The man the myth is none other than himanshu
5. PROGRAM TO IMPLEMENT BLOWFISH ALGORITHM LOGIC
AIM: Write a C/JAVA program to
implement the BlowFish algorithm logic.
Source Code:
import
javax.crypto.Cipher;
import
javax.crypto.KeyGenerator;
import
javax.crypto.SecretKey;
import
javax.swing.JOptionPane;
public class
BlowFishCipher {
public static void main(String[] args) throws Exception {
KeyGenerator
keygenerator = KeyGenerator.getInstance("Blowfish");
// create a key
SecretKey
secretkey = keygenerator.generateKey();
// create a
cipher based upon Blowfish
Cipher cipher =
Cipher.getInstance("Blowfish");
// initialise
cipher to with secret key
cipher.init(Cipher.ENCRYPT_MODE,
secretkey);
// get the text
to encrypt
String inputText
= JOptionPane.showInputDialog("Input your message: ");
// encrypt
message
byte[] encrypted
= cipher.doFinal(inputText.getBytes());
// re-initialise
the cipher to be in decrypt mode
cipher.init(Cipher.DECRYPT_MODE,
secretkey);
// decrypt
message
byte[] decrypted
= cipher.doFinal(encrypted);
// and display
the results
JOptionPane.showMessageDialog(JOptionPane.getRootFrame(),
"\nEncrypted
text: " + new String(encrypted) + "\n" +
"\nDecrypted
text: " + new String(decrypted));
System.exit(0);
}
}
Output:
Input your message: Hello
world
Encrypted text: 3ooo&&(*&*4r4
Decrypted text: Hello
world
6.
PROGRAM TO IMPLEMENT RIJNDAEL ALGORITHM LOGIC
AIM: Write a C/JAVA program to
implement the Rijndael algorithm logic.
Source Code:
import
java.security.*;
import
javax.crypto.*;
import
javax.crypto.spec.*;
import java.io.*;
Public class AES
{
public static
String asHex (byte buf[]) {
StringBuffer
strbuf = new StringBuffer(buf.length * 2);
int i;
for (i = 0; i
< buf.length; i++) {
if (((int) buf[i]
& 0xff) < 0x10)
strbuf.append("0");
strbuf.append(Long.toString((int)
buf[i] & 0xff, 16)); }
return
strbuf.toString(); }
public static
void main(String[] args) throws Exception {
String
message="AES still rocks!!";
// Get the
KeyGenerator
KeyGenerator kgen
= KeyGenerator.getInstance("AES");
kgen.init(128);
// 192 and 256 bits may not be available
// Generate the
secret key specs.
SecretKey skey =
kgen.generateKey();
byte[] raw =
skey.getEncoded();
SecretKeySpec
skeySpec = new SecretKeySpec(raw, "AES");
// Instantiate
the cipher
Cipher cipher =
Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE,
skeySpec);
byte[] encrypted
= cipher.doFinal((args.length == 0 ? message :
args[0]).getBytes());
System.out.println("encrypted
string: " + asHex(encrypted));
cipher.init(Cipher.DECRYPT_MODE,
skeySpec);
byte[] original =
cipher.doFinal(encrypted);
String
originalString=new String(original);
System.out.println("Original
string: " + originalString + " " + asHex(original));
}
}
Output:
Enter the string:
Welcome
String To Encrypt:
Welcome
Encrypted Value: BPQGHKIoMNMwc0wKvg=
7. RC4 LOGIC
AIM: Write
the RC4 logic in Java.
PROGRAM: Encrypt a string using BlowFish algorithm
AIM: Using
Java Cryptography, encrypt the text “Hello world” using BlowFish. Create your
own key using Java keytool.
