(Lianja) Decrypt S/MIME and Verify S/MIME Signatures

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

Chilkat Lianja Extension Download Chilkat Lianja Extension

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

loMime = createobject("CkMime")

// Load an S/MIME message from a file:
llSuccess = loMime.LoadMimeFile("signedMime.txt")
if (llSuccess <> .T.) then
    ? loMime.LastErrorText
    release loMime
    return
endif

// The ContainsEncryptedParts/ContainsSignedParts methods
// can be called to determine if the MIME is encrypted and/or signed:
llIsEncrypted = loMime.ContainsEncryptedParts()
llIsSigned = loMime.ContainsSignedParts()

// We don't want the "unwrap extras".  You'll see what those
// are in a few moments...
loMime.UnwrapExtras = .F.

// 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.
llSuccess = loMime.UnwrapSecurity()
if (llSuccess <> .T.) then
    // UnwrapSecurity returns .T. if all signatures were
    // verified and all parts decrypted.
    ? loMime.LastErrorText
    release loMime
    return
endif

// 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 (llIsSigned = .T.) then
    // 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 GetSignerCert with an index of 0:
    loSignerCert = loMime.GetSignerCert(0)
    if (loMime.LastMethodSuccess = .T.) then
        ? "**** Signer Cert: " + loSignerCert.SubjectCN
        release loSignerCert
    endif

endif

// If the MIME was encrypted, get the certificate used for encryption:
if (llIsEncrypted = .T.) then
    // The NumEncryptCerts property indicates how many certificates
    // were used for encrypting.  This example will assume the value is 1.
    // To get the 1st encrypt cert, call GetEncryptCert with an index of 0:
    loEncryptCert = loMime.GetEncryptCert(0)
    if (loMime.LastMethodSuccess = .T.) then
        ? "**** Encrypt Cert: " + loEncryptCert.SubjectCN
        release loEncryptCert
    endif

endif

// Display the unwrapped MIME:
? loMime.GetMime()

// Save the unwrapped MIME to a file:
llSuccess = loMime.SaveMime("unwrappedMime.txt")


release loMime