最近要做一个软件注册的功能，所以就研究了下加密解密。整理里一下，希望对大家有帮助!
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MD5加密算法：
Message Digest Algorithm MD5（中文名为消息摘要算法第五版）为计算机安全领域广泛使用的一种散列函数，用以提供消息的完整性保护。该算法的文件号为RFC 1321（R.Rivest,MIT Laboratory for Computer Science and RSA Data Security Inc. April 1992）
代码
public final class MD5Crypt {
/**
*
* Command line test rig.
* @throws NoSuchAlgorithmException
*
*/
static public void main(String argv[]) throws NoSuchAlgorithmException
{
System.out.println(crypt("daliantan0v0"));;
// if ((argv.length < 1) || (argv.length > 2))
// {
// System.err.println("Usage: MD5Crypt password salt");
// System.exit(1);
// }
//
// if (argv.length == 2)
// {
// System.err.println(MD5Crypt.crypt(argv[0], argv[1]));
// }
// else
// {
// System.err.println(MD5Crypt.crypt(argv[0]));
// }
//
// System.exit(0);
}
static private final String SALTCHARS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
static private final String itoa64 = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
static private final String to64(long v, int size)
{
StringBuffer result = new StringBuffer();
while (--size >= 0)
{
result.append(itoa64.charAt((int) (v & 0x3f)));
v >>>= 6;
}
return result.toString();
}
static private final void clearbits(byte bits[])
{
for (int i = 0; i < bits.length; i++)
{
bits[i] = 0;
}
}
/**
* convert an encoded unsigned byte value into a int
* with the unsigned value.
*/
static private final int bytes2u(byte inp)
{
return (int) inp & 0xff;
}
/**
* <p>This method actually generates a OpenBSD/FreeBSD/Linux PAM compatible
* md5-encoded password hash from a plaintext password and a
* salt.</p>
*
* <p>The resulting string will be in the form '$1$<salt>$<hashed mess></p>
*
* @param password Plaintext password
*
* @return An OpenBSD/FreeBSD/Linux-compatible md5-hashed password field.
* @throws NoSuchAlgorithmException
*/
static public final String crypt(String password) throws NoSuchAlgorithmException
{
StringBuffer salt = new StringBuffer();
java.util.Random randgen = new java.util.Random();
/* -- */
while (salt.length() < 8)
{
int index = (int) (randgen.nextFloat() * SALTCHARS.length());
salt.append(SALTCHARS.substring(index, index+1));
}
return MD5Crypt.crypt(password, salt.toString());
}
/**
* <p>This method actually generates a OpenBSD/FreeBSD/Linux PAM compatible
* md5-encoded password hash from a plaintext password and a
* salt.</p>
*
* <p>The resulting string will be in the form '$1$<salt>$<hashed mess></p>
*
* @param password Plaintext password
* @param salt A short string to use to randomize md5. May start with $1$, which
* will be ignored. It is explicitly permitted to pass a pre-existing
* MD5Crypt'ed password entry as the salt. crypt() will strip the salt
* chars out properly.
*
* @return An OpenBSD/FreeBSD/Linux-compatible md5-hashed password field.
