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java中加密算法Base64和RSA详解和Android

2016-06-29 15:55 676 查看
手机的安全重要信息容易被泄露的方式:

1.会从我们本地泄露     手机中毒等

2.会从服务器泄露  服务器人员将信息卖出去等

3.半路上,网络传输的过程中 加密传输数据    手机连接WiFi,如果在WiFi上设置监听数据,将关键的信息拦截下来,就有可能盗取个人重要信息。

-------常见的加密算法:  

AES  高级加密标准:DES的56位密钥,比较容易被破解,所以渐渐使用AES替代,目前对称加密中最流行算法之一

DES  对称加密算法:加密和解密使用相同密钥的算法

RSA  公钥加密算法 

MD5(即用户发出的MD5加密数据和服务器的MD5加密数据相匹对来验证,我用来用户名和密码的验证)

加密目的:防止数据信息泄露.

-----------------------------------------

非对称加密和对称加密区别:对称加密算法在加密和解密时使用的是同一个秘钥;而非对称加密算法需要两个密钥来进行加密和解密,这两个秘钥是公开密钥(public key,简称公钥)和私有密钥(private key,简称私钥)。

非对称加密

加密 解密 规则不一致

服务器会把公钥发送给每一个客户端,客户端在向服务器发送数据时,用公钥进行加密但是,最终解密数据,是不用公钥,而是通过私钥完成,私钥是不会发给别人,只会牢牢保护在服务器端

公钥 加密--------->  私钥解密

私钥 加签---------->公钥 验签  

对称加密

加密 解密 规则一致

-------------

RSA:

KeyPair :公私钥对

KeyPairGenerator 生成公私钥对

Cipher 加密 解密功能  

cipher.init(Cipher.ENCRYPT_MODE, publicKey); 设置为加密模式

cipher.init(Cipher.DECRYPT_MODE, privateKey); 设置为解密模式

cipher.doFinal 执行

java程序中,公钥为 X509格式   私钥为PKCS8格式

读取公钥:

<span style="white-space:pre"></span>        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);  
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);  
        PublicKey publicKey = keyFactory.generatePublic(keySpec); 
读取私钥:
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);  
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);  
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);


代码如下:

public static void main(String[] args) throws NoSuchAlgorithmException {
KeyPairGenerator kpg=KeyPairGenerator.getInstance("RSA");
KeyPair kp=kpg.genKeyPair();
System.out.println("私钥:"+kp.getPrivate());
System.out.println("-------");
System.out.println("公钥:"+kp.getPublic());
}
显示结果:



公钥是直接显示,而私钥则并没直接显示

public static void main(String[] args) throws NoSuchAlgorithmException, InvalidKeyException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
KeyPairGenerator kpg=KeyPairGenerator.getInstance("RSA");
KeyPair keyPair=kpg.genKeyPair();
PrivateKey privateKey = keyPair.getPrivate();
PublicKey publicKey = keyPair.getPublic();

String content="呵呵哈哈121adfs";
//加密
Cipher cipher=Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte[] encryptDatas = cipher.doFinal(content.getBytes());
System.out.println("加密后的密文:"+new String(encryptDatas));

//解密
Cipher cipher1=Cipher.getInstance("RSA");
cipher1.init(Cipher.DECRYPT_MODE, privateKey);
byte[] dencryptDatas=cipher1.doFinal(encryptDatas);
System.out.println("加密回来的数据:"+new String(dencryptDatas));
}



要获取公钥和私钥,则首先要打开opensl插件:

opensl生成指令:

RSA密钥生成命令

生成RSA私钥

openssl>genrsa -out rsa_private_key.pem 1024

生成RSA公钥

openssl>rsa -in rsa_private_key.pem -pubout -out rsa_public_key.pem

将RSA私钥转换成PKCS8格式

openssl>pkcs8 -topk8 -inform PEM -in rsa_private_key.pem -outform PEM -nocrypt

-----------------------------------

注解:1.1024是指生成的密文的长度,当然越大越安全,但是耗时也越多.

