NSign.Client 1.0.3

NSign.Client

Middleware/handlers for the HttpClient class from the System.Net.Http namespace to help with signing of outgoing HTTP requests and verification of signatures on incoming HTTP responses.

Usage

Signing outgoing request messages

To have outgoing request messages signed, configure the middleware/handlers on an HttpClient as in the following example. Please don't forget to adapt mandatory and optional signature components as well as signature parameters to your use case.

services
    .ConfigureMessageSigningOptions(options =>
    {
        options.SignatureName = "mysig";
        options
            .WithMandatoryComponent(SignatureComponent.Method)
            .WithMandatoryComponent(SignatureComponent.RequestTargetUri)
            .WithMandatoryComponent(SignatureComponent.Scheme)
            .WithMandatoryComponent(SignatureComponent.Query)
            .WithMandatoryComponent(SignatureComponent.Digest)
            .WithMandatoryComponent(SignatureComponent.ContentType)
            .WithOptionalComponent(SignatureComponent.ContentLength)
            .SetParameters = (signatureParams) => 
            {
                signatureParams
                    .WithCreatedNow()
                    .WithExpires(TimeSpan.FromMinutes(5))
                    .WithNonce(Guid.NewGuid().ToString("N"))
                    .WithTag("my-signature")
                    ;
            };
    })
    .AddHttpClient<IMyService, MyServiceImpl>("MyService")
    .AddSigningHandler()
    ;

You will also need to configure a signature provider that actually signs the requests. See NSign.SignatureProviders for currently available standard implemenations. It is important to register the signature provider through the ISigner interface, for instance:

services
    .AddSingleton<ISigner>(new RsaPssSha512SignatureProvider(
        new X509Certificate2(@"path\to\certificate.pfx", "PasswordForPfx"),
        "my-cert"))
    ;

NOTE: The signature provider must have access to the private key when asymmetric signatures are used. It must have access to the shared key when symmetric signatures are used.

Verifying signatures on response messages

To have incoming response messages' signatures verified, configure the middleware/handlers on an HttpClient as in the following example. Please don't forget to adapt required signature components as well as signature parameters to your use case. Also make sure that the TagsToVerify is updated to include the tags used by the remote service to identify its signatures.

services
    .Configure<SignatureVerificationOptions>((options) =>
    {
        options.TagsToVerify.Add("remote-service-signature");
        options.RequiredSignatureComponents.Add(SignatureComponent.Status));
        options.RequiredSignatureComponents.Add(SignatureComponent.RequestTargetUri));
        options.RequiredSignatureComponents.Add(SignatureComponent.ContentType));
        options.CreatedRequired =
            options.ExpiresRequired =
            options.KeyIdRequired =
            options.AlgorithmRequired =
            options.TagRequired = true;
        options.MaxSignatureAge = TimeSpan.FromMinutes(5);
    })
    .AddHttpClient<IMyService, MyServiceImpl>("MyService")
    .AddSignatureVerificationHandler()
    ;

You will also need to configure a signature provider that actually verifies signatures on the responses. See NSign.SignatureProviders for currently available standard implemenations. It is important to register the signature provider through the IVerifier interface, for instance:

services
    .AddSingleton<IVerifier>(new RsaPssSha512SignatureProvider(
        new X509Certificate2(@"path\to\certificate.cer"),
        "my-cert"))
    ;

NOTE: The signature provider only requires access to the public key when asymmetric signatures are used. It must have access to the shared key when symmetric signatures are used.

Further Information

See also:

• NSign on github.com
• HTTP Message Signatures (RFC 9421)