cz.d1x.dxcrypto.encryption.RSAKeysGenerator Maven / Gradle / Ivy

Go to download
package cz.d1x.dxcrypto.encryption;

import cz.d1x.dxcrypto.encryption.key.RSAKeyParams;

import java.math.BigInteger;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;

/**
 * 
 * Generator that can provide key pair for RSA encryption.
 * This generator can be re-used for multiple key pair generations.
 * 

 * This class is immutable and can be considered thread safe.
 * 
 *
 * @author Zdenek Obst, zdenek.obst-at-gmail.com
 */
public final class RSAKeysGenerator {

    private static final int DEFAULT_KEY_SIZE = 1024;

    private final KeyPairGenerator generator;

    /**
     * Creates a new generator of RSA keys with default 1024 size of the key.
     */
    public RSAKeysGenerator() {
        this(DEFAULT_KEY_SIZE);
    }

    /**
     * Creates a new generator of RSA keys with given key size.
     *
     * @param keySize size of the key
     */
    public RSAKeysGenerator(int keySize) throws EncryptionException {
        try {
            this.generator = KeyPairGenerator.getInstance("RSA");
            this.generator.initialize(keySize);
        } catch (NoSuchAlgorithmException e) {
            // this should not happen, it wou
            throw new EncryptionException("Unable to initialize RSA keys generator, is it supported by your JRE?", e);
        }
    }

    /**
     * Generates a new RSA keys.
     *
     * @return RSA keys array with 2 values, first value is public key, second value is private key
     */
    public RSAKeyParams[] generateKeys() {
        KeyPair keyPair = generateKeyPair();
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        RSAKeyParams[] out = new RSAKeyParams[2];
        out[0] = new RSAKeyParams(publicKey.getModulus(), publicKey.getPublicExponent());
        out[1] = new RSAKeyParams(privateKey.getModulus(), privateKey.getPrivateExponent());
        return out;
    }

    /**
     * Generates a new {@link KeyPair} for RSA.
     *
     * @return RSA key pair
     */
    public KeyPair generateKeyPair() {
        return generator.generateKeyPair();
    }


    public static class RSAKeys {
        private final BigInteger modulus;
        private final BigInteger publicExponent;
        private final BigInteger privateExponent;

        public RSAKeys(BigInteger modulus, BigInteger publicExponent, BigInteger privateExponent) {
            this.modulus = modulus;
            this.publicExponent = publicExponent;
            this.privateExponent = privateExponent;
        }

        public BigInteger getModulus() {
            return modulus;
        }

        public BigInteger getPublicExponent() {
            return publicExponent;
        }

        public BigInteger getPrivateExponent() {
            return privateExponent;
        }
    }
}