尝试这个类。package groovy;

import java.io.BufferedReader;

import java.io.FileReader;

import java.io.IOException;

import java.io.UnsupportedEncodingException;

import java.security.GeneralSecurityException;

import java.security.InvalidKeyException;

import java.security.KeyFactory;

import java.security.NoSuchAlgorithmException;

import java.security.PrivateKey;

import java.security.PublicKey;

import java.security.Signature;

import java.security.SignatureException;

import java.security.interfaces.RSAPrivateKey;

import java.security.interfaces.RSAPublicKey;

import java.security.spec.PKCS8EncodedKeySpec;

import java.security.spec.X509EncodedKeySpec;

import javax.crypto.Cipher;

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

public class RSA {

private static String getKey(String filename) throws IOException {

// Read key from file

String strKeyPEM ="";

BufferedReader br = new BufferedReader(new FileReader(filename));

String line;

while ((line = br.readLine()) != null) {

strKeyPEM += line +"n";

}

br.close();

return strKeyPEM;

}

public static RSAPrivateKey getPrivateKey(String filename) throws IOException, GeneralSecurityException {

String privateKeyPEM = getKey(filename);

return getPrivateKeyFromString(privateKeyPEM);

}

public static RSAPrivateKey getPrivateKeyFromString(String key) throws IOException, GeneralSecurityException {

String privateKeyPEM = key;

privateKeyPEM = privateKeyPEM.replace("-----BEGIN PRIVATE KEY-----n","");

privateKeyPEM = privateKeyPEM.replace("-----END PRIVATE KEY-----","");

byte[] encoded = Base64.decodeBase64(privateKeyPEM);

KeyFactory kf = KeyFactory.getInstance("RSA");

PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(encoded);

RSAPrivateKey privKey = (RSAPrivateKey) kf.generatePrivate(keySpec);

return privKey;

}

public static RSAPublicKey getPublicKey(String filename) throws IOException, GeneralSecurityException {

String publicKeyPEM = getKey(filename);

return getPublicKeyFromString(publicKeyPEM);

}

public static RSAPublicKey getPublicKeyFromString(String key) throws IOException, GeneralSecurityException {

String publicKeyPEM = key;

publicKeyPEM = publicKeyPEM.replace("-----BEGIN PUBLIC KEY-----n","");

publicKeyPEM = publicKeyPEM.replace("-----END PUBLIC KEY-----","");

byte[] encoded = Base64.decodeBase64(publicKeyPEM);

KeyFactory kf = KeyFactory.getInstance("RSA");

RSAPublicKey pubKey = (RSAPublicKey) kf.generatePublic(new PKCS8EncodedKeySpec(encoded));

return pubKey;

}

public static String sign(PrivateKey privateKey, String message) throws NoSuchAlgorithmException, InvalidKeyException, SignatureException, UnsupportedEncodingException {

Signature sign = Signature.getInstance("SHA1withRSA");

sign.initSign(privateKey);

sign.update(message.getBytes("UTF-8"));

return new String(Base64.encodeBase64(sign.sign()),"UTF-8");

}

public static boolean verify(PublicKey publicKey, String message, String signature) throws SignatureException, NoSuchAlgorithmException, UnsupportedEncodingException, InvalidKeyException {

Signature sign = Signature.getInstance("SHA1withRSA");

sign.initVerify(publicKey);

sign.update(message.getBytes("UTF-8"));

return sign.verify(Base64.decodeBase64(signature.getBytes("UTF-8")));

}

public static String encrypt(String rawText, PublicKey publicKey) throws IOException, GeneralSecurityException {

Cipher cipher = Cipher.getInstance("RSA");

cipher.init(Cipher.ENCRYPT_MODE, publicKey);

return Base64.encodeBase64String(cipher.doFinal(rawText.getBytes("UTF-8")));

}

public static String decrypt(String cipherText, PrivateKey privateKey) throws IOException, GeneralSecurityException {

Cipher cipher = Cipher.getInstance("RSA");

cipher.init(Cipher.DECRYPT_MODE, privateKey);

return new String(cipher.doFinal(Base64.decodeBase64(cipherText)),"UTF-8");

}

}

所需的jar库"common-codec-1.6 "