Question

How can you convert a byte array to a hexadecimal string and vice versa?

Answer 1

You can use Convert.ToHexString starting with .NET 5.
There’s also a method for the reverse operation: Convert.FromHexString.

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For older versions of .NET you can either use:

public static string ByteArrayToString(byte[] ba) {   StringBuilder hex = new StringBuilder(ba.Length * 2);   foreach (byte b in ba)     hex.AppendFormat("{0:x2}", b);   return hex.ToString(); } 

or:

public static string ByteArrayToString(byte[] ba) {   return BitConverter.ToString(ba).Replace("-",""); } 

There are even more variants of doing it, for example here.

The reverse conversion would go like this:

public static byte[] StringToByteArray(String hex) {   int NumberChars = hex.Length;   byte[] bytes = new byte[NumberChars / 2];   for (int i = 0; i < NumberChars; i += 2)     bytes[i / 2] = Convert.ToByte(hex.Substring(i, 2), 16);   return bytes; } 

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Using Substring is the best option in combination with Convert.ToByte. See this answer for more information. If you need better performance, you must avoid Convert.ToByte before you can drop SubString.