/// <summary>
/// Generates several raw codes. This is used to account for counter drift across 2 generators.
/// </summary>
/// <param name="window">
/// Number of additional codes to generate in each direction. For example, a value of 2 will generate 5 codes:
/// 2 after the current value, 2 before, and one for current value. Non-positive value will use defaults of 1
/// for TOTP, and 2 for HOTP.
/// </param>
/// <param name="groupSize">Optional. Maximum number of digits per digit group.</param>
/// <returns>Enumerable of generated codes.</returns>
public IEnumerable <string> GenerateWindow(int window = 0, int groupSize = 0)
{
if (window == 0)
{
window = this.Settings.Type switch
{
ChallengeType.Time => 1,
ChallengeType.Counter => 2,
_ => 0
}
}
;
var ctr = this.Settings.GetCounterValue();
for (var i = ctr - window; i <= ctr + window; i++)
{
var number = this.GenerateNumber(value: i);
if (groupSize > 0)
{
yield return(StringCodeFormatter.FormatGroupped(number, this.Settings.Digits, groupSize));
}
else
{
yield return(StringCodeFormatter.Format(number, this.Settings.Digits));
}
}
}
/// <summary>
/// Generates one-time password.
/// </summary>
/// <param name="groupSize">Optional. Maximum number of digits per digit group.</param>
/// <param name="offset">Counter offset to use when generating.</param>
/// <returns>Generated password.</returns>
public string Generate(int groupSize = 0, int offset = 0)
{
var number = this.GenerateNumber(offset);
if (groupSize > 0)
{
return(StringCodeFormatter.FormatGroupped(number, this.Settings.Digits, groupSize));
}
else
{
return(StringCodeFormatter.Format(number, this.Settings.Digits));
}
}
/// <summary>
/// Generates one-time password.
/// </summary>
/// <param name="output">Buffer to place the generated password characters in.</param>
/// <param name="groupSize">Optional. Maximum number of digits per digit group.</param>
/// <param name="offset">Counter offset to use when generating.</param>
/// <returns>Whether the operation was successful.</returns>
public bool TryGenerate(Span <char> output, int groupSize = 0, int offset = 0)
{
if (!this.TryGenerateNumber(offset, out var number))
{
return(false);
}
if (groupSize > 0)
{
return(StringCodeFormatter.TryFormatGroupped(number, this.Settings.Digits, output, groupSize));
}
else
{
return(StringCodeFormatter.TryFormat(number, this.Settings.Digits, output));
}
}
/// <summary>
/// Generates raw, numeric one-time password.
/// </summary>
/// <param name="offset">Counter offset to use when generating.</param>
/// <returns>Generated password.</returns>
public int GenerateRaw(int offset = 0)
{
var number = this.GenerateNumber(offset);
return(StringCodeFormatter.GetRawCode(number, this.Settings.Digits));
}