added md5 attack data

lib/stego-attack-lib/md5attack.cc

@@ -0,0 +1,76 @@
+// Kyle Wilson 
+// Test Driven Scrumbags
+// Compile: gcc -w -o md5attack md5attack.cpp -lcrypt
+// Run: ./md5attack <original image file> <new image file>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <openssl/md5.h>
+
+unsigned char result1[MD5_DIGEST_LENGTH];
+unsigned char result2[MD5_DIGEST_LENGTH];
+
+// Compare results; cannot use strcmp() because it requires signed char*
+int compareHashVals(unsigned char* string1, unsigned char* string2) {
+	int i;
+	for(i=0; i<MD5_DIGEST_LENGTH; i++)
+		if (string1[i]!=string2[i]) return 1;
+	return 0;
+}
+
+// Print the MD5 sum as hex-digits.
+void printMD5Sum(unsigned char* md) {
+    int i;
+    for(i=0; i <MD5_DIGEST_LENGTH; i++) {
+            printf("%02x",md[i]);
+    }
+}
+
+// Get the size of the file by its file descriptor
+unsigned long getSizeByFD(int fd) {
+    struct stat statbuf;
+    if(fstat(fd, &statbuf) < 0) exit(-1);
+    return statbuf.st_size;
+}
+
+// Gets a single file's hash and stores it in the parameter result
+void getMD5Hash(char* filename, unsigned char* result) {
+	int fileDesc;
+    unsigned long fileSize;
+    char* fileBuffer;
+
+    fileDesc = open(filename, O_RDONLY);
+    if(fileDesc < 0) exit(-1);
+
+    fileSize = getSizeByFD(fileDesc);
+
+    fileBuffer = (char*) mmap(0, fileSize, PROT_READ, MAP_SHARED, fileDesc, 0);
+    MD5((unsigned char*) fileBuffer, fileSize, result);
+    munmap(fileBuffer, fileSize); 
+
+    printMD5Sum(result);
+    printf("  %s\n", filename);
+
+}
+
+int main(int argc, char *argv[]) {
+
+    if(argc != 3) { 
+            printf("Must specify the files\n");
+            exit(-1);
+    }
+    getMD5Hash(argv[1], result1);
+    getMD5Hash(argv[2], result2);
+
+    if (compareHashVals(result1, result2)) {
+    	printf("Hashes do not match: There is a message embedded!\n");
+    }
+    else printf("Hashes match: There is no embedded message.\n");
+
+    return 0;
+}