/* See LICENSE file for copyright and license details. */
#ifndef LIBAR2_H
#define LIBAR2_H
#include <stddef.h>
#include <stdint.h>
#if defined(__clang__)
# pragma clang diagnostic push
# pragma clang diagnostic ignored "-Wpadded"
#endif
/* for internal use { */
#if defined(__GNUC__)
# define LIBAR2_NONNULL__(...) __attribute__((nonnull(__VA_ARGS__)))
#else
# define LIBAR2_NONNULL__(...)
#endif
#ifndef LIBAR2_PUBLIC__
# if defined(_MSC_VER)
# define LIBAR2_PUBLIC__ __declspec(dllexport)
# else
# define LIBAR2_PUBLIC__
# endif
#endif
#ifndef LIBAR2_PUBLIC_VARIABLE__
# if defined(_MSC_VER)
# define LIBAR2_PUBLIC_VARIABLE__ __declspec(dllexport)
# else
# define LIBAR2_PUBLIC_VARIABLE__
# endif
#endif
#if defined(UINT_LEAST32_C)
# define LIBAR2_UINT_LEAST32_C__(V) UINT_LEAST32_C(V)
#elif defined(UINT32_C)
# define LIBAR2_UINT_LEAST32_C__(V) UINT32_C(V)
#else
# define LIBAR2_UINT_LEAST32_C__(V) V##UL
#endif
#define LIBAR2_MIN_T_COST LIBAR2_UINT_LEAST32_C__(1)
#define LIBAR2_MAX_T_COST LIBAR2_UINT_LEAST32_C__(0xFFFFffff)
#define LIBAR2_MIN_M_COST LIBAR2_UINT_LEAST32_C__(8)
#define LIBAR2_MAX_M_COST ((uint_least32_t)((SIZE_MAX >> 11) & LIBAR2_UINT_LEAST32_C__(0xFFFFffff)))
#define LIBAR2_MIN_LANES LIBAR2_UINT_LEAST32_C__(1)
#define LIBAR2_MAX_LANES LIBAR2_UINT_LEAST32_C__(0xFFFFff)
#define LIBAR2_MIN_SALTLEN ((size_t)LIBAR2_UINT_LEAST32_C__(8))
#define LIBAR2_MAX_SALTLEN ((size_t)LIBAR2_UINT_LEAST32_C__(0xFFFFffff))
#define LIBAR2_MAX_KEYLEN ((size_t)LIBAR2_UINT_LEAST32_C__(0xFFFFffff))
#define LIBAR2_MAX_ADLEN ((size_t)LIBAR2_UINT_LEAST32_C__(0xFFFFffff))
#define LIBAR2_MIN_HASHLEN ((size_t)LIBAR2_UINT_LEAST32_C__(4))
#define LIBAR2_MAX_HASHLEN ((size_t)LIBAR2_UINT_LEAST32_C__(0xFFFFffff))
#define LIBAR2_IS_TYPE_OK(T) ((T) == LIBAR2_ARGON2D || (T) == LIBAR2_ARGON2I || (T) == LIBAR2_ARGON2ID || (T) == LIBAR2_ARGON2DS)
#define LIBAR2_IS_VERSION_OK(V) (!(V) || (V) == LIBAR2_ARGON2_VERSION_10 || (V) == LIBAR2_ARGON2_VERSION_13)
/* } */
/**
* List all parameter errors
*
* @param X Macro to expand for each error
* @param P A `const struct libar2_argon2_parameters *` to inspect
*/
#define LIBAR2_LIST_PARAMETER_ERRORS(X, P)\
X(LIBAR2_T_COST_TOO_SMALL, "time-cost parameter is too small", (P)->t_cost < LIBAR2_MIN_T_COST)\
X(LIBAR2_T_COST_TOO_LARGE, "time-cost parameter is too large", (P)->t_cost > LIBAR2_MAX_T_COST)\
X(LIBAR2_M_COST_TOO_SMALL, "memory-cost parameter is too small", (P)->m_cost < LIBAR2_MIN_M_COST)\
X(LIBAR2_M_COST_TOO_LARGE, "memory-cost parameter is too large", (P)->m_cost > LIBAR2_MAX_M_COST)\
X(LIBAR2_TOO_FEW_LANES, "lane-count parameter is too small", (P)->lanes < LIBAR2_MIN_LANES)\
X(LIBAR2_TOO_MANY_LANES, "lane-count parameter is too large", (P)->lanes > LIBAR2_MAX_LANES)\
X(LIBAR2_SALT_TOO_SMALL, "salt parameter is too small", (P)->saltlen < LIBAR2_MIN_SALTLEN)\
X(LIBAR2_SALT_TOO_LARGE, "salt parameter is too large", (P)->saltlen > LIBAR2_MAX_SALTLEN)\
X(LIBAR2_KEY_TOO_LARGE, "secret parameter is too large", (P)->keylen > LIBAR2_MAX_KEYLEN)\
X(LIBAR2_AD_TOO_LARGE, "associated data parameter is too large", (P)->adlen > LIBAR2_MAX_ADLEN)\
X(LIBAR2_HASH_TOO_SMALL, "tag length parameter is too small", (P)->hashlen < LIBAR2_MIN_HASHLEN)\
