md4update(3ext) [opensolaris man page]
md4(3EXT) Extended Library Functions md4(3EXT) NAME
md4, MD4Init, MD4Update, MD4Final - MD4 digest functions SYNOPSIS
cc [ flag ... ] file ... -lmd [ library ... ] #include <md4.h> void MD4Init(MD4_CTX *context); void MD4Update(MD4_CTX *context, unsigned char *input, unsigned int inlen); void MD4Final(unsigned char *output, MD4_CTX *context); DESCRIPTION
The MD4 functions implement the MD4 message-digest algorithm. The algorithm takes as input a message of arbitrary length and produces a "fingerprint" or "message digest" as output. The MD4 message-digest algorithm is intended for digital signature applications in which large files are "compressed" in a secure manner before being encrypted with a private (secret) key under a public-key cryptosystem such as RSA. MD4Init(), MD4Update(), MD4Final() The MD4Init(), MD4Update(), and MD4Final() functions allow an MD4 digest to be computed over multiple message blocks. Between blocks, the state of the MD4 computation is held in an MD4 context structure allocated by the caller. A complete digest computation consists of calls to MD4 functions in the following order: one call to MD4Init(), one or more calls to MD4Update(), and one call to MD4Final(). The MD4Init() function initializes the MD4 context structure pointed to by context. The MD4Update() function computes a partial MD4 digest on the inlen-byte message block pointed to by input, and updates the MD4 context structure pointed to by context accordingly. The MD4Final() function generates the final MD4 digest, using the MD4 context structure pointed to by context. The MD4 digest is written to output. After a call to MD4Final(), the state of the context structure is undefined. It must be reinitialized with MD4Init() before it can be used again. RETURN VALUES
These functions do not return a value. SECURITY
The MD4 digest algorithm is not currently considered cryptographically secure. It is included in libmd(3LIB) for use by legacy protocols and systems only. It should not be used by new systems or protocols. EXAMPLES
Example 1 Authenticate a message found in multiple buffers The following is a sample function that must authenticate a message that is found in multiple buffers. The calling function provides an authentication buffer that will contain the result of the MD4 digest. #include <sys/types.h> #include <sys/uio.h> #include <md4.h> int AuthenticateMsg(unsigned char *auth_buffer, struct iovec *messageIov, unsigned int num_buffers) { MD4_CTX ctx; unsigned int i; MD4Init(&ctx); for(i=0; i<num_buffers; i++) { MD4Update(&ctx, messageIov->iov_base, messageIov->iov_len); messageIov += sizeof(struct iovec); } MD4Final(auth_buffer, &ctx); return 0; } ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Committed | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
libmd(3LIB) RFC 1320 SunOS 5.11 13 Nov 2007 md4(3EXT)
Check Out this Related Man Page
MD4(3) BSD Library Functions Manual MD4(3) NAME
MD4Init, MD4Update, MD4Final, MD4End, MD4File, MD4Data -- calculate the RSA Data Security, Inc., ``MD4'' message digest LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <sys/types.h> #include <md4.h> void MD4Init(MD4_CTX *context); void MD4Update(MD4_CTX *context, const unsigned char *data, unsigned int len); void MD4Final(unsigned char digest[16], MD4_CTX *context); char * MD4End(MD4_CTX *context, char *buf); char * MD4File(const char *filename, char *buf); char * MD4Data(const unsigned char *data, unsigned int len, char *buf); DESCRIPTION
The MD4 functions calculate a 128-bit cryptographic checksum (digest) for any number of input bytes. A cryptographic checksum is a one-way hash-function, that is, you cannot find (except by exhaustive search) the input corresponding to a particular output. This net result is a ``fingerprint'' of the input-data, which doesn't disclose the actual input. MD2 is the slowest, MD4 is the fastest and MD5 is somewhere in the middle. MD2 can only be used for Privacy-Enhanced Mail. MD4 has been criticized for being too weak, so MD5 was developed in response as ``MD4 with safety-belts''. When in doubt, use MD5. The MD4Init(), MD4Update(), and MD4Final() functions are the core functions. Allocate an MD4_CTX, initialize it with MD4Init(), run over the data with MD4Update(), and finally extract the result using MD4Final(). MD4End() is a wrapper for MD4Final() which converts the return value to a 33-character (including the terminating ' ') ASCII string which represents the 128 bits in hexadecimal. MD4File() calculates the digest of a file, and uses MD4End() to return the result. If the file cannot be opened, a null pointer is returned. MD4Data() calculates the digest of a chunk of data in memory, and uses MD4End() to return the result. When using MD4End(), MD4File(), or MD4Data(), 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 33 characters of buffer space. SEE ALSO
md2(3), md4(3), md5(3) B. Kaliski, The MD2 Message-Digest Algorithm, RFC 1319. R. Rivest, The MD4 Message-Digest Algorithm, RFC 1186. R. Rivest, The MD5 Message-Digest Algorithm, RFC 1321. RSA Laboratories, Frequently Asked Questions About today's Cryptography. HISTORY
These functions appeared in NetBSD 1.3. AUTHORS
The original MD4 routines were developed by RSA Data Security, Inc., and published in the above references. This code is derived directly from these implementations by Poul-Henning Kamp <phk@login.dkuug.dk> Phk ristede runen. 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 doesn't exist. COPYRIGHT
Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All rights reserved. License to copy and use this software is granted provided that it is identified as the "RSA Data Security, Inc. MD4 Message-Digest Algorithm" in all material mentioning or referencing this software or this function. License is also granted to make and use derivative works provided that such works are identified as "derived from the RSA Data Security, Inc. MD4 Message-Digest Algorithm" in all material mentioning or ref- erencing the derived work. RSA Data Security, Inc. makes no representations concerning either the merchantability of this software or the suitability of this software for any particular purpose. It is provided "as is" without express or implied warranty of any kind. These notices must be retained in any copies of any part of this documentation and/or software. BSD
June 13, 2003 BSD