md4(3) - NetBSD Manual Pages

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MD4(3)                  NetBSD Library Functions Manual                 MD4(3)

MD4Init, MD4Update, MD4Final, MD4End, MD4File, MD4Data -- calculate the RSA Data Security, Inc., ``MD4'' message digest
Standard C Library (libc, -lc)
#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);
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 ``fin- gerprint'' 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 mid- dle. MD2 can only be used for Privacy-Enhanced Mail. MD4 has been crit- icized 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 func- tions. 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 '\0') ASCII string which repre- sents 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.
md2(3), md4(3), md5(3), openssl_MD2(3), openssl_MD4(3), openssl_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.
These functions appeared in NetBSD 1.3.
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 ristede runen.
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 (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 referencing 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 documen- tation and/or software. NetBSD 9.0 May 22, 2018 NetBSD 9.0
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