X(LIBAR2_HASH_TOO_LARGE, "tag length parameter is too large", (P)->hashlen > LIBAR2_MAX_HASHLEN)\
X(LIBAR2_INVALID_TYPE, "type parameter is invalid", !LIBAR2_IS_TYPE_OK((P)->type))\
X(LIBAR2_INVALID_VERSION, "version parameter is invalid", !LIBAR2_IS_VERSION_OK((P)->version))
/**
* Parameter errors
*/
enum libar2_parameter_error {
/**
* No error
*/
LIBAR2_OK = 0
#define LIBAR2_X__(ENUM, ERRMESG, CONDITION) ,ENUM
LIBAR2_LIST_PARAMETER_ERRORS(LIBAR2_X__,)
#undef LIBAR2_X__
};
/**
* String case
*/
enum libar2_casing {
/**
* Lower case, e.g. "argon2i"
*/
LIBAR2_LOWER_CASE = 0,
/**
* Title case, e.g. "Argon2i"
*/
LIBAR2_TITLE_CASE = 1,
/**
* Upper case, e.g. "ARGON2I"
*/
LIBAR2_UPPER_CASE = 2
};
/**
* Argon2 primitive types
*/
enum libar2_argon2_type {
/**
* Secret-dependent hashing
*
* Only for side-channel-free environments!
*/
LIBAR2_ARGON2D = 0,
/**
* Secret-independent hashing
*
* Good for side-channels but worse with respect
* to trade of attacks if only one pass is used
*/
LIBAR2_ARGON2I = 1,
/**
* Hybrid construction
*
* OK against side-channels and better with
* respect to tradeoff attacks
*/
LIBAR2_ARGON2ID = 2,
/* There is no type with value 3 */
/**
* Substition box (S-box)-hardened
*/
LIBAR2_ARGON2DS = 4
};
/**
* Argon2 versions
*/
enum libar2_argon2_version {
/**
* Argon2 version 1.0 ("10")
*/
LIBAR2_ARGON2_VERSION_10 = 0x10,
/**
* Argon2 version 1.3 ("13")
*/
LIBAR2_ARGON2_VERSION_13 = 0x13
};
/**
* Argon2 hashing parameters
*/
struct libar2_argon2_parameters {
/**
* Primitive type
*/
enum libar2_argon2_type type;
/**
* Version number; or 0 if not specified
* (which is equivalent to `LIBAR2_ARGON2_VERSION_10`)
*
* `libar2_latest_argon2_version` is recommended
*/
enum libar2_argon2_version version;
/**
* Number of passes
*
* At least 1, at most 2³²−1
*/
uint_least32_t t_cost;
/**
* Amount of required memory, in kilobytes
*
* At least 8, at most MAX(2³²−1, address-space » 11)
*/
uint_least32_t m_cost;
/**
* Number of lanes
*
* At least 1, at most 2²⁴−1
*/
uint_least32_t lanes;
/**
* Salt, binary
*
* Only modified if `.autoerase_salt` in
* `struct libar2_context` is non-zero
*/
unsigned char *salt;
/**
* The length (bytes) of the salt
*
* At least 8, at most 2³²−1
*/
size_t saltlen;
/**
* Secret (pepper), binary [optional]
*
* Only modified if `.autoerase_secret` in
* `struct libar2_context` is non-zero
*/
unsigned char *key;
/**
* The length (bytes) of the secret
*
* At least 0, at most 2³²−1
*/
size_t keylen;
/**
* Arbitrary extra associated data, binary [optional]
*
* Only modified if `.autoerase_associated_data`
* in `struct libar2_context` is non-zero
*/
unsigned char *ad;
/**
* The length (bytes) of the associated
*
* At least 0, at most 2³²−1
*/
size_t adlen;
/**
* The length (bytes) of the output hash
*
* At least 4, at most 2³²−1
*/
size_t hashlen;
};
/**
* Library settings
*/
struct libar2_context {
/**
* User-defined data
*/
void *user_data;
/**
* Whether the message shall be erased
* immediately when it's no longer need
*
* Assumming the message is a password,
* you would normally set this to non-zero
* (properly 1), unless the password is in
* read-only memory for will be needed for
