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SHA(3) FreeBSD Library Functions Manual SHA(3)
NAME
SHA_Init, SHA_Update, SHA_Final, SHA_End, SHA_File, SHA_FileChunk,
SHA_Data, SHA1_Init, SHA1_Update, SHA1_Final, SHA1_End, SHA1_File,
SHA1_FileChunk, SHA1_Data - calculate the FIPS 160 and 160-1 ``SHA''
message digests
LIBRARY
Message Digest (MD4, MD5, etc.) Support Library (libmd, -lmd)
SYNOPSIS
#include <sys/types.h>
#include <sha.h>
void
SHA_Init(SHA_CTX *context);
void
SHA_Update(SHA_CTX *context, const unsigned char *data, size_t len);
void
SHA_Final(unsigned char digest[20], SHA_CTX *context);
char *
SHA_End(SHA_CTX *context, char *buf);
char *
SHA_File(const char *filename, char *buf);
char *
SHA_FileChunk(const char *filename, char *buf, off_t offset,
off_t length);
char *
SHA_Data(const unsigned char *data, unsigned int len, char *buf);
void
SHA1_Init(SHA_CTX *context);
void
SHA1_Update(SHA_CTX *context, const unsigned char *data, size_t len);
void
SHA1_Final(unsigned char digest[20], SHA_CTX *context);
char *
SHA1_End(SHA_CTX *context, char *buf);
char *
SHA1_File(const char *filename, char *buf);
char *
SHA1_FileChunk(const char *filename, char *buf, off_t offset,
off_t length);
char *
SHA1_Data(const unsigned char *data, unsigned int len, char *buf);
SHA (or SHA-0) is the original Secure Hash Algorithm specified in FIPS
160. It was quickly proven insecure, and has been superseded by SHA-1.
SHA-0 is included for compatibility purposes only.
The SHA1_Init(), SHA1_Update(), and SHA1_Final() functions are the core
functions. Allocate an SHA_CTX, initialize it with SHA1_Init(), run over
the data with SHA1_Update(), and finally extract the result using
SHA1_Final(), which will also erase the SHA_CTX.
SHA1_End() is a wrapper for SHA1_Final() which converts the return value
to a 41-character (including the terminating '\0') ASCII string which
represents the 160 bits in hexadecimal.
SHA1_File() calculates the digest of a file, and uses SHA1_End() to
return the result. If the file cannot be opened, a null pointer is
returned. SHA1_FileChunk() is similar to SHA1_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, SHA1_FileChunk() calculates the digest from offset to the end of
file. SHA1_Data() calculates the digest of a chunk of data in memory,
and uses SHA1_End() to return the result.
When using SHA1_End(), SHA1_File(), or SHA1_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 41
characters of buffer space.
ERRORS
The SHA1_End() function called with a null buf argument may fail and
return NULL if:
[ENOMEM] Insufficient storage space is available.
The SHA1_File() and SHA1_FileChunk() may return NULL when underlying
open(2), fstat(2), lseek(2), or SHA1_End(3) fail.
SEE ALSO
md4(3), md5(3), ripemd(3), sha256(3), sha512(3), skein(3)
HISTORY
These functions appeared in FreeBSD 4.0.
AUTHORS
The core hash routines were implemented by Eric Young based on the
published FIPS standards.
BUGS
The SHA1 algorithm has been proven to be vulnerable to practical
collision attacks and should not be relied upon to produce unique
outputs, nor should it be used as part of a new cryptographic signature
scheme.
FreeBSD 14.0-RELEASE-p6 February 6, 2023 FreeBSD 14.0-RELEASE-p6