public static void testICDE() {
// Number of total operations
int numberOfTests = 5;
// Length of the p, note that n=p.q
int lengthp = 512;
Paillier esystem = new Paillier();
Random rd = new Random();
PaillierPrivateKey key = KeyGen.PaillierKey(lengthp, 122333356);
esystem.setDecryptEncrypt(key);
// let's test our algorithm by encrypting and decrypting few instances
long start = System.currentTimeMillis();
for (int i = 0; i < numberOfTests; i++) {
BigInteger m1 = BigInteger.valueOf(Math.abs(rd.nextLong()));
BigInteger m2 = BigInteger.valueOf(Math.abs(rd.nextLong()));
BigInteger c1 = esystem.encrypt(m1);
BigInteger c2 = esystem.encrypt(m2);
BigInteger c3 = esystem.multiply(c1, m2);
c1 = esystem.add(c1, c2);
c1 = esystem.add(c1, c3);
esystem.decrypt(c1);
}
long stop = System.currentTimeMillis();
System.out.println(
"Running time per comparison in milliseconds: " + ((stop - start) / numberOfTests));
}
/**
* Decrypts the given ciphertext.
*
* @param c Ciphertext as BigInteger c
* @return Decrypted value D(c) as BigInteger
*/
public BigInteger decrypt(BigInteger c) {
// Check whether everything is set for doing decryption
if (decryptMode == false) throw new IllegalStateException(this.notReadyForDecryption);
if (!(key.inModNSPlusOne(c))) throw new IllegalArgumentException("c must be less than n^2");
BigInteger c1 = null;
// first we calculate c^d mod n^2
c1 = c.modPow(deckey.getD(), deckey.getNSPlusOne());
// after we calculate c1=c^d mod n^2 = (1+n)^(m*d mod n)
// we now find (c1-1)/n=m*d mod n
// therefore m= d^-1*(c1-1)/n mod n
// TODO: Is this true?
return (deckey.getDInvs().multiply((c1.subtract(BigInteger.ONE)).divide(deckey.getN())))
.mod(deckey.getN());
}
/** This main method basically tests the different features of the Paillier encryption */
public static void test() {
Random rd = new Random();
long num = 0;
long num1 = 0;
BigInteger m = null;
BigInteger c = null;
int numberOfTests = 10;
int j = 0;
BigInteger decryption = null;
Paillier esystem = new Paillier();
PaillierPrivateKey key = KeyGen.PaillierKey(512, 122333356);
esystem.setDecryptEncrypt(key);
// let's test our algorithm by encrypting and decrypting a few instances
for (int i = 0; i < numberOfTests; i++) {
num = Math.abs(rd.nextLong());
m = BigInteger.valueOf(num);
System.out.println("number chosen : " + m.toString());
c = esystem.encrypt(m);
System.out.println("encrypted value: " + c.toString());
decryption = esystem.decrypt(c);
System.out.println("decrypted value: " + decryption.toString());
if (m.compareTo(decryption) == 0) {
System.out.println("OK");
j++;
} else System.out.println("PROBLEM");
}
System.out.println(
"out of "
+ (new Integer(numberOfTests)).toString()
+ "random encryption,# many of "
+ (new Integer(j)).toString()
+ " has passed");
// Let us check the commutative properties of the paillier encryption
System.out.println("Checking the additive properteries of the Paillier encryption");
// Obviously 1+0=1
System.out.println(
"1+0="
+ (esystem.decrypt(esystem.add(esystem.encryptone(), esystem.encryptzero())))
.toString());
// 1+1=2
System.out.println(
"1+1="
+ (esystem.decrypt(
esystem.add(esystem.encrypt(BigInteger.ONE), esystem.encrypt(BigInteger.ONE))))
.toString());
// 1+1+1=3
System.out.println(
"1+1+1="
+ (esystem.decrypt(
esystem.add(
esystem.add(
esystem.encrypt(BigInteger.ONE), esystem.encrypt(BigInteger.ONE)),
esystem.encrypt(BigInteger.ONE))))
.toString());
// 0+0=0
System.out.println(
"0+0="
+ (esystem.decrypt(
esystem.add(
esystem.encrypt(BigInteger.ZERO), esystem.encrypt(BigInteger.ZERO))))
.toString());
// 1+-1=0
System.out.println(
"1+-1="
+ (esystem.decrypt(
esystem.add(
esystem.encrypt(BigInteger.valueOf(-1).mod(key.getN())),
esystem.encrypt(BigInteger.ONE))))
.toString());
do {
num = rd.nextLong();
} while (key.inModN(BigInteger.valueOf(num)) == false);
do {
num1 = rd.nextLong();
} while (key.inModN(BigInteger.valueOf(num1)) == false);
BigInteger numplusnum1 = BigInteger.valueOf(num).add(BigInteger.valueOf(num1));
BigInteger summodnsquare = numplusnum1.mod(key.getN());
// D(E(num)+E(num1))=num+num1
System.out.println(numplusnum1.toString());
System.out.println(
summodnsquare.toString()
+ "=\n"
+ esystem
.decrypt(
esystem.add(
esystem.encrypt(BigInteger.valueOf(num)),
esystem.encrypt(BigInteger.valueOf(num1))))
.toString());
// Let us check the multiplicative properties
System.out.println("Checking the multiplicative properties");
// D(multiply(E(2),3))=6
System.out.println(
"6="
+ esystem.decrypt(
esystem.multiply(
esystem.add(esystem.encrypt(BigInteger.ONE), esystem.encrypt(BigInteger.ONE)),
3)));
}