PowerBuilder

Verfies an RSA Signature

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Verifies an RSA signature against the original data. PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Bd
integer i
oleobject loo_BdSig
oleobject loo_PubKey
oleobject loo_Rsa

li_Success = 0

// The following data was signed by the following example:
// RSA Sign using a Private Key on a USB Token or Smartcard
loo_Bd = create oleobject
li_rc = loo_Bd.ConnectToNewObject("Chilkat.BinData")
if li_rc < 0 then
    destroy loo_Bd
    MessageBox("Error","Connecting to COM object failed")
    return
end if

for i = 0 to 100
    loo_Bd.AppendEncoded("000102030405060708090A0B0C0D0E0F","hex")
next

// Load the signature
loo_BdSig = create oleobject
li_rc = loo_BdSig.ConnectToNewObject("Chilkat.BinData")

li_Success = loo_BdSig.LoadFile("rsaSignatures/test1.sig")
if li_Success = 0 then
    Write-Debug "Failed to load the RSA signature"
    destroy loo_Bd
    destroy loo_BdSig
    return
end if

// Get the public key to be used for signature verification.
loo_PubKey = create oleobject
li_rc = loo_PubKey.ConnectToNewObject("Chilkat.PublicKey")

li_Success = loo_PubKey.LoadFromFile("rsaKeys/chilkat-rsa-2048.pem")
if li_Success = 0 then
    Write-Debug loo_PubKey.LastErrorText
    destroy loo_Bd
    destroy loo_BdSig
    destroy loo_PubKey
    return
end if

loo_Rsa = create oleobject
li_rc = loo_Rsa.ConnectToNewObject("Chilkat.Rsa")

li_Success = loo_Rsa.UsePublicKey(loo_PubKey)
if li_Success = 0 then
    Write-Debug loo_Rsa.LastErrorText
    destroy loo_Bd
    destroy loo_BdSig
    destroy loo_PubKey
    destroy loo_Rsa
    return
end if

// Verify the hash of the data against the signature.
// We pass in the original data.  Internally, the hash is generated
// and used to validate the signature.
// Validating the RSA signature means two things:  
// (1) the original data is exactly what was signed, and 
// (2) it was signed by the owner of the RSA private key.
li_Success = loo_Rsa.VerifyBd(loo_Bd,"sha256",loo_BdSig)

if li_Success = 0 then
    Write-Debug loo_Rsa.LastErrorText
    Write-Debug "Signature invalid."
else
    Write-Debug "Signature valid."
end if



destroy loo_Bd
destroy loo_BdSig
destroy loo_PubKey
destroy loo_Rsa