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자바의 BigInteger 클래스를 이용하여 RSA 로직을 구현하였다.
클래스를 생성하여 콘솔에 출려하면 Public키와 Private키가 출력되고
이를 이용하여 encrypt, decrypt 를 수행 가능하다.
클래스를 생성하여 콘솔에 출려하면 Public키와 Private키가 출력되고
이를 이용하여 encrypt, decrypt 를 수행 가능하다.
·미리보기 | 소스복사·
- import java.math.BigInteger;
- import java.security.SecureRandom;
- public class RSA {
- private final static BigInteger one = new BigInteger("1");
- private final static SecureRandom random = new SecureRandom();
- private BigInteger privateKey;
- private BigInteger publicKey;
- private BigInteger modulus;
- // generate an N-bit (roughly) public and private key
- RSA(int N) {
- BigInteger p = BigInteger.probablePrime(N/2, random);
- BigInteger q = BigInteger.probablePrime(N/2, random);
- BigInteger phi = (p.subtract(one)).multiply(q.subtract(one));
- modulus = p.multiply(q);
- publicKey = new BigInteger("65537"); // common value in practice = 2^16 + 1
- privateKey = publicKey.modInverse(phi);
- }
- BigInteger encrypt(BigInteger message) {
- return message.modPow(publicKey, modulus);
- }
- BigInteger decrypt(BigInteger encrypted) {
- return encrypted.modPow(privateKey, modulus);
- }
- public String toString() {
- String s = "";
- s += "public = " + publicKey + "n";
- s += "private = " + privateKey + "n";
- s += "modulus = " + modulus;
- return s;
- }
- public static void main(String[] args) {
- int N = Integer.parseInt(args[0]);
- RSA key = new RSA(N);
- System.out.println(key);
- // create random message, encrypt and decrypt
- BigInteger message = new BigInteger(N-1, random);
- //// create message by converting string to integer
- // String s = "test";
- // byte[] bytes = s.getBytes();
- // BigInteger message = new BigInteger(s);
- BigInteger encrypt = key.encrypt(message);
- BigInteger decrypt = key.decrypt(encrypt);
- System.out.println("message = " + message);
- System.out.println("encrpyted = " + encrypt);
- System.out.println("decrypted = " + decrypt);
- }
- }
