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SHA512(3) FreeBSD Library Functions Manual SHA512(3)
NAME
SHA512_Init, SHA512_Update, SHA512_Final, SHA512_End, SHA512_File,
SHA512_FileChunk, SHA512_Data, SHA384_Init, SHA384_Update, SHA384_Final,
SHA384_End, SHA384_File, SHA384_FileChunk, SHA384_Data, SHA512_224_Init,
SHA512_224_Update, SHA512_224_Final, SHA512_224_End, SHA512_224_File,
SHA512_224_FileChunk, SHA512_224_Data SHA512_256_Init, SHA512_256_Update,
SHA512_256_Final, SHA512_256_End, SHA512_256_File, SHA512_256_FileChunk,
SHA512_256_Data - calculate the FIPS 180-4 ``SHA-512'' family of message
digests
LIBRARY
Message Digest (MD4, MD5, etc.) Support Library (libmd, -lmd)
SYNOPSIS
#include <sys/types.h>
#include <sha512.h>
void
SHA512_Init(SHA512_CTX *context);
void
SHA512_Update(SHA512_CTX *context, const unsigned char *data,
size_t len);
void
SHA512_Final(unsigned char digest[64], SHA512_CTX *context);
char *
SHA512_End(SHA512_CTX *context, char *buf);
char *
SHA512_File(const char *filename, char *buf);
char *
SHA512_FileChunk(const char *filename, char *buf, off_t offset,
off_t length);
char *
SHA512_Data(const unsigned char *data, unsigned int len, char *buf);
#include <sha384.h>
void
SHA384_Init(SHA384_CTX *context);
void
SHA384_Update(SHA384_CTX *context, const unsigned char *data,
size_t len);
void
SHA384_Final(unsigned char digest[48], SHA384_CTX *context);
char *
SHA384_End(SHA384_CTX *context, char *buf);
char *
SHA384_File(const char *filename, char *buf);
#include <sha512t.h>
void
SHA512_224_Init(SHA512_CTX *context);
void
SHA512_224_Update(SHA512_CTX *context, const unsigned char *data,
size_t len);
void
SHA512_224_Final(unsigned char digest[32], SHA512_CTX *context);
char *
SHA512_224_End(SHA512_CTX *context, char *buf);
char *
SHA512_224_File(const char *filename, char *buf);
char *
SHA512_224_FileChunk(const char *filename, char *buf, off_t offset,
off_t length);
char *
SHA512_224_Data(const unsigned char *data, unsigned int len, char *buf);
void
SHA512_256_Init(SHA512_CTX *context);
void
SHA512_256_Update(SHA512_CTX *context, const unsigned char *data,
size_t len);
void
SHA512_256_Final(unsigned char digest[32], SHA512_CTX *context);
char *
SHA512_256_End(SHA512_CTX *context, char *buf);
char *
SHA512_256_File(const char *filename, char *buf);
char *
SHA512_256_FileChunk(const char *filename, char *buf, off_t offset,
off_t length);
char *
SHA512_256_Data(const unsigned char *data, unsigned int len, char *buf);
DESCRIPTION
The SHA512_ functions calculate a 512-bit cryptographic checksum (digest)
for any number of input bytes. A cryptographic checksum is a one-way
hash function; that is, it is computationally impractical to find the
input corresponding to a particular output. This net result is a
"fingerprint" of the input-data, which does not disclose the actual
input.
The SHA512_Init(), SHA512_Update(), and SHA512_Final() functions are the
core functions. Allocate an SHA512_CTX, initialize it with
SHA512_File() calculates the digest of a file, and uses SHA512_End() to
return the result. If the file cannot be opened, a null pointer is
returned. SHA512_FileChunk() is similar to SHA512_File(), but it only
calculates the digest over a byte-range of the file specified, starting
at offset and spanning length bytes. If the length parameter is
specified as 0, or more than the length of the remaining part of the
file, SHA512_FileChunk() calculates the digest from offset to the end of
file. SHA512_Data() calculates the digest of a chunk of data in memory,
and uses SHA512_End() to return the result.
When using SHA512_End(), SHA512_File(), or SHA512_Data(), the buf
argument can be a null pointer, in which case the returned string is
allocated with malloc(3) and subsequently must be explicitly deallocated
using free(3) after use. If the buf argument is non-null it must point
to at least 129 characters of buffer space.
The SHA384_, SHA512_224, and SHA512_256_ functions are identical to the
SHA512_ functions except they use a different initial hash value and the
output is truncated to 384, 224, and 256 bits respectively.
SHA384_End() is a wrapper for SHA384_Final() which converts the return
value to a 97-character (including the terminating '\0') ASCII string
which represents the 384 bits in hexadecimal.
SHA512_224_End() is a wrapper for SHA512_Final() which converts the
return value to a 57-character (including the terminating '\0') ASCII
string which represents the 224 bits in hexadecimal.
SHA512_224_End() is a wrapper for SHA512_Final() which converts the
return value to a 57-character (including the terminating '\0') ASCII
string which represents the 224 bits in hexadecimal.
SHA512_256_End() is a wrapper for SHA512_Final() which converts the
return value to a 65-character (including the terminating '\0') ASCII
string which represents the 256 bits in hexadecimal.
ERRORS
The SHA512_End() function called with a null buf argument may fail and
return NULL if:
[ENOMEM] Insufficient storage space is available.
The SHA512_File() and SHA512_FileChunk() may return NULL when underlying
open(2), fstat(2), lseek(2), or SHA512_End(3) fail.
SEE ALSO
md4(3), md5(3), ripemd(3), sha(3), sha256(3), sha512(3), skein(3)
HISTORY
These functions appeared in FreeBSD 9.0.
AUTHORS
The core hash routines were implemented by Colin Percival based on the
published FIPS 180-2 standard.
BUGS
No method is known to exist which finds two files having the same hash
value, nor to find a file with a specific hash value. There is on the