MIME S/MIME Signing Algorithm Properties

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Demonstrates the properties that control S/MIME signing: SigningAlg (the RSA signature scheme, PKCS1-V1_5 or RSASSA-PSS), SigningHashAlg (the message-digest algorithm), Micalg and Protocol (the micalg and protocol parameters of a multipart/signed Content-Type), and UseXPkcs7 (whether historical x-pkcs7 media-type names are used). The properties are configured before creating a detached signature.

local chilkat = require("chilkat")

local mime = chilkat.Mime.new()
local success = mime:set_body_from_plain_text("This message will be signed.")
if not success then
    print(mime.last_error_text)
    return
end

-- SigningAlg is the RSA signature scheme.  The default is PKCS1-V1_5; set RSASSA-PSS (or pss) for
-- RSASSA-PSS.
mime.signing_alg = "PKCS1-V1_5"

-- SigningHashAlg is the message-digest algorithm.  The default is sha256.
mime.signing_hash_alg = "sha256"

-- Micalg and Protocol are the micalg and protocol parameters written into a multipart/signed
-- Content-Type header field.  They are normally set automatically, but can be controlled here.
mime.micalg = "sha-256"
mime.protocol = "application/pkcs7-signature"

-- UseXPkcs7 controls whether newly created S/MIME media types use the historical x-pkcs7 names.
mime.use_x_pkcs7 = false

-- Load a signing certificate (with private key access) from a PFX.  The PFX password should come
-- from a secure source rather than being hard-coded.
local pfxPassword = "myPfxPassword"
local cert = chilkat.Cert.new()
success = cert:load_pfx_file("qa_data/signer.pfx", pfxPassword)
if not success then
    print(cert.last_error_text)
    return
end

-- Create the detached signature using the algorithms configured above.
success = mime:add_detached_signature(cert)
if not success then
    print(mime.last_error_text)
    return
end

print("Signed with SigningAlg=" .. mime.signing_alg .. " SigningHashAlg=" .. mime.signing_hash_alg)