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.

load ./chilkat.dll

set success 0

set mime [new_CkMime]

set success [CkMime_SetBodyFromPlainText $mime "This message will be signed."]
if {$success == 0} then {
    puts [CkMime_lastErrorText $mime]
    delete_CkMime $mime
    exit
}

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

#  SigningHashAlg is the message-digest algorithm.  The default is sha256.
CkMime_put_SigningHashAlg $mime "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.
CkMime_put_Micalg $mime "sha-256"
CkMime_put_Protocol $mime "application/pkcs7-signature"

#  UseXPkcs7 controls whether newly created S/MIME media types use the historical x-pkcs7 names.
CkMime_put_UseXPkcs7 $mime 0

#  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.
set pfxPassword "myPfxPassword"
set cert [new_CkCert]

set success [CkCert_LoadPfxFile $cert "qa_data/signer.pfx" $pfxPassword]
if {$success == 0} then {
    puts [CkCert_lastErrorText $cert]
    delete_CkMime $mime
    delete_CkCert $cert
    exit
}

#  Create the detached signature using the algorithms configured above.
set success [CkMime_AddDetachedSignature $mime $cert]
if {$success == 0} then {
    puts [CkMime_lastErrorText $mime]
    delete_CkMime $mime
    delete_CkCert $cert
    exit
}

puts "Signed with SigningAlg=[CkMime_signingAlg $mime] SigningHashAlg=[CkMime_signingHashAlg $mime]"

delete_CkMime $mime
delete_CkCert $cert