(Excel) Ed25519ph Sign and Verify

Demonstrates how to create an Ed25519ph signature, and then to verify it.

Note: This example requires Chilkat v9.5.0.91 or greater.

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

' Use the following test vector from https://www.rfc-editor.org/rfc/rfc8032#page-30

'    -----TEST abc
' 
'    ALGORITHM:
'    Ed25519ph
' 
'    SECRET KEY:
'    833fe62409237b9d62ec77587520911e
'    9a759cec1d19755b7da901b96dca3d42
' 
'    PUBLIC KEY:
'    ec172b93ad5e563bf4932c70e1245034
'    c35467ef2efd4d64ebf819683467e2bf
' 
'    MESSAGE (length 3 bytes):
'    616263
' 
'    SIGNATURE:
'    98a70222f0b8121aa9d30f813d683f80
'    9e462b469c7ff87639499bb94e6dae41
'    31f85042463c2a355a2003d062adf5aa
'    a10b8c61e636062aaad11c2a26083406


privKeyHex = "833fe62409237b9d62ec77587520911e9a759cec1d19755b7da901b96dca3d42"

pubKeyHex = "ec172b93ad5e563bf4932c70e1245034c35467ef2efd4d64ebf819683467e2bf"

Dim privKey As Chilkat.PrivateKey
Set privKey = Chilkat.NewPrivateKey

success = privKey.LoadEd25519(privKeyHex,pubKeyHex)
If (success = False) Then
    Debug.Print privKey.LastErrorText
    Exit Sub
End If

' The data to be signed...
Dim bd As Chilkat.BinData
Set bd = Chilkat.NewBinData
Dim success As Boolean
success = bd.AppendEncoded("616263","hex")

Dim eddsa As Chilkat.EdDSA
Set eddsa = Chilkat.NewEdDSA
' Indicate we want the Ed25519ph instance.
eddsa.Algorithm = "Ed25519ph"


hexSig = eddsa.SignBdENC(bd,"hexlower",privKey)

Debug.Print "signature = "; hexSig

' The expected output is: 98a70222f0b8121aa9d30f813d683f80....

' Verify the signature..
Dim pubKey As Chilkat.PublicKey
Set pubKey = Chilkat.NewPublicKey
success = pubKey.LoadEd25519(pubKeyHex)
If (success = False) Then
    Debug.Print pubKey.LastErrorText
    Exit Sub
End If


bVerified = eddsa.VerifyBdENC(bd,hexSig,"hexlower",pubKey)
If (bVerified = False) Then
    Debug.Print eddsa.LastErrorText
    Debug.Print "Failed to verify the signature."
    Exit Sub
End If

Debug.Print "The Ed25519ph signature is verified!"