Java Tutorial/Security/RSA algorithm

Материал из Java эксперт
Перейти к: навигация, поиск

An example of using RSA to encrypt a single asymmetric key.

   <source lang="java">

import java.security.Key; import java.security.KeyPair; import java.security.KeyPairGenerator; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.spec.SecretKeySpec; public class MainClass { 

 public static void main(String[] args) throws Exception {
   KeyGenerator keyGenerator = KeyGenerator.getInstance("Blowfish");
   keyGenerator.init(128);
   Key blowfishKey = keyGenerator.generateKey();
   KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
   keyPairGenerator.initialize(1024);
   KeyPair keyPair = keyPairGenerator.genKeyPair();
   Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
   cipher.init(Cipher.ENCRYPT_MODE, keyPair.getPublic());
   byte[] blowfishKeyBytes = blowfishKey.getEncoded();
   System.out.println(new String(blowfishKeyBytes));
   byte[] cipherText = cipher.doFinal(blowfishKeyBytes);
   System.out.println(new String(cipherText));
   cipher.init(Cipher.DECRYPT_MODE, keyPair.getPrivate());
   byte[] decryptedKeyBytes = cipher.doFinal(cipherText);
   System.out.println(new String(decryptedKeyBytes));
   SecretKey newBlowfishKey = new SecretKeySpec(decryptedKeyBytes, "Blowfish");
 }

}</source>





An RSA sample application

   <source lang="java">

import java.math.BigInteger; import java.security.KeyFactory; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.spec.RSAKeyGenParameterSpec; import java.security.spec.RSAPublicKeySpec; public class MainClass { 

 public static void main(String[] args) throws Exception {
   int eValue = 79;
   int bitLength = 1024; // KeySize
   BigInteger e = e = new BigInteger(Integer.toString(eValue));
   KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
   kpg.initialize(bitLength);
   KeyPair kp = kpg.generateKeyPair();
   KeyFactory kfactory = KeyFactory.getInstance("RSA");
   RSAPublicKeySpec kspec = (RSAPublicKeySpec) kfactory.getKeySpec(kp.getPublic(),
       RSAPublicKeySpec.class);
   kpg = KeyPairGenerator.getInstance("RSA", "SunRsaSign");
   e = new BigInteger(Integer.toString(eValue));
   System.out.println("e =" + e);
   RSAKeyGenParameterSpec param = new RSAKeyGenParameterSpec(bitLength, e);
   kpg.initialize(param);
   kp = kpg.generateKeyPair();
   kfactory = KeyFactory.getInstance("RSA", "SunRsaSign");
   kspec = (RSAPublicKeySpec) kfactory.getKeySpec(kp.getPublic(),RSAPublicKeySpec.class);
 }

}</source>





Basic RSA example.

   <source lang="java">

import java.math.BigInteger; import java.security.KeyFactory; import java.security.Security; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.RSAPrivateKeySpec; import java.security.spec.RSAPublicKeySpec; import javax.crypto.Cipher; public class MainClass { 

 public static void main(String[] args) throws Exception {
   Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
   byte[] input = new byte[] { (byte) 0xbe, (byte) 0xef };
   Cipher cipher = Cipher.getInstance("RSA/None/NoPadding", "BC");
   KeyFactory keyFactory = KeyFactory.getInstance("RSA", "BC");
   RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(new BigInteger(
       "12345678", 16), new BigInteger("11", 16));
   RSAPrivateKeySpec privKeySpec = new RSAPrivateKeySpec(new BigInteger(
       "12345678", 16), new BigInteger("12345678",
       16));
   RSAPublicKey pubKey = (RSAPublicKey) keyFactory.generatePublic(pubKeySpec);
   RSAPrivateKey privKey = (RSAPrivateKey) keyFactory.generatePrivate(privKeySpec);
   cipher.init(Cipher.ENCRYPT_MODE, pubKey);
   byte[] cipherText = cipher.doFinal(input);
   System.out.println("cipher: " + new String(cipherText));
   cipher.init(Cipher.DECRYPT_MODE, privKey);
   byte[] plainText = cipher.doFinal(cipherText);
   System.out.println("plain : " + new String(plainText));
 }

}</source>





Creates a it RSA key pair and stores it to the filesystem as two files

   <source lang="java">

import java.io.ByteArrayOutputStream; import java.io.FileOutputStream; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.SecureRandom; import javax.crypto.Cipher; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.PBEKeySpec; import javax.crypto.spec.PBEParameterSpec; public class MainClass { 

 public static void main(String[] args) throws Exception {
   String password = "password";
   KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
   keyPairGenerator.initialize(1024);
   KeyPair keyPair = keyPairGenerator.genKeyPair();
   String publicKeyFilename = "public";
   byte[] publicKeyBytes = keyPair.getPublic().getEncoded();
   FileOutputStream fos = new FileOutputStream(publicKeyFilename);
   fos.write(publicKeyBytes);
   fos.close();
   String privateKeyFilename = "privateKeyFilename";
   byte[] privateKeyBytes = keyPair.getPrivate().getEncoded();
   byte[] encryptedPrivateKeyBytes = passwordEncrypt(password.toCharArray(), privateKeyBytes);
   fos = new FileOutputStream(privateKeyFilename);
   fos.write(encryptedPrivateKeyBytes);
   fos.close();
 }
 private static byte[] passwordEncrypt(char[] password, byte[] plaintext) throws Exception {
   int MD5_ITERATIONS = 1000;
   byte[] salt = new byte[8];
   SecureRandom random = new SecureRandom();
   random.nextBytes(salt);
   PBEKeySpec keySpec = new PBEKeySpec(password);
   SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithSHAAndTwofish-CBC");
   SecretKey key = keyFactory.generateSecret(keySpec);
   PBEParameterSpec paramSpec = new PBEParameterSpec(salt, MD5_ITERATIONS);
   Cipher cipher = Cipher.getInstance("PBEWithSHAAndTwofish-CBC");
   cipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
   byte[] ciphertext = cipher.doFinal(plaintext);
   ByteArrayOutputStream baos = new ByteArrayOutputStream();
   baos.write(salt);
   baos.write(ciphertext);
   return baos.toByteArray();
 }

