main.java

RSA is an asymetric method to crypt message. You can use RSA to crypt the key session of symetric me

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package rsa;

import java.math.BigInteger;
import java.util.Random;
public class Main {

    public static void main(String[] args) {
       BigInteger p=new BigInteger(512,100,new Random());
       BigInteger q=new BigInteger(512,100,new Random());
       BigInteger n=p.multiply(q);
       BigInteger phin=(p.subtract(BigInteger.ONE)).multiply((q.subtract(BigInteger.ONE)));
       BigInteger e=BigInteger.valueOf(65537);
       BigInteger d=e.modInverse(phin);
       String L="abcde521548762548";
       String M="0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
       String C=RSA.RSAES_OAEP_ENCRYPT(n,e,M,L);
       System.out.println("C= "+C);
       String clair=RSA.RSAES_OAEP_DECRYPT(n, d, C, L);
       System.out.println("Clair= "+clair);
       int sLen=21;
       String signature=RSA.RSASSA_PSS_SIGN(n, d, M, sLen);
       System.out.println("Sign= "+signature);
       String VeriySign=RSA.RSASSA_PSS_VERIFY(n, e, M, signature, sLen);
       System.out.println(VeriySign);
    }

}