Java如何实现对称加密
代码大师麦克劳瑞 人气:0Java对称加密
Cipher实现对称加密
public class EncrypDES { // 字符串默认键值 private static String strDefaultKey = "asdasdasdasdzcxczxczx"; //加密工具 private Cipher encryptCipher = null; // 解密工具 private Cipher decryptCipher = null; /** * 默认构造方法,使用默认密钥 */ public EncrypDES() throws Exception { this(strDefaultKey); } /** * 指定密钥构造方法 * @param strKey 指定的密钥 * @throws Exception */ public EncrypDES(String strKey) throws Exception { // Security.addProvider(new com.sun.crypto.provider.SunJCE()); Key key = getKey(strKey.getBytes()); encryptCipher = Cipher.getInstance("DES"); encryptCipher.init(Cipher.ENCRYPT_MODE, key); decryptCipher = Cipher.getInstance("DES"); decryptCipher.init(Cipher.DECRYPT_MODE, key); } /** * 将byte数组转换为表示16进制值的字符串, 如:byte[]{8,18}转换为:0813,和public static byte[] * * hexStr2ByteArr(String strIn) 互为可逆的转换过程 * * @param arrB 需要转换的byte数组 * @return 转换后的字符串 * @throws Exception 本方法不处理任何异常,所有异常全部抛出 */ public static String byteArr2HexStr(byte[] arrB) throws Exception { int iLen = arrB.length; // 每个byte用2个字符才能表示,所以字符串的长度是数组长度的2倍 StringBuffer sb = new StringBuffer(iLen * 2); for (int i = 0; i < iLen; i++) { int intTmp = arrB[i]; // 把负数转换为正数 while (intTmp < 0) { intTmp = intTmp + 256; } // 小于0F的数需要在前面补0 if (intTmp < 16) { sb.append("0"); } sb.append(Integer.toString(intTmp, 16)); } return sb.toString(); } /** * 将表示16进制值的字符串转换为byte数组,和public static String byteArr2HexStr(byte[] arrB) * 互为可逆的转换过程 * @param strIn 需要转换的字符串 * @return 转换后的byte数组 */ public static byte[] hexStr2ByteArr(String strIn) throws Exception { byte[] arrB = strIn.getBytes(); int iLen = arrB.length; // 两个字符表示一个字节,所以字节数组长度是字符串长度除以2 byte[] arrOut = new byte[iLen / 2]; for (int i = 0; i < iLen; i = i + 2) { String strTmp = new String(arrB, i, 2); arrOut[i / 2] = (byte) Integer.parseInt(strTmp, 16); } return arrOut; } /** * * 加密字节数组 * @param arrB 需加密的字节数组 * @return 加密后的字节数组 */ public byte[] encrypt(byte[] arrB) throws Exception { return encryptCipher.doFinal(arrB); } /** * 加密字符串 * @param strIn 需加密的字符串 * @return 加密后的字符串 */ public String encrypt(String strIn) throws Exception { return byteArr2HexStr(encrypt(strIn.getBytes())); } /** * 解密字节数组 * @param arrB 需解密的字节数组 * @return 解密后的字节数组 */ public byte[] decrypt(byte[] arrB) throws Exception { return decryptCipher.doFinal(arrB); } /** * 解密字符串 * @param strIn 需解密的字符串 * @return 解密后的字符串 */ public String decrypt(String strIn) throws Exception { return new String(decrypt(hexStr2ByteArr(strIn))); } /** * 从指定字符串生成密钥,密钥所需的字节数组长度为8位 不足8位时后面补0,超出8位只取前8位 * @param arrBTmp 构成该字符串的字节数组 * @return 生成的密钥 */ private Key getKey(byte[] arrBTmp) throws Exception { // 创建一个空的8位字节数组(默认值为0) byte[] arrB = new byte[8]; // 将原始字节数组转换为8位 for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) { arrB[i] = arrBTmp[i]; } // 生成密钥 Key key = new javax.crypto.spec.SecretKeySpec(arrB, "DES"); return key; } public static void main(String[] args) { try { String msg1 = "hello Cipher"; EncrypDES des1 = new EncrypDES();// 使用默认密钥 System.out.println("加密前的字符:" + msg1); System.out.println("加密后的字符:" + des1.encrypt(msg1)); System.out.println("解密后的字符:" + des1.decrypt(des1.encrypt(msg1))); } catch (Exception e) { e.printStackTrace(); } } }
运行main方法后得出结果是:
base64加解密
public class EncryptUtil { /** * BASE64解密 * @throws Exception */ public static byte[] decryptBASE64(String key) throws Exception { return (new BASE64Decoder()).decodeBuffer(key); } /** * BASE64加密 */ public static String encryptBASE64(byte[] key) throws Exception { return (new BASE64Encoder()).encodeBuffer(key); } public static void main(String[] args) throws Exception { String ss = "9899b43bbde94982b71efad47eed9f82-234234324-123456"; String encryptBASE64 = encryptBASE64(ss.getBytes()); System.out.println(encryptBASE64); byte[] bytes = decryptBASE64(encryptBASE64); System.out.println(new String(bytes)); } }
