PureBasic

Encrypt MIME for a Recipient Certificate

Demonstrates encrypting the current MIME entity for a single recipient using the Mime.Encrypt method. The entity is replaced with CMS/PKCS #7 encrypted S/MIME that only the holder of the recipient's private key can read.

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. S/MIME encryption uses the recipient's public certificate to protect a message so that only the matching private key can recover it. The recipient certificate must be RSA-based. Only the recipient's public key is needed to encrypt—the private key is required to decrypt.

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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

    ;  Load the recipient's certificate (public key only is sufficient for encrypting).
    cert.i = CkCert::ckCreate()
    If cert.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

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

    ;  Encrypt for the recipient.  The entity is replaced with CMS/PKCS #7 encrypted S/MIME that only
    ;  the holder of the recipient's private key can decrypt.  The certificate must be RSA-based.
    success = CkMime::ckEncrypt(mime,cert)
    If success = 0
        Debug CkMime::ckLastErrorText(mime)
        CkMime::ckDispose(mime)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

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

    Debug "Message encrypted."


    CkMime::ckDispose(mime)
    CkCert::ckDispose(cert)


    ProcedureReturn
EndProcedure