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_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);

     char *
     SHA384_FileChunk(const char *filename, char *buf, off_t offset,
         off_t length);

     char *
     SHA384_Data(const unsigned char *data, unsigned int len, char *buf);

     #include <sha512t.h>

     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_Init(), run over the data with SHA512_Update(), and finally
     extract the result using SHA512_Final(), which will also erase the
     SHA512_CTX.

     SHA512_End() is a wrapper for SHA512_Final() which converts the return
     value to a 129-character (including the terminating '\0') ASCII string
     which represents the 512 bits in hexadecimal.

     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_ 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 bits 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_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(2) 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
     other hand no guarantee that such a method does not exist.

FreeBSD 13.1-RELEASE-p6          May 21, 2019          FreeBSD 13.1-RELEASE-p6