(Unicode C) ebay: Add Digital Signature to HTTP Request

See more eBay Examples

Demonstrates how to add a digital signature to an ebay HTTP request.

For more information, see https://developer.ebay.com/develop/guides/digital-signatures-for-apis

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#include <C_CkStringBuilderW.h>
#include <C_CkDateTimeW.h>
#include <C_CkBinDataW.h>
#include <C_CkPrivateKeyW.h>
#include <C_CkEdDSAW.h>
#include <C_CkHttpW.h>
#include <C_CkHttpResponseW.h>

void ChilkatSample(void)
    {
    BOOL success;
    const wchar_t *strPrivateKey;
    const wchar_t *strPublicKey;
    const wchar_t *strJwe;
    HCkStringBuilderW sbBody;
    HCkStringBuilderW sbSigBase;
    HCkStringBuilderW sbSigInput;
    HCkDateTimeW dt;
    const wchar_t *unixTimeNow;
    HCkBinDataW bdPrivKey;
    HCkPrivateKeyW privKey;
    HCkBinDataW bdToBeSigned;
    HCkEdDSAW eddsa;
    const wchar_t *sigBase64;
    HCkHttpW http;
    HCkStringBuilderW sbContentDigestHdr;
    HCkStringBuilderW sbSigHdr;
    const wchar_t *url;
    HCkHttpResponseW resp;

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

    // Note: Ebay provides a Key Management API
    // See https://developer.ebay.com/api-docs/developer/key-management/overview.html

    // The following test keys can be used: 
    // 
    // Ed25519 
    // 
    // Private Key:
    // 
    // -----BEGIN PRIVATE KEY-----
    // MC4CAQAwBQYDK2VwBCIEIJ+DYvh6SEqVTm50DFtMDoQikTmiCqirVv9mWG9qfSnF
    // -----END PRIVATE KEY-----

    strPrivateKey = L"MC4CAQAwBQYDK2VwBCIEIJ+DYvh6SEqVTm50DFtMDoQikTmiCqirVv9mWG9qfSnF";

    // 
    // Public Key:
    // 
    // -----BEGIN PUBLIC KEY-----
    // MCowBQYDK2VwAyEAJrQLj5P/89iXES9+vFgrIy29clF9CC/oPPsw3c5D0bs=
    // -----END PUBLIC KEY-----

    strPublicKey = L"MCowBQYDK2VwAyEAJrQLj5P/89iXES9+vFgrIy29clF9CC/oPPsw3c5D0bs=";

    // This example assumes you got a JWE for your given private key from the Ebay Key Management REST API.
    // This JWE is just for example:
    strJwe = L"eyJ6aXAiOiJERUYiLCJlbmMiOiJBMjU2R0NNIiwidGFnIjoiSXh2dVRMb0FLS0hlS0Zoa3BxQ05CUSIsImFsZyI6IkEyNTZHQ01LVyIsIml2IjoiaFd3YjNoczk2QzEyOTNucCJ9.2o02pR9SoTF4g_5qRXZm6tF4H52TarilIAKxoVUqjd8.3qaF0KJN-rFHHm_P.AMUAe9PPduew09mANIZ-O_68CCuv6EIx096rm9WyLZnYz5N1WFDQ3jP0RBkbaOtQZHImMSPXIHVaB96RWshLuJsUgCKmTAwkPVCZv3zhLxZVxMXtPUuJ-ppVmPIv0NzznWCOU5Kvb9Xux7ZtnlvLXgwOFEix-BaWNomUAazbsrUCbrp514GIea3butbyxXLNi6R9TJUNh8V2uan-optT1MMyS7eMQnVGL5rYBULk.9K5ucUqAu0DqkkhgubsHHw";

    sbBody = CkStringBuilderW_Create();
    CkStringBuilderW_Append(sbBody,L"{\"hello\": \"world\"}");

    wprintf(L"Body of request:\n");
    wprintf(L"%s\n",CkStringBuilderW_getAsString(sbBody));

