I've followed this: https://dev.twitter.com/docs/auth/creating-signature
to the end but I can't find how to encode a "binary string" to base64(at the end). I wanted to try online converters first but they don't give the string the show
"tnnArxj06cWHq44gCs1OSKk/jLY="
Tried this: http://www.motobit.com/util/base64-decoder-encoder.asp
and
http://www.hash-cracker.com/base64.php#anchor
and
http://www.opinionatedgeek.com/dotnet/tools/Base64Encode/
and none give that string.
I'm going to be using java. But I think all those java tools I search for will give the same result as the online converters. What has to be done to encode a "binary string" to base64?
The problem of using those online tools isn't going to be in the base64 conversion - it's going to be parsing the hex string into a byte array to start with. In your real code that won't be a problem, as it'll be the output of another stage. Just to prove that, here's some sample Java code, using a public domain base64 encoder:
public class Test {
public static void main(String[] args) throws Exception {
byte[] data = { (byte) 0xB6, (byte) 0x79, (byte) 0xC0, (byte) 0xAF,
(byte) 0x18, (byte) 0xF4, (byte) 0xE9, (byte) 0xC5,
(byte) 0x87, (byte) 0xAB, (byte) 0x8E, (byte) 0x20,
(byte) 0x0A, (byte) 0xCD, (byte) 0x4E, (byte) 0x48,
(byte) 0xA9, (byte) 0x3F, (byte) 0x8C, (byte) 0xB6 };
String text = Base64.encodeBytes(data);
System.out.println(text);
}
}
Output: tnnArxj06cWHq44gCs1OSKk/jLY=
You can use this link to convert Binary String to Base64
https://cryptii.com/pipes/binary-to-text
Here is an example of converting Binary String to Base64 String:
Here is another example of converting Normal String to Base64 String
Related
I'm trying to decrypt an access token (it's a String), which is used to default access an Dropbox account and uploading files into it. So right now, I always need that access token to make file uploadings.
Until now, I've been generating a new initialization vector (IV) and a new secret key to encrypt and decrypt the access token. However, I want to store these two in the source code, as constant variables/attributes. The reason why I want them to remain the same ? Because I will give a crypted access token (always the same encoded one) to the users, and the app should keep the IV and the secret key inside the source code.
How can I store them in my source code ?
I tried to write the string values of the IV and of the secret key in files. I use the string from the files, and I assign the string values to string constants in my code. Then i use my constants to create byte arrays for converting into the IV and into the secret key. I'm not sure if this will work yet, it's still in development.
You'd better heed the advice. Storing the key is bad but can sometimes be defended if no other options are available. There is however generally no reason to use a static IV. You can just prefix the IV (which is 16 bytes for most modes of operation) to the ciphertext instead.
Anyway, to store them as static values, just take a look at the following code; note that you should generate them as random values in advance, not the static values you're seeing here:
private static final byte[] KEY_DATA = {
(byte) 0x00, (byte) 0x01, (byte) 0x02, (byte) 0x03,
(byte) 0x04, (byte) 0x05, (byte) 0x06, (byte) 0x07,
(byte) 0x08, (byte) 0x09, (byte) 0x0A, (byte) 0x0B,
(byte) 0x0C, (byte) 0x0D, (byte) 0x0E, (byte) 0x0F,
};
private static final byte[] IV_DATA = {
(byte) 0x00, (byte) 0x01, (byte) 0x02, (byte) 0x03,
(byte) 0x04, (byte) 0x05, (byte) 0x06, (byte) 0x07,
(byte) 0x08, (byte) 0x09, (byte) 0x0A, (byte) 0x0B,
(byte) 0x0C, (byte) 0x0D, (byte) 0x0E, (byte) 0x0F,
};
public static void main(String[] args) throws Exception {
Cipher aes = Cipher.getInstance("AES/CBC/PKCS5Padding");
SecretKey key = new SecretKeySpec(KEY_DATA, "aes");
IvParameterSpec iv = new IvParameterSpec(IV_DATA);
aes.init(Cipher.ENCRYPT_MODE, key, iv);
...
}
Note that SecretKeySpec implements the interface SecretKey for easy usage.
In the following programs, command is a byte array field in Apdu class. The problem is that my IDE (Netbeans) mark the line of
apdu.command = {(byte) 0x00, (byte)0xa4, (byte) 0x00, (byte) 0x00};
As error, with the message illegal start of expression, while it is okay to use the following instead:
byte[] bytes = {(byte) 0x00, (byte) 0xa4, (byte) 0x00, (byte) 0x00};
apdu.command = bytes;
What's wrong with the first programs?
First program:
Second Program:
You need to initialize the array variable with :
apdu.command = new byte[] {(byte) 0x00, (byte)0xa4, (byte) 0x00, (byte) 0x00};
The initialization you tried is only valid in array declaration expressions.
array syntax {} can only be used for initialization not for assignment.
you need to use apdu.command =new byte[] {(byte) 0x00, (byte)0xa4, (byte) 0x00, (byte) 0x00};.
I am using a byte array to store a text file outside of the filesystem.
