(PowerBuilder) Duplicate openssl rsautl -sign -in small.dat -inkey private.pem -out rsautl.sig

Demonstrates how to duplicate this OpenSSL command:

openssl rsautl -sign -in small.dat -inkey private.pem -out rsautl.sig

How much data can be signed with "openssl rsautl"? The maximum size (in bytes) is the key size minus the overhead for the padding. The overhead size depends on the padding. With OAEP padding, the overhead is 42 bytes. With the default PKCSv1.5 padding, the overhead is 11 bytes.

Given a 2048-bit RSA key (256 bytes) and using PKCSv1.5 padding, the max data size that can be signed is 256 - 11 = 245 bytes.

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

integer li_rc
oleobject loo_Pkey
integer li_Success
oleobject loo_Bd
oleobject loo_Rsa

// This example requires 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 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

// Load the file to be signed.
loo_Bd = create oleobject
// Use "Chilkat_9_5_0.BinData" for versions of Chilkat < 10.0.0
li_rc = loo_Bd.ConnectToNewObject("Chilkat.BinData")

li_Success = loo_Bd.LoadFile("small.dat")

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.ImportPrivateKeyObj(loo_Pkey)
if li_Success <> 1 then
    Write-Debug loo_Rsa.LastErrorText
    destroy loo_Pkey
    destroy loo_Bd
    destroy loo_Rsa
    return
end if

// OpenSSL uses big-endian.
loo_Rsa.LittleEndian = 0

// Sign bd.  If successful, bd will contain the RSA signature that contains the original data.
li_Success = loo_Rsa.OpenSslSignBd(loo_Bd)
if li_Success <> 1 then
    Write-Debug loo_Rsa.LastErrorText
    destroy loo_Pkey
    destroy loo_Bd
    destroy loo_Rsa
    return
end if

// Save the binary signature to a file.
li_Success = loo_Bd.WriteFile("rsautl.sig")
if li_Success <> 1 then
    Write-Debug "Failed to save output signature file."
    destroy loo_Pkey
    destroy loo_Bd
    destroy loo_Rsa
    return
end if

Write-Debug "Success."


destroy loo_Pkey
destroy loo_Bd
destroy loo_Rsa