RSAUTil tool class

      
package com.upex.utils.crypto;


import com.alibaba.fastjson.JSON;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.codec.binary.Base64;
import org.springframework.util.Base64Utils;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.nio.charset.StandardCharsets;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

@Slf4j
public class RSAUtil {
    private static final String CHAR_ENCODING = "UTF-8";

    private static final String RSA_ALGORITHM = "RSA/ECB/PKCS1Padding";

    private static int KEYSIZE = 1024;

    public static Map<String, String> generateKeyPair() throws Exception {
        SecureRandom sr = new SecureRandom();
        KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
        kpg.initialize(KEYSIZE, sr);
        KeyPair kp = kpg.generateKeyPair();
        Key publicKey = kp.getPublic();
        byte[] publicKeyBytes = publicKey.getEncoded();
        String pub = new String(Base64.encodeBase64(publicKeyBytes), CHAR_ENCODING);
        Key privateKey = kp.getPrivate();
        byte[] privateKeyBytes = privateKey.getEncoded();
        String pri = new String(Base64.encodeBase64(privateKeyBytes), CHAR_ENCODING);

        Map<String, String> map = new HashMap<String, String>();
        map.put("publicKey", pub);
        map.put("privateKey", pri);
        return map;
    }

    /**
     *
     * @param source
     * @param publicKey
     */
    public static String encryptByPublicKey(String source, String publicKey) throws Exception {
        Key key = getPublicKey(publicKey);
        return encrypt(source, key);
    }

    /**
     *
     * @param source
     * @param key
     * @return
     * @throws Exception
     */
    private static String encrypt(String source, Key key) throws Exception {
        Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] b = source.getBytes();
        int MAX_ENCRYPT_BLOCK = 117;
        int offSet = 0;
        byte[] resultBytes = {};
        byte[] cache = {};
        int inputLength = b.length;
        while (inputLength - offSet > 0) {
            if (inputLength - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(b, offSet, MAX_ENCRYPT_BLOCK);
                offSet += MAX_ENCRYPT_BLOCK;
            } else {
                cache = cipher.doFinal(b, offSet, inputLength - offSet);
                offSet = inputLength;
            }
            resultBytes = Arrays.copyOf(resultBytes, resultBytes.length + cache.length);
            System.arraycopy(cache, 0, resultBytes, resultBytes.length - cache.length, cache.length);
        }
        return new String(Base64.encodeBase64(resultBytes), CHAR_ENCODING);
    }

    /**
     *
     * @param cryptograph
     * @param privateKey
     */
    public static String decryptByPrivateKey(String cryptograph, String privateKey) throws Exception {
        Key key = getPrivateKey(privateKey);
        return decrypt(cryptograph, key);
    }

    private static String decrypt(String cryptograph, Key key) throws Exception {
        Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, key);
        byte[] bytes = Base64.decodeBase64(cryptograph.getBytes());
        int inputLen = bytes.length;
        int offLen = 0;
        int i = 0;
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        while (inputLen - offLen > 0) {
            byte[] cache;
            if (inputLen - offLen > 128) {
                cache = cipher.doFinal(bytes, offLen, 128);
            } else {
                cache = cipher.doFinal(bytes, offLen, inputLen - offLen);
            }
            byteArrayOutputStream.write(cache);
            i++;
            offLen = 128 * i;

        }
        byteArrayOutputStream.close();
        byte[] byteArray = byteArrayOutputStream.toByteArray();
        return new String(byteArray);
    }

    /**
     *
     * @param key 
     * @throws Exception
     */
    private static PublicKey getPublicKey(String key) throws Exception {
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(Base64.decodeBase64(key.getBytes()));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(keySpec);
        return publicKey;
    }

    /**
     *
     * @param key 
     * @throws Exception
     */
    private static PrivateKey getPrivateKey(String key) throws Exception {
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(key.getBytes()));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        return keyFactory.generatePrivate(keySpec);
    }

    public static String sign(String content, String privateKey) {
        try {
            PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKey.getBytes()));
            KeyFactory keyf = KeyFactory.getInstance("RSA");
            PrivateKey priKey = keyf.generatePrivate(priPKCS8);

            Signature signature = Signature.getInstance("SHA1WithRSA");

            signature.initSign(priKey);
            signature.update(content.getBytes(CHAR_ENCODING));

            return new String(Base64.encodeBase64(signature.sign()));
        } catch (Exception e) {
            log.error("create sign  failed", e);
        }

        return null;
    }

    public static boolean checkSign(String content, String sign, String publicKey) {
        try {
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            byte[] encodedKey = Base64.decodeBase64(publicKey);
            PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));

            Signature signature = Signature.getInstance("SHA1WithRSA");

            signature.initVerify(pubKey);
            signature.update(content.getBytes("utf-8"));
            return signature.verify(Base64.decodeBase64(sign));

        } catch (Exception e) {
            log.error("checkSign  failed", e);
        }

        return false;
    }

    public static String encryptByPrivateKey(String source, String privateKey) throws Exception {
        Key key = getPrivateKey(privateKey);
        return encrypt(source, key);
    }

    public static String decryptByPublicKey(String cryptograph, String publicKey) throws Exception {
        Key key = getPublicKey(publicKey);
        return decrypt(cryptograph, key);
    }


    public static String signByMap(TreeMap content, String privateKey) {
        try {
            PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(Base64Utils.decodeFromString(privateKey));
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PrivateKey priKey = keyFactory.generatePrivate(priPKCS8);
            Signature signature = Signature.getInstance("SHA1WithRSA");
            signature.initSign(priKey);
            signature.update(JSON.toJSONString(content).getBytes(StandardCharsets.UTF_8));
            return Base64Utils.encodeToString(signature.sign());
        } catch (Exception e) {
            throw new RuntimeException("create sign  failed", e);
        }
    }

    public static boolean checkSignByMap(TreeMap content, String sign, String publicKey) {
        try {
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(Base64Utils.decodeFromString(publicKey)));
            Signature signature = Signature.getInstance("SHA1WithRSA");
            signature.initVerify(pubKey);
            signature.update(JSON.toJSONString(content).getBytes(StandardCharsets.UTF_8));
            return signature.verify(Base64Utils.decodeFromString(sign));
        } catch (Exception e) {
            log.error("verifySign  failed", e);
            return false;
        }
    }

    public static boolean checkUrlSign(String content, String sign, String publicKey) {
        try {
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            byte[] encodedKey = Base64.decodeBase64(publicKey);
            PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));

            Signature signature = Signature.getInstance("SHA1WithRSA");

            signature.initVerify(pubKey);
            signature.update(content.getBytes("utf-8"));
            return signature.verify(Base64.decodeBase64(sign));
        } catch (Exception e) {
            log.error("checkSign  failed", e);
        }

        return true;
    }

}