/// <summary>
/// Verify an OTP value
/// </summary>
/// <param name="initialStep">The initial step to try</param>
/// <param name="valueToVerify">The value to verify</param>
/// <param name="matchedStep">Output parameter that provides the step where the match was found. If no match was found it will be 0</param>
/// <param name="window">The window to verify</param>
/// <returns>True if a match is found</returns>
protected bool Verify(long initialStep, string valueToVerify, out long matchedStep, VerificationWindow window)
{
if (window == null)
{
window = new VerificationWindow();
}
foreach (var frame in window.ValidationCandidates(initialStep))
{
var comparisonValue = Compute(frame, hashMode);
if (ValuesEqual(comparisonValue, valueToVerify))
{
matchedStep = frame;
return(true);
}
}
matchedStep = 0;
return(false);
}
private bool VerifyTotpForSpecificTime(DateTime timestamp, string totp, VerificationWindow window, out long timeStepMatched)
{
var initialStep = CalculateTimeStepFromTimestamp(timestamp);
return(Verify(initialStep, totp, out timeStepMatched, window));
}
/// <summary>
/// Verify a value that has been provided with the calculated value
/// </summary>
/// <param name="timestamp">The timestamp to use</param>
/// <param name="totp">the trial TOTP value</param>
/// <param name="timeStepMatched">
/// This is an output parameter that gives that time step that was used to find a match.
/// This is useful in cases where a TOTP value should only be used once. This value is a unique identifier of the
/// time step (not the value) that can be used to prevent the same step from being used multiple times
/// </param>
/// <param name="window">The window of steps to verify</param>
/// <returns>True if there is a match.</returns>
public bool VerifyTotp(DateTime timestamp, string totp, out long timeStepMatched, VerificationWindow window = null)
{
return(VerifyTotpForSpecificTime(correctedTime.GetCorrectedTime(timestamp), totp, window, out timeStepMatched));
}
/// <summary>
/// Verify a value that has been provided with the calculated value.
/// </summary>
/// <remarks>
/// It will be corrected against a corrected UTC time using the provided time correction. If none was provided then simply the current UTC will be used.
/// </remarks>
/// <param name="totp">the trial TOTP value</param>
/// <param name="timeStepMatched">
/// This is an output parameter that gives that time step that was used to find a match.
/// This is useful in cases where a TOTP value should only be used once. This value is a unique identifier of the
/// time step (not the value) that can be used to prevent the same step from being used multiple times
/// </param>
/// <param name="window">The window of steps to verify</param>
/// <returns>True if there is a match.</returns>
public bool VerifyTotp(string totp, out long timeStepMatched, VerificationWindow window = null)
{
return(VerifyTotpForSpecificTime(correctedTime.CorrectedUtcNow, totp, window, out timeStepMatched));
}