EncryptUtils.java

EncryptUtils.java

package sandbox;

import java.io.ByteArrayOutputStream;
import java.nio.charset.Charset;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

public class EncryptUtils {

    static final Charset UTF8 = Charset.forName("UTF-8");

    static final char[] HEX = "0123456789abcdef".toCharArray();

    static final String ALGORITHM = "Blowfish";
    static final String TRANSFORMATION = "Blowfish";

    public static String encrypt(String key, String text) {
        return toHexString(encrypt(getBytes(key), getBytes(text)));
    }

    public static byte[] encrypt(byte[] key, byte[] text) {
        try {
            SecretKeySpec spec = new SecretKeySpec(key, ALGORITHM);
            Cipher cipher = Cipher.getInstance(TRANSFORMATION);
            cipher.init(Cipher.ENCRYPT_MODE, spec);
            return cipher.doFinal(text);
        } catch (Exception e) {
            throw toRuntimeException(e);
        }
    }

    public static String decrypt(String key, String encrypted) {
        return toString(decrypt(getBytes(key), parseHexBytes(encrypted)));
    }

    public static byte[] decrypt(byte[] key, byte[] encrypted) {
        try {
            SecretKeySpec spec = new SecretKeySpec(key, ALGORITHM);
            Cipher cipher = Cipher.getInstance(TRANSFORMATION);
            cipher.init(Cipher.DECRYPT_MODE, spec);
            return cipher.doFinal(encrypted);
        } catch (Exception e) {
            throw toRuntimeException(e);
        }
    }

    static byte[] getBytes(String text) {
        return text.getBytes(UTF8);
    }

    static String toString(byte[] bytes) {
        return new String(bytes, UTF8);
    }

    static String toHexString(byte[] bytes) {
        StringBuilder sb = new StringBuilder(2 * bytes.length);
        for (int i = 0; i < bytes.length; ++i) {
            byte n = bytes[i];
            sb.append(HEX[(n >> 4) & 0xF]);
            sb.append(HEX[n & 0xF]);
        }
        return sb.toString();
    }

    static byte[] parseHexBytes(String s) {
        if (s.length() % 2 != 0) {
            s = '0' + s;
        }
        int length = s.length();
        ByteArrayOutputStream baos = new ByteArrayOutputStream(length / 2);
        for (int i = 0; i < length; i += 2) {
            baos.write(Integer.parseInt(s.substring(i, i + 2), 16));
        }
        return baos.toByteArray();
    }

    static RuntimeException toRuntimeException(Exception e) {
        if (e instanceof RuntimeException) {
            return (RuntimeException) e;
        } else {
            return new RuntimeException(e);
        }
    }

    public static void main(String [] args) {
        try {
            String encrypted = encrypt(args[0], args[1]);
            System.out.println("encrypted: " + encrypted);
            String decrypted = decrypt(args[0], encrypted);
            System.out.println("decrypted: " + decrypted);
        } catch (Exception e) {
            System.err.println(e);
            System.err.println("Usage: java EncryptUtils {key} {text}");
        }
    }

}

Java で暗号化／復号化の仕方。結構長くなった。