2.公钥生成的格式为x.509,私钥生成的格式为PKCS#8,最后还要执行最后一句命令让私钥格式为PKCS8

---------获取生成的公钥和私欲

public static void main(String[] args) throws NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException,
IllegalBlockSizeException, BadPaddingException, IOException,
InvalidKeySpecException {

// TODO Auto-generated method stub
String content = "呵呵哒呵呵123ABCD+-*/";
// 读取公钥,进行加密
File publicKeyFile = new File(
"C:/Users/Administrator/Desktop/gsy/rsa_public_key.pem");
// 对原先的Base64格式进行解码
byte[] publicBase64Datas = getKeyData(publicKeyFile);
byte[] publicOriginDatas = Base64.getDecoder()
.decode(publicBase64Datas);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicOriginDatas);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey publicKey = keyFactory.generatePublic(keySpec);
// 加密
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
//转换加密编码
byte[] encryptOriginDatas = cipher.doFinal(content.getBytes());
byte[] encryptBase64Datas =Base64.getEncoder().encode(encryptOriginDatas);
System.out.println(new String(encryptBase64Datas));
//提交数据
/*
* ----------------
*/
// 读取公钥,进行加密
File privateKeyFile = new File(
"C:/Users/Administrator/Desktop/gsy/privatekeyPKCS8.txt");
//私钥解密
byte[] privateBase64Datas= getKeyData(privateKeyFile);
byte[] privateOriginDatas = Base64.getDecoder()
.decode(privateBase64Datas);
PKCS8EncodedKeySpec keySpec1 = new PKCS8EncodedKeySpec(privateOriginDatas);
KeyFactory keyFactory1= KeyFactory.getInstance("RSA");
PrivateKey privateKey1 = keyFactory1.generatePrivate(keySpec1);
//拿着之前的数据进行解码
byte[] dencryptOriginDatas  = Base64.getDecoder().decode(encryptBase64Datas);
Cipher cipher1=Cipher.getInstance("RSA");
cipher1.init(Cipher.DECRYPT_MODE, privateKey1);
byte[] dencryptDatas=cipher1.doFinal(dencryptOriginDatas);
System.out.println(new String(dencryptDatas));
}

private static byte[] getKeyData(File publicKeyFile) throws IOException {
BufferedReader bufferedReader = new BufferedReader(
new InputStreamReader(new FileInputStream(publicKeyFile)));
String str = null;
StringBuilder stringBuilder = new StringBuilder();
while ((str = bufferedReader.readLine()) != null) {
if (str.startsWith("--")) {
continue;
}
stringBuilder.append(str);
}
bufferedReader.close();
return stringBuilder.toString().getBytes();
// TODO Auto-generated method stub

}


---------Base64解析:

Base64和RSA相伴相生,主要是为了防止乱码的产生

Base64其实不是加密解密算法,只是个编码解码的算法.

Android 自带

Base64.Encoder   编码
Base64.Decoder   解码
加密的数据只是改变其形式不出现乱码,但是发出和接手时数据未发生改变.

---------Base64流程

1.原有的公钥Key文件中存放的Base64格式的公钥,那么我们读取回来进行使用,就需要先用Base64解码,获取我们原有的公钥字节

2.加密数据

3.把加密的数据提交给服务器,但是加密过的数据时一堆乱码,直接提交会有问题,所以,我们再将这些乱码用Base64进行编码

4.将来服务器收到我们的数据,需要先用Base64解码,获取到原始加密数据
5.用私钥解密

以上是对加密算法的详细讲解,但是一般使用我们会选择别人已经完美搭建好的框架,这样便可以快捷的使用加密方法.前人种树后人乘凉,接下来就是快速的集成加密算法这个工具.

-------------------Base64Utils工具类:

public class Base64Utils {
private static char[] base64EncodeChars = new char[]
{ 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5',
'6', '7', '8', '9', '+', '/' };
private static byte[] base64DecodeChars = new byte[]
{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53,
54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29,
30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1,
-1, -1, -1 };

/**
* 加密
*
* @param data
* @return
*/
public static String encode(byte[] data)
{
StringBuffer sb = new StringBuffer();
int len = data.length;
int i = 0;
int b1, b2, b3;
while (i < len)
{
b1 = data[i++] & 0xff;
if (i == len)
{
sb.append(base64EncodeChars[b1 >>> 2]);
sb.append(base64EncodeChars[(b1 & 0x3) << 4]);
sb.append("==");
break;
}
b2 = data[i++] & 0xff;
if (i == len)
{
sb.append(base64EncodeChars[b1 >>> 2]);
sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);
sb.append("=");
break;
}
b3 = data[i++] & 0xff;
sb.append(base64EncodeChars[b1 >>> 2]);
sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);
sb.append(base64EncodeChars[b3 & 0x3f]);
}
return sb.toString();
}

