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RIPEMD(3)	      DragonFly Library Functions Manual	     RIPEMD(3)


NAME

     RIPEMD160_Init, RIPEMD160_Update, RIPEMD160_Final, RIPEMD160_End,
     RIPEMD160_File, RIPEMD160_FileChunk, RIPEMD160_Data -- calculate the
     RIPEMD160 message digest


LIBRARY

     Message Digest (MD4, MD5, etc.) Support Library (libmd, -lmd)


SYNOPSIS

     #include <sys/types.h>
     #include <ripemd.h>

     void
     RIPEMD160_Init(RIPEMD160_CTX *context);

     void
     RIPEMD160_Update(RIPEMD160_CTX *context, const unsigned char *data,
	 unsigned int len);

     void
     RIPEMD160_Final(unsigned char digest[20], RIPEMD160_CTX *context);

     char *
     RIPEMD160_End(RIPEMD160_CTX *context, char *buf);

     char *
     RIPEMD160_File(const char *filename, char *buf);

     char *
     RIPEMD160_FileChunk(const char *filename, char *buf, off_t offset,
	 off_t length);

     char *
     RIPEMD160_Data(const unsigned char *data, unsigned int len, char *buf);


DESCRIPTION

     The RIPEMD160_ functions calculate a 160-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 RIPEMD160_Init(), RIPEMD160_Update(), and RIPEMD160_Final() functions
     are the core functions.  Allocate an RIPEMD160_CTX, initialize it with
     RIPEMD160_Init(), run over the data with RIPEMD160_Update(), and finally
     extract the result using RIPEMD160_Final().

     The RIPEMD160_End() function is a wrapper for RIPEMD160_Final() which
     converts the return value to a 41-character (including the terminating
     '\0') ASCII string which represents the 160 bits in hexadecimal.

     The RIPEMD160_File() function calculates the digest of a file, and uses
     RIPEMD160_End() to return the result.  If the file cannot be opened, a
     null pointer is returned.	The RIPEMD160_FileChunk() function is similar
     to RIPEMD160_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, RIPEMD160_FileChunk() calculates the digest
     from offset to the end of file.  The RIPEMD160_Data() function calculates
     the digest of a chunk of data in memory, and uses RIPEMD160_End() to
     return the result.

     When using RIPEMD160_End(), RIPEMD160_File(), or RIPEMD160_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.


SEE ALSO

     md2(3), md4(3), md5(3), sha(3)


HISTORY

     These functions appeared in FreeBSD 4.0.


AUTHORS

     The core hash routines were implemented by Eric Young based on the pub-
     lished RIPEMD160 specification.


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.

DragonFly 4.7		       February 26, 1999		 DragonFly 4.7

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