(.NET Core C#) Ibanity HTTP Signature for XS2A, Isabel Connect, Ponto Connect

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Demonstrates how to add a Signature header for Ibanity HTTP requests.

For more information, see https://documentation.ibanity.com/http-signature

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// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

bool success;

// In order to sign your HTTP requests, you have to add 2 headers to the HTTP request: Digest: the digest of the request payload and Signature: the actual signature of the request. 

// POST /xs2a/customer-access-tokens HTTP/1.1
// Host: api.ibanity.com
// Content-Type: application/json
// Digest: SHA-512=z4PhNX7vuL3xVChQ1m2AB9Yg5AULVxXcg/SpIdNs6c5H0NE8XYXysP+DGNKHfuwvY7kxvUdBeoGlODJ6+SfaPg==
// Ibanity-Idempotency-Key: 61f02718-eeee-46e1-b5eb-e8fd6e799c2d
// Signature: keyId="62f02718-eeee-46e1-b5eb-e8fd6e799c2e",created=1599659223,algorithm="hs2019",headers="(request-target) host digest (created) ibanity-idempotency-key",signature="SjWJWbWN7i0...zsbM="
// 
// {"data":{"type":"customerAccessToken", "attributes":{"applicationCustomerReference":"15874569"}}}

// The payload (body) of the above HTTP request is the JSON.
// Build the JSON above.
// Use this online tool to generate code from sample JSON: 
// Generate Code to Create JSON
Chilkat.JsonObject json = new Chilkat.JsonObject();
json.UpdateString("data.type","customerAccessToken");
json.UpdateString("data.attributes.applicationCustomerReference","15874569");

string payload = json.Emit();
Debug.WriteLine("payload = " + payload);

// Step 1: Build the (created) virtual header

Chilkat.CkDateTime dtNow = new Chilkat.CkDateTime();
dtNow.SetFromCurrentSystemTime();
string created = dtNow.GetAsUnixTimeStr(false);
Debug.WriteLine("created = " + created);

// Step 2: Build the Digest header
Chilkat.Crypt2 crypt = new Chilkat.Crypt2();
crypt.HashAlgorithm = "sha512";
crypt.EncodingMode = "base64";
crypt.Charset = "utf-8";

Chilkat.StringBuilder sbDigestHdrValue = new Chilkat.StringBuilder();
sbDigestHdrValue.Append("SHA-512=");
sbDigestHdrValue.Append(crypt.HashStringENC(json.Emit()));

Debug.WriteLine(sbDigestHdrValue.GetAsString());

// Step 3: Build the (request target) virtual header

// In order to build the signature you will need a virtual header named (request-target) (the parentheses are important). 
// The (request-target) is the string concatenation of the HTTP method (in lowercase) with the path and query parameters.
string request_target = "post /xs2a/customer-access-tokens";

// Step 4: Build the signing string

// The signing string is the concatenation of the signed header names (in lowercase) and values separated by a LF.

// You must always sign the following headers: (request-target), host, (created), digest. 
// If used, you must also sign the authorization header and any ibanity-* headers, such as ibanity-idempotency-key. 

Chilkat.StringBuilder sbSigningString = new Chilkat.StringBuilder();
sbSigningString.Append("(request-target): ");
sbSigningString.AppendLine(request_target,false);
sbSigningString.Append("host: ");
sbSigningString.AppendLine("api.ibanity.com",false);
sbSigningString.Append("digest: ");
sbSigningString.AppendLine(sbDigestHdrValue.GetAsString(),false);
sbSigningString.Append("(created): ");
sbSigningString.AppendLine(created,false);
sbSigningString.Append("ibanity-idempotency-key: ");
string idempotencyKey = crypt.GenerateUuid();
sbSigningString.Append(idempotencyKey);

// Step 5: Build the signed headers list

// To allow Ibanity to check the signed headers, you must provide a list of the header names. They should be lowercase and in the same order used to create the signing string. 
string signed_headers_list = "(request-target) host digest (created) ibanity-idempotency-key";

// Step 6: Build the Signature header

// This is where the real signing happens. The signature header is a combination of several sub-headers -
// 
//     keyId: the identifier for the application's signature certificate, obtained from the Developer Portal
//     algorithm: the digital signature algorithm used to generate the signature (must be hs2019)
//     headers: The list of HTTP headers created in step 5
//     signature: the Base64-encoded digital signature of the signing string created in step 4.

Chilkat.PrivateKey privKey = new Chilkat.PrivateKey();
success = privKey.LoadEncryptedPemFile("my_ibanity_signature_private_key.pem","pem_password");
if (success == false) {
    Debug.WriteLine(privKey.LastErrorText);
    return;
}

Chilkat.Rsa rsa = new Chilkat.Rsa();
rsa.PssSaltLen = 32;
rsa.EncodingMode = "base64";
// Use the RSASSA-PSS signature algorithm
rsa.OaepPadding = true;

success = rsa.ImportPrivateKeyObj(privKey);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

// Sign the signing string.
string sigBase64 = rsa.SignStringENC(sbSigningString.GetAsString(),"sha-256");
if (rsa.LastMethodSuccess == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

// Build the signature header value.
Chilkat.StringBuilder sbSigHeaderValue = new Chilkat.StringBuilder();
sbSigHeaderValue.Append("keyId=\"");
// Use your identifier for the application's signature certificate, obtained from the Developer Portal
sbSigHeaderValue.Append("62f02718-eeee-46e1-b5eb-e8fd6e799c2e");
sbSigHeaderValue.Append("\",created=");
sbSigHeaderValue.Append(created);
sbSigHeaderValue.Append(",algorithm=\"hs2019\",headers=\"");
sbSigHeaderValue.Append(signed_headers_list);
sbSigHeaderValue.Append("\",signature=\"");
sbSigHeaderValue.Append(sigBase64);
sbSigHeaderValue.Append("\"");

Debug.WriteLine(sbSigHeaderValue.GetAsString());