从可执行文件中读取多个签名

时间：2014-07-22 16:13:49

标签： c++ authenticode signatures

我正在尝试编写从DLL或EXE读取签名（证书）的代码。大多数DLL或EXE只有一个签名，我的代码正确读取与此签名关联的所有证书。更具体地说，它读取签名证书，它是发行者（不是root），签名证书（带有时间戳）和它的发行者（不是root）。我有2个C ++和C＃示例程序，它们都返回相同的证书。这是C＃代码，C ++是100倍：）

static void Main(string[] args)
{
    X509Certificate2Collection collection = new X509Certificate2Collection();
    collection.Import(args[0]);
}

但是有一些DLL有2个签名，如文件属性/数字签名所示，例如C：\ Program Files（x86）\ Microsoft SQL Server \ 80 \ Tools \ Binn \ msvcr71.dll：

File properties and digital signatures for msvcr71.dll

对于此DLL，我的代码只读取与第一个签名关联的证书。

我也尝试使用signtool，它返回与我的代码相同的信息：first cert（带有它的路径）和counterignature（带有它的路径）。但最后还要注意错误。

C:\Windows>signtool verify /d /v "C:\Program Files (x86)\Microsoft SQL Server\80\Tools\Binn\msvcr71.dll"

Verifying: C:\Program Files (x86)\Microsoft SQL Server\80\Tools\Binn\msvcr71.dll
Signature Index: 0 (Primary Signature)
Hash of file (sha1): 33BBCCF6326276B413A1ECED1BF7842A6D1DDA07

Signing Certificate Chain:
Issued to: Microsoft Root Certificate Authority
Issued by: Microsoft Root Certificate Authority
Expires:   Sun May 09 19:28:13 2021
SHA1 hash: CDD4EEAE6000AC7F40C3802C171E30148030C072

    Issued to: Microsoft Code Signing PCA
    Issued by: Microsoft Root Certificate Authority
    Expires:   Wed Jan 25 19:32:32 2017
    SHA1 hash: FDD1314ED3268A95E198603BA8316FA63CBCD82D

        Issued to: Microsoft Corporation
        Issued by: Microsoft Code Signing PCA
        Expires:   Fri Feb 01 18:49:17 2013
        SHA1 hash: 8849D1C0F147A3C8327B4038783AEC3E06C76F5B

The signature is timestamped: Sat Feb 11 14:03:12 2012
Timestamp Verified by:
Issued to: Microsoft Root Certificate Authority
Issued by: Microsoft Root Certificate Authority
Expires:   Sun May 09 19:28:13 2021
SHA1 hash: CDD4EEAE6000AC7F40C3802C171E30148030C072

    Issued to: Microsoft Time-Stamp PCA
    Issued by: Microsoft Root Certificate Authority
    Expires:   Sat Apr 03 09:03:09 2021
    SHA1 hash: 375FCB825C3DC3752A02E34EB70993B4997191EF

        Issued to: Microsoft Time-Stamp Service
        Issued by: Microsoft Time-Stamp PCA
        Expires:   Thu Oct 25 16:42:17 2012
        SHA1 hash: FC33104FAE31FB538749D5F2D17FA0ECB819EAE5

SignTool Error: The signing certificate is not valid for the requested usage.
    This error sometimes means that you are using the wrong verification
    policy. Consider using the /pa option.

Number of files successfully Verified: 0
Number of warnings: 0
Number of errors: 1

我有两个问题： - 第二次签名的目的是什么？ - 如何阅读（到目前为止只有Windows资源管理器文件属性对话框可以显示它）。

谢谢！

4 个答案:

答案 0 :(得分：14)

经过大量挖掘和尝试不同的事情后，我发现函数WinVerifyTrust可以读取多个嵌入式证书。忽略函数名称，它可用于许多事物，它是一个通用函数。

WinVerifyTrust 将struct WINTRUST_DATA作为其输入/输出参数之一。文档说它是IN，但它也用于返回信息。

WINTRUST_DATA包含字段pSignatureSettings，它是指向另一个结构WINTRUST_SIGNATURE_SETTINGS的指针。此stuct具有字段dwFlags，用于控制 WinVerifyTrust 将返回的信息。

首先使用WINTRUST_SIGNATURE_SETTINGS::dwFlags = WSS_GET_SECONDARY_SIG_COUNT调用 WinVerifyTrust 以获取辅助签名的数量，这将在字段WINTRUST_SIGNATURE_SETTINGS::cSecondarySigs中返回。请注意，如果您的文件有2个签名，则cSecondarySigs将为1。

