/// <summary>Build a URI for secret key provisioning.</summary>
/// <param name="algorithm">The hashing algorithm for the HMAC computation.</param>
/// <param name="issuer">The name of the entity issuing and maintaining the key.</param>
/// <param name="account">The account name for which the one-time codes will work.</param>
/// <param name="secret">The ASCII-encoded base32-encoded shared secret.</param>
/// <param name="counter">The initial value for the counter.</param>
/// <param name="digits">The number of digits of the one-time codes.</param>
/// <returns>The provisioning URI.</returns>
public static string GetKeyUri(
HashAlgorithm algorithm,
string issuer,
string account,
byte[] secret,
long counter,
int digits = Otp.DefaultDigits)
{
Contract.Requires <ArgumentOutOfRangeException>(Enum.IsDefined(typeof(HashAlgorithm), algorithm));
Contract.Requires <ArgumentOutOfRangeException>(algorithm != HashAlgorithm.Unknown);
Contract.Requires <ArgumentNullException>(issuer != null);
Contract.Requires <ArgumentOutOfRangeException>(!string.IsNullOrWhiteSpace(issuer));
Contract.Requires <ArgumentNullException>(account != null);
Contract.Requires <ArgumentOutOfRangeException>(!string.IsNullOrWhiteSpace(account));
Contract.Requires <ArgumentNullException>(secret != null);
Contract.Requires <ArgumentException>(secret.Length > 0);
Contract.Requires <ArgumentOutOfRangeException>(digits > 0);
Contract.Requires <ArgumentOutOfRangeException>(counter >= 0);
Contract.Ensures(!string.IsNullOrWhiteSpace(Contract.Result <string>()));
return
(Otp.GetKeyUri(
OtpType.Hotp,
issuer,
account,
secret,
algorithm,
digits,
counter,
0));
}
/// <summary>Compute the one-time code for the given parameters.</summary>
/// <param name="algorithm">The hashing algorithm for the HMAC computation.</param>
/// <param name="secret">The ASCII-encoded base32-encoded shared secret.</param>
/// <param name="datetime">The date with time for which the one-time code must be computed.</param>
/// <param name="digits">The number of digits of the one-time codes.</param>
/// <param name="period">The period step used for the HMAC counter computation.</param>
/// <returns>The one-time code for the given date.</returns>
public static int GetCode(
HashAlgorithm algorithm,
string secret,
DateTime datetime,
int digits = Otp.DefaultDigits,
int period = Totp.DefaultPeriod)
{
Contract.Requires <ArgumentOutOfRangeException>(Enum.IsDefined(typeof(HashAlgorithm), algorithm));
Contract.Requires <ArgumentOutOfRangeException>(algorithm != HashAlgorithm.Unknown);
Contract.Requires <ArgumentNullException>(secret != null);
Contract.Requires <ArgumentNullException>(datetime != null);
Contract.Requires <ArgumentException>(Enum.IsDefined(typeof(DateTimeKind), datetime.Kind));
Contract.Requires <ArgumentException>(datetime.Kind != DateTimeKind.Unspecified);
Contract.Requires <ArgumentOutOfRangeException>(digits > 0);
Contract.Requires <ArgumentOutOfRangeException>(period > 0);
Contract.Ensures(Contract.Result <int>() > 0);
Contract.Ensures(Contract.Result <int>() < Math.Pow(10, digits));
datetime = datetime.Kind == DateTimeKind.Utc ? datetime : datetime.ToUniversalTime();
var unixTime = datetime.Subtract(new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc)).TotalSeconds;
var counter = (long)(unixTime * 1000) / (period * 1000);
return(Otp.GetCode(algorithm, secret, counter, digits));
}
/// <summary>Compute the one-time code for the given parameters.</summary>
/// <param name="algorithm">The hashing algorithm for the HMAC computation.</param>
/// <param name="secret">The ASCII-encoded base32-encoded shared secret.</param>
/// <param name="counter">The counter for which the one-time code must be computed.</param>
/// <param name="digits">The number of digits of the one-time code.</param>
/// <returns>The one-time code for the given counter.</returns>
public static int GetCode(
HashAlgorithm algorithm,
string secret,
long counter,
int digits = Otp.DefaultDigits)
{
Contract.Requires <ArgumentOutOfRangeException>(Enum.IsDefined(typeof(HashAlgorithm), algorithm));
Contract.Requires <ArgumentOutOfRangeException>(algorithm != HashAlgorithm.Unknown);
Contract.Requires <ArgumentNullException>(secret != null);
Contract.Requires <ArgumentOutOfRangeException>(counter >= 0);
Contract.Requires <ArgumentOutOfRangeException>(digits > 0);
Contract.Ensures(Contract.Result <int>() > 0);
Contract.Ensures(Contract.Result <int>() < Math.Pow(10, digits));
return(Otp.GetCode(algorithm, secret, counter, digits));
}