* @throws NoSuchAlgorithmException
*/
static public final String crypt(String password, String salt) throws NoSuchAlgorithmException
{
/* This string is magic for this algorithm. Having it this way,
* we can get get better later on */
String magic = "$1$";
byte finalState[];
MessageDigest ctx, ctx1;
long l;
/* -- */
/* Refine the Salt first */
/* If it starts with the magic string, then skip that */
if (salt.startsWith(magic))
{
salt = salt.substring(magic.length());
}
/* It stops at the first '$', max 8 chars */
if (salt.indexOf('$') != -1)
{
salt = salt.substring(0, salt.indexOf('$'));
}
if (salt.length() > 8)
{
salt = salt.substring(0, 8);
}
ctx = MessageDigest.getInstance("MD5");
ctx.update(password.getBytes()); // The password first, since that is what is most unknown
ctx.update(magic.getBytes()); // Then our magic string
ctx.update(salt.getBytes()); // Then the raw salt
/* Then just as many characters of the MD5(pw,salt,pw) */
ctx1 = MessageDigest.getInstance("MD5");
ctx1.update(password.getBytes());
ctx1.update(salt.getBytes());
ctx1.update(password.getBytes());
finalState = ctx1.digest();
for (int pl = password.length(); pl > 0; pl -= 16)
{
for( int i=0; i< (pl > 16 ? 16 : pl); i++ )
ctx.update(finalState[i] );
}
/* the original code claimed that finalState was being cleared
to keep dangerous bits out of memory, but doing this is also
required in order to get the right output. */
clearbits(finalState);
/* Then something really weird... */
for (int i = password.length(); i != 0; i >>>=1)
{
if ((i & 1) != 0)
{
ctx.update(finalState[0]);
}
else
{
ctx.update(password.getBytes()[0]);
}
}
finalState = ctx.digest();
/*
* and now, just to make sure things don't run too fast
* On a 60 Mhz Pentium this takes 34 msec, so you would
* need 30 seconds to build a 1000 entry dictionary...
*
* (The above timings from the C version)
*/
for (int i = 0; i < 1000; i++)
{
ctx1 = MessageDigest.getInstance("MD5");
if ((i & 1) != 0)
{
ctx1.update(password.getBytes());
}
else
{
for( int c=0; c<16; c++ )
ctx1.update(finalState[c]);
}
if ((i % 3) != 0)
{
ctx1.update(salt.getBytes());
}
if ((i % 7) != 0)
{
ctx1.update(password.getBytes());
}
if ((i & 1) != 0)
{
for( int c=0; c<16; c++ )
ctx1.update(finalState[c]);
}
else
{
ctx1.update(password.getBytes());
}
finalState = ctx1.digest();
}
/* Now make the output string */
StringBuffer result = new StringBuffer();
result.append(magic);
result.append(salt);
result.append("$");
l = (bytes2u(finalState[0]) << 16) | (bytes2u(finalState[6]) << 8) | bytes2u(finalState[12]);
result.append(to64(l, 4));
l = (bytes2u(finalState[1]) << 16) | (bytes2u(finalState[7]) << 8) | bytes2u(finalState[13]);
result.append(to64(l, 4));
l = (bytes2u(finalState[2]) << 16) | (bytes2u(finalState[8]) << 8) | bytes2u(finalState[14]);
result.append(to64(l, 4));
l = (bytes2u(finalState[3]) << 16) | (bytes2u(finalState[9]) << 8) | bytes2u(finalState[15]);
result.append(to64(l, 4));
l = (bytes2u(finalState[4]) << 16) | (bytes2u(finalState[10]) << 8) | bytes2u(finalState[5]);
result.append(to64(l, 4));
l = bytes2u(finalState[11]);
result.append(to64(l, 2));
/* Don't leave anything around in vm they could use. */
clearbits(finalState);
return result.toString();
}
}
RSA算法是第一个能同时用于加密和数字签名的算法，也易于理解和操作。 RSA是被研究得最广泛的公钥算法，从提出到现在已近二十年，经历了各种攻击的考验，逐渐为人们接受，普遍认为是目前最优秀的公钥方案之一。
代码
public class RSAEncrypt {
public static void main(String[] args) {
try {
RSAEncrypt encrypt = new RSAEncrypt();
String encryptText = "ganlisxn1104";
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
keyPairGen.initialize(1024);
KeyPair keyPair = keyPairGen.generateKeyPair();
// Generate keys
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
byte[] e = encrypt.encrypt(publicKey,encryptText.getBytes());
byte[] de = encrypt.decrypt(privateKey, e);
System.out.println("加密:"+encrypt.bytesToString(e));
System.out.println("解密:"+encrypt.bytesToString(de));
} catch (Exception e) {
e.printStackTrace();
}
}
public void doDecrypt(String encryptText) throws NoSuchAlgorithmException{
RSAEncrypt encrypt = new RSAEncrypt();
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
keyPairGen.initialize(1024);
KeyPair keyPair = keyPairGen.generateKeyPair();
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
// byte[] e = ' &r? ????gf??￤?_???(?)Z!-Dl?tA/??rl???`l???????iR?"|$?;D?I???|?F?JH???h???S?)u-?H??"`?M?2?#￠]?￢?6r?(??Y??:? b ';
//encrypt.encrypt(publicKey,encryptText.getBytes());
byte[] de = encrypt.decrypt(privateKey, encryptText.getBytes());
// System.out.println("加密:"+encrypt.bytesToString(e));
System.out.println("11111111111111");
System.out.println("解密:"+encrypt.bytesToString(de));
}
/** */
/**
* Change byte array to String.