然后在循环for (int i = 0; i <= cSecondarySigs; i++)中，使用WINTRUST_SIGNATURE_SETTINGS::dwFlags = WSS_VERIFY_SPECIFIC和WINTRUST_SIGNATURE_SETTINGS::dwIndex = i调用 WinVerifyTrust 。

在每次 WinVerifyTrust 调用之后，您可以通过此调用序列从WINTRUST_DATA::hWVTStateData获取证书信息（包括签名）：

WTHelperProvDataFromStateData(hWVTStateData);
WTHelperGetProvSignerFromChain(...);
WTHelperGetProvCertFromChain(...);

我没有深入研究.NET API，但它似乎只能读取第一个签名。请注意，在Windows 8中添加了WINTRUST_SIGNATURE_SETTINGS，它似乎是读取多个签名的关键，因此在较旧的操作系统上，您将无法读取它，至少不能使用MS API。

答案 1 :(得分：5)

扩展Dima的答案，我想提供一个示例代码，演示如何检查所有嵌入（和嵌套）叶子（不在证书链中间）证书。

BOOL CheckCertificateIssuer(HANDLE hWVTStateData, const std::set<CString> &stValidIssuers)
{
    CRYPT_PROVIDER_DATA *pCryptProvData = WTHelperProvDataFromStateData(hWVTStateData);
    CRYPT_PROVIDER_SGNR *pSigner = WTHelperGetProvSignerFromChain(pCryptProvData, 0, FALSE, 0);
    CRYPT_PROVIDER_CERT *pCert = WTHelperGetProvCertFromChain(pSigner, 0);

    CString sIssuer;
    int nLength = CertGetNameString(pCert->pCert, CERT_NAME_SIMPLE_DISPLAY_TYPE, CERT_NAME_ISSUER_FLAG, NULL, NULL, 0);
    if (!nLength)
    {
        ASSERT(FALSE && "Cannot get the length of the Issuer string");
        return FALSE;
    }

    if (!CertGetNameString(pCert->pCert, CERT_NAME_SIMPLE_DISPLAY_TYPE, CERT_NAME_ISSUER_FLAG, NULL, sIssuer.GetBuffer(nLength), nLength))
    {
        ASSERT(FALSE && "Cannot get the Issuer string");
        return FALSE;
    }
    sIssuer.ReleaseBuffer(nLength);
    if (stValidIssuers.find(sIssuer) == stValidIssuers.end())
    {
        ASSERT(FALSE && "Certificate issuer is invalid");
        return FALSE;
    }
    return TRUE;
}
BOOL CheckCertificate(CString filename)
{
    std::set<CString> stValidIssuers;
    stValidIssuers.insert(L"VeriSign Class 3 Code Signing 2010 CA");
    stValidIssuers.insert(L"Symantec Class 3 SHA256 Code Signing CA");

    bool UseStrongSigPolicy = false;

    DWORD Error = ERROR_SUCCESS;
    bool WintrustCalled = false;
    GUID GenericActionId = WINTRUST_ACTION_GENERIC_VERIFY_V2;
    WINTRUST_DATA WintrustData = {};
    WINTRUST_FILE_INFO FileInfo = {};
    WINTRUST_SIGNATURE_SETTINGS SignatureSettings = {};
    CERT_STRONG_SIGN_PARA StrongSigPolicy = {};

    // Setup data structures for calling WinVerifyTrust
    WintrustData.cbStruct = sizeof(WINTRUST_DATA);
    WintrustData.dwStateAction = WTD_STATEACTION_VERIFY;
    WintrustData.dwUIChoice = WTD_UI_NONE;
    WintrustData.fdwRevocationChecks = WTD_REVOKE_NONE;
    WintrustData.dwUnionChoice = WTD_CHOICE_FILE;

    FileInfo.cbStruct = sizeof(WINTRUST_FILE_INFO_);
    FileInfo.pcwszFilePath = filename;
    WintrustData.pFile = &FileInfo;

