MIME S/MIME Signing Algorithm Properties

See more MIME Examples

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

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

    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;
    }

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

    //  SigningHashAlg is the message-digest algorithm.  The default is sha256.
    CkMime_putSigningHashAlg(mime,"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.
    CkMime_putMicalg(mime,"sha-256");
    CkMime_putProtocol(mime,"application/pkcs7-signature");

    //  UseXPkcs7 controls whether newly created S/MIME media types use the historical x-pkcs7 names.
    CkMime_putUseXPkcs7(mime,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.
    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;
    }

    //  Create the detached signature using the algorithms configured above.
    success = CkMime_AddDetachedSignature(mime,cert);
    if (success == FALSE) {
        printf("%s\n",CkMime_lastErrorText(mime));
        CkMime_Dispose(mime);
        CkCert_Dispose(cert);
        return;
    }

    printf("Signed with SigningAlg=%s SigningHashAlg=%s\n",CkMime_signingAlg(mime),CkMime_signingHashAlg(mime));


    CkMime_Dispose(mime);
    CkCert_Dispose(cert);

    }