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/* af_alg.h - Compute message digests from file streams and buffers.
Copyright (C) 2018 Free Software Foundation, Inc.
This program 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, or (at your option) any
later version.
This program 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 this program; if not, see <https://www.gnu.org/licenses/>. */
/* Written by Matteo Croce <mcroce@redhat.com>, 2018.
Documentation by Bruno Haible <bruno@clisp.org>, 2018. */
/* Declare specific functions for computing message digests
using the Linux kernel crypto API, if available. This kernel API gives
access to specialized crypto instructions (that would also be available
in user space) or to crypto devices (not directly available in user space).
For a more complete set of facilities that use the Linux kernel crypto API,
look at libkcapi. */
#ifndef AF_ALG_H
# define AF_ALG_H 1
# include <stdio.h>
# include <errno.h>
# ifdef __cplusplus
extern "C" {
# endif
# if USE_LINUX_CRYPTO_API
/* Compute a message digest of a memory region.
The memory region starts at BUFFER and is LEN bytes long.
ALG is the message digest algorithm; see the file /proc/crypto.
RESBLOCK points to a block of HASHLEN bytes, for the result.
HASHLEN must be the length of the message digest, in bytes, in particular:
alg | hashlen
-------+--------
md5 | 16
sha1 | 20
sha224 | 28
sha256 | 32
sha384 | 48
sha512 | 64
If successful, fill RESBLOCK and return 0.
Upon failure, return a negated error number. */
int
afalg_buffer (const char *buffer, size_t len, const char *alg,
void *resblock, ssize_t hashlen);
/* Compute a message digest of data read from STREAM.
STREAM is an open file stream. The last operation on STREAM should
not be 'ungetc', and if STREAM is also open for writing it should
have been fflushed since its last write. Read from the current
position to the end of STREAM. Handle regular files efficently.
ALG is the message digest algorithm; see the file /proc/crypto.
RESBLOCK points to a block of HASHLEN bytes, for the result.
HASHLEN must be the length of the message digest, in bytes, in particular:
alg | hashlen
-------+--------
md5 | 16
sha1 | 20
sha224 | 28
sha256 | 32
sha384 | 48
sha512 | 64
If successful, fill RESBLOCK and return 0.
Upon failure, return a negated error number.
Unless returning 0 or -EIO, restore STREAM's file position so that
the caller can fall back on some other method. */
int
afalg_stream (FILE *stream, const char *alg,
void *resblock, ssize_t hashlen);
# else
static inline int
afalg_buffer (const char *buffer, size_t len, const char *alg,
void *resblock, ssize_t hashlen)
{
return -EAFNOSUPPORT;
}
static inline int
afalg_stream (FILE *stream, const char *alg,
void *resblock, ssize_t hashlen)
{
return -EAFNOSUPPORT;
}
# endif
# ifdef __cplusplus
}
# endif
#endif /* AF_ALG_H */
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