运行main方法得出的:
对称加密与非对称加密
加密方式大致分为两种,对称加密和非对称加密。对称加密是最快速、最简单的一种加密方式,加密(encryption)与解密(decryption)用的是同样的密钥(secret key)。非对称加密为数据的加密与解密提供了一个非常安全的方法,它使用了一对密钥,公钥(public key)和私钥(private key)。私钥只能由一方安全保管,不能外泄,而公钥则可以发给任何请求它的人。因此安全性大大提高。
对称加密
所谓对称加密算法即:加密和解密使用相同密钥的算法。常见的有DES、3DES、AES、PBE等加密算法,这几种算法安全性依次是逐渐增强的。
DES加密
DES是一种对称加密算法,是一种非常简便的加密算法,但是密钥长度比较短。DES加密算法出自IBM的研究,后来被美国正式采用,之后开始广泛流传,但是近些年使用越来越少,因为DES使用56位密钥,以现代计算能力,24小时内即可被破解。虽然如此,在某些简单应用中,我们还是可以使用DES加密算法.简单的DES加密算法实现:
import java.security.NoSuchAlgorithmException; import java.security.SecureRandom; import java.security.spec.InvalidKeySpecException; import java.util.logging.Level; import java.util.logging.Logger; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.SecretKeySpec; import org.apache.commons.codec.binary.Base64; public class DESUtil { private static final String KEY_ALGORITHM = "DES"; private static final String DEFAULT_CIPHER_ALGORITHM = "DES/ECB/PKCS5Padding";// 默认的加密算法 /** * DES 加密操作 * * @param content * 待加密内容 * @param key * 加密密钥 * @return 返回Base64转码后的加密数据 */ public static String encrypt(String content, String key) { try { Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);// 创建密码器 byte[] byteContent = content.getBytes("utf-8"); //初始化为加密模式的密码器 //方法一 //cipher.init(Cipher.DECRYPT_MODE, getSecretKey(key)); //方法二 cipher.init(Cipher.ENCRYPT_MODE, getSecretKeySpec(key)); byte[] result = cipher.doFinal(byteContent);// 加密 return Base64.encodeBase64String(result);// 通过Base64转码返回 } catch (Exception ex) { Logger.getLogger(DESUtil.class.getName()).log(Level.SEVERE, null, ex); } return null; } /** * DES 解密操作 * * @param content * @param key * @return */ public static String decrypt(String content, String key) { try { // 实例化 Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM); // 使用密钥初始化,设置为解密模式 //方法一 //cipher.init(Cipher.DECRYPT_MODE, getSecretKey(key)); //方法二 cipher.init(Cipher.DECRYPT_MODE, getSecretKeySpec(key)); // 执行操作 byte[] result = cipher.doFinal(Base64.decodeBase64(content)); return new String(result, "utf-8"); } catch (Exception ex) { Logger.getLogger(DESUtil.class.getName()).log(Level.SEVERE, null, ex); } return null; } /** * 生成加密秘钥 * * @return */ private static SecretKey getSecretKey(final String key) { try { SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(), KEY_ALGORITHM); SecretKey sk = SecretKeyFactory.getInstance(KEY_ALGORITHM).generateSecret(keySpec); return sk; } catch (InvalidKeySpecException e) { e.printStackTrace(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } return null; } /** * 生成加密秘钥 * * @return */ private static SecretKeySpec getSecretKeySpec(final String key) { // 返回生成指定算法密钥生成器的 KeyGenerator 对象 KeyGenerator kg = null; try { kg = KeyGenerator.getInstance(KEY_ALGORITHM); // DES 要求密钥长度为 56 kg.init(56, new SecureRandom(key.getBytes())); // 生成一个密钥 SecretKey secretKey = kg.generateKey(); return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);// 转换为DES专用密钥 } catch (NoSuchAlgorithmException ex) { Logger.getLogger(DESUtil.class.getName()).log(Level.SEVERE, null, ex); } return null; } public static void main(String[] args) { String content = "hello,您好"; String key = "sde@5f98H*^hsff%dfs$r344&df8543*er"; System.out.println("content:" + content); String s1 = DESUtil.encrypt(content, key); System.out.println("s1:" + s1); System.out.println("s2:" + DESUtil.decrypt(s1, key)); } }
3DES加密
3DES是一种对称加密算法,在 DES 的基础上,使用三重数据加密算法,对数据进行加密,它相当于是对每个数据块应用三次 DES 加密算法。由于计算机运算能力的增强,原版 DES 密码的密钥长度变得容易被暴力 破 解;3DES 即是设计用来提供一种相对简单的方法,即通过增加 DES 的密钥长度来避免类似的攻击,而不是设计一种全新的块密码算法这样来说,破解的概率就小了很多。缺点由于使用了三重数据加密算法,可能会比较耗性能。简单的3DES加密算法实现:
