Add a Detached Signature (Separate Key, Header Control)

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Demonstrates the Chilkat Mime.AddDetachedSignaturePk2 method, which creates a detached signature with a separately supplied certificate and private key, and a third argument controlling transfer of the existing message header fields 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: This combines the two variations — certificate and key supplied separately, plus explicit header placement — for the case that needs both. It is the most flexible of the detached-signature methods; choose it when your key material is separate and you also care about where the message headers end up on the signed result.

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

void ChilkatSample(void)
    {
    BOOL success;
    HCkMime mime;
    HCkCert cert;
    HCkPrivateKey privKey;
    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 certificate and its private key separately.
    cert = CkCert_Create();
    success = CkCert_LoadFromFile(cert,"qa_data/signer.cer");
    if (success == FALSE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkMime_Dispose(mime);
        CkCert_Dispose(cert);
        return;
    }

    privKey = CkPrivateKey_Create();
    success = CkPrivateKey_LoadPemFile(privKey,"qa_data/signer_privkey.pem");
    if (success == FALSE) {
        printf("%s\n",CkPrivateKey_lastErrorText(privKey));
        CkMime_Dispose(mime);
        CkCert_Dispose(cert);
        CkPrivateKey_Dispose(privKey);
        return;
    }

    //  Create a detached signature with separately supplied cert and private key, where the 3rd
    //  argument controls whether the existing message header fields are transferred to the new outer
    //  multipart/signed entity.
    transferHeaderFields = TRUE;
    success = CkMime_AddDetachedSignaturePk2(mime,cert,privKey,transferHeaderFields);
    if (success == FALSE) {
        printf("%s\n",CkMime_lastErrorText(mime));
        CkMime_Dispose(mime);
        CkCert_Dispose(cert);
        CkPrivateKey_Dispose(privKey);
        return;
    }

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

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


    CkMime_Dispose(mime);
    CkCert_Dispose(cert);
    CkPrivateKey_Dispose(privKey);

    }