2008年02月20日 08:17:45
java实现RSA加密解密算法
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实现一对密钥对整个项目所有加密解密文件都适用的方法,采用先生成一对密钥.保存到xml文件中,以后获得私匙和公钥只需要从xml文件中取得就可以了. /** * 把成生的一对密钥保存到RSAKey.xml文件中 */ public void saveRSAKey() { try { SecureRandom sr = new SecureRandom(); KeyPairGenerator kg = KeyPairGenerator.getInstance("RSA", new org.bouncycastle.jce.provider.BouncyCastleProvider()); //注意密钥大小最好为1024,否则解密会有乱码情况. kg.initialize(1024, sr); FileOutputStream fos = new FileOutputStream("C:/RSAKey.xml"); ObjectOutputStream oos = new ObjectOutputStream(fos); //生成密钥 oos.writeObject(kg.generateKeyPair()); oos.close(); } catch (Exception e) { e.printStackTrace(); } } 注意:需要从http://www.bouncycastle.org下载bcprov-jdk14-137.jar包. 获取密钥方法如下: /** * 获得RSA加密的密钥。 * @return KeyPair返回对称密钥 */ public static KeyPair getKeyPair() { //产生新密钥对 KeyPair kp; try { String fileName = "conf/RASKey.xml"; InputStream is = FileUtils.class.getClassLoader() .getResourceAsStream(fileName); ObjectInputStream oos = new ObjectInputStream(is); kp = (KeyPair) oos.readObject(); oos.close(); } catch (Exception e) { throw new EprasRuntimeException("读取加密文件出错.", e); } return kp; } 文件采用RSA算法加密文件 /** * 文件file进行加密并保存目标文件destFile中 * @param srcFileName * 要加密的文件 如c:/test/srcFile.txt * @param destFileName * 加密后存放的文件名 如c:/加密后文件.txt */ public static void encryptFile(String srcFileName, String destFileName) throws Exception { OutputStream outputWriter = null; InputStream inputReader = null; try { Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding", new org.bouncycastle.jce.provider.BouncyCastleProvider()); byte[] buf = new byte[100]; int bufl; cipher.init(Cipher.ENCRYPT_MODE, getKeyPair().getPublic()); outputWriter = new FileOutputStream(destFileName); inputReader = new FileInputStream(srcFileName); while ((bufl = inputReader.read(buf)) != -1) { byte[] encText = null; byte[] newArr = null; if (buf.length == bufl) { newArr = buf; } else { newArr = new byte[bufl]; for (int i = 0; i < bufl; i++) { newArr = (byte) buf; } } encText = cipher.doFinal(newArr); outputWriter.write(encText); } outputWriter.flush(); } catch (Exception e) { throw e; } finally { try { if (outputWriter != null) { outputWriter.close(); } if (inputReader != null) { inputReader.close(); } } catch (Exception e) { } } } 文件采用RSA算法解密文件 /** * 文件file进行加密并保存目标文件destFile中 * @param srcFileName * 已加密的文件 如c:/加密后文件.txt * @param destFileName * 解密后存放的文件名 如c:/ test/解密后文件.txt */ public static void decryptFile(String srcFileName, String destFileName) throws Exception { OutputStream outputWriter = null; InputStream inputReader = null; try { Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding", new org.bouncycastle.jce.provider.BouncyCastleProvider()); byte[] buf = new byte[128]; int bufl; cipher.init(Cipher.DECRYPT_MODE, getKeyPair().getPrivate()); outputWriter = new FileOutputStream(destFileName); inputReader = new FileInputStream(srcFileName); while ((bufl = inputReader.read(buf)) != -1) { byte[] encText = null; byte[] newArr = null; if (buf.length == bufl) { newArr = buf; } else { newArr = new byte[bufl]; for (int i = 0; i < bufl; i++) { newArr = (byte) buf; } } encText = cipher.doFinal(newArr); outputWriter.write(encText); } outputWriter.flush(); } catch (Exception e) { throw e; } finally { try { if (outputWriter != null) { outputWriter.close(); } if (inputReader != null) { inputReader.close(); } } catch (Exception e) { } } } 如果对于大文件加密采用RSA算法执行速度要非常非常慢; |
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