*
* @return byte[]
*/
protected String bytesToString(byte[] encrytpByte) {
String result = "";
for (Byte bytes : encrytpByte) {
result += (char) bytes.intValue();
}
return result;
}
/** */
/**
* Encrypt String.
*
* @return byte[]
*/
protected byte[] encrypt(RSAPublicKey publicKey, byte[] obj) {
if (publicKey != null) {
try {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
return cipher.doFinal(obj);
} catch (Exception e) {
e.printStackTrace();
}
}
return null;
}
/** */
/**
* Basic decrypt method
*
* @return byte[]
*/
protected byte[] decrypt(RSAPrivateKey privateKey, byte[] obj) {
if (privateKey != null) {
try {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, privateKey);
return cipher.doFinal(obj);
} catch (Exception e) {
e.printStackTrace();
}
}
return null;
}
}
DES加密
数据加密算法（Data Encryption Algorithm，DEA）的数据加密标准（Data Encryption Standard，DES）是规范的描述，它出自IBM 的研究工作，并在 1977 年被美国政府正式采纳。它很可能是使用最广泛的密钥系统，特别是在保护金融数据的安全中，最初开发的 DES 是嵌入硬 件中的。通常，自动取款机（Automated Teller Machine，ATM）都使用 DES。
安全散列算法SHA
(Secure Hash Algorithm，SHA)
是美国国家标准和技术局发布的国家标准FIPS PUB 180-1，一般称为SHA-1。其对长度不超过264二进制位的消息产生160位的消息摘要输出，按512比特块处理其输入。
SHA是一种数据加密算法，该算法经过加密专家多年来的发展和改进已日益完善，现在已成为公认的最安全的散列算法之一，并被广泛使用。该算法的思想是接收一段明文，然后以一种不可逆的方式将它转换成一段（通常更小）密文，也可以简单的理解为取一串输入码（称为预映射或信息），并把它们转化为长度较短、位数固定的输出序列即散列值（也称为信息摘要或信息认证代码）的过程。散列函数值可以说时对明文的一种“指纹”或是“摘要”所以对散列值的数字签名就可以视为对此明文的数字签名。
代码
/**
* 加密解密
*
* @author shy.qiu
* @since http://blog.csdn.net/qiushyfm
*/
public class Crypt {
/**
* 进行SHA加密
*
* @param info
* 要加密的信息
* @return String 加密后的字符串
*/
public String encryptToSHA(String info) {
byte[] digesta = null;
try {
// 得到一个SHA-1的消息摘要
MessageDigest alga = MessageDigest.getInstance("SHA-1");
// 添加要进行计算摘要的信息
alga.update(info.getBytes());
// 得到该摘要
digesta = alga.digest();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
// 将摘要转为字符串
String rs = byte2hex(digesta);
return rs;
}
// //////////////////////////////////////////////////////////////////////////
/**
* 创建密匙
*
* @param algorithm
* 加密算法,可用 DES,DESede,Blowfish
* @return SecretKey 秘密（对称）密钥
*/
public SecretKey createSecretKey(String algorithm) {
// 声明KeyGenerator对象
KeyGenerator keygen;
// 声明 密钥对象
SecretKey deskey = null;
try {
// 返回生成指定算法的秘密密钥的 KeyGenerator 对象
keygen = KeyGenerator.getInstance(algorithm);
// 生成一个密钥
deskey = keygen.generateKey();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
// 返回密匙
return deskey;
}
/**
* 根据密匙进行DES加密
*
* @param key
* 密匙
* @param info
* 要加密的信息
* @return String 加密后的信息
*/
public String encryptToDES(SecretKey key, String info) {
// 定义 加密算法,可用 DES,DESede,Blowfish
String Algorithm = "DES";
// 加密随机数生成器 (RNG),(可以不写)
SecureRandom sr = new SecureRandom();
// 定义要生成的密文
byte[] cipherByte = null;
try {
// 得到加密/解密器
Cipher c1 = Cipher.getInstance(Algorithm);
// 用指定的密钥和模式初始化Cipher对象
// 参数:(ENCRYPT_MODE, DECRYPT_MODE, WRAP_MODE,UNWRAP_MODE)
