com.samsung.knoxwsm.util.KnoxEncryptionUtility Maven / Gradle / Ivy

package com.samsung.knoxwsm.util;

import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.spec.X509EncodedKeySpec;

/**
 * @author e.jaucian 7/15/19
 *
 * To use KnoxEncryptionUtility, instantiate said class. Pass the text to be encrypted to
 * encrypt(textToEncrypt) method. Said method will return an encrypted text.
 * Text to be encrypted should not be greater than 245 bytes.
 *
 * ex:
 * KnoxEncryptionUtility knoxEncryptionUtil = new KnoxEncryptionUtility();
 * String encryptedText = knoxEncryptionUtil.encrypt(textToBeEncrypted);
 */
public class KnoxEncryptionUtility {

    private static final String ENCRYPTION_PUBLIC_KEY = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAu4NECyudg9kYyLqdcfaOiRY+ImD3PYpnMXItzWR9YL1BeJOt1lwLG32aIix2SvED+5w8q0aLINeS8zDiJ28gsz5waUSIZHDzuPg9GOaDumua6FWcXxqI1i209lPF7rzbtHWU/2AngPX/hb5a/L7nYuTpDTNFMvQ1k1xw3fghtUb5lP+tRPYIgdKjRdS5WCRCR3I8ppyKABFisYHn1jm0op16AyIyX6lbCTb7HppkfDU2V0tdPBqTT5C1qNJKkPVLQzqN3lKQdY0bx+Ebf9zA+QPeorTTGurmnAe4JuNYO3G26WtFZ91RaMaKXogT1l+2++oaoSGZk1fm6z2ojLdz4wIDAQAB";

    private static final String ALGORITHM = "RSA";

    private PublicKey publicKey;

    private Cipher encryptionCipher;

    private static final String EXCEPTION_MESSAGE = "Exception encountered while encrypting text.";

    public KnoxEncryptionUtility() throws Exception {
        try {
            publicKey = getPublicKey();
            encryptionCipher = Cipher.getInstance(ALGORITHM);
            encryptionCipher.init(Cipher.ENCRYPT_MODE, publicKey);
        } catch (Exception e) {
            throw new Exception(EXCEPTION_MESSAGE);
        }
    }

    private static PublicKey getPublicKey() throws Exception {
        byte[] publicKeyBytes = Base64.decodeBase64(ENCRYPTION_PUBLIC_KEY);
        X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(publicKeyBytes);
        KeyFactory publicKeyFactory = KeyFactory.getInstance(ALGORITHM);

        return publicKeyFactory.generatePublic(publicKeySpec);
    }

    /**
     * A method used to encrypt texts. Text to be encrypted should not be greater than 245 bytes.
     *
     * @param text text to be encrypted.
     * @return Encrypted text.
     * @throws Exception When the text couldn't be encrypted properly
     */
    public String encrypt(String text) throws Exception {

        if(text == null || text.trim().length() == 0) {
            throw new IllegalArgumentException("Text cannot be null or empty.");
        }

        try {
            if (encryptionCipher == null) {
                encryptionCipher = Cipher.getInstance(ALGORITHM);
                encryptionCipher.init(Cipher.ENCRYPT_MODE, publicKey);
            }

            byte[] cipherText = encryptionCipher.doFinal(text.getBytes());
            return Base64.encodeBase64String(cipherText);
        } catch (Exception e) {
            throw new Exception(EXCEPTION_MESSAGE);
        }
    }
}