MIME S/MIME Signing Algorithm Properties

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Demonstrates the properties that control S/MIME signing: SigningAlg (the RSA signature scheme, PKCS1-V1_5 or RSASSA-PSS), SigningHashAlg (the message-digest algorithm), Micalg and Protocol (the micalg and protocol parameters of a multipart/signed Content-Type), and UseXPkcs7 (whether historical x-pkcs7 media-type names are used). The properties are configured before creating a detached signature.

#include <CkMimeW.h>
#include <CkCertW.h>

void ChilkatSample(void)
    {
    bool success = false;

    CkMimeW mime;
    success = mime.SetBodyFromPlainText(L"This message will be signed.");
    if (success == false) {
        wprintf(L"%s\n",mime.lastErrorText());
        return;
    }

    //  SigningAlg is the RSA signature scheme.  The default is PKCS1-V1_5; set RSASSA-PSS (or pss) for
    //  RSASSA-PSS.
    mime.put_SigningAlg(L"PKCS1-V1_5");

    //  SigningHashAlg is the message-digest algorithm.  The default is sha256.
    mime.put_SigningHashAlg(L"sha256");

    //  Micalg and Protocol are the micalg and protocol parameters written into a multipart/signed
    //  Content-Type header field.  They are normally set automatically, but can be controlled here.
    mime.put_Micalg(L"sha-256");
    mime.put_Protocol(L"application/pkcs7-signature");

    //  UseXPkcs7 controls whether newly created S/MIME media types use the historical x-pkcs7 names.
    mime.put_UseXPkcs7(false);

    //  Load a signing certificate (with private key access) from a PFX.  The PFX password should come
    //  from a secure source rather than being hard-coded.
    const wchar_t *pfxPassword = L"myPfxPassword";
    CkCertW cert;
    success = cert.LoadPfxFile(L"qa_data/signer.pfx",pfxPassword);
    if (success == false) {
        wprintf(L"%s\n",cert.lastErrorText());
        return;
    }

    //  Create the detached signature using the algorithms configured above.
    success = mime.AddDetachedSignature(cert);
    if (success == false) {
        wprintf(L"%s\n",mime.lastErrorText());
        return;
    }

    wprintf(L"Signed with SigningAlg=%s SigningHashAlg=%s\n",mime.signingAlg(),mime.signingHashAlg());
    }