Specify a Certificate for Encrypted Email

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Demonstrates the Chilkat Email.AddEncryptCert method, which explicitly specifies a certificate to use when sending encrypted email. Call it once per recipient certificate; ClearEncryptCerts clears the list. This example loads a recipient certificate, registers it, and enables encrypted sending.

Background: When encrypting to multiple people, each recipient needs to be able to decrypt with their own private key. S/MIME handles this by encrypting the message's one-time content key separately under each recipient's public certificate and including all of those wrapped keys in the message. AddEncryptCert is how you build that recipient list — one call per certificate — giving explicit control over exactly whose certificates are used rather than relying on automatic lookup.

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#include <C_CkEmail.h>
#include <C_CkCert.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkEmail email;
    HCkCert cert;

    success = FALSE;

    //  Demonstrates the AddEncryptCert method, which explicitly specifies a certificate for
    //  sending encrypted email.  Call it once per recipient certificate.  Use ClearEncryptCerts
    //  to clear the list.

    email = CkEmail_Create();
    CkEmail_putSubject(email,"Encrypted email");
    CkEmail_putBody(email,"Encrypted to the specified recipient certificate(s).");
    CkEmail_putFrom(email,"alice@example.com");
    CkEmail_AddTo(email,"Bob","bob@example.com");

    //  Load a recipient certificate (public key) and add it to the encryption cert list.
    cert = CkCert_Create();
    success = CkCert_LoadFromFile(cert,"qa_data/certs/recipient.cer");
    if (success == FALSE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkEmail_Dispose(email);
        CkCert_Dispose(cert);
        return;
    }

    success = CkEmail_AddEncryptCert(email,cert);
    if (success == FALSE) {
        printf("%s\n",CkEmail_lastErrorText(email));
        CkEmail_Dispose(email);
        CkCert_Dispose(cert);
        return;
    }

    //  Request encrypted sending.
    CkEmail_putSendEncrypted(email,TRUE);

    printf("Added the recipient's encryption certificate.\n");

    //  Note: The path "qa_data/certs/recipient.cer" is a relative local filesystem path,
    //  relative to the current working directory of the running application.


    CkEmail_Dispose(email);
    CkCert_Dispose(cert);

    }