key Secret key, as generated by `new_hmac_key()`.
*/
void crypto_hmac(uint8_t auth[_Nonnull CRYPTO_HMAC_SIZE], const uint8_t key[_Nonnull CRYPTO_HMAC_KEY_SIZE], const uint8_t *_Nonnull data, size_t length);
/**
* @brief Verify an HMAC authenticator.
*/
bool crypto_hmac_verify(const uint8_t auth[_Nonnull CRYPTO_HMAC_SIZE], const uint8_t key[_Nonnull CRYPTO_HMAC_KEY_SIZE], const uint8_t *_Nonnull data, size_t length);
/**
* @brief Compare 2 public keys of length @ref CRYPTO_PUBLIC_KEY_SIZE, not vulnerable to
* timing attacks.
*
* @retval true if both mem locations of length are equal
* @retval false if they are not
*/
bool pk_equal(const uint8_t pk1[_Nonnull CRYPTO_PUBLIC_KEY_SIZE], const uint8_t pk2[_Nonnull CRYPTO_PUBLIC_KEY_SIZE]);
/**
* @brief Copy a public key from `src` to `dest`.
*/
void pk_copy(uint8_t dest[_Nonnull CRYPTO_PUBLIC_KEY_SIZE], const uint8_t src[_Nonnull CRYPTO_PUBLIC_KEY_SIZE]);
/**
* @brief Compare 2 SHA512 checksums of length CRYPTO_SHA512_SIZE, not vulnerable to
* timing attacks.
*
* @return true if both mem locations of length are equal, false if they are not.
*/
bool crypto_sha512_eq(const uint8_t cksum1[_Nonnull CRYPTO_SHA512_SIZE], const uint8_t cksum2[_Nonnull CRYPTO_SHA512_SIZE]);
/**
* @brief Compare 2 SHA256 checksums of length CRYPTO_SHA256_SIZE, not vulnerable to
* timing attacks.
*
* @return true if both mem locations of length are equal, false if they are not.
*/
bool crypto_sha256_eq(const uint8_t cksum1[_Nonnull CRYPTO_SHA256_SIZE], const uint8_t cksum2[_Nonnull CRYPTO_SHA256_SIZE]);
/**
* @brief Return a random 8 bit integer.
*/
uint8_t random_u08(const Random *_Nonnull rng);
/**
* @brief Return a random 16 bit integer.
*/
uint16_t random_u16(const Random *_Nonnull rng);
/**
* @brief Return a random 32 bit integer.
*/
uint32_t random_u32(const Random *_Nonnull rng);
/**
* @brief Return a random 64 bit integer.
*/
uint64_t random_u64(const Random *_Nonnull rng);
/**
* @brief Return a random 32 bit integer between 0 and upper_bound (excluded).
*
* This function guarantees a uniform distribution of possible outputs.
*/
uint32_t random_range_u32(const Random *_Nonnull rng, uint32_t upper_bound);
/**
* @brief Cryptographically signs a message using the supplied secret key and puts the resulting signature
* in the supplied buffer.
*
* @param[out] signature The buffer for the resulting signature, which must have room for at
* least CRYPTO_SIGNATURE_SIZE bytes.
* @param message The message being signed.
* @param message_length The length in bytes of the message being signed.
* @param secret_key The secret key used to create the signature. The key should be
* produced by either `create_extended_keypair` or the libsodium function `crypto_sign_keypair`.
*
* @retval true on success.
*/
bool crypto_signature_create(uint8_t signature[_Nonnull CRYPTO_SIGNATURE_SIZE], const uint8_t *_Nonnull message, uint64_t message_length, const uint8_t secret_key[_Nonnull SIG_SECRET_KEY_SIZE]);
/** @brief Verifies that the given signature was produced by a given message and public key.
*
* @param signature The signature we wish to verify.
* @param message The message we wish to verify.
* @param message_length The length of the message.
* @param public_key The public key counterpart of the secret key that was used to
* create the signature.
*
* @retval true on success.
*/
bool crypto_signature_verify(const uint8_t signature[_Nonnull CRYPTO_SIGNATURE_SIZE], const uint8_t *_Nonnull message, uint64_t message_length,
const uint8_t public_key[_Nonnull SIG_PUBLIC_KEY_SIZE]);
/**
* @brief Fill the given nonce with random bytes.
