Chilkat Examples

ChilkatHOMEAndroid™Classic ASPCC++C#Mono C#.NET Core C#C# UWP/WinRTDataFlexDelphi ActiveXDelphi DLLVisual FoxProJavaLianjaMFCObjective-CPerlPHP ActiveXPHP ExtensionPowerBuilderPowerShellPureBasicCkPythonChilkat2-PythonRubySQL ServerSwift 2Swift 3,4,5...TclUnicode CUnicode C++Visual Basic 6.0VB.NETVB.NET UWP/WinRTVBScriptXojo PluginNode.jsExcelGo

C# UWP/WinRT Examples

Web API Categories

ASN.1
Amazon EC2
Amazon Glacier
Amazon S3
Amazon S3 (new)
Amazon SES
Amazon SNS
Amazon SQS
Azure Cloud Storage
Azure Service Bus
Azure Table Service
Base64
Bounced Email
Box
CAdES
CSR
CSV
Certificates
Compression
DKIM / DomainKey
DSA
Diffie-Hellman
Digital Signatures
Dropbox
Dynamics CRM
EBICS
ECC
Ed25519
Email Object
Encryption
FTP
FileAccess
Firebase
GMail REST API
GMail SMTP/IMAP/POP
Geolocation
Google APIs
Google Calendar
Google Cloud SQL
Google Cloud Storage
Google Drive
Google Photos
Google Sheets
Google Tasks
Gzip
HTML-to-XML/Text
HTTP

HTTP Misc
IMAP
JSON
JSON Web Encryption (JWE)
JSON Web Signatures (JWS)
JSON Web Token (JWT)
Java KeyStore (JKS)
MHT / HTML Email
MIME
MS Storage Providers
Microsoft Graph
NTLM
OAuth1
OAuth2
OIDC
Office365
OneDrive
OpenSSL
Outlook
Outlook Calendar
Outlook Contact
PDF Signatures
PEM
PFX/P12
PKCS11
POP3
PRNG
REST
REST Misc
RSA
SCP
SCard
SFTP
SMTP
SSH
SSH Key
SSH Tunnel
ScMinidriver
SharePoint
Socket/SSL/TLS
Spider
Stream
Tar Archive
Upload
WebSocket
XAdES
XML
XML Digital Signatures
XMP
Zip
curl

 

 

 

(C# UWP/WinRT) Verify Signature of Alexa Custom Skill Request

This example verifies the signature of an Alexa Custom Skill Request.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads

Chilkat for the Universal Windows Platform (UWP)

// This example assumes you have a web service that will receive requests from Alexa.
// A sample request sent by Alexa will look like the following:

// Connection: Keep-Alive
// Content-Length: 2583
// Content-Type: application/json; charset=utf-8
// Accept: application/json
// Accept-Charset: utf-8
// Host: your.web.server.com
// User-Agent: Apache-HttpClient/4.5.x (Java/1.8.0_172)
// Signature: dSUmPwxc9...aKAf8mpEXg==
// SignatureCertChainUrl: https://s3.amazonaws.com/echo.api/echo-api-cert-6-ats.pem
// 
// {"version":"1.0","session":{"new":true,"sessionId":"amzn1.echo-api.session.433 ... }}

// First, assume we've written code to get the 3 pieces of data we need:
string signature = "dSUmPwxc9...aKAf8mpEXg==";
string certChainUrl = "https://s3.amazonaws.com/echo.api/echo-api-cert-6-ats.pem";
string jsonBody = "{\"version\":\"1.0\",\"session\":{\"new\":true,\"sessionId\":\"amzn1.echo-api.session.433 ... }}";

// To validate the signature, we do the following:

// First, download the PEM-encoded X.509 certificate chain that Alexa used to sign the message 
Chilkat.Http http = new Chilkat.Http();
Chilkat.StringBuilder sbPem = new Chilkat.StringBuilder();
bool success = await http.QuickGetSbAsync(certChainUrl,sbPem);
if (success == false) {
    Debug.WriteLine(http.LastErrorText);
    return;
}

Chilkat.Pem pem = new Chilkat.Pem();
success = await pem.LoadPemAsync(sbPem.GetAsString(),"passwordNotUsed");
if (success == false) {
    Debug.WriteLine(pem.LastErrorText);
    return;
}

// The 1st certificate should be the signing certificate.
Chilkat.Cert cert = pem.GetCert(0);
if (pem.LastMethodSuccess == false) {
    Debug.WriteLine(pem.LastErrorText);
    return;
}

// Get the public key from the cert.
Chilkat.PublicKey pubKey = cert.ExportPublicKey();
if (cert.LastMethodSuccess == false) {
    Debug.WriteLine(cert.LastErrorText);

    return;
}

// Use the public key extracted from the signing certificate to decrypt the encrypted signature to produce the asserted hash value.
Chilkat.Rsa rsa = new Chilkat.Rsa();
success = rsa.ImportPublicKeyObj(pubKey);
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);

    return;
}

// RSA "decrypt" the signature.
// (Amazon's documentation is confusing, because we're simply verifiying the signature against the SHA-1 hash
// of the request body.  This happens in a single call to VerifyStringENC...)
rsa.EncodingMode = "base64";
bool bVerified = rsa.VerifyStringENC(jsonBody,"sha1",signature);
if (bVerified == true) {
    Debug.WriteLine("The signature is verified against the JSON body of the request. Yay!");
}
else {
    Debug.WriteLine("Sorry, not verified.  Crud!");
}


 

© 2000-2022 Chilkat Software, Inc. All Rights Reserved.