(MFC) Verify and Unwrap S/MIME, and get Information about CMS Signature

Demonstrates calling the Verify method to verify and unwrap S/MIME. The MIME is restored to the original structure that it would have originally had prior to signing. The Verify method works with both detached signatures, as well as opaque/attached signatures.

Calls LastJsonData to get information about the signature(s) that were verified.

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkMime.h>
#include <CkJsonObject.h>
#include <CkDtObj.h>

void ChilkatSample(void)
    {
    CkString strOut;

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

    CkMime mime;

    // Load the signed MIME from a file...
    bool success = mime.LoadMimeFile("qa_data/mime/detached_sig.eml");
    if (success == false) {
        strOut.append(mime.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Verify the S/MIME and restore the MIME
    // to the structure/content it had prior to signing.
    bool verified = mime.Verify();
    if (verified == false) {
        strOut.append(mime.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Examine the details of what was verified.
    CkJsonObject *json = mime.LastJsonData();
    json->put_EmitCompact(false);
    strOut.append(json->emit());
    strOut.append("\r\n");

    // The code to parse the following JSON (i.e. extract desired information) is shown below..

    // {
    //   "pkcs7": {
    //     "verify": {
    //       "certs": [
    //         {
    //           "issuerCN": "VeriSign Class 1 Public Primary Certification Authority - G3",
    //           "serial": "0702A21A85B84B659E180A6EE6F5A365"
    //         },
    //         {
    //           "issuerCN": "VeriSign Class 1 Public Primary Certification Authority - G3",
    //           "serial": "008B5B75568454850B00CFAF3848CEB1A4"
    //         },
    //         {
    //           "issuerCN": "Symantec Class 1 Individual Subscriber CA - G5",
    //           "serial": "619C55C32FF6BD1A7B7E0330D21C8F3C"
    //         }
    //       ],
    //       "digestAlgorithms": [
    //         "sha1"
    //       ],
    //       "signerInfo": [
    //         {
    //           "cert": {
    //             "serialNumber": "619C55C32FF6BD1A7B7E0330D21C8F3C",
    //             "issuerCN": "Symantec Class 1 Individual Subscriber CA - G5",
    //             "digestAlgOid": "1.3.14.3.2.26",
    //             "digestAlgName": "SHA1"
    //           },
    //           "contentType": "1.2.840.113549.1.7.1",
    //           "signingTime": "160428055000Z",
    //           "messageDigest": "2hJJVmO/jtaJV5uCKMFzIkRRvtY=",
    //           "signingAlgOid": "1.2.840.113549.1.1.1",
    //           "signingAlgName": "RSA-PKCSV-1_5",
    //           "authAttr": {
    //             "1.2.840.113549.1.9.3": {
    //               "name": "contentType",
    //               "oid": "1.2.840.113549.1.7.1"
    //             },
    //             "1.2.840.113549.1.9.5": {
    //               "name": "signingTime",
    //               "utctime": "160428055000Z"
    //             },
    //             "1.2.840.113549.1.9.4": {
    //               "name": "messageDigest",
    //               "digest": "2hJJVmO/jtaJV5uCKMFzIkRRvtY="
    //             },
    //             "1.2.840.113549.1.9.15": {
    //               "der": "MFAwCwYJYIZIAWUDBAECMAoGCCqGSIb3DQMHMA4GCCqGSIb3DQMCAgIAgDANBggqhkiG9w0DAgIBQDAHBgUrDgMCBzANBggqhkiG9w0DAgIBKA=="
    //             },
    //             "1.3.6.1.4.1.311.16.4": {
    //               "der": "MIG7MIG...7fgMw0hyPPA=="
    //             }
    //           }
    //         }
    //       ]
    //     }
    //   }
    // }

    // Use this online tool to generate parsing code from sample JSON: 
    // Generate Parsing Code from JSON

    CkDtObj signingTime;
    CkDtObj authAttrSigningTimeUtctime;
    const char *issuerCN = 0;
    const char *serial = 0;
    const char *strVal = 0;
    const char *certSerialNumber = 0;
    const char *certIssuerCN = 0;
    const char *certDigestAlgOid = 0;
    const char *certDigestAlgName = 0;
    const char *contentType = 0;
    const char *messageDigest = 0;
    const char *signingAlgOid = 0;
    const char *signingAlgName = 0;
    const char *authAttrContentTypeName = 0;
    const char *authAttrContentTypeOid = 0;
    const char *authAttrSigningTimeName = 0;
    const char *authAttrMessageDigestName = 0;
    const char *authAttrMessageDigestDigest = 0;
    const char *authAttr1_2_840_113549_1_9_15Der = 0;
    const char *authAttr1_3_6_1_4_1_311_16_4Der = 0;

    int i = 0;
    int count_i = json->SizeOfArray("pkcs7.verify.certs");
    while (i < count_i) {
        json->put_I(i);
        issuerCN = json->stringOf("pkcs7.verify.certs[i].issuerCN");
        serial = json->stringOf("pkcs7.verify.certs[i].serial");
        i = i + 1;
    }

    i = 0;
    count_i = json->SizeOfArray("pkcs7.verify.digestAlgorithms");
    while (i < count_i) {
        json->put_I(i);
        strVal = json->stringOf("pkcs7.verify.digestAlgorithms[i]");
        i = i + 1;
    }

    i = 0;
    count_i = json->SizeOfArray("pkcs7.verify.signerInfo");
    while (i < count_i) {
        json->put_I(i);
        certSerialNumber = json->stringOf("pkcs7.verify.signerInfo[i].cert.serialNumber");
        certIssuerCN = json->stringOf("pkcs7.verify.signerInfo[i].cert.issuerCN");
        certDigestAlgOid = json->stringOf("pkcs7.verify.signerInfo[i].cert.digestAlgOid");
        certDigestAlgName = json->stringOf("pkcs7.verify.signerInfo[i].cert.digestAlgName");
        contentType = json->stringOf("pkcs7.verify.signerInfo[i].contentType");
        json->DtOf("pkcs7.verify.signerInfo[i].signingTime",false,signingTime);
        messageDigest = json->stringOf("pkcs7.verify.signerInfo[i].messageDigest");
        signingAlgOid = json->stringOf("pkcs7.verify.signerInfo[i].signingAlgOid");
        signingAlgName = json->stringOf("pkcs7.verify.signerInfo[i].signingAlgName");
        authAttrContentTypeName = json->stringOf("pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.3\".name");
        authAttrContentTypeOid = json->stringOf("pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.3\".oid");
        authAttrSigningTimeName = json->stringOf("pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.5\".name");
        json->DtOf("pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.5\".utctime",false,authAttrSigningTimeUtctime);
        authAttrMessageDigestName = json->stringOf("pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.4\".name");
        authAttrMessageDigestDigest = json->stringOf("pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.4\".digest");
        authAttr1_2_840_113549_1_9_15Der = json->stringOf("pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.15\".der");
        authAttr1_3_6_1_4_1_311_16_4Der = json->stringOf("pkcs7.verify.signerInfo[i].authAttr.\"1.3.6.1.4.1.311.16.4\".der");
        i = i + 1;
    }

    delete json;


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }