CIS 644 Lab 6 Hash function crack

Crypto-lab6-digt.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/evp.h>

void getHash(char * hashname, char *msg, unsigned char *md_value) {
	EVP_MD_CTX *mdctx;
	const EVP_MD *md;
	//unsigned char md_value[EVP_MAX_MD_SIZE];
	int md_len, i;
	OpenSSL_add_all_digests();
	md = EVP_get_digestbyname(hashname);
	if(!md) {
		printf("Unknown message digest %s\n", hashname);
		exit(1);
	}
	mdctx = EVP_MD_CTX_create();
	EVP_DigestInit_ex(mdctx, md, NULL);
	EVP_DigestUpdate(mdctx, msg, strlen(msg));
	EVP_DigestFinal_ex(mdctx, md_value, &md_len);
	EVP_MD_CTX_destroy(mdctx);
	// shrink the digest's length to 24 (3 words)
	//strncpy( digt, md_value, 3);
}

void setRndStr(char *msg) {
	int i;
	for (i=0;i<11;i++)
		msg[i] = rand()%256-128;
}

int crackOneWayHash(char * hashname) {
	char msg1[11], msg2[11];
	unsigned char digt1[EVP_MAX_MD_SIZE], digt2[EVP_MAX_MD_SIZE];
	// we do not need to generate words, instead generating number only
	int count=0, i;
	setRndStr(msg1);
    	//sprintf(msg1, "%d", rand());	// convert to string
	// get an initial message
	getHash(hashname, msg1, digt1);
	// run the crack
	do {
    		//sprintf(msg2, "%d", rand());	// convert to string
		setRndStr(msg2);
		getHash(hashname, msg2, digt2);
		count++;
	} while (strncmp(digt1, digt2, 3)!=0);
	//printf("\n cracked after %d tries! %s and %s has same digest ", count, msg1, msg2);
	printf("cracked after %d tries! same digest ", count, msg1, msg2);
	for(i = 0; i < 3; i++) printf("%02x", digt1[i]);
	printf("\n");
	return count;
}

int crackCollisionHash(char * hashname) {
	char msg1[11], msg2[11];
	unsigned char digt1[EVP_MAX_MD_SIZE], digt2[EVP_MAX_MD_SIZE];
	// we do not need to generate words, instead generating number only
	int count=0, i;
	// run the crack
	do {
    		//sprintf(msg1, "%d", rand());	// convert to string
		setRndStr(msg1);
		getHash(hashname, msg1, digt1);
    		//sprintf(msg2, "%d", rand());	// convert to string
		setRndStr(msg2);
		getHash(hashname, msg2, digt2);
		count++;
	} while (strncmp(digt1, digt2, 3)!=0);
	//printf("\n cracked after %d tries! %s and %s has same digest ", count, msg1, msg2);
	printf("cracked after %d tries! same digest ", count);
	for(i = 0; i < 3; i++) printf("%02x", digt1[i]);
	printf("\n");
	return count;
}

main(int argc, char *argv[])
{
	char *hashname;
	if(!argv[1])
		// set to md5 by default
		hashname = "md5";
	else
		hashname = argv[1];
	srand((int)time(0));	// init random seed
	int i,count;
	for (i=0,count=0;i<15;i++)
		count+=crackCollisionHash(hashname);
	printf("average time cracking collision-free: %d \n", count/15);
	for (i=0,count=0;i<5;i++)
		count+=crackOneWayHash(hashname);
	printf("average time cracking one-way: %d \n", count/5);
}

Makefile

INC=/usr/local/ssl/include/
LIB=/usr/local/ssl/lib/

all:
  gcc -I$(INC) -L$(LIB) -o digt digt.c -lcrypto

md5_count_difference.sh

#!/bin/bash

# This is bash!! do not run it using "sh"!
 
# set the file which we want to hash
FILE1="Testfile1"
FILE2="Testfile2"
# you also can try sha256 / md5
ENCRY="md5"

echo 'Running.. Please wait'

# upper case H1 and H2, for ibase/obase convertion
declare -u H1
declare -u H2

H1=`openssl dgst -$ENCRY $FILE1 | awk '{print $2}'`
H2=`openssl dgst -$ENCRY $FILE2 | awk '{print $2}'`

echo "The hash value (in HEX) of $FILE1 is $H1."
echo "The hash value (in HEX) of $FILE2 is $H2."

BITS1=`echo "ibase=16;obase=2;$H1" | bc`
BITS2=`echo "ibase=16;obase=2;$H2" | bc`

# now count how many bits are actually different (the "one" bits)
BITS1=`echo "$BITS1" | sed 's/\\\r*//g'`
BITS2=`echo "$BITS2" | sed 's/\\\r*//g'`

LEN=`expr length "$BITS1"`

COUNT=0
for i in `seq 1 $LEN`
do
    B1=$(echo $BITS1 | awk "{print substr (\$0, $i, 1)}")
    B2=$(echo $BITS2 | awk "{print substr (\$0, $i, 1)}")
    if [ "$B1" -ne "$B2" ]; then
        COUNT=`expr $COUNT + 1`
    fi
done
 
echo "$COUNT bits are different."