Tcl Requires Chilkat v11.0.0+

Decrypt S/MIME and Verify S/MIME Signatures

See more MIME Examples

_LANGUAGE_ example to decrypt S/MIME and verify S/MIME signatures. The S/MIME is unwrapped to get the original MIME prior to signing/encrypting. Tcl

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 mime [new_CkMime]

#  Load an S/MIME message from a file:
set success [CkMime_LoadMimeFile $mime "signedMime.txt"]
if {$success == 0} then {
    puts [CkMime_lastErrorText $mime]
    delete_CkMime $mime
    exit
}

#  The ContainsEncryptedParts/ContainsSignedParts methods
#  can be called to determine if the MIME is encrypted and/or signed:
set isEncrypted [CkMime_ContainsEncryptedParts $mime]
set isSigned [CkMime_ContainsSignedParts $mime]

#  We don't want the "unwrap extras".  You'll see what those
#  are in a few moments...
CkMime_put_UnwrapExtras $mime 0

#  To verify the signature, call UnwrapSecurity.  This will
#  verify the signature(s) and decrypt the S/MIME and restore
#  the MIME to the unsigned/unencrypted state.
#  The results of what was found are present in the MIME object's
#  properties, as well as extra header fields that are added
#  to the unwrapped MIME.
set success [CkMime_UnwrapSecurity $mime]
if {$success != 1} then {
    #  UnwrapSecurity returns 1 if all signatures were
    #  verified and all parts decrypted.
    puts [CkMime_lastErrorText $mime]
    delete_CkMime $mime
    exit
}

#  The mime.UnwrapExtras property controls whether or not
#  these additional fields are added to the unwrapped MIME:
#  
#  X-NumPartsSigned: 1
#  X-SignaturesValid: yes
#  X-NumPartsEncrypted: 1
#  X-Decrypted: no
#  
#  The X-NumPartsSigned/X-SignaturesValid headers are added
#  if the MIME was signed.  
#  
#  The X-NumPartsEncrypted/X-Decrypted headers are added
#  if the MIME was encrypted.
#  

#  If the MIME was signed, get the certificate used for signing.
if {$isSigned == 1} then {
    set signerCert [new_CkCert]

    #  The NumSignerCerts property indicates how many certificates
    #  were used for signing.  This example will assume the value is 1.
    #  To get the 1st signer cert, call LastSignerCert with an index of 0:
    set success [CkMime_LastSignerCert $mime 0 $signerCert]
    if {$success == 1} then {
        puts "**** Signer Cert: [CkCert_subjectCN $signerCert]"
    }

}

#  If the MIME was encrypted, get the certificate used for decryption
if {$isEncrypted == 1} then {
    #  The NumDecryptCerts property indicates how many certificates
    #  were used for decrypting.  This example will assume the value is 1.
    #  To get the 1st decrypt cert, call LastDecryptCert with an index of 0:
    set decryptCert [new_CkCert]

    set success [CkMime_LastDecryptCert $mime 0 $decryptCert]
    if {$success == 1} then {
        puts "**** Decrypt Cert: [CkCert_subjectCN $decryptCert]"
    }

}

#  Display the unwrapped MIME:
puts [CkMime_getMime $mime]

#  Save the unwrapped MIME to a file:
set success [CkMime_SaveMime $mime "unwrappedMime.txt"]

delete_CkMime $mime
delete_CkCert $signerCert
delete_CkCert $decryptCert