Okay, I know how to do it in C#.
It's as simple as:
Convert.ToBase64String(byte[])
and Convert.FromBase64String(string) to get byte[] back.
How can I do this in Java?
Java 8+
Encode or decode byte arrays:
byte[] encoded = Base64.getEncoder().encode("Hello".getBytes());
println(new String(encoded)); // Outputs "SGVsbG8="
byte[] decoded = Base64.getDecoder().decode(encoded);
println(new String(decoded)) // Outputs "Hello"
Or if you just want the strings:
String encoded = Base64.getEncoder().encodeToString("Hello".getBytes());
println(encoded); // Outputs "SGVsbG8="
String decoded = new String(Base64.getDecoder().decode(encoded.getBytes()));
println(decoded) // Outputs "Hello"
For more info, see Base64.
Java < 8
Base64 is not bundled with Java versions less than 8. I recommend using Apache Commons Codec.
For direct byte arrays:
Base64 codec = new Base64();
byte[] encoded = codec.encode("Hello".getBytes());
println(new String(encoded)); // Outputs "SGVsbG8="
byte[] decoded = codec.decode(encoded);
println(new String(decoded)) // Outputs "Hello"
Or if you just want the strings:
Base64 codec = new Base64();
String encoded = codec.encodeBase64String("Hello".getBytes());
println(encoded); // Outputs "SGVsbG8="
String decoded = new String(codec.decodeBase64(encoded));
println(decoded) // Outputs "Hello"
Spring
If you're working in a Spring project already, you may find their org.springframework.util.Base64Utils class more ergonomic:
For direct byte arrays:
byte[] encoded = Base64Utils.encode("Hello".getBytes());
println(new String(encoded)) // Outputs "SGVsbG8="
byte[] decoded = Base64Utils.decode(encoded);
println(new String(decoded)) // Outputs "Hello"
Or if you just want the strings:
String encoded = Base64Utils.encodeToString("Hello".getBytes());
println(encoded); // Outputs "SGVsbG8="
String decoded = Base64Utils.decodeFromString(encoded);
println(new String(decoded)) // Outputs "Hello"
Android (with Java < 8)
If you are using the Android SDK before Java 8 then your best option is to use the bundled android.util.Base64.
For direct byte arrays:
byte[] encoded = Base64.encode("Hello".getBytes());
println(new String(encoded)) // Outputs "SGVsbG8="
byte [] decoded = Base64.decode(encoded);
println(new String(decoded)) // Outputs "Hello"
Or if you just want the strings:
String encoded = Base64.encodeToString("Hello".getBytes());
println(encoded); // Outputs "SGVsbG8="
String decoded = new String(Base64.decode(encoded));
println(decoded) // Outputs "Hello"
Use:
byte[] data = Base64.encode(base64str);
Encoding converts to Base64
You would need to reference commons codec from your project in order for that code to work.
For java8:
import java.util.Base64
Additionally, for our Android friends (API Level 8):
import android.util.Base64
...
Base64.encodeToString(bytes, Base64.DEFAULT);
In case you happen to be using Spring framework along with java, there is an easy way around.
Import the following.
import org.springframework.util.Base64Utils;
Convert like this.
byte[] bytearr ={0,1,2,3,4};
String encodedText = Base64Utils.encodeToString(bytearr);
To decode you can use the decodeToString method of the Base64Utils class.
Related
Decoding with base64 an unencoded string on Android does not gives any error but returns a string with some special characters e.g encoded like.
It should throw some IllegalArgumentException. Is there some native way in android to check that other than regex ?
private String decodeThisString = "I am a java String";
bytes[] deocdedBytes = Base64.decode(decodeThisString.getBytes(), Base64.DEFAULT);
I think you do not need to remove the character when you will decode it, automatically they will be discarded at the time of decode. I have tested with encoding and decoding with the provided code and get the exact string after decode.
String decodeThisString = "I am a java String";
//encode
byte[] data = Base64.encode(decodeThisString.getBytes(StandardCharsets.UTF_8), Base64.DEFAULT);
String text = new String(data, StandardCharsets.UTF_8);
//decode
byte[] datas = Base64.decode(text, Base64.DEFAULT);
String texts = new String(datas, StandardCharsets.UTF_8);
I am trying to encrypt a string and using the Google's Tink library.
When I call the method encrypt and the encrypted string returns something like \<Ï~ß¾Ò0ÑP[oxRæ±E*;ÑRÂÉD«Øô§½:î. I tried Base64.DEFAULT, UTF-8 ISO-8859-1, US-ASCI and even StandarCharset.UTF_8 and similar charsets but nothing works. Please help, here is the snippet.
...
KeysetHandle keysetHandle = KeysetHandle.generateNew(AeadKeyTemplates.AES256_GCM);
Aead aead = AeadFactory.getPrimitive(keysetHandle);
byte [] str1 = str.getBytes("UTF-8");
...
byte [] output = aead.encrypt(str1, str2);
String outputStr = new String(output, "UTF-8");
...
If you need the binary output from the encryption method as a string, you can use java.util.Base64 to encode it as such.
In practice, it would look something like:
import java.util.Base64;
...
KeysetHandle keysetHandle = KeysetHandle.generateNew(AeadKeyTemplates.AES256_GCM);
Aead aead = AeadFactory.getPrimitive(keysetHandle);
byte [] str1 = str.getBytes("UTF-8");
...
byte [] output = aead.encrypt(str1, str2);
String outputStr = Base64.getEncoder().encodeToString(output);
...
I have a string like that "QQBkADEBbgAxAXoA" I am creating a byte array of the string and using this code to convert it to string in c#.
string value = new UnicodeEncoding()).GetString(array)
I need this UnicodeEncoding in java. Is there a class that can perform it in java?
