Add a Detached Signature (Header Placement Control)

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Demonstrates the Chilkat Mime.AddDetachedSignature2 method, which creates the same multipart/signed structure as AddDetachedSignature, with a second argument controlling whether the existing message header fields are transferred to the new outer entity.

Note: 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: Signing wraps the content in a new outer multipart/signed, which raises the question of where the message-level headers (Subject, From, To) should live. This variant lets you choose: transfer them up to the outer entity so the signed message looks like a normal email, or leave them on the inner part. Transferring is typical for email; the finer control matters when the signed entity is embedded in a larger structure.

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#include <C_CkMime.h>
#include <C_CkCert.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkMime mime;
    const char *pfxPassword;
    HCkCert cert;
    BOOL transferHeaderFields;

    success = FALSE;

    mime = CkMime_Create();
    success = CkMime_SetBodyFromPlainText(mime,"This message will be signed.");
    if (success == FALSE) {
        printf("%s\n",CkMime_lastErrorText(mime));
        CkMime_Dispose(mime);
        return;
    }

    //  Load the signing certificate (which must have access to its private key) from a PFX file.
    //  The PFX password should come from a secure source rather than being hard-coded.
    pfxPassword = "myPfxPassword";
    cert = CkCert_Create();
    success = CkCert_LoadPfxFile(cert,"qa_data/signer.pfx",pfxPassword);
    if (success == FALSE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkMime_Dispose(mime);
        CkCert_Dispose(cert);
        return;
    }

    //  AddDetachedSignature2 is the same as AddDetachedSignature, but the 2nd argument controls whether
    //  the existing message header fields are transferred to the new outer multipart/signed entity.
    transferHeaderFields = TRUE;
    success = CkMime_AddDetachedSignature2(mime,cert,transferHeaderFields);
    if (success == FALSE) {
        printf("%s\n",CkMime_lastErrorText(mime));
        CkMime_Dispose(mime);
        CkCert_Dispose(cert);
        return;
    }

    success = CkMime_SaveMime(mime,"qa_output/signed.eml");
    if (success == FALSE) {
        printf("%s\n",CkMime_lastErrorText(mime));
        CkMime_Dispose(mime);
        CkCert_Dispose(cert);
        return;
    }

    printf("Detached signature added (headers transferred).\n");


    CkMime_Dispose(mime);
    CkCert_Dispose(cert);

    }