System hacks: three ways to know whether a file is digitally signed or not

A digital signature is a record of information that verifies the authenticity of a digitally created document. It is a method of publishing a ciphertext that has been encrypted with a private key and a public key in a specific algorithm, and decrypting and verifying the authenticity of the document with the public key when used. Strictly speaking, digital signatures can be created for all files, not just program files, TXT or any document, but we most often see digital signatures for programs or emails. So, how do you check if a file is digitally signed? Three methods are described below.

Tip: This article is only about the method of verifying whether a file is digitally signed or not, for more content such as how to add digital signature and digital signature algorithm, it is not in the scope of this article.

First, you can verify whether a file is digitally signed by using File Explorer. Select a file to be verified, such as a Photoshop program file, right-click and select “Properties” from the shortcut menu to open the program file properties window, and if you see the “Digital Signature” tab, the program has been digitally signed (Figure 1). If you see the “Digital Signature” tab, the program has been digitally signed (Figure 1).

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If the program is not digitally signed, right-clicking on the program file and displaying its properties window will not bring up the “Digitally Signed” tab. But this does not mean that the unsigned software can not be installed or run, you will find a green program without a digital signature EXE, can still run normally. For unsigned driver installation, Microsoft will have protective tips, but the choice of initiative lies with the user, can be resolved by selecting “Disable mandatory driver signature” in the advanced startup settings.

For programs with digital signatures, click the “Details” button under the “Digital Signatures” tab to see specific information about the program’s signer, including the signer’s name, email and time of signature (Figure 2). Clicking on the “View Certificate” button allows you to view the details of the signed certificate, including the purpose of issuing the certificate, the issuer and to whom it was issued, the validity period of the certificate, the details of the certificate, the path to the certificate, etc. The “Advanced” tab in the “Digital Signature Details” window allows you to see the serial number, algorithm and other information. Click the “Install Certificate” button in the View Certificate window, and the “Certificate Import Wizard” will pop up, according to which we can copy the certificate and its trust list from disk to the certificate store. The certificate store is the system area where certificates are stored. The certificate is a guarantee of identity confirmation, data protection and network connection security.

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In addition to using the File Properties window to verify digital signatures, DigiCert Certificate Utility, a third-party software, can also be used to verify digital signatures. After running the software, click the “I Accept” button to accept the terms of use. After entering the main interface, click the Code Signing item in the left column, then click the Check Signature button in the toolbar at the top of the right pane, and then find the program you want to check the certificate in the file dialog window and click the Open button. In the certificate verification window that pops up, if both round buttons are green, it means that it has been digitally signed and the time stamp is valid (Figure 3).

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There is a SignTool tool in the Microsoft Windows 10 SDK suite that also verifies the digital signature of programs. Since the SDK is mainly aimed at developers, the component is not included in the everyday use of Windows and needs to be downloaded and installed. After installation, verify the signed file with the following command. signtool verify MyFile.exe

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