    //
    // First verify the primary signature (index 0) to determine how many secondary signatures
    // are present. We use WSS_VERIFY_SPECIFIC and dwIndex to do this, also setting
    // WSS_GET_SECONDARY_SIG_COUNT to have the number of secondary signatures returned.
    //
    SignatureSettings.cbStruct = sizeof(WINTRUST_SIGNATURE_SETTINGS);
    SignatureSettings.dwFlags = WSS_GET_SECONDARY_SIG_COUNT | WSS_VERIFY_SPECIFIC;
    SignatureSettings.dwIndex = 0;
    WintrustData.pSignatureSettings = &SignatureSettings;

    if (UseStrongSigPolicy != false)
    {
        StrongSigPolicy.cbSize = sizeof(CERT_STRONG_SIGN_PARA);
        StrongSigPolicy.dwInfoChoice = CERT_STRONG_SIGN_OID_INFO_CHOICE;
        StrongSigPolicy.pszOID = szOID_CERT_STRONG_SIGN_OS_CURRENT;
        WintrustData.pSignatureSettings->pCryptoPolicy = &StrongSigPolicy;
    }
    BOOL bResult = E_NOT_SET;
    TRACE(L"Verifying primary signature... ");
    Error = WinVerifyTrust(NULL, &GenericActionId, &WintrustData);
    WintrustCalled = true;
    if (Error == ERROR_SUCCESS)
    {
        if (CheckCertificateIssuer(WintrustData.hWVTStateData, stValidIssuers))
        {
            if (bResult == E_NOT_SET)
                bResult = TRUE;
        }
        else
        {
            bResult = FALSE;
        }

        TRACE(L"Success!\n");

        TRACE(L"Found %d secondary signatures\n", WintrustData.pSignatureSettings->cSecondarySigs);

        // Now attempt to verify all secondary signatures that were found
        for (DWORD x = 1; x <= WintrustData.pSignatureSettings->cSecondarySigs; x++)
        {
            TRACE(L"Verify secondary signature at index %d... ", x);

            // Need to clear the previous state data from the last call to WinVerifyTrust
            WintrustData.dwStateAction = WTD_STATEACTION_CLOSE;
            Error = WinVerifyTrust(NULL, &GenericActionId, &WintrustData);
            if (Error != ERROR_SUCCESS)
            {
                //No need to call WinVerifyTrust again
                WintrustCalled = false;
                TRACE(L"%s", utils::error::getText(Error));
                ASSERT(FALSE);
                break;
            }

            WintrustData.hWVTStateData = NULL;

            // Caller must reset dwStateAction as it may have been changed during the last call
            WintrustData.dwStateAction = WTD_STATEACTION_VERIFY;
            WintrustData.pSignatureSettings->dwIndex = x;
            Error = WinVerifyTrust(NULL, &GenericActionId, &WintrustData);
            if (Error != ERROR_SUCCESS)
            {
                TRACE(L"%s", utils::error::getText(Error));
                ASSERT(FALSE);
                break;
            }

            if (CheckCertificateIssuer(WintrustData.hWVTStateData, stValidIssuers))
            {
                if (bResult == E_NOT_SET)
                    bResult = TRUE;
            }
            else
            {
                bResult = FALSE;
            }


            TRACE(L"Success!\n");
        }
    }
    else
    {
        TRACE(utils::error::getText(Error));
        ASSERT(FALSE);
    }

    //
    // Caller must call WinVerifyTrust with WTD_STATEACTION_CLOSE to free memory
    // allocate by WinVerifyTrust
    //
    if (WintrustCalled != false)
    {
        WintrustData.dwStateAction = WTD_STATEACTION_CLOSE;
        WinVerifyTrust(NULL, &GenericActionId, &WintrustData);
    }

    return bResult;

}

答案 2 :(得分：0)

看着

The signature is timestamped: Sat Feb 11 14:03:12 2012

和

Issued to: Microsoft Time-Stamp Service

我假设第二个签名/证书用于time-stamping个文件。很可能MS有两个不同的组织单位，其中一个签署代码以确认其完整性，另一个（稍后）使用自己的证书再次签署代码，专门用于安全时间戳文件。

可以创建证书并将其分配给某些用法。用于时间戳的证书可以这样标记，因此signtool在遇到时间戳证书时可能会出错，因为默认情况下它需要证书来验证代码的真实性/完整性验证，而不是时间戳。

答案 3 :(得分：0)

最新版本的SignTool.exe可以处理多个签名。

一个是使用/ ds开关。这使您可以选择签名索引。

更好的是，这是一个很好的C＃示例，它将读取和验证多个签名。 Code signing an executable twice

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