Source Code:
import
javax.crypto.Cipher;
import
javax.crypto.KeyGenerator;
import
javax.crypto.SecretKey;
import
javax.swing.JOptionPane;
public class
BlowFishCipher {
public static
void main(String[] args) throws Exception {
// create a key
generator based upon the Blowfish cipher
KeyGenerator
keygenerator = KeyGenerator.getInstance("Blowfish");
// create a key
SecretKey
secretkey = keygenerator.generateKey();
// create a
cipher based upon Blowfish
Cipher cipher =
Cipher.getInstance("Blowfish");
// initialise
cipher to with secret key
cipher.init(Cipher.ENCRYPT_MODE,
secretkey);
// get the text
to encrypt
String inputText
= JOptionPane.showInputDialog("Input your message: ");
// encrypt
message
byte[] encrypted
= cipher.doFinal(inputText.getBytes());
// re-initialise
the cipher to be in decrypt mode
cipher.init(Cipher.DECRYPT_MODE,
secretkey);
// decrypt
message
byte[] decrypted
= cipher.doFinal(encrypted);
// and display
the results
JOptionPane.showMessageDialog(JOptionPane.getRootFrame(),
"\nEncrypted
text: " + new String(encrypted) + "\n" +
"\nDecrypted
text: " + new String(decrypted));
System.exit(0);
}
}
Output:
Input your message: Hello
world
Encrypted text: 3ooo&&(*&*4r4
Decrypted text: Hello world
8. RSA ALGORITHM
AIM: Write
a Java program to implement RSA Algoithm.
Description:
RSA
Algorithm is used to encrypt and decrypt data in modern computer systems and
other electronic devices. RSA algorithm is an asymmetric cryptographic
algorithm as it creates 2 different keys for the purpose of encryption and
decryption. ... RSA makes use of prime numbers (arbitrary large numbers) to
function.
Source Code:
import
java.util.*;
public class RSA
{
public static void main(String args[])
{
Scanner sc=new
Scanner(System.in);
int d=0,e,i;
double c,msg;
System.out.println("Enter
the numbered message: ");
int m=sc.nextInt();
System.out.println("Enter
two prime numbers: ");
int p=sc.nextInt();
int q=sc.nextInt();
int n=p*q;
int phi=(p-1)*(q-1);
System.out.println("the
value of totent function = "+phi);
for(e=2;e<phi;e++) {
if(gcd(e,phi)==1)
break;
}
System.out.println("The
value of e = "+e);
for(i=1;i<phi;i++) {
if((e*i)%phi == 1)
{
d=i;
break;
}
}
System.out.println("The
value of d = "+d);
c=(Math.pow(m,e))%n;
System.out.println("Encrypted
message is: ");
System.out.println(c);
msg=(Math.pow(c,d))%n;
System.out.println("Derypted
message is: ");
System.out.println(msg);
}
static int gcd(int a,int b) {
if(a%b == 0)
return b;
else
return gcd(b,a%b);
}
}
Output:
Enter the
numbered message: 2
Enter two prime
numbers: 7 11
the value of
totent function = 60
The value of e =
7
The value of d =
43
Encrypted message is: 51.0
Derypted message is: 12.0
9.
DIFFIE-HELLMAN
AIM: Implement
the Diffie-Hellman Key Exchange mechanism using HTML and JavaScript. Consider
the end user as one of the parties (Alice) and the JavaScript application as
other party (bob).
Description:
The
Diffie-Hellmann key exchange is a secure method for exchanging cryptographic
keys. This method allows two parties which have no prior knowledge of each
other to establish a shared, secret key, even over an insecure channel.
Source Code:
import java.io.*;
import
java.util.*;
class
DiffieHellman {
public static void main(String args[])
{
Scanner s=new
Scanner(System.in);
System.out.println("Enter
modulo(p)");
int
p=s.nextInt();
System.out.println("Enter
primitive root of "+p);
int
g=s.nextInt();
System.out.println("Choose
1st secret no(Alice)");
int
a=s.nextInt();
System.out.println("Choose
2nd secret no(BOB)");
int
b=s.nextInt();
int
A = (int)Math.pow(g,a)%p;
int
B = (int)Math.pow(g,b)%p;
int
S_A = (int)Math.pow(B,a)%p;
int
S_B =(int)Math.pow(A,b)%p;
if(S_A==S_B)
{
System.out.println("ALice
and Bob can communicate with each other!!!");
System.out.println("They
share a secret no = "+S_A);
}
else
System.out.println("ALice
and Bob cannot communicate with each other!!!");
}
}
Output:
Enter modulo(p)
: 17
Enter primitive
root of : 17 3
Choose 1st secret
no(Alice) : 12
Choose 2nd secret
no(BOB) : 14
ALice and Bob can
communicate with each other!!!