* rehashing with a stronger algorithm or
* new parameters
*/
unsigned char autoerase_message;
/**
* Whether the secret shall be erased
* immediately when it's no longer need
*/
unsigned char autoerase_secret;
/**
* Whether the salt shall be erased
* immediately when it's no longer need
*/
unsigned char autoerase_salt;
/**
* Whether the associated data shall be
* erased immediately when it's no longer
* need
*/
unsigned char autoerase_associated_data;
/**
* Memory allocation function
*
* It is safe to assume that `.allocate` and
* `.deallocate` will be called in stack order
* and never in threads run using `.run_thread`
*
* Example implementation:
*
* static void *
* allocate(size_t num, size_t size, size_t alignment, struct libar2_context *ctx)
* {
* void *ptr;
* int err;
* (void) ctx;
* if (num > SIZE_MAX / size) {
* errno = ENOMEM;
* return NULL;
* }
* if (alignment < sizeof(void *))
* alignment = sizeof(void *);
* err = posix_memalign(&ptr, alignment, num * size);
* if (err) {
* errno = err;
* return NULL;
* } else {
* return ptr;
* }
* }
*
* @param num The number of elements to allocate, never 0
* @param size The size of each element, never 0
* @param alignment Requires memory alignment, never 0
* @param ctx The structure containing the callback
* @return Pointer to the allocated memory, `NULL` on failure
*/
void *(*allocate)(size_t num, size_t size, size_t alignment, struct libar2_context *ctx);
/**
* Memory deallocation function
*
* The application may which to erase the memory before
* deallocating it; this is not done by the library.
* This can be done using `libar2_erase`;
*
* Example implementation:
*
* static void
* deallocate(void *ptr, struct libar2_context *ctx)
* {
* (void) ctx;
* free(ptr);
* }
*
* @param ptr The pointer to the memory to deallocate,
* always a pointer returned by `.allocate`
* @param ctx The structure containing the callback
*/
void (*deallocate)(void *ptr, struct libar2_context *ctx);
/**
* Initialise the thread pool
*
* If thread support is desired, but the application do not
* want to keep track of the threads using a thread pool,
* this function must store `desired` in `*createdp`. The
* application must also, in this case, make sure that
* `.join_thread_pool` returns after all started threads
* have stopped, and `.get_ready_threads` store unique
* indices within the range [0, `desired`) (start with
* `i = 0` and each time an index is stored, calculate it
* with `i++ % desired`). Alternatively, and more preferably,
* this scheme can be used, but adapted to limit the number
* of concurrent threads, keeping track of the number of
* running threads, and not let `.get_ready_threads` return
* before this number is small enough; `*createdp` must however
* still set to `desired` so that to threads are not running
* concurrently with the same memory segment as the provided
* argument for the function to run, as this could be a source
* of memory corruption. It is however recommended to implement
* proper thread pooling as the library will call `.run_thread`
* `4 * params->t_cost * params->lanes` times where `params`
* is the used `struct libar2_argon2_parameters *`.
