这是我第一次在这里寻求帮助，我的部门(政府)已经在市场上发布了一些应用程序(Google Play)，直到昨天我拿到果冻 bean 时，加密和描述都运行良好4.2 在我的 Nexus 上。 加密工作正常，它实际上是加密要存储的信息。虽然在解密时，我得到了一个完全像这样的异常:pad block corrupted。 我已经检查了该字符串，它与其他设备上的字符串一致(使用相同的 key 进行测试)，这意味着它完全相同。 问题是我们需要保持与以前版本的向后兼容性，这意味着如果我更改代码中的某些内容，它应该能够读取旧的加密信息。它存储在 SQLite 上的加密信息，因为我需要将它编码为 Base64。异常发生在这一行 byte[] decrypted = cipher.doFinal(encrypted);
这是我的类(class):
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import android.util.Base64;
public class EncodeDecodeAES {
private final static String HEX = "0123456789ABCDEF";
public static String encrypt(String seed, String cleartext) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = encrypt(rawKey, cleartext.getBytes());
String fromHex = toHex(result);
String base64 = new String(Base64.encodeToString(fromHex.getBytes(), 0));
return base64;
}
public static String decrypt(String seed, String encrypted) throws Exception {
String base64 = new String(Base64.decode(encrypted, 0));
byte[] rawKey = getRawKey(seed.getBytes());
byte[] enc = toByte(base64);
byte[] result = decrypt(rawKey, enc);
return new String(result);
}
public static byte[] encryptBytes(String seed, byte[] cleartext) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = encrypt(rawKey, cleartext);
return result;
}
public static byte[] decryptBytes(String seed, byte[] encrypted) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = decrypt(rawKey, encrypted);
return result;
}
private static byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(seed);
try {
kgen.init(256, sr);
} catch (Exception e) {
// Log.w(LOG, "This device doesn't suppor 256bits, trying 192bits.");
try {
kgen.init(192, sr);
} catch (Exception e1) {
// Log.w(LOG, "This device doesn't suppor 192bits, trying 128bits.");
kgen.init(128, sr);
}
}
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 static void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
}
}
我想知道(如果有人帮助我)，我对这段代码做错了什么，或者它是否是 Android 4.2 的问题，如果有任何解决方法，是否是 4.2 的问题？
谢谢
最佳答案
警告 此答案使用 SecureRandom 进行 key 派生，这与其目的相反。 SecureRandom 是一个随机数生成器，不保证在平台之间产生一致的输出(这是导致问题的原因)。 key 派生的正确机制是 SecretKeyFactory。这个 nelenkov's blog post 在这个问题上有一篇很好的文章。当您受到向后兼容性要求的约束时，此答案为您提供了解决方案；但是，您应该尽快迁移到正确的实现。
好吧，今天有更多时间做一些研究(并删除我的旧帖子，那实际上是行不通的，抱歉)我得到了一个工作正常的答案，我实际上在 Android 2.3.6 上测试过它， 2.3.7(基本相同)、4.0.4 和 4.2 都有效。 我对这些链接做了一些研究:
Encryption error on Android 4.2 ,
BouncyCastle AES error when upgrading to 1.45 ,
http://en.wikipedia.org/wiki/Padding_(cryptography)
然后由于上面这些链接上的内容，我得到了这个解决方案。 这是我的类(class)(现在工作正常):
package au.gov.dhsJobSeeker.main.readwriteprefssettings.util;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import android.util.Base64;
public class EncodeDecodeAES {
private final static String HEX = "0123456789ABCDEF";
private final static int JELLY_BEAN_4_2 = 17;
private final static byte[] key = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
// static {
// Security.addProvider(new BouncyCastleProvider());
// }
public static String encrypt(String seed, String cleartext) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = encrypt(rawKey, cleartext.getBytes());
String fromHex = toHex(result);
String base64 = new String(Base64.encodeToString(fromHex.getBytes(), 0));
return base64;
}
public static String decrypt(String seed, String encrypted) throws Exception {
byte[] seedByte = seed.getBytes();
System.arraycopy(seedByte, 0, key, 0, ((seedByte.length < 16) ? seedByte.length : 16));
String base64 = new String(Base64.decode(encrypted, 0));
byte[] rawKey = getRawKey(seedByte);
byte[] enc = toByte(base64);
byte[] result = decrypt(rawKey, enc);
return new String(result);
}
public static byte[] encryptBytes(String seed, byte[] cleartext) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = encrypt(rawKey, cleartext);
return result;
}
public static byte[] decryptBytes(String seed, byte[] encrypted) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = decrypt(rawKey, encrypted);
return result;
}
private static byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("AES"); // , "SC");
SecureRandom sr = null;
if (android.os.Build.VERSION.SDK_INT >= JELLY_BEAN_4_2) {
sr = SecureRandom.getInstance("SHA1PRNG", "Crypto");
} else {
sr = SecureRandom.getInstance("SHA1PRNG");
}
sr.setSeed(seed);
try {
kgen.init(256, sr);
// kgen.init(128, sr);
} catch (Exception e) {
// Log.w(LOG, "This device doesn't suppor 256bits, trying 192bits.");
try {
kgen.init(192, sr);
} catch (Exception e1) {
// Log.w(LOG, "This device doesn't suppor 192bits, trying 128bits.");
kgen.init(128, sr);
}
}
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"); // /ECB/PKCS7Padding", "SC");
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"); // /ECB/PKCS7Padding", "SC");
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));
}
}
但是 PBrando 的答案(上面，也有效，因为我将其标记为解决方案。)，虽然我正在寻找一种方法来保持与现在相似的应用程序文件大小，但我选择使用这种方法.因为我不需要导入外部 Jars。 我确实放了整个类(class)，以防万一你们中的任何人遇到同样的问题，并且只想复制并粘贴它。
关于Android 4.2 破坏了我的 AES 加密/解密代码，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/13389870/