Lua Requires Chilkat v9.5.0.85+

PDF Signatures with Built-in SVG Graphics

See more PDF Signatures Examples

This example demonstrates the built-in SVG graphics that can be applied to the appearance when signing a PDF. Lua

local chilkat = require("chilkat")

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

local pdf = chilkat.Pdf.new()

-- Load a PDF to be signed.
-- The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
local success = pdf:load_file("qa_data/pdf/hello.pdf")
if not success then
    print(pdf.last_error_text)
    return
end

-- Options for signing are specified in JSON.
local json = chilkat.JsonObject.new()

-- In most cases, the signingCertificateV2 and signingTime attributes are required.
json:update_int("signingCertificateV2", 1)
json:update_int("signingTime", 1)

-- Specify the location/position, scale, and content of the signature's appearance.
json:update_int("page", 1)
json:update_string("appearance.y", "top")
json:update_string("appearance.x", "left")
json:update_string("appearance.fontScale", "10.0")
json:update_string("appearance.text[0]", "Digitally signed by: cert_cn")
json:update_string("appearance.text[1]", "current_dt")
json:update_string("appearance.text[2]", "The crazy brown fox jumps over the lazy dog.")

-- In addition to the above, this example adds a built-in SVG graphic to the appearance.
-- The built-in SVG graphic is specified by a name, such as "green-check-grey-circle".
-- The full list of graphic names and images are shown below.
json:update_string("appearance.image", "green-check-grey-circle")

-- The graphic can be placed "left", "center", or "right".
-- If "center", then the graphic is displayed behind the text.
json:update_string("appearance.imagePlacement", "left")

-- The graphic's opacity can range from 1 to 100.
-- Centered graphics look best with less opacity (50 or less).
-- In this example, we'll keep the opacity at 100.
json:update_string("appearance.imageOpacity", "100")

-- Here's an example of the signature's appearance if we centered the SVG graphic with an opacity of 40%
-- 

-- Load the signing certificate. (Use your own certificate.)
local cert = chilkat.Cert.new()
success = cert:load_pfx_file("qa_data/pfx/myPdfSigningCert.pfx", "secret")
if not success then
    print(cert.last_error_text)
    return
end

-- Tell the pdf object to use the certificate for signing.
success = pdf:set_signing_cert(cert)
if not success then
    print(pdf.last_error_text)
    return
end

success = pdf:sign_pdf(json, "qa_output/hello_signed.pdf")
if not success then
    print(pdf.last_error_text)
    return
end

print("The PDF has been successfully cryptographically signed.")

-- The appearance of the signature appears in Adobe Acrobat as shown here:

-- 

-- The SVG icon graphics are embedded within the Chilkat library,
-- and were graciously provided by uxwing - Free SVG Icons
--
-- The uxwing licensing terms are reproduced here and can be verified at uxwing licensing

-- Icons from uxwing.com are free (see https://uxwing.com/license/)
--     - All icons on UXWing free to download, and use personal, commercial projects.
--     - Attribution and Credit is NOT required, however, any credit will be much appreciated.
--     - There is no limit to the number of times you can use.
--     - You may modify the resources according to your requirements.

-- The set of SVG names and the corresponding graphics are shown below.
--
-- For example, if we specify "green-check-green-circle"
json:update_string("appearance.image", "green-check-green-circle")
-- We get:
-- 

-- "application-approved"
-- 

-- "application-rejected"
-- 

-- "document-accepted"
-- 

-- "approved"
-- 

-- "blue-check-mark"
-- 

-- "green-check-mark"
-- 

-- "green-check-grey-circle"
-- 

-- "red-x-red-circle"
-- 

-- "rejected"
-- 

-- "result-failure"
-- 

-- "result-pass"
-- 

-- "signature"
-- 

-- "document-check"
-- 

-- "document-x"
-- 

-- "red-x-grey-circle"
--