    // -------------------------------------------------
    // Build the signature base string...

    sbSigBase = CkStringBuilderW_Create();

    CkStringBuilderW_Append(sbSigBase,L"\"content-digest\": sha-256=:");
    CkStringBuilderW_Append(sbSigBase,CkStringBuilderW_getHash(sbBody,L"sha256",L"base64",L"utf-8"));
    CkStringBuilderW_Append(sbSigBase,L":\n");

    CkStringBuilderW_Append(sbSigBase,L"\"x-ebay-signature-key\": ");
    CkStringBuilderW_Append(sbSigBase,strJwe);
    CkStringBuilderW_Append(sbSigBase,L"\n");

    CkStringBuilderW_Append(sbSigBase,L"\"@method\": POST\n");

    // This is the path part of the URL without query params...
    CkStringBuilderW_Append(sbSigBase,L"\"@path\": ");
    CkStringBuilderW_Append(sbSigBase,L"/verifysignature");
    CkStringBuilderW_Append(sbSigBase,L"\n");

    // The is the domain, such as "api.ebay.com" w/ port if the port is something unusual.
    // In this example, we're testing against a local docker test server (see the info at https://developer.ebay.com/develop/guides/digital-signatures-for-apis)
    // Normally, I think it would just be "api.ebay.com" instead of "localhost:8080".
    CkStringBuilderW_Append(sbSigBase,L"\"@authority\": ");
    CkStringBuilderW_Append(sbSigBase,L"localhost:8080");
    CkStringBuilderW_Append(sbSigBase,L"\n");

    CkStringBuilderW_Append(sbSigBase,L"\"@signature-params\": ");

    sbSigInput = CkStringBuilderW_Create();
    CkStringBuilderW_Append(sbSigInput,L"(\"content-digest\" \"x-ebay-signature-key\" \"@method\" \"@path\" \"@authority\")");
    CkStringBuilderW_Append(sbSigInput,L";created=");

    dt = CkDateTimeW_Create();
    CkDateTimeW_SetFromCurrentSystemTime(dt);
    unixTimeNow = CkDateTimeW_getAsUnixTimeStr(dt,FALSE);
    CkStringBuilderW_Append(sbSigInput,unixTimeNow);

    CkStringBuilderW_AppendSb(sbSigBase,sbSigInput);

    // -------------------------------------------------
    // Sign the signature base string using the Ed25519 private key

    bdPrivKey = CkBinDataW_Create();
    CkBinDataW_AppendEncoded(bdPrivKey,strPrivateKey,L"base64");

    privKey = CkPrivateKeyW_Create();
    success = CkPrivateKeyW_LoadAnyFormat(privKey,bdPrivKey,L"");
    if (success == FALSE) {
        wprintf(L"%s\n",CkPrivateKeyW_lastErrorText(privKey));
        CkStringBuilderW_Dispose(sbBody);
        CkStringBuilderW_Dispose(sbSigBase);
        CkStringBuilderW_Dispose(sbSigInput);
        CkDateTimeW_Dispose(dt);
        CkBinDataW_Dispose(bdPrivKey);
        CkPrivateKeyW_Dispose(privKey);
        return;
    }

    bdToBeSigned = CkBinDataW_Create();
    CkBinDataW_AppendSb(bdToBeSigned,sbSigBase,L"utf-8");

    eddsa = CkEdDSAW_Create();
    sigBase64 = CkEdDSAW_signBdENC(eddsa,bdToBeSigned,L"base64",privKey);
    if (CkEdDSAW_getLastMethodSuccess(eddsa) == FALSE) {
        wprintf(L"%s\n",CkEdDSAW_lastErrorText(eddsa));
        CkStringBuilderW_Dispose(sbBody);
        CkStringBuilderW_Dispose(sbSigBase);
        CkStringBuilderW_Dispose(sbSigInput);
        CkDateTimeW_Dispose(dt);
        CkBinDataW_Dispose(bdPrivKey);
        CkPrivateKeyW_Dispose(privKey);
        CkBinDataW_Dispose(bdToBeSigned);
        CkEdDSAW_Dispose(eddsa);
        return;
    }

    wprintf(L"sigBase64:\n");
    wprintf(L"%s\n",sigBase64);

