PowerBuilder

Verify the RSA Signature of a SHA256 Hash

See more RSA Examples

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

integer li_rc
integer li_Success
oleobject loo_PubKey
oleobject loo_Rsa
oleobject loo_BdHash
oleobject loo_BdSig
string ls_Enc

li_Success = 0

// 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.

loo_PubKey = create oleobject
li_rc = loo_PubKey.ConnectToNewObject("Chilkat.PublicKey")
if li_rc < 0 then
    destroy loo_PubKey
    MessageBox("Error","Connecting to COM object failed")
    return
end if
li_Success = loo_PubKey.LoadFromFile("rsaPubKey.pem")
if li_Success = 0 then
    Write-Debug loo_PubKey.LastErrorText
    destroy loo_PubKey
    return
end if

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

// Get the public key.
li_Success = loo_Rsa.UsePublicKey(loo_PubKey)
if li_Success = 0 then
    Write-Debug loo_Rsa.LastErrorText
    destroy loo_PubKey
    destroy loo_Rsa
    return
end if

// Get the 32-byte SHA256 hash.
loo_BdHash = create oleobject
li_rc = loo_BdHash.ConnectToNewObject("Chilkat.BinData")

li_Success = loo_BdHash.LoadFile("myHash.sha256")
if li_Success = 0 then
    Write-Debug "Failed to load SHA256 hash."
    destroy loo_PubKey
    destroy loo_Rsa
    destroy loo_BdHash
    return
end if

// Get the RSA signature to be validated.
loo_BdSig = create oleobject
li_rc = loo_BdSig.ConnectToNewObject("Chilkat.BinData")

li_Success = loo_BdSig.LoadFile("mySig.sig")
if li_Success = 0 then
    Write-Debug "Failed to load RSA signature."
    destroy loo_PubKey
    destroy loo_Rsa
    destroy loo_BdHash
    destroy loo_BdSig
    return
end if

// Verify the signature against the SHA256 hash.
ls_Enc = "base64"
loo_Rsa.EncodingMode = ls_Enc
li_Success = loo_Rsa.VerifyHashENC(loo_BdHash.GetEncoded(ls_Enc),"sha256",loo_BdSig.GetEncoded(ls_Enc))
if li_Success = 0 then
    Write-Debug loo_Rsa.LastErrorText
    destroy loo_PubKey
    destroy loo_Rsa
    destroy loo_BdHash
    destroy loo_BdSig
    return
end if

Write-Debug "Signature validated."


destroy loo_PubKey
destroy loo_Rsa
destroy loo_BdHash
destroy loo_BdSig