c1.init(Cipher.ENCRYPT_MODE, key, sr);
// 对要加密的内容进行编码处理,
cipherByte = c1.doFinal(info.getBytes());
} catch (Exception e) {
e.printStackTrace();
}
// 返回密文的十六进制形式
return byte2hex(cipherByte);
}
/**
* 根据密匙进行DES解密
*
* @param key
* 密匙
* @param sInfo
* 要解密的密文
* @return String 返回解密后信息
*/
public String decryptByDES(SecretKey key, String sInfo) {
// 定义 加密算法,
String Algorithm = "DES";
// 加密随机数生成器 (RNG)
SecureRandom sr = new SecureRandom();
byte[] cipherByte = null;
try {
// 得到加密/解密器
Cipher c1 = Cipher.getInstance(Algorithm);
// 用指定的密钥和模式初始化Cipher对象
c1.init(Cipher.DECRYPT_MODE, key, sr);
// 对要解密的内容进行编码处理
cipherByte = c1.doFinal(hex2byte(sInfo));
} catch (Exception e) {
e.printStackTrace();
}
// return byte2hex(cipherByte);
return new String(cipherByte);
}
// /////////////////////////////////////////////////////////////////////////////
/**
* 创建密匙组，并将公匙，私匙放入到指定文件中
*
* 默认放入mykeys.bat文件中
* @throws IOException
*/
public void createPairKey() throws IOException {
try {
// 根据特定的算法一个密钥对生成器
KeyPairGenerator keygen = KeyPairGenerator.getInstance("DSA");
// 加密随机数生成器 (RNG)
SecureRandom random = new SecureRandom();
// 重新设置此随机对象的种子
random.setSeed(1000);
// 使用给定的随机源（和默认的参数集合）初始化确定密钥大小的密钥对生成器
keygen.initialize(512, random);// keygen.initialize(512);
// 生成密钥组
KeyPair keys = keygen.generateKeyPair();
// 得到公匙
PublicKey pubkey = keys.getPublic();
// 得到私匙
PrivateKey prikey = keys.getPrivate();
//取得公司名称，写入公钥中
GetProperties gp = new GetProperties();
String company = gp.getCompany();
// 将公匙私匙写入到文件当中
doObjToFile("mykeys.bat", new Object[] { prikey, pubkey ,company});
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
}
/**
* 利用私匙对信息进行签名 把签名后的信息放入到指定的文件中
*
* @param info
* 要签名的信息
* @param signfile
* 存入的文件
*/
public void signToInfo(String info, String signfile) {
// 从文件当中读取私匙
PrivateKey myprikey = (PrivateKey) getObjFromFile("mykeys.bat", 1);
// 从文件中读取公匙
PublicKey mypubkey = (PublicKey) getObjFromFile("mykeys.bat", 2);
String in = (String) getObjFromFile("mykeys.bat", 3);
System.out.println("****"+in);
try {
// Signature 对象可用来生成和验证数字签名
Signature signet = Signature.getInstance("DSA");
// 初始化签署签名的私钥
signet.initSign(myprikey);
// 更新要由字节签名或验证的数据
signet.update(info.getBytes());
// 签署或验证所有更新字节的签名，返回签名
byte[] signed = signet.sign();
// 将数字签名,公匙,信息放入文件中
doObjToFile("d:\\"+signfile, new Object[] { signed, mypubkey, info ,in});
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 读取数字签名文件 根据公匙，签名，信息验证信息的合法性
*
* @return true 验证成功 false 验证失败
*/
public boolean validateSign(String signfile) {
// 读取公匙
PublicKey mypubkey = (PublicKey) getObjFromFile(signfile, 2);
System.out.println("mypubkey==="+mypubkey);
// 读取签名
byte[] signed = (byte[]) getObjFromFile(signfile, 1);
// 读取信息
String info = (String) getObjFromFile(signfile, 3);
System.out.println("info==="+info);
try {
// 初始一个Signature对象,并用公钥和签名进行验证
