(Tcl) Sign PDF using ARSS (Aruba Remote Signing Service)

See more Signing in the Cloud Examples

Demonstrates how to digitally sign a PDF using the Aruba Remote Signing Service (ARSS). The example loads a local PDF and certificate, configures the ARSS cloud signer credentials, specifies the OTP authentication type with typeOtpAuth, and creates an LTV-enabled signed PDF where the private key remains protected on the Aruba signing server.

Note: This example requires Chilkat v11.5.0 or greater.

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load ./chilkat.dll

set success 0

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

set pdf [new_CkPdf]

# Load the PDF that will be digitally signed.
set success [CkPdf_LoadFile $pdf "qa_data/pdf/hello.pdf"]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf]
    delete_CkPdf $pdf
    exit
}

# Signing options are specified in a JSON object.
set json [new_CkJsonObject]

# Enable LTV (Long-Term Validation).
# When ltvOcsp is true, OCSP validation information is embedded in the PDF
# so that signature validation can continue to succeed in the future,
# even if the original OCSP responder is no longer available.
CkJsonObject_UpdateBool $json "ltvOcsp" 1

# Specify the visual appearance of the signature on the PDF page.
CkJsonObject_UpdateInt $json "page" 1
CkJsonObject_UpdateString $json "appearance.y" "top"
CkJsonObject_UpdateString $json "appearance.x" "left"
CkJsonObject_UpdateString $json "appearance.fontScale" "10.0"

# Text lines displayed in the visible signature appearance.
# Special values such as "cert_cn" and "current_dt" are replaced
# with the certificate common name and current date/time.
CkJsonObject_UpdateString $json "appearance.text[0]" "Digitally signed by: cert_cn"
CkJsonObject_UpdateString $json "appearance.text[1]" "current_dt"
CkJsonObject_UpdateString $json "appearance.text[2]" "This is an LTV-enabled signature."

# Load the signing certificate.
# 
# The private key is NOT stored locally.  Instead, the private key is
# stored and protected on the Aruba Remote Signing Service (ARSS).
# 
# Even though the signing operation will occur remotely, Chilkat still
# needs the corresponding public certificate locally so that it can
# construct the CMS/PAdES signature and embed the certificate chain
# in the signed PDF.
set cert [new_CkCert]

set success [CkCert_LoadFromFile $cert "qa_data/certs/myCert.cer"]
if {$success == 0} then {
    puts [CkCert_lastErrorText $cert]
    delete_CkPdf $pdf
    delete_CkJsonObject $json
    delete_CkCert $cert
    exit
}

# Configure Aruba Remote Signing Service (ARSS) credentials.
# 
# When SetCloudSigner is called, Chilkat is instructed to perform
# cryptographic signing operations through the ARSS web service.
# The PDF is assembled locally, but the actual RSA signature operation
# is performed remotely using the private key held by Aruba.
set jsonArss [new_CkJsonObject]

# Required.  Indicates that the cloud signing provider is ARSS.
CkJsonObject_UpdateString $jsonArss "service" "ARSS"

# The ARSS certificate identifier (for example, "AS0").
# This identifies which remote certificate/private key pair should be used.
# The remote certificate should correspond to the certificate loaded above.
CkJsonObject_UpdateString $jsonArss "certID" "YOUR_ARSS_CERT_ID"

# OTP password associated with the Aruba remote-signing account.
# Depending on the ARSS configuration, an OTP may be required to
# authorize each signing operation.
CkJsonObject_UpdateString $jsonArss "otpPwd" "YOUR_OTP_PWD"

# Specifies the OTP authentication environment.
# 
# Common values are:
#   "demoprod" - Demo/Test environment
#   "prod"     - Production environment
# 
# This value is sent to the ARSS service and determines how the OTP
# authentication is validated.  The correct value depends on the type
# of Aruba account and environment that has been provisioned.
# 
# If signing fails with an authentication-related error, verify that
# the typeOtpAuth value matches the environment associated with the
# ARSS account credentials being used.
CkJsonObject_UpdateString $jsonArss "typeOtpAuth" "demoprod"

# ARSS account username.
CkJsonObject_UpdateString $jsonArss "user" "YOUR_ARSS_USERNAME"

# ARSS account password.
CkJsonObject_UpdateString $jsonArss "userPWD" "YOUR_ARSS_PASSWORD"

# Beginning with Chilkat v11.5.0, the ARSS endpoint can be explicitly
# specified.  This allows the application to target a particular
# Aruba signing service endpoint when required.
CkJsonObject_UpdateString $jsonArss "endpoint" "https://app1.firma-remota.it/ArubaSignerService/webresources/signerservice"

set success [CkCert_SetCloudSigner $cert $jsonArss]
if {$success == 0} then {
    puts [CkCert_lastErrorText $cert]
    delete_CkPdf $pdf
    delete_CkJsonObject $json
    delete_CkCert $cert
    delete_CkJsonObject $jsonArss
    exit
}

# Associate the certificate with the PDF object.
# All subsequent signing operations will use this certificate.
set success [CkPdf_SetSigningCert $pdf $cert]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf]
    delete_CkPdf $pdf
    delete_CkJsonObject $json
    delete_CkCert $cert
    delete_CkJsonObject $jsonArss
    exit
}

# Create the signed PDF.
# 
# Chilkat performs all PDF processing locally.  When the time comes
# to generate the cryptographic signature value, Chilkat sends the
# hash to ARSS, which signs it using the remote private key and returns
# the signature.  The private key never leaves the Aruba service.
set success [CkPdf_SignPdf $pdf $json "qa_output/hello_ltv_signed.pdf"]
if {$success == 0} then {
    puts [CkPdf_lastErrorText $pdf]
    delete_CkPdf $pdf
    delete_CkJsonObject $json
    delete_CkCert $cert
    delete_CkJsonObject $jsonArss
    exit
}

puts "The PDF has been successfully cryptographically signed with long-term validation."

delete_CkPdf $pdf
delete_CkJsonObject $json
delete_CkCert $cert
delete_CkJsonObject $jsonArss