import java.security.NoSuchAlgorithmException; import java.security.SecureRandom; import java.security.spec.InvalidKeySpecException; import java.util.logging.Level; import java.util.logging.Logger; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.SecretKeySpec; import org.apache.commons.codec.binary.Base64; public class TripDESUtil { private static final String KEY_ALGORITHM = "DESede"; private static final String DEFAULT_CIPHER_ALGORITHM = "DESede/ECB/PKCS5Padding";// 默认的加密算法 /** * DESede 加密操作 * * @param content * 待加密内容 * @param key * 加密密钥 * @return 返回Base64转码后的加密数据 */ public static String encrypt(String content, String key) { try { Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);// 创建密码器 byte[] byteContent = content.getBytes("utf-8"); //初始化为加密模式的密码器 //方法一 //cipher.init(Cipher.DECRYPT_MODE, getSecretKey(key)); //方法二 cipher.init(Cipher.ENCRYPT_MODE, getSecretKeySpec(key)); byte[] result = cipher.doFinal(byteContent);// 加密 return Base64.encodeBase64String(result);// 通过Base64转码返回 } catch (Exception ex) { Logger.getLogger(TripDESUtil.class.getName()).log(Level.SEVERE, null, ex); } return null; } /** * DESede 解密操作 * * @param content * @param key * @return */ public static String decrypt(String content, String key) { try { // 实例化 Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM); // 使用密钥初始化,设置为解密模式 //方法一 //cipher.init(Cipher.DECRYPT_MODE, getSecretKey(key)); //方法二 cipher.init(Cipher.DECRYPT_MODE, getSecretKeySpec(key)); // 执行操作 byte[] result = cipher.doFinal(Base64.decodeBase64(content)); return new String(result, "utf-8"); } catch (Exception ex) { Logger.getLogger(TripDESUtil.class.getName()).log(Level.SEVERE, null, ex); } return null; } /** * 生成加密秘钥 * * @return */ private static SecretKey getSecretKey(final String key) { try { SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(), KEY_ALGORITHM); SecretKey sk = SecretKeyFactory.getInstance(KEY_ALGORITHM).generateSecret(keySpec); return sk; } catch (InvalidKeySpecException e) { e.printStackTrace(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } return null; } /** * 生成加密秘钥 * * @return */ private static SecretKeySpec getSecretKeySpec(final String key) { // 返回生成指定算法密钥生成器的 KeyGenerator 对象 KeyGenerator kg = null; try { kg = KeyGenerator.getInstance(KEY_ALGORITHM); // DESede kg.init(new SecureRandom(key.getBytes())); // 生成一个密钥 SecretKey secretKey = kg.generateKey(); return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);// 转换为DESede专用密钥 } catch (NoSuchAlgorithmException ex) { Logger.getLogger(TripDESUtil.class.getName()).log(Level.SEVERE, null, ex); } return null; } public static void main(String[] args) { String content = "hello,您好"; String key = "sde@5f98H*^hsff%dfs$r344&df8543*er"; System.out.println("content:" + content); String s1 = TripDESUtil.encrypt(content, key); System.out.println("s1:" + s1); System.out.println("s2:" + TripDESUtil.decrypt(s1, key)); } }
AES加密
AES是一种对称加密算法,在 DES 的基础上,使用三重数据加密算法,对数据进行加密,它相当于是对每个数据块应用三次 DES 加密算法。由于计算机运算能力的增强,原版 DES 密码的密钥长度变得容易被暴力 破解;3DES 即是设计用来提供一种相对简单的方法,即通过增加 DES 的密钥长度来避免类似的攻击,而不是设计一种全新的块密码算法这样来说,破解的概率就小了很多。缺点由于使用了三重数据加密算法,可能会比较耗性能。简单的AES加密算法实现:
import java.security.NoSuchAlgorithmException; import java.security.SecureRandom; import java.security.spec.InvalidKeySpecException; import java.util.logging.Level; import java.util.logging.Logger; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.SecretKeySpec; import org.apache.commons.codec.binary.Base64; public class AESUtil { private static final String KEY_ALGORITHM = "AES"; private static final String DEFAULT_CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";//默认的加密算法 /** * AES 加密操作 * * @param content 待加密内容 * @param key 加密密钥 * @return 返回Base64转码后的加密数据 */ public static String encrypt(String content, String key) { try { Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);// 创建密码器 byte[] byteContent = content.getBytes("utf-8"); //初始化为加密模式的密码器 //方法一 //cipher.init(Cipher.DECRYPT_MODE, getSecretKey(key)); //方法二 cipher.init(Cipher.ENCRYPT_MODE, getSecretKeySpec(key)); byte[] result = cipher.doFinal(byteContent);// 加密 return Base64.encodeBase64String(result);//通过Base64转码返回 } catch (Exception ex) { Logger.getLogger(AESUtil.class.getName()).log(Level.SEVERE, null, ex); } return null; } /** * AES 解密操作 * * @param content * @param key * @return */ public static String decrypt(String content, String key) { try { //实例化 Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM); // 使用密钥初始化,设置为解密模式 //方法一 //cipher.init(Cipher.DECRYPT_MODE, getSecretKey(key)); //方法二 cipher.init(Cipher.DECRYPT_MODE, getSecretKeySpec(key)); //执行操作 byte[] result = cipher.doFinal(Base64.decodeBase64(content)); return new String(result, "utf-8"); } catch (Exception ex) { Logger.getLogger(AESUtil.class.getName()).log(Level.SEVERE, null, ex); } return null; } /** * 生成加密秘钥 * * @return */ private static SecretKey getSecretKey(final String key) { try { SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(), KEY_ALGORITHM); SecretKey sk = SecretKeyFactory.getInstance(KEY_ALGORITHM).generateSecret(keySpec); return sk; } catch (InvalidKeySpecException e) { e.printStackTrace(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } return null; } /** * 生成加密秘钥 * * @return */ private static SecretKeySpec getSecretKeySpec(final String key) { //返回生成指定算法密钥生成器的 KeyGenerator 对象 KeyGenerator kg = null; try { kg = KeyGenerator.getInstance(KEY_ALGORITHM); //AES 要求密钥长度为 128 kg.init(128, new SecureRandom(key.getBytes())); //生成一个密钥 SecretKey secretKey = kg.generateKey(); return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);// 转换为AES专用密钥 } catch (NoSuchAlgorithmException ex) { Logger.getLogger(AESUtil.class.getName()).log(Level.SEVERE, null, ex); } return null; } public static void main(String[] args) { String content = "hello,您好"; String key = "sde@5f98H*^hsff%dfs$r344&df8543*er"; System.out.println("content:" + content); String s1 = AESUtil.encrypt(content, key); System.out.println("s1:" + s1); System.out.println("s2:"+AESUtil.decrypt(s1, key)); } }
非对称加密
非对称加密算法需要两个密钥:公开密钥(publickey)和私有密钥(privatekey)。公开密钥与私有密钥是一对,如果用公开密钥对数据进行加密,只有用对应的私有密钥才能解密;如果用私有密钥对数据进行加密,那么只有用对应的公开密钥才能解密。一般公钥是公开的,私钥是自己保存。因为加密和解密使用的是两个不同的密钥,所以这种算法叫作非对称加密算法。安全性相对对称加密来说更高,是一种高级加密方式。
RSA加密
RSA是一种非对称加密算法.RSA有两个密钥,一个是公开的,称为公开密钥;一个是私密的,称为私密密钥。公开密钥是对大众公开的,私密密钥是服务器私有的,两者不能互推得出。用公开密钥对数据进行加密,私密密钥可解密;私密密钥对数据加密,公开密钥可解密。速度较对称加密慢。简单的RSA加密算法实现:
import java.io.ByteArrayOutputStream; import java.security.Key; import java.security.KeyFactory; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.PrivateKey; import java.security.PublicKey; import java.security.Signature; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.PKCS8EncodedKeySpec; import java.security.spec.X509EncodedKeySpec; import java.util.HashMap; import java.util.Map; import javax.crypto.Cipher; /** * <p> * RSA公钥/私钥/签名工具包 * </p> * <p> * 字符串格式的密钥在未在特殊说明情况下都为BASE64编码格式<br/> * 由于非对称加密速度极其缓慢,一般文件不使用它来加密而是使用对称加密,<br/> * 非对称加密算法可以用来对对称加密的密钥加密,这样保证密钥的安全也就保证了数据的安全 * </p> * */ public class RSAUtils { /** * 加密算法RSA */ public static final String KEY_ALGORITHM = "RSA"; /** * 签名算法 */ public static final String SIGNATURE_ALGORITHM = "MD5withRSA"; /** * 获取公钥的key */ private static final String PUBLIC_KEY = "RSAPublicKey"; /** * 获取私钥的key */ private static final String PRIVATE_KEY = "RSAPrivateKey"; /** * RSA最大加密明文大小 */ private static final int MAX_ENCRYPT_BLOCK = 117; /** * RSA最大解密密文大小 */ private static final int MAX_DECRYPT_BLOCK = 128; /** * <p> * 生成密钥对(公钥和私钥) * </p> * * @return * @throws Exception */ public static Map<String, Object> genKeyPair() throws Exception { KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM); keyPairGen.initialize(1024); KeyPair keyPair = keyPairGen.generateKeyPair(); RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); Map<String, Object> keyMap = new