ServiceCredentialsSecurityTokenManager.CreateSecurityTokenProvider Method

internal class MyServiceCredentialsSecurityTokenManager : 
    ServiceCredentialsSecurityTokenManager
{
    MyServiceCredentials credentials;

    public MyServiceCredentialsSecurityTokenManager(
        MyServiceCredentials credentials)
        : base(credentials)
    {
        this.credentials = credentials;
    }

    public override SecurityTokenProvider CreateSecurityTokenProvider(
        SecurityTokenRequirement requirement)
    {
        SecurityTokenProvider result = null;
        if (requirement.TokenType == SecurityTokenTypes.X509Certificate)
        {
            MessageDirection direction = requirement.
                GetProperty<MessageDirection>(
                ServiceModelSecurityTokenRequirement.
                MessageDirectionProperty);
            if (direction == MessageDirection.Input)
            {
                if (requirement.KeyUsage == SecurityKeyUsage.Exchange)
                {
                    result = new X509SecurityTokenProvider(
                        credentials.ServiceEncryptingCertificate);
                }
                else
                {
                    result = new X509SecurityTokenProvider(
                        credentials.ClientSigningCertificate);
                }
            }
            else
            {
                if (requirement.KeyUsage == SecurityKeyUsage.Signature)
                {
                    result = new X509SecurityTokenProvider(
                        credentials.ServiceSigningCertificate);
                }
                else
                {
                    result = new X509SecurityTokenProvider(
                        credentials.ClientEncryptingCertificate);
                }
            }
        }
        else
        {
            result = base.CreateSecurityTokenProvider(requirement);
        }
        return result;
    }
}