CODEWITHSUNDEEP
c#encryptionaes
cool breeze
cool breeze

Reputation: 4811

Trying to decode an input string to Decrypt using AES

I'm working with a vendor who is supplying us with a sample AES encrypted message, we have a shared key, and I am just testing encryption/decription.

The decrypted message they are providing looks like this. Usually I would be expecting a string, but this is what they have provided:

d4 ee 84 87 f4 e2 0d c2 ef 07 e4 2c 9f b2 48 9e

  1. I'm a little confused, what kind of notation is that?

  2. My encryption/decrption method is using string as the input, and string as the output, but internally I am using a byte array:

    byte[] plainBytes = Encoding.Unicode.GetBytes(plainText);

How can I convert that above input into a byte array?

Upvotes: 0

Views: 275

Answers (2)

Crowcoder
Crowcoder

Reputation: 11514

After this code runs, theBytes will contain your byte array:

byte[] theBytes = new byte[15];
string hexstring = "d4ee8487f4e20dc2ef07e42c9fb2489e";

for (int i = 0; i < 15; i++)
{
 string thisByte = hexstring.Substring(i * 2, 2);
 int intValue = Convert.ToInt16(thisByte, 16);
 theBytes[i] = BitConverter.GetBytes(intValue)[0];
}

Upvotes: 1

Eser
Eser

Reputation: 12546

It is hexadecimal represantation of bytes

string bytes = "d4 ee 84 87 f4 e2 0d c2 ef 07 e4 2c 9f b2 48 9e";
var buf = bytes.Split(' ').Select(s => Convert.ToByte(s, 16)).ToArray();

if your hex string doesn't contain any spaces

string bytes = "d4ee8487f4e20dc2ef07e42c9fb2489e";
var buf = Regex.Matches(bytes, ".{2}").Cast<Match>()
               .Select(x => Convert.ToByte(x.Value, 16)).ToArray();

You can even use System.Runtime.Remoting.Metadata.W3cXsd2001.SoapHexBinary class that can parse hex strings with or without spaces.

string bytes = "d4ee8487f4e20dc2ef07e42c9fb2489e";
var buf = SoapHexBinary.Parse(bytes).Value;

BTW:

You should note that every byte array can not be safely converted to string by Encoding.Unicode.GetString in case you are using it.

var buf = new byte[] { 0xff, 0xff, 0xff };
string str = Encoding.Unicode.GetString(buf);
var buf2 = Encoding.Unicode.GetBytes(str);

buf2 will not be equal to buf. To convert byte arrays to string, either use Convert.ToBase64String or BitConverter.ToString

Upvotes: 3

Related Questions