HashMap<String, Object>(2); keyMap.put(PUBLIC_KEY, publicKey); keyMap.put(PRIVATE_KEY, privateKey); return keyMap; } /** * <p> * 用私钥对信息生成数字签名 * </p> * * @param data 已加密数据 * @param privateKey 私钥(BASE64编码) * * @return * @throws Exception */ public static String sign(byte[] data, String privateKey) throws Exception { byte[] keyBytes = Base64Utils.decode(privateKey); PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec); Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM); signature.initSign(privateK); signature.update(data); return Base64Utils.encode(signature.sign()); } /** * <p> * 校验数字签名 * </p> * * @param data 已加密数据 * @param publicKey 公钥(BASE64编码) * @param sign 数字签名 * * @return * @throws Exception * */ public static boolean verify(byte[] data, String publicKey, String sign) throws Exception { byte[] keyBytes = Base64Utils.decode(publicKey); X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); PublicKey publicK = keyFactory.generatePublic(keySpec); Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM); signature.initVerify(publicK); signature.update(data); return signature.verify(Base64Utils.decode(sign)); } /** * <P> * 私钥解密 * </p> * * @param encryptedData 已加密数据 * @param privateKey 私钥(BASE64编码) * @return * @throws Exception */ public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey) throws Exception { byte[] keyBytes = Base64Utils.decode(privateKey); PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); Key privateK = keyFactory.generatePrivate(pkcs8KeySpec); Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm()); cipher.init(Cipher.DECRYPT_MODE, privateK); int inputLen = encryptedData.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; byte[] cache; int i = 0; // 对数据分段解密 while (inputLen - offSet > 0) { if (inputLen - offSet > MAX_DECRYPT_BLOCK) { cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK); } else { cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * MAX_DECRYPT_BLOCK; } byte[] decryptedData = out.toByteArray(); out.close(); return decryptedData; } /** * <p> * 公钥解密 * </p> * * @param encryptedData 已加密数据 * @param publicKey 公钥(BASE64编码) * @return * @throws Exception */ public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey) throws Exception { byte[] keyBytes = Base64Utils.decode(publicKey); X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); Key publicK = keyFactory.generatePublic(x509KeySpec); Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm()); cipher.init(Cipher.DECRYPT_MODE, publicK); int inputLen = encryptedData.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; byte[] cache; int i = 0; // 对数据分段解密 while (inputLen - offSet > 0) { if (inputLen - offSet > MAX_DECRYPT_BLOCK) { cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK); } else { cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * MAX_DECRYPT_BLOCK; } byte[] decryptedData = out.toByteArray(); out.close(); return decryptedData; } /** * <p> * 公钥加密 * </p> * * @param data 源数据 * @param publicKey 公钥(BASE64编码) * @return * @throws Exception */ public static byte[] encryptByPublicKey(byte[] data, String publicKey) throws Exception { byte[] keyBytes = Base64Utils.decode(publicKey); X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); Key publicK = keyFactory.generatePublic(x509KeySpec); // 对数据加密 Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm()); cipher.init(Cipher.ENCRYPT_MODE, publicK); int inputLen = data.