Android 加密解密字符串详解

概述加密和解密的字符串:复制代码代码如下:packageeoe.demo;importjava.security.SecureRandom;importjavax.crypto.Cipher;importjavax.crypto.KeyGenerator;importjavax.crypto.SecretKey;importjavax.crypto.spec.Secr @H_502_0@加密和解密的字符串:
复制代码 代码如下:
package eoe.demo;
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");
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));
}
}

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