/**
* 解密
*
* @param str
* @return
*/
public static byte[] decode(String str)
{
try
{
return decodePrivate(str);
} catch (UnsupportedEncodingException e)
{
e.printStackTrace();
}
return new byte[]
{};
}

private static byte[] decodePrivate(String str) throws UnsupportedEncodingException
{
StringBuffer sb = new StringBuffer();
byte[] data = null;
data = str.getBytes("US-ASCII");
int len = data.length;
int i = 0;
int b1, b2, b3, b4;
while (i < len)
{

do
{
b1 = base64DecodeChars[data[i++]];
} while (i < len && b1 == -1);
if (b1 == -1)
break;

do
{
b2 = base64DecodeChars[data[i++]];
} while (i < len && b2 == -1);
if (b2 == -1)
break;
sb.append((char) ((b1 << 2) | ((b2 & 0x30) >>> 4)));

do
{
b3 = data[i++];
if (b3 == 61)
return sb.toString().getBytes("iso8859-1");
b3 = base64DecodeChars[b3];
} while (i < len && b3 == -1);
if (b3 == -1)
break;
sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));

do
{
b4 = data[i++];
if (b4 == 61)
return sb.toString().getBytes("iso8859-1");
b4 = base64DecodeChars[b4];
} while (i < len && b4 == -1);
if (b4 == -1)
break;
sb.append((char) (((b3 & 0x03) << 6) | b4));
}
return sb.toString().getBytes("iso8859-1");
}

}


--------RSAUtils工具类:

public class RSAUtils {
private static String RSA = "RSA";

/**
* 随机生成RSA密钥对(默认密钥长度为1024)
*
* @return
*/
public static KeyPair generateRSAKeyPair() {
return generateRSAKeyPair(1024);
}

/**
* 随机生成RSA密钥对
*
* @param keyLength
*            密钥长度,范围:512~2048<br>
*            一般1024
* @return
*/
public static KeyPair generateRSAKeyPair(int keyLength) {
try {
KeyPairGenerator kpg = KeyPairGenerator.getInstance(RSA);
kpg.initialize(keyLength);
return kpg.genKeyPair();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
return null;
}
}

/**
* 用公钥加密 <br>
* 每次加密的字节数,不能超过密钥的长度值减去11
*
* @param data
*            需加密数据的byte数据
* @param pubKey
*            公钥
* @return 加密后的byte型数据
*/
public static byte[] encryptData(byte[] data, PublicKey publicKey) {
try {
Cipher cipher = Cipher.getInstance(RSA);
// 编码前设定编码方式及密钥
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
// 传入编码数据并返回编码结果
return cipher.doFinal(data);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}

/**
* 用私钥解密
*
* @param encryptedData
*            经过encryptedData()加密返回的byte数据
* @param privateKey
*            私钥
* @return
*/
public static byte[] decryptData(byte[] encryptedData, PrivateKey privateKey) {
try {
Cipher cipher = Cipher.getInstance(RSA);
cipher.init(Cipher.DECRYPT_MODE, privateKey);
return cipher.doFinal(encryptedData);
} catch (Exception e) {
return null;
}
}

/**
* 通过公钥byte[](publicKey.getEncoded())将公钥还原,适用于RSA算法
*
* @param keyBytes
* @return
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
*/
public static PublicKey getPublicKey(byte[] keyBytes)
throws NoSuchAlgorithmException, InvalidKeySpecException {
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(RSA);
PublicKey publicKey = keyFactory.generatePublic(keySpec);
return publicKey;
}

/**
* 通过私钥byte[]将公钥还原,适用于RSA算法
*
* @param keyBytes
* @return
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
*/
public static PrivateKey getPrivateKey(byte[] keyBytes)
throws NoSuchAlgorithmException, InvalidKeySpecException {
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(RSA);
PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
return privateKey;
}

/**
* 使用N、e值还原公钥
*
* @param modulus
* @param publicExponent
* @return
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
*/
public static PublicKey getPublicKey(String modulus, String publicExponent)
throws NoSuchAlgorithmException, InvalidKeySpecException {
BigInteger bigIntModulus = new BigInteger(modulus);
BigInteger bigIntPrivateExponent = new BigInteger(publicExponent);
RSAPublicKeySpec keySpec = new RSAPublicKeySpec(bigIntModulus,
bigIntPrivateExponent);
KeyFactory keyFactory = KeyFactory.getInstance(RSA);
PublicKey publicKey = keyFactory.generatePublic(keySpec);
return publicKey;
}

/**
* 使用N、d值还原私钥
*
* @param modulus
* @param privateExponent
* @return
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
*/
public static PrivateKey getPrivateKey(String modulus,
String privateExponent) throws NoSuchAlgorithmException,
InvalidKeySpecException {
BigInteger bigIntModulus = new BigInteger(modulus);
BigInteger bigIntPrivateExponent = new BigInteger(privateExponent);
RSAPublicKeySpec keySpec = new RSAPublicKeySpec(bigIntModulus,
bigIntPrivateExponent);
KeyFactory keyFactory = KeyFactory.getInstance(RSA);
PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
return privateKey;
}

