使用java实现RSA

我在java中实现了RSA我遇到了一个代码，下面给出的代码在解密明文后以数字forms显示明文，但我想用简单的英文输入它。 我不想使用java api。

TestRsa.Java

import java.io.IOException; import java.math.BigInteger; import java.util.Random; public class TestRsa { private BigInteger p, q; private BigInteger n; private BigInteger PhiN; private BigInteger e, d; public TestRsa() { initialize(); } public void initialize() { int SIZE = 512; /* Step 1: Select two large prime numbers. Say p and q. */ p = new BigInteger(SIZE, 15, new Random()); q = new BigInteger(SIZE, 15, new Random()); /* Step 2: Calculate n = pq */ n = p.multiply(q); /* Step 3: Calculate ø(n) = (p - 1).(q - 1) */ PhiN = p.subtract(BigInteger.valueOf(1)); PhiN = PhiN.multiply(q.subtract(BigInteger.valueOf(1))); /* Step 4: Find e such that gcd(e, ø(n)) = 1 ; 1 < e < ø(n) */ do { e = new BigInteger(2 * SIZE, new Random()); } while ((e.compareTo(PhiN) != 1) || (e.gcd(PhiN).compareTo(BigInteger.valueOf(1)) != 0)); /* Step 5: Calculate d such that ed = 1 (mod ø(n)) */ d = e.modInverse(PhiN); } public BigInteger encrypt(BigInteger plaintext) { return plaintext.modPow(e, n); } public BigInteger decrypt(BigInteger ciphertext) { return ciphertext.modPow(d, n); } public static void main(String[] args) throws IOException { TestRsa app = new TestRsa(); int plaintext; System.out.println("Enter any character : "); plaintext = System.in.read(); BigInteger bplaintext, bciphertext; bplaintext = BigInteger.valueOf((long) plaintext); bciphertext = app.encrypt(bplaintext); System.out.println("Plaintext : " + bplaintext.toString()); System.out.println("Ciphertext : " + bciphertext.toString()); bplaintext = app.decrypt(bciphertext); System.out.println("After Decryption Plaintext : " + bplaintext.toString()); } } 

Answer 1

我的RSA课程：

 package com.infovale.cripto; import java.io.UnsupportedEncodingException; import java.math.BigInteger; import java.security.InvalidKeyException; import java.security.KeyFactory; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.NoSuchAlgorithmException; import java.security.PrivateKey; import java.security.PublicKey; import java.security.spec.InvalidKeySpecException; import java.security.spec.PKCS8EncodedKeySpec; import java.util.Arrays; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeException; import javax.crypto.NoSuchPaddingException; public class RSA { static String kPublic = ""; static String kPrivate = ""; public RSA() { } public String Encrypt(String plain) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException { String encrypted; byte[] encryptedBytes; KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA"); kpg.initialize(1024); KeyPair kp = kpg.genKeyPair(); PublicKey publicKey = kp.getPublic(); PrivateKey privateKey = kp.getPrivate(); byte[] publicKeyBytes = publicKey.getEncoded(); byte[] privateKeyBytes = privateKey.getEncoded(); kPublic = bytesToString(publicKeyBytes); kPrivate = bytesToString(privateKeyBytes); Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, publicKey); encryptedBytes = cipher.doFinal(plain.getBytes()); encrypted = bytesToString(encryptedBytes); return encrypted; } public String Decrypt(String result) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException { byte[] decryptedBytes; byte[] byteKeyPrivate = stringToBytes(kPrivate); KeyFactory kf = KeyFactory.getInstance("RSA"); PrivateKey privateKey = null; try { privateKey = kf.generatePrivate(new PKCS8EncodedKeySpec(byteKeyPrivate)); } catch (InvalidKeySpecException e) { e.printStackTrace(); } String decrypted; Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.DECRYPT_MODE, privateKey); decryptedBytes = cipher.doFinal(stringToBytes(result)); decrypted = new String(decryptedBytes); return decrypted; } public String bytesToString(byte[] b) { byte[] b2 = new byte[b.length + 1]; b2[0] = 1; System.arraycopy(b, 0, b2, 1, b.length); return new BigInteger(b2).toString(36); } public byte[] stringToBytes(String s) { byte[] b2 = new BigInteger(s, 36).toByteArray(); return Arrays.copyOfRange(b2, 1, b2.length); } } 

Answer 2

试试这些：

 System.out.println("Plaintext : " + new String(bplaintext.toByteArray() ) ); System.out.println("Ciphertext : " + new String(bciphertext.toByteArray() ) ); bplaintext = app.decrypt(bciphertext); System.out.println("After Decryption Plaintext : " + new String(bplaintext.toByteArray() ) );