PureBasic

Encrypt MIME for Multiple Recipients

Demonstrates encrypting the current MIME entity for several recipients at once. A certificate is added for each recipient with AddEncryptCert, and EncryptN then produces a single CMS/PKCS #7 message that each recipient can independently decrypt.

The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background. When a message targets more than one recipient, each recipient's certificate is added to the internal list and EncryptN wraps the message key separately for each one. Any single recipient can then decrypt with their own private key.

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PureBasic

IncludeFile "CkCert.pb"
IncludeFile "CkMime.pb"

Procedure ChilkatExample()

    success.i = 0

    mime.i = CkMime::ckCreate()
    If mime.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkMime::ckSetBodyFromPlainText(mime,"This message will be encrypted.")
    If success = 0
        Debug CkMime::ckLastErrorText(mime)
        CkMime::ckDispose(mime)
        ProcedureReturn
    EndIf

    ;  Add a certificate for each intended recipient.  Every recipient receives an independently
    ;  wrapped copy of the message key.
    cert1.i = CkCert::ckCreate()
    If cert1.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkCert::ckLoadFromFile(cert1,"qa_data/recipient1.cer")
    If success = 0
        Debug CkCert::ckLastErrorText(cert1)
        CkMime::ckDispose(mime)
        CkCert::ckDispose(cert1)
        ProcedureReturn
    EndIf

    success = CkMime::ckAddEncryptCert(mime,cert1)
    If success = 0
        Debug CkMime::ckLastErrorText(mime)
        CkMime::ckDispose(mime)
        CkCert::ckDispose(cert1)
        ProcedureReturn
    EndIf

    cert2.i = CkCert::ckCreate()
    If cert2.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkCert::ckLoadFromFile(cert2,"qa_data/recipient2.cer")
    If success = 0
        Debug CkCert::ckLastErrorText(cert2)
        CkMime::ckDispose(mime)
        CkCert::ckDispose(cert1)
        CkCert::ckDispose(cert2)
        ProcedureReturn
    EndIf

    success = CkMime::ckAddEncryptCert(mime,cert2)
    If success = 0
        Debug CkMime::ckLastErrorText(mime)
        CkMime::ckDispose(mime)
        CkCert::ckDispose(cert1)
        CkCert::ckDispose(cert2)
        ProcedureReturn
    EndIf

    ;  Encrypt for every added recipient at once.
    success = CkMime::ckEncryptN(mime)
    If success = 0
        Debug CkMime::ckLastErrorText(mime)
        CkMime::ckDispose(mime)
        CkCert::ckDispose(cert1)
        CkCert::ckDispose(cert2)
        ProcedureReturn
    EndIf

    success = CkMime::ckSaveMime(mime,"qa_output/encrypted_multi.eml")
    If success = 0
        Debug CkMime::ckLastErrorText(mime)
        CkMime::ckDispose(mime)
        CkCert::ckDispose(cert1)
        CkCert::ckDispose(cert2)
        ProcedureReturn
    EndIf

    Debug "Message encrypted for multiple recipients."


    CkMime::ckDispose(mime)
    CkCert::ckDispose(cert1)
    CkCert::ckDispose(cert2)


    ProcedureReturn
EndProcedure