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 algo‐
rithm takes as input a message of arbitrary length and produces a "fin‐
gerprint" or "message digest" as output. The MD4 message-digest algo‐
rithm 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 allo‐
cated 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 ALSOlibmd(3LIB)
RFC 1320
SunOS 5.11 13 Nov 2007 md4(3EXT)