*/
void random_nonce(const Random *_Nonnull rng, uint8_t nonce[_Nonnull CRYPTO_NONCE_SIZE]);
/**
* @brief Fill an array of bytes with random values.
*/
void random_bytes(const Random *_Nonnull rng, uint8_t *_Nonnull bytes, size_t length);
/**
* @brief 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[_Nonnull CRYPTO_PUBLIC_KEY_SIZE]);
typedef struct Extended_Public_Key {
uint8_t enc[CRYPTO_PUBLIC_KEY_SIZE];
uint8_t sig[CRYPTO_SIGN_PUBLIC_KEY_SIZE];
} Extended_Public_Key;
typedef struct Extended_Secret_Key {
uint8_t enc[CRYPTO_SECRET_KEY_SIZE];
uint8_t sig[CRYPTO_SIGN_SECRET_KEY_SIZE];
} Extended_Secret_Key;
/**
* @brief Creates an extended keypair: curve25519 and ed25519 for encryption and signing
* respectively. The Encryption keys are derived from the signature keys.
*
* NOTE: This does *not* use Random, so any code using this will not be fuzzable.
* TODO: Make it use Random.
*
* @param[out] pk The buffer where the public key will be stored. Must have room for EXT_PUBLIC_KEY_SIZE bytes.
* @param[out] sk The buffer where the secret key will be stored. Must have room for EXT_SECRET_KEY_SIZE bytes.
* @param rng The random number generator to use for the key generator seed.
*
* @retval true on success.
*/
bool create_extended_keypair(Extended_Public_Key *_Nonnull pk, Extended_Secret_Key *_Nonnull sk, const Random *_Nonnull rng);
/** Functions for groupchat extended keys */
const uint8_t *_Nonnull get_enc_key(const Extended_Public_Key *_Nonnull key);
const uint8_t *_Nonnull get_sig_pk(const Extended_Public_Key *_Nonnull key);
void set_sig_pk(Extended_Public_Key *_Nonnull key, const uint8_t *_Nonnull sig_pk);
const uint8_t *_Nonnull get_sig_sk(const Extended_Secret_Key *_Nonnull key);
const uint8_t *_Nonnull get_chat_id(const Extended_Public_Key *_Nonnull key);
/**
* @brief Verifies that `sig_pk` corresponds to `enc_pk`.
*
* Note: This function assumes that `enc_pk` was generated via `create_extended_keypair()`.
*
* @param enc_pk The public encryption key that we want to validate the signature key against.
* @param sig_pk The public signature key that we want to validate.
*
* @retval true on success.
*/
bool validate_sig_pk(const uint8_t *_Nonnull enc_pk, const uint8_t *_Nonnull sig_pk);
/**
* @brief Generate a new random keypair.
*
* Every call to this function is likely to generate a different keypair.
*/
int32_t crypto_new_keypair(const Random *_Nonnull rng, uint8_t public_key[_Nonnull CRYPTO_PUBLIC_KEY_SIZE], uint8_t secret_key[_Nonnull CRYPTO_SECRET_KEY_SIZE]);
/**
* @brief Derive the public key from a given secret key.
*/
void crypto_derive_public_key(uint8_t public_key[_Nonnull CRYPTO_PUBLIC_KEY_SIZE], const uint8_t secret_key[_Nonnull CRYPTO_SECRET_KEY_SIZE]);
/**
* @brief Encrypt message to send from secret key to public key.
*
* Encrypt plain text of the given length to encrypted of
* `length + CRYPTO_MAC_SIZE` using the public key (@ref CRYPTO_PUBLIC_KEY_SIZE
* bytes) of the receiver and the secret key of the sender and a
* @ref CRYPTO_NONCE_SIZE byte nonce.
*
* @retval -1 if there was a problem.
* @return length of encrypted data if everything was fine.
*/
int32_t encrypt_data(const Memory *_Nonnull mem, const uint8_t public_key[_Nonnull CRYPTO_PUBLIC_KEY_SIZE], const uint8_t secret_key[_Nonnull CRYPTO_SECRET_KEY_SIZE],
const uint8_t nonce[_Nonnull CRYPTO_NONCE_SIZE], const uint8_t *_Nonnull plain, size_t length, uint8_t *_Nonnull encrypted);
/**
* @brief Decrypt message from public key to secret key.
