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

Excel 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

 

 

 

(Excel) ECDSA Sign and Verify

Demonstrates how to create an ECDSA signature on the SHA256 hash of some data, and then verify.

Download Excel Class Modules

Chilkat Excel Class Modules

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

' First load an ECDSA private key to be used for signing.
Dim privKey As Chilkat.PrivateKey
Set privKey = Chilkat.NewPrivateKey

success = privKey.LoadEncryptedPemFile("qa_data/ecc/secp256r1-key-pkcs8-secret.pem","secret")
If (success = False) Then
    Debug.Print privKey.LastErrorText
    Exit Sub
End If

' Sign the SHA256 hash of some data.
Dim bd As Chilkat.BinData
Set bd = Chilkat.NewBinData
success = bd.LoadFile("qa_data/hamlet.xml")
If (success = False) Then
    Debug.Print "Failed to load file to be hashed."
    Exit Sub
End If

Dim crypt As Chilkat.Crypt2
Set crypt = Chilkat.NewCrypt2
crypt.HashAlgorithm = "sha256"
crypt.EncodingMode = "base64"

hashStr = crypt.HashBdENC(bd)

Dim ecdsa As Chilkat.Ecc
Set ecdsa = Chilkat.NewEcc
Dim prng As Chilkat.Prng
Set prng = Chilkat.NewPrng
' Returns ASN.1 signature as a base64 string.

sig = ecdsa.SignHashENC(hashStr,"base64",privKey,prng)
Debug.Print "sig = "; sig

' The signature is in ASN.1 format (which may be described as the "encoded DSS signature").
' SEQUENCE (2 elem)
'   INTEGER (255 bit) 4849395540832462044300553275435608522154141569743642905628579547100940...
'   INTEGER (255 bit) 3680701124244788134409868118208591399799457104230118295614152238560005...

' If you wish, you can get the r and s components of the signature like this:
Dim asn As Chilkat.Asn
Set asn = Chilkat.NewAsn
Dim success As Boolean
success = asn.LoadEncoded(sig,"base64")
Dim xml As Chilkat.Xml
Set xml = Chilkat.NewXml
success = xml.LoadXml(asn.AsnToXml())

Debug.Print xml.GetXml()

' We now have this:
' <?xml version="1.0" encoding="utf-8"?>
' <sequence>
'     <int>6650D422D86BA4A228B5617604E59052591B9B2C32EF324C44D09EF67E5F0060</int>
'     <int>0CFD9F6AC85042FC70F672C141BA6B2A4CAFBB906C3D907BCCC1BED62B28326F</int>
' </sequence>

' Get the "r" and "s" as hex strings

r = xml.GetChildContentByIndex(0)

s = xml.GetChildContentByIndex(1)

Debug.Print "r = "; r
Debug.Print "s = "; s

' --------------------------------------------------------------------
' Now verify against the hash of the original data.

' Get the corresponding public key.
Dim pubKey As Chilkat.PublicKey
Set pubKey = Chilkat.NewPublicKey
success = pubKey.LoadFromFile("qa_data/ecc/secp256r1-pub.pem")
If (success = False) Then
    Debug.Print pubKey.LastErrorText
    Exit Sub
End If

' We already have the SHA256 hash of the original data (hashStr) so no need to re-do it..
Dim ecc2 As Chilkat.Ecc
Set ecc2 = Chilkat.NewEcc

result = ecc2.VerifyHashENC(hashStr,sig,"base64",pubKey)
If (result <> 1) Then
    Debug.Print ecc2.LastErrorText
    Exit Sub
End If

Debug.Print "Verified!"

' Note: If we have only r,s and wish to reconstruct the ASN.1 signature, we do it like this:
Dim xml2 As Chilkat.Xml
Set xml2 = Chilkat.NewXml
xml2.Tag = "sequence"
xml2.NewChild2 "int",r
xml2.NewChild2 "int",s

Dim asn2 As Chilkat.Asn
Set asn2 = Chilkat.NewAsn
success = asn2.LoadAsnXml(xml2.GetXml())

encodedSig = asn2.GetEncodedDer("base64")
Debug.Print "encoded DSS signature: "; encodedSig

' You can go to https://lapo.it/asn1js/  and copy/paste the base64 encodedSig into the online tool, then press the "decode" button.
' You will see the ASN.1 such as this:

' SEQUENCE (2 elem)
'   INTEGER (255 bit) 4849395540832462044300553275435608522154141569743642905628579547100940...
'   INTEGER (255 bit) 3680701124244788134409868118208591399799457104230118295614152238560005...

 

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