It looks like this:
private static final byte[] CDRIVES = new byte[] {
(byte)0xe0, 0x4f, (byte)0xd0, 0x20, (byte)0xea, 0x3a, 0x69, 0x10,
(byte)0xa2, (byte)0xd8, 0x08, 0x00, 0x2b, 0x30, 0x30, (byte)0x9d,
(byte)0xba, (byte)0x8a, 0x0d, 0x45, 0x25, (byte)0xad, (byte)0xd0, 0x11,
(byte)0x98, (byte)0xa8, 0x08, 0x00, 0x36, 0x1b, 0x11, 0x03,
(byte)0x80, 0x53, 0x1c, (byte)0x87, (byte)0xa0, 0x42, 0x69, 0x10,
(byte)0xa2, (byte)0xea, 0x08, 0x00, 0x2b, 0x30, 0x30, (byte)0x9d
...
...
...
};
Is there a way to avoid casting to (byte) for better visual interpretation?
I don't mind using other data type, but I need to be able build an InputStream out of it and do it the fastest way if possible. (for example storing a text file into a String variable is not the best way...)
Well one simple approach would be to use base64 - but perform the conversion on class initialization, so you only take the performance hit once:
private static final byte[] CDRIVES = Base64.decode("YOURBASE64HERE");
Or if it's genuinely text, perform that encoding once in a similar way:
private static final byte[] CDRIVES =
"Your constant text here".getBytes(StandardCharsets.UTF_8);
Again, the performance hit occurs exactly once, and then you can use the bytes multiple times. I would be very surprised if the cost of encoding text into bytes at class initialization time is genuinely a bottleneck for you.
I am using following code but It's not decrypting the text properly, what am I getting as output is
ciphered: %öNo2F?¢¶SHºûÅ“?¾
plaintext: hello × am originÎl
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
// Dernier exemple CTR mode
// Clé 16 bits
byte[] keyBytes = new byte[] { (byte) 0x36, (byte) 0xf1, (byte) 0x83,
(byte) 0x57, (byte) 0xbe, (byte) 0x4d, (byte) 0xbd,
(byte) 0x77, (byte) 0xf0, (byte) 0x50, (byte) 0x51,
(byte) 0x5c, 0x73, (byte) 0xfc, (byte) 0xf9, (byte) 0xf2 };
// IV 16 bits (préfixe du cipherText)
byte[] ivBytes = new byte[] { (byte) 0x69, (byte) 0xdd, (byte) 0xa8,
(byte) 0x45, (byte) 0x5c, (byte) 0x7d, (byte) 0xd4,
(byte) 0x25, (byte) 0x4b, (byte) 0xf3, (byte) 0x53,
(byte) 0xb7, (byte) 0x73, (byte) 0x30, (byte) 0x4e, (byte) 0xec };
// Initialisation
SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
// Mode
Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
String originalText = "hello i am original";
// ///////////////////////////////ENCRYPTING
cipher.init(Cipher.ENCRYPT_MODE, key, ivSpec);
byte[] ciphered = cipher.doFinal(originalText.getBytes());
String cipherText = new String(ciphered,"UTF-8");
System.out.println("ciphered: " + cipherText);
// ///////////////////////////////DECRYPTING
cipher = Cipher.getInstance("AES/CTR/NoPadding");
cipher.**init(Cipher.DECRYPT_MODE**, key, ivSpec);
byte[] plain = **cipher.doFinal(ciphered);**
originalText = new String(plain,"UTF-8");
System.out.println("plaintext: " + originalText);
}
I couldn't figure out what am I doing wrong.any help is deeply appreciated.
also is this proper way to encrypted some data this time I am trying to encrypt 4byte city pin code.
thank in advance
////
I made those changes n' it's working fine but what's the issue if I passes
cipherText.getByte() in cipher.init() function. Like
byte[] plain = cipher.doFinal(cipherText.getByte("UTF-8"));
n' Thanks for all your help.
For decryption you need to initialize the Cipher in DECRYPT_MODE. And also the byte[] to String conversion is not correct (See other answer).
You cannot convert the encrypted bytes to a String like that. "bytes" and "chars" are two entirely different things. remove the code which turns the bytes to a String and back again between encrypting and decrypting and your code should work (as pointed out in other answer, the second step should be using DECRYPT_MODE).
note that you need to be careful when using the platform character encoding to convert between bytes and chars/String, as this may be different on different platforms. this may cause problems if your data needs to move cross platform. it can also be lossy if your default platform encoding doesn't support all the characters in the text you are using.
As the title says; is there a APDU command for retrieving the UID of a tag? I am using Java, with an ACR122-u cardreader and the javax.smartcardio.* package and I want to get the UID from a tag on the scanner. The smartcardio library can send CommandAPDU's but I need to figure out what APDU to send. Google has not been very friendly to me on this one, providing me with thousands of unhelpful datasheets of some sort...
Any help would be great :)
Better late than never but there is actually an APDU to JUST retrieve the UID: (byte) 0xFF, (byte) 0xCA, (byte) 0x00, (byte) 0x00, (byte) 0x00
FF CA 00 00 00
In Java: byte[] getuid = new byte[] { (byte) 0xFF, (byte) 0xCA, (byte) 0x00,
(byte) 0x00, (byte) 0x00 };
If you send this APDU, the response data will be just the UID of the card :) (Much easier than having more info and having to set an offset to get just the info you need...)
The APDU Command for Read UID is
byte[] baReadUID = new byte[5];
baReadUID = new byte[] { (byte) 0xFF, (byte) 0xCA, (byte) 0x00,
(byte) 0x00, (byte) 0x00 };
All Complete code is here....