void
SHA1Init(SHA1_CTX *context)
void
SHA1Update(SHA1_CTX *context, const u_char *data, u_int len)
void
SHA1Final(u_char digest[20], SHA1_CTX *context)
void
SHA1Transform(uint32_t state[5], u_char buffer[64])
char *
SHA1End(SHA1_CTX *context, char *buf)
char *
SHA1File(char *filename, char *buf)
char *
SHA1Data(u_char *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.
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;
u_char results[20];
char *buf;
int n;
buf = "abc";
n = strlen(buf);
SHA1Init(&sha);
SHA1Update(&sha, (u_char *)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;
u_char output[41];
char *buf = "abc";
printf("0x%s", SHA1Data(buf, strlen(buf), output));
The
SHA1End(),
SHA1File(),
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.