*
* @param desired The number of threads that, at a maximum,
* will be used by the library, from the
* thread pool
* @param createdp Output parameter for the number of threads
* allocated, 0 if threading is disabled,
* which is preferable if `desired` is 1
* @param ctx The structure containing the callback
* @return 0 on success, -1 on failure (the calling
* function will exit indicating error and keep
* the value of `errno` set by this function)
*/
int (*init_thread_pool)(size_t desired, size_t *createdp, struct libar2_context *ctx);
/**
* Wait until at least one thread in the pool is ready
* (may be immediately), and get some of their indices
*
* @param indices Output array for the indices of the ready threads
* @param n The maximum number of thread indices to store in `indices`;
* this number may exceed the number of created, or even
* requested, threads, or the number of threads the function
* will attempt to use
* @param ctx The structure containing the callback
* @return The number of ready threads (non-zero, but may exceed `n`);
* 0 on failure (the calling function will exit indicating
* error and keep the value of `errno` set by this function)
*/
size_t (*get_ready_threads)(size_t *indices, size_t n, struct libar2_context *ctx);
/**
* Run a function in a thread
*
* The requested thread will be guaranteed by
* `.get_ready_threads` to be ready
*
* @param index The index of the thread to use
* @param function The function to run
* @param data Argument to provide to `function`
* @param ctx The structure containing the callback
* @return 0 on success, -1 on failure (the calling
* function will exit indicating error and keep
* the value of `errno` set by this function)
*/
int (*run_thread)(size_t index, void (*function)(void *data), void *data, struct libar2_context *ctx);
/**
* Wait until all threads in the thread pool are resting
*
* @param ctx The structure containing the callback
* @return 0 on success, -1 on failure (the calling
* function will exit indicating error and keep
* the value of `errno` set by this function)
*/
int (*join_thread_pool)(struct libar2_context *ctx);
/**
* Destroy the thread pool, and all threads in it
* (each of the will be resting)
*
* Will be called iff `.init_thread_pool` was called
* successfully and returned a non-zero thread
* count, except, not if `.join_thread_pool` or
* `.get_ready_threads` failed
*
* @param ctx The structure containing the callback
* @return 0 on success, -1 on failure (the calling
* function will exit indicating error and keep
* the value of `errno` set by this function)
*/
int (*destroy_thread_pool)(struct libar2_context *ctx);
};
/**
* The latest version of Argon2 that is supported
*/
extern const enum libar2_argon2_version libar2_latest_argon2_version;
/**
* Convert an Argon2 primitive type value to a string
*
* @param type The primitive type
* @param casing The case that the string shalll use
* @return String representing the type, `NULL` (with `errno`
* set to EINVAL) if either argument is invalid
*/
LIBAR2_PUBLIC__
const char *libar2_type_to_string(enum libar2_argon2_type type, enum libar2_casing casing);
/**
* Convert a string to an Argon2 primitive type value
*
* @param str String representing the primitive type
* @param typep Output parameter for the primitive type
* @return 0 on success, -1 (with `errno` set to EINVAL) if `str` is invalid
*/
LIBAR2_PUBLIC__ LIBAR2_NONNULL__(1, 2)
int libar2_string_to_type(const char *str, enum libar2_argon2_type *typep);
/**
* Convert an Argon2 version number value to a string,
* will be returned without a dot
*
* @param version The version number value
* @return String representing the version, `NULL` (with
* `errno` set to EINVAL) if `version` is invalid
*/
LIBAR2_PUBLIC__
const char *libar2_version_to_string(enum libar2_argon2_version version);
/**
* Convert an Argon2 version number value to a string,
* will be returned with a dot
*
* @param version The version number value
* @return String representing the version, `NULL` (with
* `errno` set to EINVAL) if `version` is invalid
*/
LIBAR2_PUBLIC__
const char *libar2_version_to_string_proper(enum libar2_argon2_version version);
/**
* Convert a string to an Argon2 version number value
*
* @param str String representing the version
* @param versionp Output parameter for the version number value
* @return 0 on success, -1 (with `errno` set to EINVAL) if `str` is invalid
*/
LIBAR2_PUBLIC__ LIBAR2_NONNULL__(1, 2)
int libar2_string_to_version(const char *str, enum libar2_argon2_version *versionp);
/**
* Encode hashing parameters
*
* Secret, associated data, and tag length (`params->hashlen`)
* will not be included in the output
*
* To encode a string with both the parameters and the
* hash, simply append the output of `libar2_encode_base64`
* over the hash onto the output of this function
*
* @param buf Output buffer, or `NULL`
* @param params Hashing parameters
* @return The number of bytes required for `buf`,
* including the NUL byte added to the end
*/
LIBAR2_PUBLIC__ LIBAR2_NONNULL__(2)
size_t libar2_encode_params(char *buf, const struct libar2_argon2_parameters *params);
/**
* Encode data with base64 encoding, which is what
* Argon2 uses, rather than B64 which is what crypt(3)
* uses; however this version of base64 is not padded
* to a length divible by 4
*
* @param buf Output buffer, or `NULL`
* @param data The data to encode, may be
* `NULL` if `buf` is `NULL`
* @param len The number of bytes in `data`
* @return The number of bytes required for `buf`,
* including the NUL byte added to the end
*/
LIBAR2_PUBLIC__
size_t libar2_encode_base64(char *buf, const void *data, size_t len);
/**
* Decode hashing parameters
*
* Secret and associated data will be set to zero-length
*
* It is recommended that application stores that default
* parameters encoded with `libar2_encode_params` using
* a hash of only null bytes. When the allocation decodes
* this string before generating the hash for a new password,
* it would refill the salt buffer with random bytes. The
* salt buffer will be allocated by this function.
