这个way 我将图像转换为字符串。 现在我想在服务器中发送数据之前加密此字符串。有没有一种简单的方法来加密和解密字符串？
答案 0 :(得分：10)
<强> javax.crypto中
此软件包为加密应用程序提供了实现加密，解密或密钥协议算法的类和接口。
支持流密码以及非对称，对称和分组密码。可以使用SPI（服务提供者接口）抽象类来集成来自不同提供者的密码实现。使用SealedObject类，程序员可以通过使用密码加密来保护对象。
认证可以基于MAC（消息认证码），例如HMAC（哈希MAC，即具有SHA-1哈希函数）。
示例：
使用AES128加密和解密字符串的简单帮助程序类。结果是Ascii编码（实际上是十六进制，没有base64），因此不必存储byte []。 SEED值用作共享密钥（“主密码”）。只有使用相同的SEED才能解密存储的值。
package com.xxx;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
/**
* Usage:
* <pre>
* String crypto = SimpleCrypto.encrypt(masterpassword, cleartext)
* ...
* String cleartext = SimpleCrypto.decrypt(masterpassword, crypto)
* </pre>
* @author ferenc.hechler
*/
public class SimpleCrypto {
public static String encrypt(String seed, String cleartext) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = encrypt(rawKey, cleartext.getBytes());
return toHex(result);
}
public static String decrypt(String seed, String encrypted) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] enc = toByte(encrypted);
byte[] result = decrypt(rawKey, enc);
return new String(result);
}
private static byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", "Crypto");
sr.setSeed(seed);
kgen.init(128, sr); // 192 and 256 bits may not be available
SecretKey skey = kgen.generateKey();
byte[] raw = skey.getEncoded();
return raw;
}
private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(clear);
return encrypted;
}
private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
public static String toHex(String txt) {
return toHex(txt.getBytes());
}
public static String fromHex(String hex) {
return new String(toByte(hex));
}
public static byte[] toByte(String hexString) {
int len = hexString.length()/2;
byte[] result = new byte[len];
for (int i = 0; i < len; i++)
result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();
return result;
}
public static String toHex(byte[] buf) {
if (buf == null)
return "";
StringBuffer result = new StringBuffer(2*buf.length);
for (int i = 0; i < buf.length; i++) {
appendHex(result, buf[i]);
}
return result.toString();
}
private final static String HEX = "0123456789ABCDEF";
private static void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));
}
}
有关详细信息，请查看Android Security How to encrypt and decrypt strings?和Encryption on Android & BouncyCastle
答案 1 :(得分：0)
public class SecureCredentialsCrypto {
public static String encrypt(String seed, String cleartext) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = encrypt(rawKey, cleartext.getBytes());
return toHex(result);
}
public static String decrypt(String seed, String encrypted) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] enc = toByte(encrypted);
byte[] result = decrypt(rawKey, enc);
return new String(result);
}
private static byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(seed);
kgen.init(128, sr); // 192 and 256 bits may not be available
SecretKey skey = kgen.generateKey();
byte[] raw = skey.getEncoded();
return raw;
}
private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(clear);
return encrypted;
}
private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
public static String toHex(String txt) {
return toHex(txt.getBytes());
}
public static String fromHex(String hex) {
return new String(toByte(hex));
}
public static byte[] toByte(String hexString) {
int len = hexString.length()/2;
byte[] result = new byte[len];
for (int i = 0; i < len; i++)
result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();
return result;
}
public static String toHex(byte[] buf) {
if (buf == null)
return "";
StringBuffer result = new StringBuffer(2*buf.length);
for (int i = 0; i < buf.length; i++) {
appendHex(result, buf[i]);
}
return result.toString();
}
private final static String HEX = "0123456789ABCDEF";
private static void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));
}
}
//for storing encrypt it
String crypto_email = SecureCredentialsCrypto.encrypt("secure", email.toString().trim());
//for reading decrypt it
//crypto is object name to read
String correctEmail=SecureCredentialsCrypto.decrypt("secure", crypto);
答案 2 :(得分：-1)
package com.duplicate;
public class RSAEncryptionDescription {
private static final String PUBLIC_KEY_FILE = "Public.key";
private static final String PRIVATE_KEY_FILE = "Private.key";
public static void main(String[] args) throws IOException {
try {
System.out.println("-------GENRATE PUBLIC and PRIVATE KEY-------------");
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
keyPairGenerator.initialize(2048); //1024 used for normal securities
KeyPair keyPair = keyPairGenerator.generateKeyPair();
PublicKey publicKey = keyPair.getPublic();
PrivateKey privateKey = keyPair.getPrivate();
System.out.println("Public Key - " + publicKey);
System.out.println("Private Key - " + privateKey);
//Pullingout parameters which makes up Key
