Sortix 1.1dev nightly manual
This manual documents Sortix 1.1dev nightly, a development build that has not been officially released. You can instead view this document in the latest official manual.
|HMAC(3)||Library Functions Manual||HMAC(3)|
HMAC message authentication code
#include <openssl/hmac.h>unsigned char *
HMAC(const EVP_MD *evp_md, const void *key, int key_len, const unsigned char *d, size_t n, unsigned char *md, unsigned int *md_len); HMAC_CTX *
HMAC_CTX_reset(HMAC_CTX *ctx); void
HMAC_CTX_free(HMAC_CTX *ctx); void
HMAC_CTX_init(HMAC_CTX *ctx); void
HMAC_CTX_cleanup(HMAC_CTX *ctx); void
HMAC_cleanup(HMAC_CTX *ctx); int
HMAC_Init_ex(HMAC_CTX *ctx, const void *key, int key_len, const EVP_MD *md, ENGINE *impl); int
HMAC_Init(HMAC_CTX *ctx, const void *key, int key_len, const EVP_MD *md); int
HMAC_Update(HMAC_CTX *ctx, const unsigned char *data, size_t len); int
HMAC_Final(HMAC_CTX *ctx, unsigned char *md, unsigned int *len); int
HMAC_CTX_copy(HMAC_CTX *dctx, HMAC_CTX *sctx); void
HMAC_CTX_set_flags(HMAC_CTX *ctx, unsigned long flags); const EVP_MD *
HMAC_CTX_get_md(const HMAC_CTX *ctx); size_t
HMAC_size(const HMAC_CTX *e);
HMAC() computes the message authentication code of the n bytes at d using the hash function evp_md and the key key which is key_len bytes long. It places the result in md, which must have space for the output of the hash function, which is no more than
EVP_MAX_MD_SIZEbytes. If md is
NULL, the digest is placed in a static array, which is not thread safe. The size of the output is placed in md_len, unless it is
NULL. evp_md can be EVP_sha1(3), EVP_ripemd160(3), etc.
HMAC_CTX_new() allocates and initializes a new HMAC_CTX object.
HMAC_CTX_reset() zeroes and re-initializes ctx and associated resources, making it suitable for new computations as if it was deleted with
HMAC_CTX_free() and newly created with
HMAC_CTX_free() erases the key and other data from ctx, releases any associated resources, and finally frees ctx itself.
HMAC_CTX_init() is a deprecated function to initialize an empty HMAC_CTX object, similar to
CTX_new() but without the allocation. Calling it is required for static objects and objects on the stack before using them.
HMAC_CTX_cleanup() is a deprecated function to erase the key and other data from ctx and release any associated resources, similar to
HMAC_CTX_free() but without freeing ctx itself. Calling it is required for static objects and objects on the stack that were initialized with
HMAC_CTX_init() and are no longer needed.
HMAC_cleanup() is an alias for
HMAC_CTX_cleanup() included for backward compatibility with 0.9.6b. It is deprecated and implemented as a macro. The following functions may be used if the message is not completely stored in memory:
HMAC_Init_ex() sets up or reuses ctx to use the hash function evp_md and the key key. Either can be
NULL, in which case the existing one is reused. The ctx must have been created with
HMAC_CTX_new() or initialized with
HMAC_CTX_init() before the first use in this function. If
HMAC_Init_ex() is called with a
NULLkey but evp_md is neither
NULLnor the same as the previous digest used by ctx, then an error is returned because reuse of an existing key with a different digest is not supported.
HMAC_Init() is a deprecated wrapper around
HMAC_Init_ex(). If called with both key and md, it calls
HMAC_CTX_init() first, which only makes sense for an empty, uninitialized ctx, but not for one already initialized with
HMAC_CTX_init(). If key or md is
NULL, it does not call
HMAC_CTX_init(); so in this case, ctx already needs to be initialized with
HMAC_Update() can be called repeatedly with chunks of the message to be authenticated (len bytes at data).
HMAC_Final() places the message authentication code in md, which must have space for the hash function output.
HMAC_CTX_copy() copies all of the internal state from sctx into dctx.
HMAC_CTX_set_flags() applies the specified flags to the internal EVP_MD_CTX objects. Possible flag values
EVP_MD_CTX_FLAG_*are defined in
HMAC_size() returns the length in bytes of the underlying hash function output. It is implemented as a macro.
HMAC() returns a pointer to the message authentication code or
NULLif an error occurred.
HMAC_CTX_new() returns a pointer to the new HMAC_CTX object or
NULLif an error occurred.
HMAC_CTX_copy() return 1 for success or 0 if an error occurred.
HMAC_CTX_get_md() returns the message digest that was previously set for ctx with
NULLif none was set.
HMAC_size() returns the length in bytes of the underlying hash function output or 0 on error. CMAC_Init(3), EVP_DigestInit(3)
HMAC_size() first appeared in SSLeay 0.9.0 and have been available since OpenBSD 2.4.
HMAC_Init_ex() first appeared in OpenSSL 0.9.7 and have been available since OpenBSD 3.2.
HMAC_CTX_set_flags() first appeared in OpenSSL 0.9.7f and have been available since OpenBSD 3.8.
HMAC_CTX_copy() first appeared in OpenSSL 1.0.0 and has been available since OpenBSD 4.9.
HMAC_CTX_get_md() first appeared in OpenSSL 1.1.0 and have been available since OpenBSD 6.3.
|June 24, 2020||Debian|