Signature signetcheck = Signature.getInstance("DSA");
// 初始化验证签名的公钥
signetcheck.initVerify(mypubkey);
// 使用指定的 byte 数组更新要签名或验证的数据
signetcheck.update(info.getBytes());
// 验证传入的签名
return signetcheck.verify(signed);
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
/**
* 将二进制转化为16进制字符串
*
* @param b
* 二进制字节数组
* @return String
*/
public String byte2hex(byte[] b) {
String hs = "";
String stmp = "";
for (int n = 0; n < b.length; n++) {
stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
if (stmp.length() == 1) {
hs = hs + "0" + stmp;
} else {
hs = hs + stmp;
}
}
return hs.toUpperCase();
}
/**
* 十六进制字符串转化为2进制
*
* @param hex
* @return
*/
public byte[] hex2byte(String hex) {
byte[] ret = new byte[8];
byte[] tmp = hex.getBytes();
for (int i = 0; i < 8; i++) {
ret[i] = uniteBytes(tmp[i * 2], tmp[i * 2 + 1]);
}
return ret;
}
/**
* 将两个ASCII字符合成一个字节； 如："EF"--> 0xEF
*
* @param src0
* byte
* @param src1
* byte
* @return byte
*/
public static byte uniteBytes(byte src0, byte src1) {
byte _b0 = Byte.decode("0x" + new String(new byte[] { src0 }))
.byteValue();
_b0 = (byte) (_b0 << 4);
byte _b1 = Byte.decode("0x" + new String(new byte[] { src1 }))
.byteValue();
byte ret = (byte) (_b0 ^ _b1);
return ret;
}
/**
* 将指定的对象写入指定的文件
*
* @param file
* 指定写入的文件
* @param objs
* 要写入的对象
*/
public void doObjToFile(String file, Object[] objs) {
ObjectOutputStream oos = null;
try {
FileOutputStream fos = new FileOutputStream(file);
oos = new ObjectOutputStream(fos);
for (int i = 0; i < objs.length; i++) {
oos.writeObject(objs[i]);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
oos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 返回在文件中指定位置的对象
*
* @param file
* 指定的文件
* @param i
* 从1开始
* @return
*/
public Object getObjFromFile(String file, int i) {
ObjectInputStream ois = null;
Object obj = null;
try {
FileInputStream fis = new FileInputStream(file);
ois = new ObjectInputStream(fis);
for (int j = 0; j < i; j++) {
obj = ois.readObject();
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
ois.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return obj;
}
/**
* 测试
*
* @param args
* @throws IOException
*/
public static void main(String[] args) throws IOException {
Crypt jiami = new Crypt();
// 执行MD5加密"Hello world!"
System.out.println("Hello经过MD5:" + jiami.encryptToMD5("tanovo"));
// 生成一个DES算法的密匙
SecretKey key = jiami.createSecretKey("DES");
// 用密匙加密信息"Hello world!"
String str1 = jiami.encryptToDES(key, "tanovo");
System.out.println("使用des加密信息tanovo为:" + str1);
// 使用这个密匙解密
String str2 = jiami.decryptByDES(key, str1);
System.out.println("解密后为：" + str2);
// 创建公匙和私匙
jiami.createPairKey();
// 对Hello world!使用私匙进行签名
jiami.signToInfo("Hello", "mysign.bat");
// 利用公匙对签名进行验证。
if (jiami.validateSign("mysign.bat")) {
System.out.println("Success!");
} else {
System.out.println("Fail!");
}
}
}