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; byte[] cache; int i = 0; // 对数据分段加密 while (inputLen - offSet > 0) { if (inputLen - offSet > MAX_ENCRYPT_BLOCK) { cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK); } else { cache = cipher.doFinal(data, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * MAX_ENCRYPT_BLOCK; } byte[] encryptedData = out.toByteArray(); out.close(); return encryptedData; } /** * <p> * 私钥加密 * </p> * * @param data 源数据 * @param privateKey 私钥(BASE64编码) * @return * @throws Exception */ public static byte[] encryptByPrivateKey(byte[] data, String privateKey) throws Exception { byte[] keyBytes = Base64Utils.decode(privateKey); PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); Key privateK = keyFactory.generatePrivate(pkcs8KeySpec); Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm()); cipher.init(Cipher.ENCRYPT_MODE, privateK); int inputLen = data.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; byte[] cache; int i = 0; // 对数据分段加密 while (inputLen - offSet > 0) { if (inputLen - offSet > MAX_ENCRYPT_BLOCK) { cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK); } else { cache = cipher.doFinal(data, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * MAX_ENCRYPT_BLOCK; } byte[] encryptedData = out.toByteArray(); out.close(); return encryptedData; } /** * <p> * 获取私钥 * </p> * * @param keyMap 密钥对 * @return * @throws Exception */ public static String getPrivateKey(Map<String, Object> keyMap) throws Exception { Key key = (Key) keyMap.get(PRIVATE_KEY); return Base64Utils.encode(key.getEncoded()); } /** * <p> * 获取公钥 * </p> * * @param keyMap 密钥对 * @return * @throws Exception */ public static String getPublicKey(Map<String, Object> keyMap) throws Exception { Key key = (Key) keyMap.get(PUBLIC_KEY); return Base64Utils.encode(key.getEncoded()); } } import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.InputStream; import java.io.OutputStream; import com.sun.org.apache.xml.internal.security.utils.Base64; public class Base64Utils { /** * 文件读取缓冲区大小 */ private static final int CACHE_SIZE = 1024; /** * <p> * BASE64字符串解码为二进制数据 * </p> * * @param base64 * @return * @throws Exception */ public static byte[] decode(String base64) throws Exception { return Base64.decode(base64.getBytes()); } /** * <p> * 二进制数据编码为BASE64字符串 * </p> * * @param bytes * @return * @throws Exception */ public static String encode(byte[] bytes) throws Exception { return new String(Base64.encode(bytes)); } /** * <p> * 将文件编码为BASE64字符串 * </p> * <p> * 大文件慎用,可能会导致内存溢出 * </p> * * @param filePath * 文件绝对路径 * @return * @throws Exception */ public static String encodeFile(String filePath) throws Exception { byte[] bytes = fileToByte(filePath); return encode(bytes); } /** * <p> * BASE64字符串转回文件 * </p> * * @param filePath * 文件绝对路径 * @param base64 * 编码字符串 * @throws Exception */ public static void decodeToFile(String filePath, String base64) throws Exception { byte[] bytes = decode(base64); byteArrayToFile(bytes, filePath); } /** * <p> * 文件转换为二进制数组 * </p> * * @param filePath * 文件路径 * @return * @throws Exception */ public static byte[] fileToByte(String filePath) throws Exception { byte[] data = new byte[0]; File file = new File(filePath); if (file.exists()) { FileInputStream in = new FileInputStream(file); ByteArrayOutputStream out = new ByteArrayOutputStream(2048); byte[] cache = new byte[CACHE_SIZE]; int nRead = 0; while ((nRead = in.read(cache)) != -1) { out.write(cache, 0, nRead); out.flush(); } out.close(); in.close(); data = out.toByteArray(); } return data; } /** * <p> * 二进制数据写文件 * </p> * * @param bytes * 二进制数据 * @param filePath * 文件生成目录 */ public static void byteArrayToFile(byte[] bytes, String filePath) throws Exception { InputStream in = new ByteArrayInputStream(bytes); File destFile = new File(filePath); if (!destFile.getParentFile().exists()) { destFile.getParentFile().mkdirs(); } destFile.createNewFile(); OutputStream out = new FileOutputStream(destFile); byte[] cache = new byte[CACHE_SIZE]; int nRead = 0; while ((nRead = in.read(cache)) != -1) { out.write(cache, 0, nRead); out.flush(); } out.close(); in.close(); } }
以上为个人经验,希望能给大家一个参考,也希望大家多多支持。
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