/// <inheritdoc cref="VerifyCode(byte[], string, TotpSettings)"/>
public static bool VerifyCode(string?key, string?code, TotpSettings settings) =>
!string.IsNullOrEmpty(key) &&
!string.IsNullOrEmpty(code) &&
Base32F.FromBase32String(key).Switch(
some: k => VerifyCode(k, code, settings),
none: false
);
/// <summary>
/// Verify a code
/// </summary>
/// <param name="key">Secret key</param>
/// <param name="code">Code to be verified</param>
/// <param name="settings">TotpSettings</param>
public static bool VerifyCode(byte[] key, string code, TotpSettings settings)
{
// Generate expected code and compare it
var expected = GenerateCode(key, settings);
if (expected == code)
{
return(true);
}
else if (!settings.IntervalTolerance)
{
return(false);
}
// Generate codes either side of current interval to compare
var interval = GetCurrentInterval(settings.PeriodSeconds);
var before = GenerateCode(key, interval - 1, settings.CodeLength);
var after = GenerateCode(key, interval + 1, settings.CodeLength);
return(new[] { before, after }.Contains(code));
}
/// <summary>
/// Generate a time-based code from the specified key
/// </summary>
/// <param name="key">Secret key</param>
/// <param name="settings">TotpSettings</param>
public static string GenerateCode(byte[] key, TotpSettings settings)
{
var counter = GetCurrentInterval(settings.PeriodSeconds);
return(GenerateCode(key, counter, settings.CodeLength));
}
// Demo: Inject an instance of an AppSettingsModel class into the constructor of the consuming class,
// and let dependency injection handle the rest
public TotpController(IOptions <TotpSettings> appSettings)
{
this.AppSettings = appSettings.Value;
}
