Problem with copy byte[] into another byte[]

Question

I have a method to create a hashed password. However it crashes at salt.CopyTo(pwd, 0); Says that the target byte[] is too small. How do I solve the problem?

public static byte[] CreateHashedPassword(string password, byte[] salt)
        {
            SHA1 sha1 = SHA1.Create();
            byte[] pwd = CustomHelpers.StringToByteArray(password);
            salt.CopyTo(pwd, 0);
            sha1.ComputeHash(pwd);

            return pwd;            
        }

Answer 1

You need to create a longer byte array to contain both the salt and the password:

    byte[] result = new byte[salt.Length + password.Length];
    salt.CopyTo(result, 0);
    password.CopyTo(result, salt.Length);

Answer 2

How big is the salt? Are you intending to add it to the password?

Here's how to add it to the start of the password:

byte[] pwdAndSalt = new byte[pwd.Length + salt.Length];
for (int i = 0; i < pwdAndSalt.Length; i++)
{
    if (i < salt.Length)
    {
        pwdAndSalt[i] = salt[i];
    }
    else
    {
        pwdAndSalt[i] = pwd[i - salt.Length];
    }
}

Answer 3

Maybe something like this?

public static byte[] CreateHashedPassword(string password, byte[] salt) 
{ 
    SHA1 sha1 = SHA1.Create(); 
    byte[] pwd = CustomHelpers.StringToByteArray(password);
    byte[] pwdPlusSalt = new byte[salt.Length + pwd.Length];
    salt.CopyTo(pwdPlusSalt, 0); 
    pwd.CopyTo(pwdPlusSalt, salt.Length); 

    return sha1.ComputeHash(pwdPlusSalt);
}