VeraCrypt

VeraCrypt is an absolute legend in the cryptographic community and the undisputed, de facto standard for free, open-source, highly secure disk encryption. It is the direct spiritual and technical successor to the famously abandoned TrueCrypt project. Because it is completely open-source, its underlying cryptographic code has been mercilessly audited by independent security researchers globally, ensuring that it contains absolutely no government backdoors or proprietary vulnerabilities, making it the software of choice for privacy advocates, journalists, and highly security-conscious individuals. The core capability of VeraCrypt is "On-the-Fly Encryption" (OTFE). It can encrypt an entire hard drive (including the partition where Windows is installed) or create a massive, highly encrypted virtual file that acts as a secure vault (a "container"). When a user mounts this vault and enters their massive passphrase, the encrypted file behaves exactly like a normal USB drive. The encryption is entirely transparent to the user; files are automatically encrypted right before they are saved to the disk and decrypted right after they are loaded into RAM, without any user intervention. Furthermore, VeraCrypt is famous for its "Plausible Deniability" feature. It allows a user to create a highly secret "Hidden Volume" inside a standard encrypted volume. The outer volume has a password, and the hidden inner volume has a different password. If a user is physically coerced (extortion) into surrendering their password, they can surrender the password to the outer volume (which contains innocuous data). The attacker cannot mathematically prove that the hidden inner volume (containing the truly sensitive data) even exists. For absolute, uncompromising, un-backdoored privacy, VeraCrypt is unmatched.