(Xojo Plugin) Verify the RSA Signature of a SHA256 Hash

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Demonstrates how to verify an RSA signature of a SHA256 hash.

Chilkat Xojo Plugin Download Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

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

// Let's say you have a file containing the 32-bytes of a SHA256 hash,
// and a file that is an RSA signature of those 32 bytes.
// Here's how you verify using the RSA public key found in a PEM.

Dim pubKey As New Chilkat.PublicKey
Dim success As Boolean
success = pubKey.LoadFromFile("rsaPubKey.pem")
If (success = False) Then
    System.DebugLog(pubKey.LastErrorText)
    Return
End If

Dim rsa As New Chilkat.Rsa

// Get the public key.
success = rsa.ImportPublicKeyObj(pubKey)
If (success = False) Then
    System.DebugLog(rsa.LastErrorText)
    Return
End If

// Get the 32-byte SHA256 hash.
Dim bdHash As New Chilkat.BinData
success = bdHash.LoadFile("myHash.sha256")
If (success = False) Then
    System.DebugLog("Failed to load SHA256 hash.")
    Return
End If

// Get the RSA signature to be validated.
Dim bdSig As New Chilkat.BinData
success = bdSig.LoadFile("mySig.sig")
If (success = False) Then
    System.DebugLog("Failed to load RSA signature.")
    Return
End If

// Verify the signature against the SHA256 hash.
Dim enc As String
enc = "base64"
rsa.EncodingMode = enc
success = rsa.VerifyHashENC(bdHash.GetEncoded(enc),"sha256",bdSig.GetEncoded(enc))
If (success = False) Then
    System.DebugLog(rsa.LastErrorText)
    Return
End If

System.DebugLog("Signature validated.")