*
* Decrypt encrypted text of the given @p length to plain text of the given
* `length - CRYPTO_MAC_SIZE` using the public key (@ref CRYPTO_PUBLIC_KEY_SIZE
* bytes) of the sender, the secret key of the receiver and a
* @ref CRYPTO_NONCE_SIZE byte nonce.
*
* @retval -1 if there was a problem (decryption failed).
* @return length of plain text data if everything was fine.
*/
int32_t decrypt_data(const Memory *_Nonnull mem, const uint8_t public_key[_Nonnull CRYPTO_PUBLIC_KEY_SIZE], const uint8_t secret_key[_Nonnull CRYPTO_SECRET_KEY_SIZE],
const uint8_t nonce[_Nonnull CRYPTO_NONCE_SIZE], const uint8_t *_Nonnull encrypted, size_t length, uint8_t *_Nonnull plain);
/**
* @brief 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 performed on every
* encrypt/decrypt.
*/
int32_t encrypt_precompute(const uint8_t public_key[_Nonnull CRYPTO_PUBLIC_KEY_SIZE], const uint8_t secret_key[_Nonnull CRYPTO_SECRET_KEY_SIZE],
uint8_t shared_key[_Nonnull CRYPTO_SHARED_KEY_SIZE]);
/**
* @brief Encrypt message with precomputed shared key.
*
* Encrypts plain of length length to encrypted of length + @ref CRYPTO_MAC_SIZE
* using a shared key @ref CRYPTO_SYMMETRIC_KEY_SIZE big and a @ref CRYPTO_NONCE_SIZE
* byte nonce.
*
* @retval -1 if there was a problem.
* @return length of encrypted data if everything was fine.
*/
int32_t encrypt_data_symmetric(const Memory *_Nonnull mem, const uint8_t shared_key[_Nonnull CRYPTO_SHARED_KEY_SIZE], const uint8_t nonce[_Nonnull CRYPTO_NONCE_SIZE],
const uint8_t *_Nonnull plain, size_t length, uint8_t *_Nonnull encrypted);
/**
* @brief Decrypt message with precomputed shared key.
*
* Decrypts encrypted of length length to plain of length
* `length - CRYPTO_MAC_SIZE` using a shared key @ref CRYPTO_SYMMETRIC_KEY_SIZE
* big and a @ref CRYPTO_NONCE_SIZE byte nonce.
*
* @retval -1 if there was a problem (decryption failed).
* @return length of plain data if everything was fine.
*/
int32_t decrypt_data_symmetric(const Memory *_Nonnull mem, const uint8_t shared_key[_Nonnull CRYPTO_SHARED_KEY_SIZE], const uint8_t nonce[_Nonnull CRYPTO_NONCE_SIZE],
const uint8_t *_Nonnull encrypted, size_t length, uint8_t *_Nonnull plain);
/**
* @brief Increment the given nonce by 1 in big endian (rightmost byte incremented first).
*/
void increment_nonce(uint8_t nonce[_Nonnull CRYPTO_NONCE_SIZE]);
/**
* @brief Increment the given nonce by a given number.
*
* The number should be in host byte order.
*/
void increment_nonce_number(uint8_t nonce[_Nonnull CRYPTO_NONCE_SIZE], uint32_t increment);
/**
* @brief Fill a key @ref CRYPTO_SYMMETRIC_KEY_SIZE big with random bytes.
*/
void new_symmetric_key(const Random *_Nonnull rng, uint8_t key[_Nonnull CRYPTO_SYMMETRIC_KEY_SIZE]);
/**
* @brief Locks `length` bytes of memory pointed to by `data`.
*
* This will attempt to prevent the specified memory region from being swapped
* to disk.
*
* @return true on success.
*/
bool crypto_memlock(void *_Nonnull data, size_t length);
/**
* @brief Unlocks `length` bytes of memory pointed to by `data`.
*
* This allows the specified memory region to be swapped to disk.
*
* This function call has the side effect of zeroing the specified memory region
* whether or not it succeeds. Therefore it should only be used once the memory
* is no longer in use.
*
* @return true on success.
*/
bool crypto_memunlock(void *_Nonnull data, size_t length);
/**
* @brief Generate a random secret HMAC key.
*/
void new_hmac_key(const Random *_Nonnull rng, uint8_t key[_Nonnull CRYPTO_HMAC_KEY_SIZE]);
#ifdef __cplusplus
} /* extern "C" */
#endif
#endif /* C_TOXCORE_TOXCORE_CRYPTO_CORE_H */