android Encrypt/Decrypt Strings 在4.2中无法解密解决办法

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修改如下方法

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 availableSecretKey skey = kgen.generateKey();byte[] raw = skey.getEncoded();return raw;}

或者在Android 4.2 可以改用MD5 改变getrawkey()算法，它更加具有可操作性，MD5哈希计算在所有平台上都一样

private static byte[] getRawKey(byte[] seed) throws Exception {     MessageDigest md = MessageDigest.getInstance("MD5");     byte[] md5Bytes = md.digest(seed); // 128 Bit = 16 byte SecretKey     skey = new SecretKeySpec(md5Bytes, "AES");     byte[] raw = skey.getEncoded();     return raw; }

原来方法为

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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