RSA簽名算法(密鑰簽名、公鑰驗籤)

public static final String CHARSET_NAME = "utf-8";

/**
 * 簽名
 * @param plaintext 明文
 * @return
 * @throws Exception
 */
public static String sign(String plaintext) throws Exception{
    KeyFactory factory = KeyFactory.getInstance("RSA");
    byte[] privateKeyBytes = Base64.getDecoder().decode("你的密鑰");
    Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
    PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(privateKeyBytes);
    PrivateKey privateKey = factory.generatePrivate(pkcs8EncodedKeySpec);
    Signature sign = Signature.getInstance("SHA1withRSA");
    sign.initSign(privateKey);
    sign.update(plaintext.getBytes(CHARSET_NAME));
    byte[] signBytes = sign.sign();
    return bytesToBase64(signBytes);
}

 

/**
 * 驗籤
 * @param plaintext 明文
 * @param sign 簽名
 * @return
 * @throws Exception
 */
public static boolean verifySign(String plaintext, String sign) throws Exception{
    byte[] publicKeyBytes = Base64.getDecoder().decode(HFBPublicKey);
    X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec("你的公鑰");
    KeyFactory factory = KeyFactory.getInstance("RSA");
    PublicKey publicKey = factory.generatePublic(x509EncodedKeySpec);
    Signature verifySign = Signature.getInstance("SHA1withRSA");
    verifySign.initVerify(publicKey);
    verifySign.update(plaintext.getBytes(CHARSET_NAME));
    boolean signedSuccess = verifySign.verify(Base64.getDecoder().decode(sign));
    return signedSuccess;
}