    // ----------------------------------------------------------
    // Send the JSON POST

    http = CkHttpW_Create();

    CkHttpW_SetRequestHeader(http,L"x-ebay-signature-key",strJwe);

    sbContentDigestHdr = CkStringBuilderW_Create();
    CkStringBuilderW_Append(sbContentDigestHdr,L"sha-256=:");
    CkStringBuilderW_Append(sbContentDigestHdr,CkStringBuilderW_getHash(sbBody,L"sha256",L"base64",L"utf-8"));
    CkStringBuilderW_Append(sbContentDigestHdr,L":");
    CkHttpW_SetRequestHeader(http,L"Content-Digest",CkStringBuilderW_getAsString(sbContentDigestHdr));

    sbSigHdr = CkStringBuilderW_Create();
    CkStringBuilderW_Append(sbSigHdr,L"sig1=:");
    CkStringBuilderW_Append(sbSigHdr,sigBase64);
    CkStringBuilderW_Append(sbSigHdr,L":");
    CkHttpW_SetRequestHeader(http,L"Signature",CkStringBuilderW_getAsString(sbSigHdr));

    CkStringBuilderW_Prepend(sbSigInput,L"sig1=");
    CkHttpW_SetRequestHeader(http,L"Signature-Input",CkStringBuilderW_getAsString(sbSigInput));

    // Add this header to make eBay actually check the signature.
    CkHttpW_SetRequestHeader(http,L"x-ebay-enforce-signature",L"true");

    // Set the OAuth2 access token to add the "Authorization: Bearer <access_token>" to the header.
    CkHttpW_putAuthToken(http,L"your_oauth2_access_token");

    // The signature base string constructed above is valid if we send this POST to "http://localhost:8080/verifysignature"
    // Normally, you'll send your POST to some api.ebay.com endpoint.
    url = L"http://localhost:8080/verifysignature";

    resp = CkHttpW_PostJson2(http,L"http://localhost:8080/verifysignature",L"application/json",CkStringBuilderW_getAsString(sbBody));
    if (CkHttpW_getLastMethodSuccess(http) == FALSE) {
        wprintf(L"%s\n",CkHttpW_lastErrorText(http));
        CkStringBuilderW_Dispose(sbBody);
        CkStringBuilderW_Dispose(sbSigBase);
        CkStringBuilderW_Dispose(sbSigInput);
        CkDateTimeW_Dispose(dt);
        CkBinDataW_Dispose(bdPrivKey);
        CkPrivateKeyW_Dispose(privKey);
        CkBinDataW_Dispose(bdToBeSigned);
        CkEdDSAW_Dispose(eddsa);
        CkHttpW_Dispose(http);
        CkStringBuilderW_Dispose(sbContentDigestHdr);
        CkStringBuilderW_Dispose(sbSigHdr);
        return;
    }

    wprintf(L"Response status code: %d\n",CkHttpResponseW_getStatusCode(resp));
    wprintf(L"Response body:\n");
    wprintf(L"%s\n",CkHttpResponseW_bodyStr(resp));

    CkHttpResponseW_Dispose(resp);


    CkStringBuilderW_Dispose(sbBody);
    CkStringBuilderW_Dispose(sbSigBase);
    CkStringBuilderW_Dispose(sbSigInput);
    CkDateTimeW_Dispose(dt);
    CkBinDataW_Dispose(bdPrivKey);
    CkPrivateKeyW_Dispose(privKey);
    CkBinDataW_Dispose(bdToBeSigned);
    CkEdDSAW_Dispose(eddsa);
    CkHttpW_Dispose(http);
    CkStringBuilderW_Dispose(sbContentDigestHdr);
    CkStringBuilderW_Dispose(sbSigHdr);

    }