RSA 前端js公鑰加密，後端Java私鑰解密

前端公鑰加密

1、引入jsencrypt.min.js

2、公鑰我這邊是從後端傳給前端的，用一個input放着，按下面的方式就可以獲得加密後的密碼

var encrypt=new JSEncrypt();
encrypt.setPublicKey($("#publicKey").val());
var password=encrypt.encrypt($("#password").val());

後端私鑰解密

1、建一個RSAUtils類

public class RSAUtils {

/** *//**
 * RSA最大解密密文大小
 */
private static final int MAX_DECRYPT_BLOCK = 128;

/** *//**
 * <P>
 * 私鑰解密
 * </p>
 *
 * @param encryptedData 已加密數據
 * @param privateKey 私鑰(BASE64編碼)
 * @return
 * @throws Exception
 */
public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey)
        throws Exception {
    byte[] keyBytes = Base64Utils.decode(privateKey);
    PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
    KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
    Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
    Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
    cipher.init(Cipher.DECRYPT_MODE, privateK);
    int inputLen = encryptedData.length;
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    int offSet = 0;
    byte[] cache;
    int i = 0;
    // 對數據分段解密
    while (inputLen - offSet > 0) {
        if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
            cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
        } else {
            cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
        }
        out.write(cache, 0, cache.length);
        i++;
        offSet = i * MAX_DECRYPT_BLOCK;
    }
    byte[] decryptedData = out.toByteArray();
    out.close();
    return decryptedData;
} 

}

2、

public class Base64Utils {

/** *//**
 * <p>
 * BASE64字符串解碼爲二進制數據
 * </p>
 *
 * @param base64
 * @return
 * @throws Exception
 */
public static byte[] decode(String base64) throws Exception {
    return Base64.decodeBase64(base64.getBytes());
}

}

3、調用 (privateKey私密密鑰，可從文件裏獲取）

byte[] decryptByPrivateKey = RSAUtils.decryptByPrivateKey(Base64Utils.decode(password), privateKey);

//解密後的密碼
String password = new String(decryptByPrivateKey);