(C) CoSign PKCS7/CMS Signed Data

See more Digital Signatures Examples

Demonstrates how to add a 2nd signature to a CMS SignedData. This is to add an additional signature, SignerInfo and certificate(s) to an existing CMS signed data.

In this example, we cosign an existing pdf.p7s

Note: The CoSign method is added in Chilkat v9.5.0.89.

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#include <C_CkCrypt2.h>
#include <C_CkCert.h>
#include <C_CkBinData.h>

void ChilkatSample(void)
    {
    HCkCrypt2 crypt;
    HCkCert cert;
    BOOL success;
    HCkBinData bd;
    HCkBinData bd2;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    crypt = CkCrypt2_Create();
    cert = CkCert_Create();

    // If loading from a smart card, set the smartcard PIN.
    CkCert_putSmartCardPin(cert,"0000");

    // Load a certificate in some way, such as from a smart card.
    // Chilkat provides other methods to load from a .pfx, .pem, or from the Windows certificate stores..
    success = CkCert_LoadFromSmartcard(cert,"");
    if (success == FALSE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkCrypt2_Dispose(crypt);
        CkCert_Dispose(cert);
        return;
    }

    success = CkCrypt2_SetSigningCert(crypt,cert);
    if (success == FALSE) {
        printf("%s\n",CkCrypt2_lastErrorText(crypt));
        CkCrypt2_Dispose(crypt);
        CkCert_Dispose(cert);
        return;
    }

    // Load the file to be co-signed.
    // NOTE:  This is to cosign a PDF file contained within a CMS (PKCS7) message.
    // (In other words, the PDF is contained within the CMS SignedData, rather than the other way around
    // where a CMS signature is contained within a PDF.  Use Chilkat's PDF class to sign a PDF, which is
    // to embed a CMS signature within the PDF.)
    bd = CkBinData_Create();
    success = CkBinData_LoadFile(bd,"qa_data/p7s/cosign/sample.pdf.p7s");
    if (success == FALSE) {
        printf("Failed to load pdf.p7s input file.\n");
        CkCrypt2_Dispose(crypt);
        CkCert_Dispose(cert);
        CkBinData_Dispose(bd);
        return;
    }

    // bd2 will contain the co-signed result.
    bd2 = CkBinData_Create();
    success = CkCrypt2_CoSign(crypt,bd,cert,bd2);
    if (success == FALSE) {
        printf("%s\n",CkCrypt2_lastErrorText(crypt));
        CkCrypt2_Dispose(crypt);
        CkCert_Dispose(cert);
        CkBinData_Dispose(bd);
        CkBinData_Dispose(bd2);
        return;
    }

    success = CkBinData_WriteFile(bd,"qa_output/cosigned.pdf.p7s");
    if (success == FALSE) {
        printf("Failed to save pdf.p7s output file.\n");
        CkCrypt2_Dispose(crypt);
        CkCert_Dispose(cert);
        CkBinData_Dispose(bd);
        CkBinData_Dispose(bd2);
        return;
    }

    printf("Success!\n");


    CkCrypt2_Dispose(crypt);
    CkCert_Dispose(cert);
    CkBinData_Dispose(bd);
    CkBinData_Dispose(bd2);

    }