Tcl

Create CMS Signed File (PDF) with Multiple Signing Certificates

See more Digital Signatures Examples

Demonstrates how to sign a file by adding multiple signatures (multiple certificates). This example signs a PDF file to produce an output file that is a CMS signature wrapping the original PDF. (Note: This is different than modifying a PDF by injecting a signature into the PDF file format.)

Note: This example requires Chilkat v9.5.0.83 or greater.

Tcl

load ./chilkat.dll

set success 0

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

set crypt [new_CkCrypt2]

# ------------ This example requires Chilkat v9.5.0.83 or greater.

set cert1 [new_CkCert]

set success [CkCert_LoadPfxFile $cert1 "qa_data/pfx/cert_test123.pfx" "test123"]
if {$success != 1} then {
    puts [CkCert_lastErrorText $cert1]
    delete_CkCrypt2 $crypt
    delete_CkCert $cert1
    exit
}

set cert2 [new_CkCert]

set success [CkCert_LoadPfxFile $cert2 "qa_data/pfx/test_secret.pfx" "secret"]
if {$success != 1} then {
    puts [CkCert_lastErrorText $cert2]
    delete_CkCrypt2 $crypt
    delete_CkCert $cert1
    delete_CkCert $cert2
    exit
}

# ------------ This example requires Chilkat v9.5.0.83 or greater.

# Tell the crypt component to use both certificates for signing. 
# When we create the signature, it will be signed by both certificates.
set success [CkCrypt2_AddSigningCert $crypt $cert1]
if {$success != 1} then {
    puts [CkCrypt2_lastErrorText $crypt]
    delete_CkCrypt2 $crypt
    delete_CkCert $cert1
    delete_CkCert $cert2
    exit
}

set success [CkCrypt2_AddSigningCert $crypt $cert2]
if {$success != 1} then {
    puts [CkCrypt2_lastErrorText $crypt]
    delete_CkCrypt2 $crypt
    delete_CkCert $cert1
    delete_CkCert $cert2
    exit
}

# The CadesEnabled property applies to all methods that create PKCS7 signatures. 
# To create a CAdES-BES signature, set this property equal to true. 
CkCrypt2_put_CadesEnabled $crypt 1

CkCrypt2_put_HashAlgorithm $crypt "sha256"

# We can sign any type of file, creating a .p7s as output.
# The .p7s contains the signature and also embeds the data of the file that is signed.
set inFile "qa_data/pdf/sample.pdf"
set p7sFile "qa_output/sample.pdf.p7s"

# Create the CAdES-BES attached signature, which contains the original data.
# Note: Chilkat's function naming is not accurate.  CreateP7M creates a PKCS7 signature where the signed file
# is contained within the signature.  CreateP7S creates a detached PKCS7 signature where the signed file
# is NOT contained within the signature.  We want the data to be contained in the signature, therefore
# we call CreateP7M even though we are naming our output file .p7s.
set success [CkCrypt2_CreateP7M $crypt $inFile $p7sFile]
if {$success == 0} then {
    puts [CkCrypt2_lastErrorText $crypt]
    delete_CkCrypt2 $crypt
    delete_CkCert $cert1
    delete_CkCert $cert2
    exit
}

# Verify the .p7s file and extract the original file from the .p7s. 
set extractedToFilePath "qa_output/sample.pdf"
set success [CkCrypt2_VerifyP7M $crypt $p7sFile $extractedToFilePath]
if {$success == 0} then {
    puts [CkCrypt2_lastErrorText $crypt]
    delete_CkCrypt2 $crypt
    delete_CkCert $cert1
    delete_CkCert $cert2
    exit
}

puts "Success!"

delete_CkCrypt2 $crypt
delete_CkCert $cert1
delete_CkCert $cert2