C# class UnicodeEncoding encodes on UTF-16.
String value = new String(bytes, "UTF-16LE");
The code above worked for me, since c# was using little endian representation, and Java UTF-16 is big endian.
The C# class UnicodeEncoding encodes the string using the UTF-16 encoding.
In Java you should be able to convert the bytes back to a string like this:
byte[] bytes = ...;
String value = new String(bytes, "UTF-16");
Or the other way around, convert a Java string to bytes using UTF-16 encoding:
byte[] bytes = value.getBytes("UTF-16");
How can I convert this byte[] to String :
byte[] mytest = new byte[] {100,25,28,-122,-26,94,-3,-26};
i get this : "d��^�" when I use :
new String( mytest , "UTF-8" )
Here is code java for creation of key :
m_key = new javax.crypto.spec.SecretKeySpec(new byte[] {100,25,28,-122,-26,94,-3,-26}, "DES");
Thanks.
In order to decode the byte array into something like ASCII, you need to know its original encoding. Otherwise you would need to treat it as binary.
Note: Base64 is intended for transferring binary data across networks.
I would suggest Base64 encoding your byte array. Then in your PHP code decoding the Base64 string back into a UTF-8 string.
In Java, here's how to Base64 encode your byte array and then decode it back to UTF-8:
import org.apache.commons.codec.binary.Base64;
public class MyTest {
public static void main(String[] args) throws Exception {
byte[] byteArray = new byte[] {100,25,28,-122,-26,94,-3,-26};
System.out.println("To UTF-8 string: " + new String(byteArray, "UTF-8"));
byte[] base64 = Base64.encodeBase64(byteArray);
System.out.println("To Base64 string: " + new String(base64, "UTF-8"));
byte[] decoded = Base64.decodeBase64(base64);
System.out.println("Back to UTF-8 string: " + new String(decoded, "UTF-8"));
/* the decoded byte array is the same as the original byte array */
for (int i = 0; i < decoded.length; i++) {
assert byteArray[i] == decoded[i];
}
}
}
The output from the above code is:
To UTF-8 string: d��^�
To Base64 string: ZBkchuZe/eY=
Back to UTF-8 string: d��^�
So if you wanted to use the same binary data in your PHP code, cut and paste the Base64 string into your PHP code and decode it back to UTF-8. Something like this:
<?php
$str = 'ZBkchuZe/eY=';
$key = base64_decode($str);
echo $key;
?>
I don't code in PHP, but you should be able to decode Base64 using this method:
http://php.net/manual/en/function.base64-decode.php
The above code should echo back the original binary data as UTF-8 (albeit with funny characters). The point is that the funny-looking string in the $key variable is representing the same binary data you had in the Java byte array:
d��^�
You should be able to pass the $key variable into your PHP encryption method.
with the way you are doing it makes no sense imo. you are creating a new string with the byte[] as an argument. i dont think that function is suppose to parse. so what you end up with is a lot of junk. but a little bit of googling got me this: http://www.mkyong.com/java/how-do-convert-byte-array-to-string-in-java/
Would m_key.getEncoded() give you the desired result.
Javadocs - SecretKeySpec
If not, you have to identify the Key provider that was used for the encoding (which resulted in the byte array that you have now) and decode.
I need to convert a salt value randomly generated and store it in the database. To store it in the database I converted it to a string. Then for retrieving the original value, I convert it back to byte. But both value are not matching. I have tried "UTF-8","UTF-16", BASE64Encoder.
SecureRandom ranGen = new SecureRandom();
byte[] aesKey = new byte[16]; // 16 bytes = 128 bits
ranGen.nextBytes(aesKey);
System.out.println(aesKey);
String a=new String(aesKey,"UTF-16");
byte[] b=new byte[16];
b=a.getBytes("UTF-16");
System.out.println(b);
Outputs for the above code(Executed it 2 times):
[B#11563ff
[B#1581593
and
[B#170888e
[B#11563ff
You really ought to use Base64 for converting binary data to Strings. There are lots of free implementations available, for example the one found in Apache Commons Codec.
Also, it's really easy to use, for example:
For encoding:
import org.apache.commons.codec.binary.Base64;
...
byte[] abValue = {...}; // Your data to encode
Base64 base64 = new Base64();
String strEncodedData = base64.encodeToString(abValue).trim();
For decoding:
import org.apache.commons.codec.binary.Base64;
...
String strEncodedData = "..."; // Your previously encoded data
Base64 base64 = new Base64();
byte[] abValue = base64.decode(strValue);
As your code is written above, printing aesKey and then b, what you are actually printing is the output of the toString method for an array object, which is just the default Object toString method. So I don't see how you can expect them to be the same.
If you really want to check they are the same you should compare them byte by byte.
In terms of your actual question regarding storing a byte[] as a String in the DB, your best bet is to Base64 encode it. I would suggest using the Apache Commons Codec library for this. See the user guide.
EDIT:
Using the BASE64Encode and BASE64Decoder you have referred to, the code would be like this:
SecureRandom ranGen = new SecureRandom();
byte[] aesKey = new byte[16]; // 16 bytes = 128 bits
ranGen.nextBytes(aesKey);
String a = new BASE64Encoder().encode(aesKey);
System.out.println(a);
byte[] b = new BASE64Decoder().decodeBuffer(a);
System.out.println(new BASE64Encoder().encode(b));
for (int i = 0; i < aesKey.length; i++) {
System.out.println(aesKey[i] + " " + b[i]);
}
Here, I have also looped through the bytes individually, to show that they are indeed equal.