/// <summary>
/// Generates a new transfer code.
/// </summary>
/// <param name="length">Length of the code.</param>
/// <param name="randomSource">Cryptographically safe random generator.</param>
/// <returns>New transfer code.</returns>
public static string GenerateCode(int length, ICryptoRandomService randomSource)
{
StringBuilder sb = new StringBuilder();
int remainingLength = length;
do
{
int binaryLength = (int)Math.Floor((remainingLength * 3.0 / 4.0) + 1.0);
byte[] binaryString = randomSource.GetRandomBytes(binaryLength);
// We take advantage of the fast base64 encoding
string base64String = Convert.ToBase64String(binaryString);
foreach (char letter in base64String)
{
if (UnmixableAlphabet.IsOfCorrectAlphabet(letter))
{
sb.Append(letter);
}
}
// If too many characters have been removed, we repeat the procedure
remainingLength = length - sb.Length;
}while (remainingLength > 0);
if (sb.Length > length)
{
sb.Remove(length, sb.Length - length);
}
return(sb.ToString());
}
public void TransferCodeIsOfCorrectAlphabet()
{
for (int length = 0; length < 999; length++)
{
string code = TransferCode.GenerateCode(length, CommonMocksAndStubs.CryptoRandomService());
Assert.IsTrue(UnmixableAlphabet.IsOfCorrectAlphabet(code));
}
}
public void IsOfCorrectAlphabetWorksCorrectly()
{
for (int i = 0; i < 512; i++)
{
bool evaluated = UnmixableAlphabet.IsOfCorrectAlphabet((char)i);
bool expected = IsOfCorrectAlphabet((char)i);
Assert.AreEqual(expected, evaluated);
}
}
/// <summary>
/// Tries to read unser input and brings it into a wellformed format without whitespaces.
/// </summary>
/// <param name="code">User input to validate.</param>
/// <param name="sanitizedCode">Wellformed code.</param>
/// <returns>Returns true if the user input was a valid code, otherwise false.</returns>
public static bool TrySanitizeUserInput(string code, out string sanitizedCode)
{
sanitizedCode = null;
if (string.IsNullOrWhiteSpace(code))
{
return(false);
}
// remove whitespaces
sanitizedCode = code.Replace(" ", string.Empty).Replace("-", string.Empty);
if (sanitizedCode.Length != CodeLength)
{
return(false);
}
if (!UnmixableAlphabet.IsOfCorrectAlphabet(sanitizedCode))
{
return(false);
}
return(true);
}