/**
* 从字符串中加载公钥
*
* @param publicKeyStr
*            公钥数据字符串
* @throws Exception
*             加载公钥时产生的异常
*/
public static PublicKey loadPublicKey(String publicKeyStr) throws Exception {
try {
byte[] buffer = Base64Utils.decode(publicKeyStr);
KeyFactory keyFactory = KeyFactory.getInstance(RSA);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
return (RSAPublicKey) keyFactory.generatePublic(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new Exception("无此算法");
} catch (InvalidKeySpecException e) {
throw new Exception("公钥非法");
} catch (NullPointerException e) {
throw new Exception("公钥数据为空");
}
}

/**
* 从字符串中加载私钥<br>
* 加载时使用的是PKCS8EncodedKeySpec(PKCS#8编码的Key指令)。
*
* @param privateKeyStr
* @return
* @throws Exception
*/
public static PrivateKey loadPrivateKey(String privateKeyStr)
throws Exception {
try {
byte[] buffer = Base64Utils.decode(privateKeyStr);
// X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
KeyFactory keyFactory = KeyFactory.getInstance(RSA);
return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new Exception("无此算法");
} catch (InvalidKeySpecException e) {
throw new Exception("私钥非法");
} catch (NullPointerException e) {
throw new Exception("私钥数据为空");
}
}

/**
* 从文件中输入流中加载公钥
*
* @param in
*            公钥输入流
* @throws Exception
*             加载公钥时产生的异常
*/
public static PublicKey loadPublicKey(InputStream in) throws Exception {
try {
return loadPublicKey(readKey(in));
} catch (IOException e) {
throw new Exception("公钥数据流读取错误");
} catch (NullPointerException e) {
throw new Exception("公钥输入流为空");
}
}

/**
* 从文件中加载私钥
*
* @param keyFileName
*            私钥文件名
* @return 是否成功
* @throws Exception
*/
public static PrivateKey loadPrivateKey(InputStream in) throws Exception {
try {
return loadPrivateKey(readKey(in));
} catch (IOException e) {
throw new Exception("私钥数据读取错误");
} catch (NullPointerException e) {
throw new Exception("私钥输入流为空");
}
}

/**
* 读取密钥信息
*
* @param in
* @return
* @throws IOException
*/
private static String readKey(InputStream in) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String readLine = null;
StringBuilder sb = new StringBuilder();
while ((readLine = br.readLine()) != null) {
if (readLine.charAt(0) == '-') {
continue;
} else {
sb.append(readLine);
sb.append('\r');
}
}

return sb.toString();
}

/**
* 打印公钥信息
*
* @param publicKey
*/
public static void printPublicKeyInfo(PublicKey publicKey) {
RSAPublicKey rsaPublicKey = (RSAPublicKey) publicKey;
System.out.println("----------RSAPublicKey----------");
System.out.println("Modulus.length="
+ rsaPublicKey.getModulus().bitLength());
System.out.println("Modulus=" + rsaPublicKey.getModulus().toString());
System.out.println("PublicExponent.length="
+ rsaPublicKey.getPublicExponent().bitLength());
System.out.println("PublicExponent="
+ rsaPublicKey.getPublicExponent().toString());
}

public static void printPrivateKeyInfo(PrivateKey privateKey) {
RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) privateKey;
System.out.println("----------RSAPrivateKey ----------");
System.out.println("Modulus.length="
+ rsaPrivateKey.getModulus().bitLength());
System.out.println("Modulus=" + rsaPrivateKey.getModulus().toString());
System.out.println("PrivateExponent.length="
+ rsaPrivateKey.getPrivateExponent().bitLength());
System.out.println("PrivatecExponent="
+ rsaPrivateKey.getPrivateExponent().toString());

}

}
----------------------集成使用
public static void main(String[] args) throws FileNotFoundException, Exception {
String content = "呵呵哈哈123ABD+-*/";
// 读取公钥,进行加密
File publicKeyFile = new File(
"C:/Users/Administrator/Desktop/gsy/rsa_public_key.pem");//公钥路径
//加密
PublicKey loadPublicKey = RSAUtils.loadPublicKey(new FileInputStream(publicKeyFile));
byte[] encryptData = RSAUtils.encryptData(content.getBytes(), loadPublicKey);
System.out.println(new String(encryptData));
//解密
File privateKeyFile = new File(
"C:/Users/Administrator/Desktop/gsy/privatekeyPKCS8.txt");//私钥路径
PrivateKey loadPrivateKey = RSAUtils.loadPrivateKey(new FileInputStream(privateKeyFile));
byte[] decryptData = RSAUtils.decryptData(encryptData, loadPrivateKey);
System.out.println(new String(decryptData));
}
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