(VB.NET) Sign JSON (or any Text) to Create a Detached PKCS7 Signature

Demonstrates how to sign JSON or any string using a certificate + private key from a .p12/.pfx to create a detached PKCS7 signature. (A detached signature is one that does not embed the original signed data.)

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

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

Dim crypt As New Chilkat.Crypt2

Dim cert As New Chilkat.Cert
Dim success As Boolean = cert.LoadPfxFile("qa_data/pfx/cert_test123.pfx","test123")
If (success <> True) Then
    Debug.WriteLine(cert.LastErrorText)
    Exit Sub
End If


' Tell the crypt component to use this cert.
success = crypt.SetSigningCert(cert)
If (success <> True) Then
    Debug.WriteLine(crypt.LastErrorText)
    Exit Sub
End If



crypt.HashAlgorithm = "sha256"

' By default, all the certs in the chain of authentication are included in the signature.
' If desired, we can choose to only include the signing certificate:
crypt.IncludeCertChain = False

' Create the detached signature, which does NOT contain the original data.
' To create a PKCS7 signature that contains the original data, see CAdES Sign JSON
crypt.Charset = "utf-8"
Dim detachedSig() As Byte
Dim stringToSign As String = "{ ""abc"": 123}"
detachedSig = crypt.SignString(stringToSign)
If (crypt.LastMethodSuccess = False) Then
    Debug.WriteLine(crypt.LastErrorText)
    Exit Sub
End If


' Verify the signature against the original data.
Dim verified As Boolean = crypt.VerifyString(stringToSign,detachedSig)
If (verified = False) Then
    Debug.WriteLine(crypt.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("Success!")