RIPEMD(3)

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

LIBRARY
libmd

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(), which will also erase the RIPEMD160_CTX.

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.

ERRORS
The RIPEMD160_End() function called with a null buf argument may fail and return NULL if:

[ENOMEM]
    Insufficient storage space is available.

The RIPEMD160_File() and RIPEMD160_FileChunk() may return NULL when underlying open(2), fstat(2), lseek(2), or RIPEMD160_End(3) fail.

SEE ALSO
md4(3), md5(3), sha(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 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.