}</source>





RSA example with OAEP Padding and random key generation.

   <source lang="java">

import java.security.Key; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.SecureRandom; import java.security.Security; import javax.crypto.Cipher; public class MainClass { 

 public static void main(String[] args) throws Exception {
   Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
   byte[] input = "abc".getBytes();
   Cipher cipher = Cipher.getInstance("RSA/None/OAEPWithSHA1AndMGF1Padding", "BC");
   SecureRandom random = new SecureRandom();
   KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA", "BC");
   generator.initialize(386, random);
   KeyPair pair = generator.generateKeyPair();
   Key pubKey = pair.getPublic();
   Key privKey = pair.getPrivate();
   cipher.init(Cipher.ENCRYPT_MODE, pubKey, random);
   byte[] cipherText = cipher.doFinal(input);
   System.out.println("cipher: " + new String(cipherText));
   cipher.init(Cipher.DECRYPT_MODE, privKey);
   byte[] plainText = cipher.doFinal(cipherText);
   System.out.println("plain : " + new String(plainText));
 }

}</source>





RSA example with PKCS #1 Padding.

   <source lang="java">

import java.security.Key; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.SecureRandom; import java.security.Security; import javax.crypto.Cipher; public class MainClass { 

 public static void main(String[] args) throws Exception {
   Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
   byte[] input = "abc".getBytes();
   Cipher cipher = Cipher.getInstance("RSA/None/PKCS1Padding", "BC");
   SecureRandom random = new SecureRandom();
   KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA", "BC");
   generator.initialize(256, random);
   KeyPair pair = generator.generateKeyPair();
   Key pubKey = pair.getPublic();
   Key privKey = pair.getPrivate();
   cipher.init(Cipher.ENCRYPT_MODE, pubKey, random);
   byte[] cipherText = cipher.doFinal(input);
   System.out.println("cipher: " + new String(cipherText));
   cipher.init(Cipher.DECRYPT_MODE, privKey);
   byte[] plainText = cipher.doFinal(cipherText);
   System.out.println("plain : " + new String(plainText));
 }

}</source>





RSA example with random key generation.

   <source lang="java">

import java.security.Key; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.SecureRandom; import java.security.Security; import javax.crypto.Cipher; public class MainClass { 

 public static void main(String[] args) throws Exception {
   Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
   byte[] input = "aa".getBytes();
   Cipher cipher = Cipher.getInstance("RSA/None/NoPadding", "BC");
   SecureRandom random = new SecureRandom();
   KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA", "BC");
   generator.initialize(256, random);
   KeyPair pair = generator.generateKeyPair();
   Key pubKey = pair.getPublic();
   Key privKey = pair.getPrivate();
   cipher.init(Cipher.ENCRYPT_MODE, pubKey, random);
   byte[] cipherText = cipher.doFinal(input);
   System.out.println("cipher: " + new String(cipherText));
   cipher.init(Cipher.DECRYPT_MODE, privKey);
   byte[] plainText = cipher.doFinal(cipherText);
   System.out.println("plain : " + new String(plainText));
 }

}</source>





RSA Signature Generation

   <source lang="java">

import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.SecureRandom; import java.security.Security; import java.security.Signature; public class MainClass { 

 public static void main(String[] args) throws Exception {
   Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
   KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA", "BC");
   keyGen.initialize(512, new SecureRandom());
   KeyPair keyPair = keyGen.generateKeyPair();
   Signature signature = Signature.getInstance("SHA1withRSA", "BC");
   signature.initSign(keyPair.getPrivate(), new SecureRandom());
   byte[] message = "abc".getBytes();
   signature.update(message);
   byte[] sigBytes = signature.sign();
   signature.initVerify(keyPair.getPublic());
   signature.update(message);
   System.out.println(signature.verify(sigBytes));
 }

}</source>





Simple Digital Signature Example

   <source lang="java">

import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.Signature; import sun.misc.BASE64Encoder; public class MainClass { 

 public static void main(String[] args) throws Exception {
   KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
   kpg.initialize(1024);
   KeyPair keyPair = kpg.genKeyPair();
   byte[] data = "test".getBytes("UTF8");
   Signature sig = Signature.getInstance("MD5WithRSA");
   sig.initSign(keyPair.getPrivate());
   sig.update(data);
   byte[] signatureBytes = sig.sign();
   System.out.println("Singature:" + new BASE64Encoder().encode(signatureBytes));
   sig.initVerify(keyPair.getPublic());
   sig.update(data);
   System.out.println(sig.verify(signatureBytes));
 }

}</source>


Источник — «http://jexp.ru/index.php?title=Java_Tutorial/Security/RSA_algorithm&oldid=4328»