Encrypting a file or document is the simplest way to prevent other people from accessing its content. Thus, unless we have the password or decryption key, it will be practically impossible to see what it contains. In the next post we will see what methods we can use in most operating systems to encrypt a file securely.
Before starting it would also be interesting to clarify that the encrypted files are not 100% indecipherable. A good hacker can (albeit with difficulty) bypass encryption protection. Something that can happen if we save the passwords and cryptographic keys in an unencrypted file or our system is infected by a keylogger. If we have really valuable information, the most recommended solution is to hire an encryption service in the cloud (mainly oriented to companies).
It is also recommended to make an unencrypted backup of all sensitive files, in case we lose the unlock passwords. It is best to save these backups on physical storage -memory or external disk-, preferably offline.
How to encrypt a file on Android
As of Android 6.0, all Android phones and devices already come with encrypted internal memory as standard, we can always choose to also encrypt the SD card.
In case we want to protect a single file, we can do it using applications such as Andrognito, which uses a 256-bit AES algorithm with military grade encryption to safeguard user files.
Download QR-Code Andrognito - Hide Files, Photos, Videos Developer: CODEX Price: Free To encrypt a file with Andrognito, once we have installed the application, we open it and follow these 4 steps:
- We register and enter a 4-digit PIN or unlock pattern.
- By default the system will create a vault or "Vault”. All the files that we add to this vault will be protected and encrypted.
- To add files to our vault, we just have to click on the "+" icon and select the document by making a long press and confirming on the "OK" icon that we will see at the top right. If the encryption has been done correctly we will see a green message.
If later we want to decrypt Some of these documents can be done by simply entering the vault and clicking on the drop-down menu next to each file and selecting "Decrypt and export”.
One of the interesting details of this application is that it saves encrypted documents in the cloud, thus freeing up storage space and allowing access to the file from any other device (as long as we use the same account, of course).
How to encrypt a file in Windows
If we want to protect a file with important information on a Windows computer we have several options.
We can use BitLocker -the most reliable method-, a tool that is integrated into Windows 10, but that does not allow you to encrypt files individually. Something that we can do with SAI (Encrypted File System), although it is not the most recommended solution if we handle very sensitive data. The third alternative is to use a dedicated program, this being the only possible solution in case we have a system with Windows 10 Home Edition.
SAI
EFS is an encryption tool that Windows uses in a way that allows you to encrypt both individual files and folders on NTFS drives. It is only available in the Professional, Enterprise and Education versions of Windows.
The system works by making encrypted files available only if the person who encrypted them is logged into the PC. Here Windows generates an encryption key which in turn is also encrypted and stored locally. It is a simple method, but not very secure (a good hacker could screw us if he really wants to). However, if all we want is to protect certain information from curious friends or family it may be more than enough.
To encrypt a file or folder with EFS:
- We open the file explorer and right click on the file that we want to encrypt and select "Properties”.
- Click on "Advanced"And activate the tab"Encrypt content to protect data”. We click on "To accept"And then in"Apply”.
- If we have only selected a file, Windows will invite us to also encrypt the folder for greater security. If we only want to encrypt the file we mark "Encrypt only the file”And we accept.
- The system will then recommend to make a backup of the certificate and the file encryption key in case the system is damaged or corrupted. If we are interested, we only have to insert a pendrive, click on "Make a backup now”And follow the instructions of the wizard.
Third party apps
Windows 10 Home users do not have the EFS utility, so in these cases it is necessary to install a program that allows us to encrypt files. One of the most efficient and easy to use in this regard is AxCrypt.
With this program we can change the extension to any file and replace it with the .AXX extension. In this way, the file can only be opened from AxCrypt by entering the previously established password used to encrypt the document in question.
As an alternative, we can also use the program 7-Zip, which helps us to compress files in 7z and ZIP format and incidentally encrypt them with maximum security with AES-256 encryption.
How to encrypt a document on iPhone
Since the launch of the long-standing iPhone 3GS, all mobile phones with an iOS system include basic hardware-level encryption. However, if we want to protect our encrypted files, it is necessary that we protect our iPhone or iPad with an access password.
That said, if we want to encrypt a sensitive document, photo or delicate video, we will have to install an application for this purpose, such as Folder Lock. The application works in a very similar way to Andrognito, hiding the files and protecting them with an access password.
How to encrypt a file in Linux
If we are working from a Linux computer we can encrypt any file or folder using the GPG command. The only way to decrypt the file and access the information it contains is by entering the correct password.
Suppose we have the file ~ / Documents / Important.docx and we want to encrypt it.
- First we open a terminal window and move to the folder where the file is located. In this case we would go to the folder "Documents”.
- Next, we write the command “gpg -c Important.docx " (without quotation marks).
- Now we enter a complex password and press enter. We confirm the password.
From this moment on, we will see how the document has changed its extension to “Important.docx.gpg”. If we want to decrypt it, we only have to reopen a terminal, go to the folder where the file is located and write the command "gpg -c Important.docx.gpg”. The system will ask us to enter the password and we will be able to access it again without problems.
How to encrypt a file on MacOS
AES Crypt is an open source software that allows us to encrypt any file in MacOS individually. We can download it completely free from its official website HERE (it is also available for Windows, Android and Linux).
Its operation is very simple. We just have to locate the file, drag it to the AES Crypt icon (padlock icon) that we will see in the dock menu and enter a password. It is important that we write down the password somewhere, since there is no password recovery process.
Once this is done, the program will generate an encrypted version of the existing file. This means that we will have 2 versions of the same file: one encrypted and one unencrypted. Therefore, it is necessary that we proceed to eliminate the original file or save it on a pendrive as a backup.
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