java非對稱加密的原始碼(rsa)
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java非對稱加密的原始碼rsa有哪些基本知識,下面yjbys小編為大家一一講解!
鑑於rsa加密的重要性和相關原始碼的匱乏,經過整理特此貼出。需要下載。
import er;
import rity.*;
import ublicKeySpec;
import rivateKeySpec;
import lidKeySpecException;
import rivateKey;
import ublicKey;
import .*;
import nteger;
/**
* RSA 工具類。提供加密,解密,生成金鑰對等方法。
* 需要到下載。
*
*/
public class RSAUtil {
/**
* 生成金鑰對
* @return KeyPair
* @throws EncryptException
*/
public static KeyPair generateKeyPair() throws EncryptException {
try {
KeyPairGenerator keyPairGen = nstance("RSA",
new cyCastleProvider());
final int KEY_SIZE = 1024;//沒什麼好說的'了,這個值關係到塊加密的大小,可以更改,但是不要太大,否則效率會低
ialize(KEY_SIZE, new SecureRandom());
KeyPair keyPair = eyPair();
return keyPair;
} catch (Exception e) {
throw new EncryptException(essage());
}
}
/**
* 生成公鑰
* @param modulus
* @param publicExponent
* @return RSAPublicKey
* @throws EncryptException
*/
public static RSAPublicKey generateRSAPublicKey(byte[] modulus, byte[] publicExponent) throws EncryptException {
KeyFactory keyFac = null;
try {
keyFac = nstance("RSA", new cyCastleProvider());
} catch (NoSuchAlgorithmException ex) {
throw new EncryptException(essage());
}
RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(new BigInteger(modulus), new BigInteger(publicExponent));
try {
return (RSAPublicKey) ratePublic(pubKeySpec);
} catch (InvalidKeySpecException ex) {
throw new EncryptException(essage());
}
}
/**
* 生成私鑰
* @param modulus
* @param privateExponent
* @return RSAPrivateKey
* @throws EncryptException
*/
public static RSAPrivateKey generateRSAPrivateKey(byte[] modulus, byte[] privateExponent) throws EncryptException {
KeyFactory keyFac = null;
try {
keyFac = nstance("RSA", new cyCastleProvider());
} catch (NoSuchAlgorithmException ex) {
throw new EncryptException(essage());
}
RSAPrivateKeySpec priKeySpec = new RSAPrivateKeySpec(new BigInteger(modulus), new BigInteger(privateExponent));
try {
return (RSAPrivateKey) ratePrivate(priKeySpec);
} catch (InvalidKeySpecException ex) {
throw new EncryptException(essage());
}
}
/**
* 加密
* @param key 加密的金鑰
* @param data 待加密的明文資料
* @return 加密後的資料
* @throws EncryptException
*/
public static byte[] encrypt(Key key, byte[] data) throws EncryptException {
try {
Cipher cipher = nstance("RSA", new cyCastleProvider());
(YPT_MODE, key);
int blockSize = lockSize();//獲得加密塊大小,如:加密前資料為128個byte,而key_size=1024 加密塊大小為127 byte,加密後為128個byte;因此共有2個加密塊,第一個127 byte第二個為1個byte
int outputSize = utputSize(th);//獲得加密塊加密後塊大小
int leavedSize = th % blockSize;
int blocksSize = leavedSize != 0 ? th / blockSize + 1 : th / blockSize;
byte[] raw = new byte[outputSize * blocksSize];
int i = 0;
while (th - i * blockSize > 0) {
if (th - i * blockSize > blockSize)
nal(data, i * blockSize, blockSize, raw, i * outputSize);
else
nal(data, i * blockSize, th - i * blockSize, raw, i * outputSize);
//這裡面doUpdate方法不可用,檢視原始碼後發現每次doUpdate後並沒有什麼實際動作除了把byte[]放到ByteArrayOutputStream中,而最後doFinal的時候才將所有的byte[]進行加密,可是到了此時加密塊大小很可能已經超出了OutputSize所以只好用dofinal方法。
i++;
}
return raw;
} catch (Exception e) {
throw new EncryptException(essage());
}
}
/**
* 解密
* @param key 解密的金鑰
* @param raw 已經加密的資料
* @return 解密後的明文
* @throws EncryptException
*/
public static byte[] decrypt(Key key, byte[] raw) throws EncryptException {
try {
Cipher cipher = nstance("RSA", new cyCastleProvider());
(YPT_MODE, key);
int blockSize = lockSize();
ByteArrayOutputStream bout = new ByteArrayOutputStream(64);
int j = 0;
while (th - j * blockSize > 0) {
e(nal(raw, j * blockSize, blockSize));
j++;
}
return teArray();
} catch (Exception e) {
throw new EncryptException(essage());
}
}
/**
*
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
File file = new File("");
FileInputStream in = new FileInputStream(file);
ByteArrayOutputStream bout = new ByteArrayOutputStream();
byte[] tmpbuf = new byte[1024];
int count = 0;
while ((count = (tmpbuf)) != -1) {
e(tmpbuf, 0, count);
tmpbuf = new byte[1024];
}
e();
byte[] orgData = teArray();
KeyPair keyPair = rateKeyPair();
RSAPublicKey pubKey = (RSAPublicKey) ublic();
RSAPrivateKey priKey = (RSAPrivateKey) rivate();
byte[] pubModBytes = odulus()teArray();
byte[] pubPubExpBytes = ublicExponent()teArray();
byte[] priModBytes = odulus()teArray();
byte[] priPriExpBytes = rivateExponent()teArray();
RSAPublicKey recoveryPubKey = rateRSAPublicKey(pubModBytes,pubPubExpBytes);
RSAPrivateKey recoveryPriKey = rateRSAPrivateKey(priModBytes,priPriExpBytes);
byte[] raw = ypt(priKey, orgData);
file = new File("encrypt_");
OutputStream out = new FileOutputStream(file);
e(raw);
e();
byte[] data = ypt(recoveryPubKey, raw);
file = new File("decrypt_");
out = new FileOutputStream(file);
e(data);
h();
e();
}
}
加密可以用公鑰,解密用私鑰;或者加密用私鑰。通常非對稱加密是非常消耗資源的,因此可以對大資料用對稱加密如:des(具體程式碼可以看我以前發的貼子),而對其對稱金鑰進行非對稱加密,這樣既保證了資料的安全,還能保證效率。
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