*
* The tag length (`params->hashlen`) will calculated from
* that hash at the end of `str`, however, the encoded length
* of the hash will not be included in the function's return
* value
*
* @param str Hashing parameter string
* @param params Output parameter for the hashing parameters
* @param bufp Output parameter for buffer containing variable
* length data in `params`; will be allocated
* using `ctx->allocate`
* @param ctx `.allocate` and `.deallocate` must be set
* @return The number of bytes read, 0 if `str` is improperly
* formatted (EINVAL), contain an unrecognised primitive
* type (EINVAL), or contained a value that is too large
* to be stored (ERANGE) (otherwise invalid parameters
* are not checked); if a callback from `ctx` fails, 0
* is returned with `errno` set to the value set by the
* callback; if non-zero is returned, and `str` contains
* a hash, and not just parameters, `&str[return]` will
* point to the hash
*/
LIBAR2_PUBLIC__ LIBAR2_NONNULL__(1, 2, 3, 4)
size_t libar2_decode_params(const char *str, struct libar2_argon2_parameters *params, char **bufp, struct libar2_context *ctx);
/**
* Decode data encoded with base64 (padding with '=' is optional)
*
* @param str The data to decode
* @param data Output buffer for the decoded data, or `NULL`
* @param lenp Output parameter for the length of the decoded data
* @return The number of bytes read
*/
LIBAR2_PUBLIC__ LIBAR2_NONNULL__(1, 3)
size_t libar2_decode_base64(const char *str, void *data, size_t *lenp);
/**
* Validate hashing parameters
*
* @param params The hashing parameters
* @param errmsgp Output parameter for the error message, or `null`
* @return The first detected error, or LIBAR2_OK (0) if none
*/
LIBAR2_PUBLIC__ LIBAR2_NONNULL__(1)
enum libar2_parameter_error libar2_validate_params(const struct libar2_argon2_parameters *params, const char **errmsgp);
/**
* Securily erase memory
*
* @param mem The memory to erase
* @param size The number of bytes to erase
*/
LIBAR2_PUBLIC__
void libar2_erase(volatile void *mem, size_t size);
/**
* Hash a message
*
* The recommended why of verify a password is to hash the
* provided password with this function, convert the known
* hash with `libar2_decode_base64` to binary (if it's not
* already in binary), and let `h` be the result of this
* function, `k` be the known password hash, and `n` be
* `params->hashlen`, then the password is correct iff
* `d`, as computed below, is 0:
*
* unsigned char d = 0;
* size_t i;
* for (i = 0; i < n; i++) {
* d |= h[i] ^ k[i];
* }
*
* It is preferable this check is done by the process that
* knowns the correct password hash, and that the tried
* password is hashed before it is sent to that process
*
* Note that on failure, the function will not necessarily
* have erased data configured in `ctx` to be automatically
* erased
*
* @param hash Binary hash ("tag") output buffer, shall be at
* least `libar2_hash_buf_size(params)` bytes large
* @param msg Message (password) to hash; only modified if
* `ctx->autoerase_message` is non-zero
* @param msglen The length of `msg`; at least 0, at most 2³²−1
* @param params Hashing parameters
* @param ctx Library settings
* @return 0 on success, -1 on failure
*/
LIBAR2_PUBLIC__ LIBAR2_NONNULL__(1, 4, 5)
int libar2_hash(void *hash, void *msg, size_t msglen, struct libar2_argon2_parameters *params, struct libar2_context *ctx);
/**
* Return the number of bytes that is required for
* the first parameter, the output parmeter, of
* `libar2_hash`
*
* If `params->hashlen <= 64`, this function will
* return `params->hashlen` as is
*
* @param params Hashing parameters
* @return The required allocation size of the
* output parameter of `libar2_hash`, 0
* with errno set to EOVERFLOW if the
* result is too large
*/
LIBAR2_PUBLIC__ LIBAR2_NONNULL__(1)
size_t libar2_hash_buf_size(struct libar2_argon2_parameters *params);
#if defined(__clang__)
# pragma clang diagnostic pop
#endif
#endif
