How to Encrypt Pictures (2024)

Image encryption can be used to watermark digital images for copyright purposes and to make your personal images safe from prying eyes. For images that are stored on laptops, smartphones, or in the cloud, encryption gives you an extra layer of security to help keep your images private. Special software is needed to encrypt images and is readily available as freeware, shareware, and for sale on the Internet for all major operating systems.

Why Images Are Encrypted

Images are encrypted for many reasons, including identifying the creator of an image, protecting copyright information, deterring piracy, and blocking images from being viewed by users who shouldn't have access to them. By encrypting images, you can send them through email or over the Internet without worrying about your images are being viewed by people that you don't want to see them. Encrypting images on your home computer will also give you a measure of security in case a hacker gains access to your hard drive, and encrypting the images on your laptop or smartphone will likewise make your images safer if your computer or laptop are lost or stolen.

Steganography

Steganography is a way of hiding messages within an image, text, or even in video, but it is not a true encryption process. With digital images, a second picture may be hidden inside a first by selectively replacing some of the binary data that represent each pixel's color and intensity with opposite values. One common steganographic method, called the least significant bit method, changes the unit values of the binary image data so ones become zeros and zeros become ones. Only a portion of the binary image data needs to be changed to hide another picture. Steganography may be used to add digital watermarks to images to help protect copyrighted material from theft, but it can also be used to hide stolen data or sensitive information. Steganographic images are easily deciphered unless they're also encrypted by other software.

Encryption Process

A picture can be encrypted in the same way that text is encrypted by software. By running a sequence of mathematical operations, called an algorithm, on the binary data that comprises an image, encryption software changes the values of the numbers in a predictable way. A software key is necessary to unlock the encryption code, and it's created by the same software that scrambles the picture. The encrypted image and the key are sent to the recipient separately to minimize the chance that a hacker could intercept both. The software key, which is usually a type of password, is typed into decryption software to decipher the encoded image. The security of the encryption depends on how difficult the encrypted data are to unencrypt.

Encryption Software

You will need encryption software to encode images. Major computer operating systems come with some form of encryption software, but third-party applications are also available for personal computers, tablets, and smartphones. Microsoft provides BitLocker with Windows 7, while the Mac OS X comes with FileVault. One third-party program is TrueCrypt, which can create a decoy operating system to confuse hackers. Dropbox, PowerFoler, and Cloudfogger are online file storage systems that include encryption as part of their data security. Some encryption programs will let you batch process images, and most can handle common image files such as BMP, TIF, RAW, PSD, and JPG. Phone apps enable you to encrypt your images directly on your phone. Encryption apps for Android-based smartphones include WhisperCore and Droid Crypt, and iPhone apps include Kryptos and SecuMail.

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