(Visual Basic 6.0) Duplicate openssl dgst -sha256 -verify pubKey.pem -signature signature.sig in.dat

Demonstrates how to duplicate this OpenSSL command:

openssl dgst -sha256 -verify pubKey.pem -signature signature.sig in.dat

1. Creates a SHA256 digest of the contents of the input file.
2. Verifies the SHA256 digest using the public key.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

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

Dim pubKey As New PublicKey

' Load the public key from an PEM file:
Dim success As Long
success = pubKey.LoadFromFile("pubKey.pem")
If (success <> 1) Then
    Debug.Print pubKey.LastErrorText
    Exit Sub
End If

' Load the data of the original file that was signed.
Dim bdFileData As New ChilkatBinData
success = bdFileData.LoadFile("in.dat")

' Load the signature.
Dim bdSig As New ChilkatBinData
success = bdSig.LoadFile("signature.sig")

Dim rsa As New ChilkatRsa

' Import the public key into the RSA component:
success = rsa.ImportPublicKeyObj(pubKey)
If (success <> 1) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

' OpenSSL uses big-endian.
rsa.LittleEndian = 0

success = rsa.VerifyBd(bdFileData,"sha256",bdSig)
If (success <> 1) Then
    Debug.Print rsa.LastErrorText
    Debug.Print "The signature was invalid."
    Exit Sub
End If

Debug.Print "The signature was verified."