(Xojo Plugin) 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.

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

Dim pubKey As New Chilkat.PublicKey

// Load the public key from an PEM file:
Dim success As Boolean
success = pubKey.LoadFromFile("pubKey.pem")
If (success <> True) Then
    System.DebugLog(pubKey.LastErrorText)
    Return
End If

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

// Load the signature.
Dim bdSig As New Chilkat.BinData
success = bdSig.LoadFile("signature.sig")

Dim rsa As New Chilkat.Rsa

// Import the public key into the RSA component:
success = rsa.ImportPublicKeyObj(pubKey)
If (success <> True) Then
    System.DebugLog(rsa.LastErrorText)
    Return
End If

// OpenSSL uses big-endian.
rsa.LittleEndian = False

success = rsa.VerifyBd(bdFileData,"sha256",bdSig)
If (success <> True) Then
    System.DebugLog(rsa.LastErrorText)
    System.DebugLog("The signature was invalid.")
    Return
End If

System.DebugLog("The signature was verified.")