They share a
secret no = 16
10. SHA-1
AIM: Calculate the message digest of a text using the SHA-1 algorithm
in JAVA.
Description:
SHA-1 or Secure Hash Algorithm 1 is a cryptographic hash
function which takes an input and produces a 160-bit (20-byte) hash value. This
hash value is known as a message digest. ... To calculate cryptographic hashing
value in Java, Message Digest Class is used, under the package java.security.
Source
Code:
import java.util.*;
import java.io.IOException;
public class SHA {
private static Random
r = new Random(9999);
public static void
main(String args[]) throws Exception {
Scanner s = new Scanner(System.in);
String
st = s.nextLine();
System.out.println("Encrypted
string :" + encrypt(st));
System.out.println("Decrypted string :" +
decrypt(encrypt(st)));
}
public static String
encrypt(String str) {
Base64.Encoder
e = Base64.getEncoder();
byte[]
s = new byte[8];
r.nextBytes(s);
return
e.encodeToString(s) + e.encodeToString(str.getBytes());
}
public static String
decrypt(String estr) {
if
(estr.length() > 12) {
String
c = estr.substring(12);
Base64.Decoder
d = Base64.getDecoder();
return
new String(d.decode(c));
}
return null;
}
}
Output:
Hello
Encrypted string :5OKn4ZevXxA=SGVsbG8=
Decrypted
string :Hello
11. MD5
AIM: Calculate
the message digest(MD5) of a text using the SHA-1 algorithm in JAVA
Source Code:
import
java.security.*;
public
class MD5 {
public
static void main(String[] a) {
//
TODO code application logic here
try
{
MessageDigest
md = MessageDigest.getInstance("MD5");
System.out.println("Message
digest object info: ");
System.out.println("
Algorithm = " +md.getAlgorithm());
System.out.println("
Provider = " +md.getProvider());
System.out.println("
ToString = " +md.toString());
String
input = "";
md.update(input.getBytes());
byte[]
output = md.digest();
System.out.println();
System.out.println("MD5(\""+input+"\")
= " +bytesToHex(output));
input
= "abc";
md.update(input.getBytes());
output
= md.digest();
System.out.println();
System.out.println("MD5(\""+input+"\")
= " +bytesToHex(output));
input
= "abcdefghijklmnopqrstuvwxyz";
md.update(input.getBytes());
output
= md.digest();
System.out.println();
System.out.println("MD5(\""
+input+"\") = " +bytesToHex(output));
System.out.println("");
}
catch
(Exception e) {
System.out.println("Exception:
" +e); }
}
public
static String bytesToHex(byte[] b) {
char
hexDigit[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C',
'D', 'E', 'F'};
StringBufferbuf
= new StringBuffer();
for
(int j=0; j<b.length; j++) {
buf.append(hexDigit[(b[j]
>> 4) & 0x0f]);
buf.append(hexDigit[b[j]
& 0x0f]); }
return
buf.toString();
}
}
Output:
Message digest
object info:
Algorithm
= MD5
Provider
= SUN version 1.6
ToString
= MD5 Message Digest from SUN, <initialized>
MD5("")
= D41D8CD98F00B204E9800998ECF8427E
MD5("abc")
= 900150983CD24FB0D6963F7D28E17F72
MD5("abcdefghijklmnopqrstuvwxyz") = C3FCD3D76192E4007DFB496CCA67E13B
