(MFC) Verify a .p7m and get Algorithm Information

Demonstrates how to verify a .p7m and then examine the algorithms used by the signature.

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

See Also: Using MFC CString in Chilkat

#include <CkCrypt2.h>
#include <CkJsonObject.h>

void ChilkatSample(void)
    {
    CkString strOut;

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

    CkCrypt2 crypt;

    const char *inFile = "qa_data/p7m/brainpoolP256r1.p7m";
    const char *outFile = "qa_output/something.dat";

    // Verify and extract the signed data.
    bool success = crypt.VerifyP7M(inFile,outFile);
    if (success == false) {
        strOut.append(crypt.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Examine details about the signature(s)
    CkJsonObject *json = crypt.LastJsonData();
    json->put_EmitCompact(false);
    strOut.append(json->emit());
    strOut.append("\r\n");

    // Sample output

    // {
    //   "pkcs7": {
    //     "verify": {
    //       "digestAlgorithms": [
    //         "sha256"
    //       ],
    //       "signerInfo": [
    //         {
    //           "cert": {
    //             "serialNumber": "FFFFE552B302FFFFFF1E34C3ACEB2FFFF",
    //             "issuerCN": "The common name of the cert...",
    //             "issuerDN": "",
    //             "digestAlgOid": "2.16.840.1.101.3.4.2.1",
    //             "digestAlgName": "SHA256"
    //           },
    //           "contentType": "1.2.840.113549.1.7.1",
    //           "signingTime": "190409140500Z",
    //           "messageDigest": "lQe9If7vZKFf/NlSYu5Esmlw3phVK/RFsbbb1uH73t8=",
    //           "signingAlgOid": "1.2.840.10045.4.3.2",
    //           "signerDigest": "lQe9If7vZKFf/NlSYu5Esmlw3phVK/RFsbbb1uH73t8=",
    //           "authAttr": [
    //             {
    //               "oid": "1.2.840.113549.1.9.3",
    //               "oidName": "contentType"
    //             },
    //             {
    //               "oid": "1.2.840.113549.1.9.5",
    //               "oidName": "signingTime"
    //             },
    //             {
    //               "oid": "1.2.840.113549.1.9.52",
    //               "oidName": "1.2.840.113549.1.9.52",
    //               "der": "MBs ... AwI="
    //             },
    //             {
    //               "oid": "1.2.840.113549.1.9.4",
    //               "oidName": "messageDigest"
    //             },
    //             {
    //               "oid": "1.2.840.113549.1.9.16.2.47",
    //               "oidName": "signingCertificateV2",
    //               "der": "MCYw .. 7PlQ=="
    //             },
    //             {
    //               "oid": "1.2.840.113549.1.9.20",
    //               "oidName": "1.2.840.113549.1.9.20"
    //             }
    //           ]
    //         }
    //       ]
    //     }
    //   }
    // }

    // Code for parsing the above JSON...
    int i;
    int count_i;
    const char *strVal = 0;
    const char *certSerialNumber = 0;
    const char *certIssuerCN = 0;
    const char *certIssuerDN = 0;
    const char *certDigestAlgOid = 0;
    const char *certDigestAlgName = 0;
    const char *contentType = 0;
    const char *signingTime = 0;
    const char *messageDigest = 0;
    const char *signingAlgOid = 0;
    const char *signerDigest = 0;
    int j;
    int count_j;
    const char *oid = 0;
    const char *oidName = 0;
    const char *der = 0;

    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");
        certIssuerDN = json->stringOf("pkcs7.verify.signerInfo[i].cert.issuerDN");
        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");
        signingTime = json->stringOf("pkcs7.verify.signerInfo[i].signingTime");
        messageDigest = json->stringOf("pkcs7.verify.signerInfo[i].messageDigest");
        signingAlgOid = json->stringOf("pkcs7.verify.signerInfo[i].signingAlgOid");
        signerDigest = json->stringOf("pkcs7.verify.signerInfo[i].signerDigest");
        j = 0;
        count_j = json->SizeOfArray("pkcs7.verify.signerInfo[i].authAttr");
        while (j < count_j) {
            json->put_J(j);
            oid = json->stringOf("pkcs7.verify.signerInfo[i].authAttr[j].oid");
            oidName = json->stringOf("pkcs7.verify.signerInfo[i].authAttr[j].oidName");
            der = json->stringOf("pkcs7.verify.signerInfo[i].authAttr[j].der");
            j = j + 1;
        }

        i = i + 1;
    }

    delete json;

    strOut.append("Success!");
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }