这篇文章主要介绍了Java中RSA加密解密的实现方法,结合具体实例形式分析了java实现RSA加密解密算法的具体步骤与相关操作技巧,并附带了关于RSA算法密钥长度/密文长度/明文长度的参考说明,需要的朋友可以参考下
本文实例讲述了Java中RSA加密解密的实现方法。分享给大家供大家参考，具体如下：
public static void main(String[] args) throws Exception { // TODO Auto-generated method stub HashMap map = RSAUtils.getKeys(); //生成公钥和私钥 RSAPublicKey publicKey = (RSAPublicKey) map.get("public"); RSAPrivateKey privateKey = (RSAPrivateKey) map.get("private"); //模 String modulus = publicKey.getModulus().toString(); //公钥指数 String public_exponent = publicKey.getPublicExponent().toString(); //私钥指数 String private_exponent = privateKey.getPrivateExponent().toString(); //明文 String ming = "123456789"; //使用模和指数生成公钥和私钥 RSAPublicKey pubKey = RSAUtils.getPublicKey(modulus, public_exponent); RSAPrivateKey priKey = RSAUtils.getPrivateKey(modulus, private_exponent); //加密后的密文 String mi = RSAUtils.encryptByPublicKey(ming, pubKey); System.err.println(mi); //解密后的明文 ming = RSAUtils.decryptByPrivateKey(mi, priKey); System.err.println(ming); } RSAUtils.Java
package yyy.test.rsa; import java.math.BigInteger; import java.security.KeyFactory; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.NoSuchAlgorithmException; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.RSAPrivateKeySpec; import java.security.spec.RSAPublicKeySpec; import java.util.HashMap; import javax.crypto.Cipher; public class RSAUtils { /** * 生成公钥和私钥 * @throws NoSuchAlgorithmException * */ public static HashMap getKeys() throws NoSuchAlgorithmException{ HashMap map = new HashMap(); KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA"); keyPairGen.initialize(1024); KeyPair keyPair = keyPairGen.generateKeyPair(); RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); map.put("public", publicKey); map.put("private", privateKey); return map; } /** * 使用模和指数生成RSA公钥 * 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA * /None/NoPadding】 * * @param modulus * 模 * @param exponent * 指数 * @return */ public static RSAPublicKey getPublicKey(String modulus, String exponent) { try { BigInteger b1 = new BigInteger(modulus); BigInteger b2 = new BigInteger(exponent); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2); return (RSAPublicKey) keyFactory.generatePublic(keySpec); } catch (Exception e) { e.printStackTrace(); return null; } } /** * 使用模和指数生成RSA私钥 * 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA * /None/NoPadding】 * * @param modulus * 模 * @param exponent * 指数 * @return */ public static RSAPrivateKey getPrivateKey(String modulus, String exponent) { try { BigInteger b1 = new BigInteger(modulus); BigInteger b2 = new BigInteger(exponent); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(b1, b2); return (RSAPrivateKey) keyFactory.generatePrivate(keySpec); } catch (Exception e) { e.printStackTrace(); return null; } } /** * 公钥加密 * * @param data * @param publicKey * @return * @throws Exception */ public static String encryptByPublicKey(String data, RSAPublicKey publicKey) throws Exception { Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, publicKey); // 模长 int key_len = publicKey.getModulus().bitLength() / 8; // 加密数据长度 <= 模长-11 String[] datas = splitString(data, key_len - 11); String mi = ""; //如果明文长度大于模长-11则要分组加密 for (String s : datas) { mi += bcd2Str(cipher.doFinal(s.getBytes())); } return mi; } /** * 私钥解密 * * @param data * @param privateKey * @return * @throws Exception */ public static String decryptByPrivateKey(String data, RSAPrivateKey privateKey) throws Exception { Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.DECRYPT_MODE, privateKey); //模长 int key_len = privateKey.getModulus().bitLength() / 8; byte[] bytes = data.getBytes(); byte[] bcd = ASCII_To_BCD(bytes, bytes.length); System.err.println(bcd.length); //如果密文长度大于模长则要分组解密 String ming = ""; byte[][] arrays = splitArray(bcd, key_len); for(byte[] arr : arrays){ ming += new String(cipher.doFinal(arr)); } return ming; } /** * ASCII码转BCD码 * */ public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) { byte[] bcd = new byte[asc_len / 2]; int j = 0; for (int i = 0; i <(asc_len + 1) / 2; i++) { bcd[i] = asc_to_bcd(ascii[j++]); bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4)); } return bcd; } public static byte asc_to_bcd(byte asc) { byte bcd; if ((asc >= '0') && (asc <= '9')) bcd = (byte) (asc - '0'); else if ((asc >= 'A') && (asc <= 'F')) bcd = (byte) (asc - 'A' + 10); else if ((asc >= 'a') && (asc <= 'f')) bcd = (byte) (asc - 'a' + 10); else bcd = (byte) (asc - 48); return bcd; } /** * BCD转字符串 */ public static String bcd2Str(byte[] bytes) { char t以上就是Java中RSA加密解密的实现方法分析的详细内容，更多请关注0133技术站其它相关文章！
