Check if a MIME Entity is Signed (S/MIME)

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Demonstrates the Chilkat Mime.IsSigned method, which returns whether the entity is a complete CMS/PKCS #7 signed S/MIME wrapper, including detached multipart/signed and opaque forms. It takes no arguments.

Note: The file path is relative to the application's current working directory. Absolute paths may also be used. Supply the path to your own file.

Background: Before verifying a signature you need to know one is present, and this is the check. A signed S/MIME message comes in two shapes — detached (multipart/signed, signature alongside the content) and opaque (application/pkcs7-mime, content wrapped inside the signature) — and this recognizes both. Follow a true result with Verify.

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#include <C_CkMime.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkMime mime;

    success = FALSE;

    //  Demonstrates the Mime.IsSigned method, which returns whether the entity is a complete CMS/PKCS #7 signed S/MIME wrapper.  It takes no arguments.

    mime = CkMime_Create();
    success = CkMime_LoadMimeFile(mime,"qa_data/signed.eml");
    if (success == FALSE) {
        printf("%s\n",CkMime_lastErrorText(mime));
        CkMime_Dispose(mime);
        return;
    }

    if (CkMime_IsSigned(mime)) {
        printf("This is a signed S/MIME message.\n");
    }
    else {
        printf("This is not a signed S/MIME message.\n");
    }



    CkMime_Dispose(mime);

    }