android客户端加密代码

Java代码







package com.devchina.scurity;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class SecurityEnDe {

private static
final String defalutSeed = "devchina";
private static
final String algorithm = "AES";
private final
static String HEX = "0123456789ABCDEF";

public static String encrypt(String cleartext)
throws Exception {
return encrypt(defalutSeed, cleartext);
}

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 encrypted)
throws Exception {
return decrypt(defalutSeed, encrypted);
}

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(algorithm);
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, algorithm);

Cipher cipher = Cipher.getInstance(algorithm);
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, algorithm);

Cipher cipher = Cipher.getInstance(algorithm);
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 static
void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b >> 4) &
0x0f)).append(HEX.charAt(b & 0x0f));
}

}