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

Dim success As Boolean

// 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-----

Dim strPrivateKey As String
strPrivateKey = "MC4CAQAwBQYDK2VwBCIEIJ+DYvh6SEqVTm50DFtMDoQikTmiCqirVv9mWG9qfSnF"

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

Dim strPublicKey As String
strPublicKey = "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:
Dim strJwe As String
strJwe = "eyJ6aXAiOiJERUYiLCJlbmMiOiJBMjU2R0NNIiwidGFnIjoiSXh2dVRMb0FLS0hlS0Zoa3BxQ05CUSIsImFsZyI6IkEyNTZHQ01LVyIsIml2IjoiaFd3YjNoczk2QzEyOTNucCJ9.2o02pR9SoTF4g_5qRXZm6tF4H52TarilIAKxoVUqjd8.3qaF0KJN-rFHHm_P.AMUAe9PPduew09mANIZ-O_68CCuv6EIx096rm9WyLZnYz5N1WFDQ3jP0RBkbaOtQZHImMSPXIHVaB96RWshLuJsUgCKmTAwkPVCZv3zhLxZVxMXtPUuJ-ppVmPIv0NzznWCOU5Kvb9Xux7ZtnlvLXgwOFEix-BaWNomUAazbsrUCbrp514GIea3butbyxXLNi6R9TJUNh8V2uan-optT1MMyS7eMQnVGL5rYBULk.9K5ucUqAu0DqkkhgubsHHw"

Dim sbBody As New Chilkat.StringBuilder
success = sbBody.Append("{""hello"": ""world""}")

System.DebugLog("Body of request:")
System.DebugLog(sbBody.GetAsString())

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

Dim sbSigBase As New Chilkat.StringBuilder

success = sbSigBase.Append("""content-digest"": sha-256=:")
success = sbSigBase.Append(sbBody.GetHash("sha256","base64","utf-8"))
success = sbSigBase.Append(":" + EndOfLine.Unix)

success = sbSigBase.Append("""x-ebay-signature-key"": ")
success = sbSigBase.Append(strJwe)
success = sbSigBase.Append(EndOfLine.Unix)

success = sbSigBase.Append("""@method"": POST" + EndOfLine.Unix)

// This is the path part of the URL without query params...
success = sbSigBase.Append("""@path"": ")
success = sbSigBase.Append("/verifysignature")
success = sbSigBase.Append(EndOfLine.Unix)

// 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".
success = sbSigBase.Append("""@authority"": ")
success = sbSigBase.Append("localhost:8080")
success = sbSigBase.Append(EndOfLine.Unix)

success = sbSigBase.Append("""@signature-params"": ")

Dim sbSigInput As New Chilkat.StringBuilder
success = sbSigInput.Append("(""content-digest"" ""x-ebay-signature-key"" ""@method"" ""@path"" ""@authority"")")
success = sbSigInput.Append(";created=")

Dim dt As New Chilkat.CkDateTime
success = dt.SetFromCurrentSystemTime()
Dim unixTimeNow As String
unixTimeNow = dt.GetAsUnixTimeStr(False)
success = sbSigInput.Append(unixTimeNow)

success = sbSigBase.AppendSb(sbSigInput)

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

Dim bdPrivKey As New Chilkat.BinData
success = bdPrivKey.AppendEncoded(strPrivateKey,"base64")

Dim privKey As New Chilkat.PrivateKey
success = privKey.LoadAnyFormat(bdPrivKey,"")
If (success = False) Then
    System.DebugLog(privKey.LastErrorText)
    Return
End If

Dim bdToBeSigned As New Chilkat.BinData
success = bdToBeSigned.AppendSb(sbSigBase,"utf-8")

Dim eddsa As New Chilkat.EdDSA
Dim sigBase64 As String
sigBase64 = eddsa.SignBdENC(bdToBeSigned,"base64",privKey)
If (eddsa.LastMethodSuccess = False) Then
    System.DebugLog(eddsa.LastErrorText)
    Return
End If

System.DebugLog("sigBase64:")
System.DebugLog(sigBase64)

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

Dim http As New Chilkat.Http

http.SetRequestHeader "x-ebay-signature-key",strJwe

Dim sbContentDigestHdr As New Chilkat.StringBuilder
success = sbContentDigestHdr.Append("sha-256=:")
success = sbContentDigestHdr.Append(sbBody.GetHash("sha256","base64","utf-8"))
success = sbContentDigestHdr.Append(":")
http.SetRequestHeader "Content-Digest",sbContentDigestHdr.GetAsString()

Dim sbSigHdr As New Chilkat.StringBuilder
success = sbSigHdr.Append("sig1=:")
success = sbSigHdr.Append(sigBase64)
success = sbSigHdr.Append(":")
http.SetRequestHeader "Signature",sbSigHdr.GetAsString()

success = sbSigInput.Prepend("sig1=")
http.SetRequestHeader "Signature-Input",sbSigInput.GetAsString()

// Add this header to make eBay actually check the signature.
http.SetRequestHeader "x-ebay-enforce-signature","true"

// Set the OAuth2 access token to add the "Authorization: Bearer <access_token>" to the header.
http.AuthToken = "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.
Dim url As String
url = "http://localhost:8080/verifysignature"

Dim resp As Chilkat.HttpResponse
resp = http.PostJson2("http://localhost:8080/verifysignature","application/json",sbBody.GetAsString())
If (http.LastMethodSuccess = False) Then
    System.DebugLog(http.LastErrorText)
    Return
End If

System.DebugLog("Response status code: " + Str(resp.StatusCode))
System.DebugLog("Response body:")
System.DebugLog(resp.BodyStr)