PowerBuilder

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

See more OpenSSL Examples

Demonstrates how to duplicate this OpenSSL command:

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

The small.dat file is a small file that can contain text or binary data of any type. The "openssl rsautl" command is different than "openssl dgst -sign" because it signs the input data directly with the RSA algorithm. The "openssl dgst -sign" command first digests the input data and then signs the digest.

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.

PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Pkey
oleobject loo_Bd
oleobject loo_Rsa

li_Success = 0

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

loo_Pkey = create oleobject
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 = 0 then
    Write-Debug loo_Pkey.LastErrorText
    destroy loo_Pkey
    return
end if

// Load the file to be signed.
loo_Bd = create oleobject
li_rc = loo_Bd.ConnectToNewObject("Chilkat.BinData")

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

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

li_Success = loo_Rsa.UsePrivateKey(loo_Pkey)
if li_Success = 0 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.SignRawBd(loo_Bd)
if li_Success = 0 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