System.out.println("\n------- PULLING OUT PARAMETERS WHICH MAKES KEYPAIR----------\n");
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPublicKeySpec rsaPubKeySpec = keyFactory.getKeySpec(publicKey, RSAPublicKeySpec.class);
RSAPrivateKeySpec rsaPrivKeySpec = keyFactory.getKeySpec(privateKey, RSAPrivateKeySpec.class);
System.out.println("PubKey Modulus : " + rsaPubKeySpec.getModulus());
System.out.println("PubKey Exponent : " + rsaPubKeySpec.getPublicExponent());
System.out.println("PrivKey Modulus : " + rsaPrivKeySpec.getModulus());
System.out.println("PrivKey Exponent : " + rsaPrivKeySpec.getPrivateExponent());
//Share public key with other so they can encrypt data and decrypt thoses using private key(Don't share with Other)
System.out.println("\n--------SAVING PUBLIC KEY AND PRIVATE KEY TO FILES-------\n");
RSAEncryptionDescription rsaObj = new RSAEncryptionDescription();
rsaObj.saveKeys(PUBLIC_KEY_FILE, rsaPubKeySpec.getModulus(), rsaPubKeySpec.getPublicExponent());
rsaObj.saveKeys(PRIVATE_KEY_FILE, rsaPrivKeySpec.getModulus(), rsaPrivKeySpec.getPrivateExponent());
//Encrypt Data using Public Key
byte[] encryptedData = rsaObj.encryptData("Anuj Patel - Classified Information !");
//Descypt Data using Private Key
rsaObj.decryptData(encryptedData);
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}catch (InvalidKeySpecException e) {
e.printStackTrace();
}
}
/**
* Save Files
* @param fileName
* @param mod
* @param exp
* @throws IOException
*/
private void saveKeys(String fileName,BigInteger mod,BigInteger exp) throws IOException{
FileOutputStream fos = null;
ObjectOutputStream oos = null;
try {
System.out.println("Generating "+fileName + "...");
fos = new FileOutputStream(fileName);
oos = new ObjectOutputStream(new BufferedOutputStream(fos));
oos.writeObject(mod);
oos.writeObject(exp);
System.out.println(fileName + " generated successfully");
} catch (Exception e) {
e.printStackTrace();
}
finally{
if(oos != null){
oos.close();
if(fos != null){
fos.close();
}
}
}
}
/**
* Encrypt Data
* @param data
* @throws IOException
*/
private byte[] encryptData(String data) throws IOException {
System.out.println("\n----------------ENCRYPTION STARTED------------");
System.out.println("Data Before Encryption :" + data);
byte[] dataToEncrypt = data.getBytes();
byte[] encryptedData = null;
try {
PublicKey pubKey = readPublicKeyFromFile(PUBLIC_KEY_FILE);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, pubKey);
encryptedData = cipher.doFinal(dataToEncrypt);
System.out.println("Encryted Data: " + encryptedData);
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("----------------ENCRYPTION COMPLETED------------");
return encryptedData;
}
/**
* Encrypt Data
* @param data
* @throws IOException
*/
private void decryptData(byte[] data) throws IOException {
System.out.println("\n----------------DECRYPTION STARTED------------");
byte[] descryptedData = null;
try {
PrivateKey privateKey = readPrivateKeyFromFile(PRIVATE_KEY_FILE);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, privateKey);
descryptedData = cipher.doFinal(data);
System.out.println("Decrypted Data: " + new String(descryptedData));
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("----------------DECRYPTION COMPLETED------------");
}
/**
* read Public Key From File
* @param fileName
* @return PublicKey
* @throws IOException
*/
public PublicKey readPublicKeyFromFile(String fileName) throws IOException{
FileInputStream fis = null;
ObjectInputStream ois = null;
try {
fis = new FileInputStream(new File(fileName));
ois = new ObjectInputStream(fis);
BigInteger modulus = (BigInteger) ois.readObject();
BigInteger exponent = (BigInteger) ois.readObject();
//Get Public Key
RSAPublicKeySpec rsaPublicKeySpec = new RSAPublicKeySpec(modulus, exponent);
KeyFactory fact = KeyFactory.getInstance("RSA");
PublicKey publicKey = fact.generatePublic(rsaPublicKeySpec);
return publicKey;
} catch (Exception e) {
e.printStackTrace();
}
finally{
if(ois != null){
ois.close();
if(fis != null){
fis.close();
}
}
}
return null;
}
/**
* read Public Key From File
* @param fileName
* @return
* @throws IOException
*/
public PrivateKey readPrivateKeyFromFile(String fileName) throws IOException{
FileInputStream fis = null;
ObjectInputStream ois = null;
try {
fis = new FileInputStream(new File(fileName));
ois = new ObjectInputStream(fis);
BigInteger modulus = (BigInteger) ois.readObject();
BigInteger exponent = (BigInteger) ois.readObject();
//Get Private Key
RSAPrivateKeySpec rsaPrivateKeySpec = new RSAPrivateKeySpec(modulus, exponent);
KeyFactory fact = KeyFactory.getInstance("RSA");
PrivateKey privateKey = fact.generatePrivate(rsaPrivateKeySpec);
return privateKey;
} catch (Exception e) {
e.printStackTrace();
}
finally{
if(ois != null){
ois.close();
if(fis != null){
fis.close();
}
}
}
return null;
}
}