Visual Basic 6.0

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

See more OpenSSL Examples

Demonstrates how to duplicate this OpenSSL command:

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

The in.dat file contains the original data that was signed, and can contain text or binary data of any type. The above OpenSSL command does the following:

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

Visual Basic 6.0

Dim success As Long
success = 0

' 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:
success = pubKey.LoadFromFile("pubKey.pem")
If (success = 0) 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.UsePublicKey(pubKey)
If (success = 0) 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."