java RSA 私钥解密、公钥解密

import org.apache.commons.codec.binary.Base64;
import sun.security.rsa.RSAPrivateCrtKeyImpl;

import org.bouncycastle.util.encoders.Hex;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.security.Key;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.security.spec.X509EncodedKeySpec;

public class CountRsaUtil {

    /**
     * 私钥解密
     * @param encryptedData 加密数据
     * @param privateKey 私钥
     * @return 解密结果
     */
    public static byte[] decryptByPrivateKey(String encryptedData, String privateKey) {
        try {
            byte[] encryptedDataByte = hexStr2Bytes(encryptedData);
            byte[] keyBytes = Base64.decodeBase64(privateKey);
            PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
            Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
            cipher.init(Cipher.DECRYPT_MODE, privateK);
            int inputLen = encryptedDataByte.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段解密
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > 128) {
                    cache = cipher.doFinal(encryptedDataByte, offSet, 128);
                } else {
                    cache = cipher.doFinal(encryptedDataByte, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * 128;
            }
            byte[] decryptedData = out.toByteArray();
            out.close();
            return decryptedData;
        } catch (Exception e) {
        }
        return null;
    }

    /**
     * 公钥解密
     *
     * @param encryptedData 已加密数据
     * @param privateKey    私钥(BASE64编码)
     * @return 解密结果
     */
    public static byte[] decryptByPublicKey(String encryptedData, String privateKey) {
        try {
            byte[] keyBytes = Base64.decodeBase64(privateKey);
            PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            RSAPrivateCrtKeyImpl privateK = (RSAPrivateCrtKeyImpl) keyFactory.generatePrivate(pkcs8KeySpec);
            RSAPublicKeySpec rsaPubKeySpec = new RSAPublicKeySpec(privateK.getModulus(), privateK.getPublicExponent());
            RSAPublicKey rsaPublicKey = (RSAPublicKey) keyFactory.generatePublic(rsaPubKeySpec);
            X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
            PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
            Cipher cipher = Cipher.getInstance("RSA");
            // 初始化解密
            cipher.init(Cipher.DECRYPT_MODE, publicKey);

            byte[] encryptedDataByte = hexStr2Bytes(encryptedData);
            int inputLen = encryptedDataByte.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段解密
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > 128) {
                    cache = cipher.doFinal(encryptedDataByte, offSet, 128);
                } else {
                    cache = cipher.doFinal(encryptedDataByte, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * 128;
            }
            byte[] decryptedData = out.toByteArray();
            out.close();
            return decryptedData;
        } catch (Exception e) {
        }
        return null;
    }
　　　

public static byte[] hexStr2Bytes(String var0) {
    return Hex.decode(var0);
}

}