(PowerBuilder) Duplicating OpenSSL rsautl (creating RSA signatures)

Demonstrates how to duplicate OpenSSL rsautil RSA signatures.

The Chilkat RSA component's methods for creating RSA signatures (SignBytes, SignBytesENC, SignString, and SignStringENC) are very different from OpenSSL's rsautl command. First, we'll explain what Chilkat's signing methods do, and then what OpenSSL's rsautl does. New signing methods have been added to Chilkat RSA to duplicate OpenSSL rsautl: OpenSslSignBytes, OpenSslSignBytesENC, OpenSslSignString, and OpenSslSignStringENC.

Here's what Chilkat's RSA Sign* methods do:
(Note: Chilkat RSA's Sign* methods generate signatures according to RSA Laboratories' "PKCS #1 v2.0: RSA Cryptography Standard".)

1. Input data is hashed using the hashing algorithm specified.
2. The hash is padded using either PKCS1 v1.5 or PKCS1 PSS padding. PKCS v1.5 involves encoding to ASN.1 before padding.
3. The padded hash is finally RSA signed (i.e. modular exponentiation) and the signature is returned.

OpenSSL rsautl is very different. Here's what it does:

1. The input data is not hashed. It must be a small enough amount of data such that it can be padded and signed. PKCS v1.5 padding is always used. The data is not ASN.1 encoded before padding.
2. The PKCS v1.5 padded data is RSA signed and the signature is returned.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

integer li_rc
oleobject loo_Pkey
integer li_Success
string ls_PkeyXml
oleobject loo_Rsa
string ls_StrData
string ls_HexSig
oleobject loo_Pubkey
string ls_PubkeyXml
oleobject loo_Rsa2
string ls_OriginalData

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

loo_Pkey = create oleobject
// Use "Chilkat_9_5_0.PrivateKey" for versions of Chilkat < 10.0.0
li_rc = loo_Pkey.ConnectToNewObject("Chilkat.PrivateKey")
if li_rc < 0 then
    destroy loo_Pkey
    MessageBox("Error","Connecting to COM object failed")
    return
end if

// Load the private key from an RSA PEM file:
li_Success = loo_Pkey.LoadPemFile("private.pem")
if li_Success <> 1 then
    Write-Debug loo_Pkey.LastErrorText
    destroy loo_Pkey
    return
end if

// Get the private key in XML format:
ls_PkeyXml = loo_Pkey.GetXml()

loo_Rsa = create oleobject
// Use "Chilkat_9_5_0.Rsa" for versions of Chilkat < 10.0.0
li_rc = loo_Rsa.ConnectToNewObject("Chilkat.Rsa")

// Import the private key into the RSA component:
li_Success = loo_Rsa.ImportPrivateKey(ls_PkeyXml)
if li_Success <> 1 then
    Write-Debug loo_Rsa.LastErrorText
    destroy loo_Pkey
    destroy loo_Rsa
    return
end if

// This example will sign a string, and receive the signature
// in a hex-encoded string.  Therefore, set the encoding mode
// to "hex":
loo_Rsa.EncodingMode = "hex"

ls_StrData = "secret"

// Create an OpenSSL style signature:
ls_HexSig = loo_Rsa.OpenSslSignStringENC(ls_StrData)

Write-Debug ls_HexSig

// Recover the data using the corresponding public key:
loo_Pubkey = create oleobject
// Use "Chilkat_9_5_0.PublicKey" for versions of Chilkat < 10.0.0
li_rc = loo_Pubkey.ConnectToNewObject("Chilkat.PublicKey")

// Load the public key from a PEM file:
li_Success = loo_Pubkey.LoadFromFile("public.pem")
if li_Success <> 1 then
    Write-Debug loo_Pubkey.LastErrorText
    destroy loo_Pkey
    destroy loo_Rsa
    destroy loo_Pubkey
    return
end if

// Get the public key in XML format:
ls_PubkeyXml = loo_Pubkey.GetXml()

loo_Rsa2 = create oleobject
// Use "Chilkat_9_5_0.Rsa" for versions of Chilkat < 10.0.0
li_rc = loo_Rsa2.ConnectToNewObject("Chilkat.Rsa")

// Import the public key into the RSA component:
li_Success = loo_Rsa2.ImportPublicKey(ls_PubkeyXml)
if li_Success <> 1 then
    Write-Debug loo_Rsa2.LastErrorText
    destroy loo_Pkey
    destroy loo_Rsa
    destroy loo_Pubkey
    destroy loo_Rsa2
    return
end if

loo_Rsa2.EncodingMode = "hex"

// Recover the original data.

ls_OriginalData = loo_Rsa2.OpenSslVerifyStringENC(ls_HexSig)

Write-Debug ls_OriginalData


destroy loo_Pkey
destroy loo_Rsa
destroy loo_Pubkey
destroy loo_Rsa2