我在理解两个设备上的密码器/加密器方面遇到了真正的问题。
1. 如果我们使用Cipher AES在iOS和Android上加密一条消息，并且字符串的字符长度不超过16（例如“abcdefghijklmno”），则使用相同的密钥/密码加密后，我们会得到相同的结果。
2. 但是，如果我们使用一个更长的消息，在iOS和Android上得到的结果将不同（例如“abcdefghijklmnop”）。
我进行了大量的研究以找到两个设备上相同的参数，起初我认为这是安全的。
这是我的加密Cipher代码:
public String encode(Context context, String password, String text)
throws NoPassGivenException, NoTextGivenException {
if (password.length() == 0 || password == null) {
throw new NoPassGivenException("Please give Password");
}
if (text.length() == 0 || text == null) {
throw new NoTextGivenException("Please give text");
}
try {
SecretKeySpec skeySpec = getKey(password);
byte[] clearText = text.getBytes("UTF8");
//IMPORTANT TO GET SAME RESULTS ON iOS and ANDROID
final byte[] iv = new byte[16];
Arrays.fill(iv, (byte) 0x00);
IvParameterSpec ivParameterSpec = new IvParameterSpec(iv);
// Cipher is not thread safe
//EDITED AFTER RIGHT ANSWER FROM
//*** Cipher cipher = Cipher.getInstance("AES"); ***//
// TO
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, ivParameterSpec);
String encrypedValue = Base64.encodeToString(
cipher.doFinal(clearText), Base64.DEFAULT);
Log.d(TAG, "Encrypted: " + text + " -> " + encrypedValue);
return encrypedValue;
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
} catch (InvalidAlgorithmParameterException e) {
e.printStackTrace();
}
return "";
}
public SecretKeySpec getKey(String password)
throws UnsupportedEncodingException {
int keyLength = 128;
byte[] keyBytes = new byte[keyLength / 8];
// explicitly fill with zeros
Arrays.fill(keyBytes, (byte) 0x0);
// if password is shorter then key length, it will be zero-padded
// to key length
byte[] passwordBytes = password.getBytes("UTF-8");
int length = passwordBytes.length < keyBytes.length ? passwordBytes.length
: keyBytes.length;
System.arraycopy(passwordBytes, 0, keyBytes, 0, length);
SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
return key;
}
这是我同事的iOS配套设备:
- (NSData *)AES128EncryptWithKey:(NSString *)key {
// 'key' should be 32 bytes for AES256,
// 16 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeAES128 + 1]; // room for terminator (unused)
bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
// insert key in char array
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesEncrypted = 0;
// the encryption method, use always same attributes in android and iPhone (f.e. PKCS7Padding)
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
kCCAlgorithmAES128,
kCCOptionPKCS7Padding,
keyPtr,
kCCKeySizeAES128,
NULL /* initialization vector (optional) */,
[self bytes], dataLength, /* input */
buffer, bufferSize, /* output */
&numBytesEncrypted);
if (cryptStatus == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
}
free(buffer);
return nil;
}
我很想了解它们的区别以及如何避免出现这种情况。通过测试长度超过15个字符的字符串，我获得了一些线索，但我不知道为什么会这样 :)
提前感谢！
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");- A.S.