mamo.vanillaVotifier.utils.RsaUtils.java Source code

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Here is the source code for mamo.vanillaVotifier.utils.RsaUtils.java

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/*
 * Copyright (C) 2016  Matteo Morena
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package mamo.vanillaVotifier.utils;

import org.bouncycastle.util.encoders.Base64;
import org.jetbrains.annotations.NotNull;

import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

public class RsaUtils {
    @NotNull
    public static KeyPair genKeyPair() {
        return genKeyPair(2048);
    }

    @NotNull
    public static KeyPair genKeyPair(int keySize) {
        try {
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
            keyPairGenerator.initialize(keySize);
            return keyPairGenerator.genKeyPair();
        } catch (NoSuchAlgorithmException e) {
            // Can't happen
            return null;
        }
    }

    @NotNull
    public static PublicKey bytesToPublicKey(@NotNull byte[] bytes) throws InvalidKeySpecException {
        try {
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(bytes);
            KeyFactory kf = KeyFactory.getInstance("RSA");
            return kf.generatePublic(keySpec);
        } catch (NoSuchAlgorithmException e) {
            // Can't happen
            return null;
        }
    }

    @NotNull
    public static PrivateKey bytesToPrivateKey(@NotNull byte[] bytes) throws InvalidKeySpecException {
        try {
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(bytes);
            KeyFactory kf = KeyFactory.getInstance("RSA");
            return kf.generatePrivate(keySpec);
        } catch (NoSuchAlgorithmException e) {
            // Can't happen
            return null;
        }
    }

    @NotNull
    public static Cipher getEncryptCipher(@NotNull PublicKey key) {
        try {
            Cipher cipher;
            cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, key);
            return cipher;
        } catch (GeneralSecurityException e) { // NoSuchAlgorithmException and NoSuchPaddingException
            // Can't happen
            return null;
        }
    }

    @NotNull
    public static Cipher getDecryptCipher(@NotNull PrivateKey key) {
        try {
            Cipher cipher;
            cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, key);
            return cipher;
        } catch (GeneralSecurityException e) { // NoSuchAlgorithmException and NoSuchPaddingException
            // Can't happen
            return null;
        }
    }

    @NotNull
    public static String keyToString(Key key) {
        return new String(Base64.encode(key.getEncoded()));
    }
}