SHA1(3) | Library Functions Manual | SHA1(3) |
SHA1Init
, SHA1Update
,
SHA1Final
, SHA1Transform
,
SHA1End
, SHA1File
,
SHA1FileChunk
, SHA1Data
—
#include <sys/types.h>
#include <sha1.h>
void
SHA1Init
(SHA1_CTX
*context);
void
SHA1Update
(SHA1_CTX
*context, const uint8_t
*data, u_int
len);
void
SHA1Final
(uint8_t
digest[20], SHA1_CTX
*context);
void
SHA1Transform
(uint32_t
state[5], uint8_t
buffer[64]);
char *
SHA1End
(SHA1_CTX
*context, char
*buf);
char *
SHA1File
(char
*filename, char
*buf);
char *
SHA1FileChunk
(const
char *filename, char
*buf, off_t offset,
off_t length);
char *
SHA1Data
(uint8_t
*data, size_t len,
char *buf);
The SHA1 functions are considered to be more secure than the md4(3) and md5(3) functions with which they share a similar interface.
The SHA1Init
() function initializes a
SHA1_CTX context for use with
SHA1Update
(), and
SHA1Final
(). The
SHA1Update
() function adds
data of length len to the
SHA1_CTX specified by context.
SHA1Final
() is called when all data has been added
via SHA1Update
() and stores a message digest in the
digest parameter. When a null pointer is passed to
SHA1Final
() as first argument only the final padding
will be applied and the current context can still be used with
SHA1Update
().
The SHA1Transform
() function is used by
SHA1Update
() to hash 512-bit blocks and forms the
core of the algorithm. Most programs should use the interface provided by
SHA1Init
(), SHA1Update
() and
SHA1Final
() instead of calling
SHA1Transform
() directly.
The SHA1End
() function is a front end for
SHA1Final
() which converts the digest into an ASCII
representation of the 160 bit digest in hexadecimal.
The SHA1File
() function calculates the
digest for a file and returns the result via
SHA1End
(). If SHA1File
() is
unable to open the file a NULL pointer is returned.
SHA1FileChunk
() behaves like
SHA1File
() but calculates the digest only for that
portion of the file starting at offset and continuing
for length bytes or until end of file is reached,
whichever comes first. A zero length can be specified
to read until end of file. A negative length or
offset will be ignored.
The SHA1Data
() function calculates the
digest of an arbitrary string and returns the result via
SHA1End
().
For each of the SHA1End
(),
SHA1File
(), and SHA1Data
()
functions the buf parameter should either be a string
of at least 41 characters in size or a NULL pointer. In the latter case,
space will be dynamically allocated via
malloc(3) and should be freed
using free(3) when it is no
longer needed.
SHA1_CTX sha; uint8_t results[20]; char *buf; int n; buf = "abc"; n = strlen(buf); SHA1Init(&sha); SHA1Update(&sha, (uint8_t *)buf, n); SHA1Final(results, &sha); /* Print the digest as one long hex value */ printf("0x"); for (n = 0; n < 20; n++) printf("%02x", results[n]); putchar('\n');
Alternately, the helper functions could be used in the following way:
SHA1_CTX sha; uint8_t output[41]; char *buf = "abc"; printf("0x%s", SHA1Data(buf, strlen(buf), output));
J. Burrows, The Secure Hash Standard, FIPS PUB 180-1.
The SHA1End
(),
SHA1File
(), SHA1FileChunk
(),
and SHA1Data
() helper functions are derived from
code written by Poul-Henning Kamp.
If a message digest is to be copied to a multi-byte type (ie: an array of five 32-bit integers) it will be necessary to perform byte swapping on little endian machines such as the i386, alpha, and VAX.
November 27, 2018 | NetBSD 9.0 |