/// <summary>
/// Looks up the value to be used for the openid.session_type parameter.
/// </summary>
/// <param name="protocol">The protocol version that is to be used.</param>
/// <param name="hashSizeInBits">The hash size (in bits) that the DH session must have.</param>
/// <returns>The value to be used for the openid.session_type parameter, or null if no match was found.</returns>
internal static string GetNameForSize(Protocol protocol, int hashSizeInBits)
{
Requires.NotNull(protocol, "protocol");
DHSha match = diffieHellmanSessionTypes.FirstOrDefault(dhsha => dhsha.Algorithm.HashSize == hashSizeInBits);
return(match != null?match.GetName(protocol) : null);
}
/// <summary>
/// Looks up the value to be used for the openid.session_type parameter.
/// </summary>
/// <param name="protocol">The protocol version that is to be used.</param>
/// <param name="hashSizeInBits">The hash size (in bits) that the DH session must have.</param>
/// <returns>The value to be used for the openid.session_type parameter, or null if no match was found.</returns>
internal static string GetNameForSize(Protocol protocol, int hashSizeInBits)
{
Contract.Requires <ArgumentNullException>(protocol != null);
DHSha match = diffieHellmanSessionTypes.FirstOrDefault(dhsha => dhsha.Algorithm.HashSize == hashSizeInBits);
return(match != null?match.GetName(protocol) : null);
}
/// <summary>
/// Finds the hashing algorithm to use given an openid.session_type value.
/// </summary>
/// <param name="protocol">The protocol version of the message that named the session_type to be used.</param>
/// <param name="sessionType">The value of the openid.session_type parameter.</param>
/// <returns>The hashing algorithm to use.</returns>
/// <exception cref="ProtocolException">Thrown if no match could be found for the given <paramref name="sessionType"/>.</exception>
public static HashAlgorithm Lookup(Protocol protocol, string sessionType)
{
Requires.NotNull(protocol, "protocol");
Requires.NotNull(sessionType, "sessionType");
// We COULD use just First instead of FirstOrDefault, but we want to throw ProtocolException instead of InvalidOperationException.
DHSha match = diffieHellmanSessionTypes.FirstOrDefault(dhsha => string.Equals(dhsha.GetName(protocol), sessionType, StringComparison.Ordinal));
ErrorUtilities.VerifyProtocol(match != null, OpenIdStrings.NoSessionTypeFound, sessionType, protocol.Version);
return(match.Algorithm);
}
