File Encryption vs Disk Encryption: Key Differences
Understand the key differences between file-level and disk-level encryption to choose the right data protection strategy for your needs.
Disk encryption (BitLocker on Windows, FileVault 2 on macOS, LUKS/dm-crypt on Linux, APFS on iOS) protects the entire drive with one key unlocked at boot — once you're logged in, every file is accessible to every running process. File encryption (age, 7-Zip AES-256, GPG, Cryptomator) protects individual files with per-file keys that stay locked even after login. Disk encryption defends against a stolen laptop; file encryption defends against malware, nosy coworkers, and cloud sync providers. For most security postures, you want both — they solve different problems and compose cleanly.
What disk encryption actually does
BitLocker uses AES-XTS-256 over the entire volume. The Volume Master Key encrypts the Full Volume Encryption Key; the VMK itself is protected by TPM-sealed measurements plus optionally a PIN or recovery key. On boot, TPM verifies the boot path (UEFI, bootloader, kernel), releases the VMK, which unlocks the FVEK, which decrypts disk reads on the fly. FileVault 2 works similarly with the T2/M-series Secure Enclave holding keys. LUKS uses LUKS2 format with Argon2id key derivation. Once the volume is mounted, every file on it is accessible to the logged-in user and every process running as that user.
What file encryption actually does
File encryption treats each file (or each archive) as an independent ciphertext with its own key. A .7z protected with AES-256 stays encrypted while sitting on an unlocked, decrypted disk. A GPG-encrypted .pdf on your Desktop is still unreadable without the private key. Tools range from archive-style (7-Zip, WinRAR, age -p) to transparent-mount (Cryptomator, gocryptfs, EncFS) to single-file (age, GPG, openssl enc). The key for each file can be different — a per-recipient public key, a per-file random key wrapped with a password, or a folder-level password derived via scrypt.
The threat each defends against
Disk encryption defends against physical theft. Laptop stolen from a coffee shop, hard drive pulled from a decommissioned server, tablet seized at a border. Without the boot credentials, the disk is a paperweight. File encryption defends against post-boot threats. A colleague using your unlocked workstation can't read the encrypted pay stub. Malware running as your user can't exfiltrate encrypted confidential files. A cloud sync provider can't read files encrypted before sync. A subpoena against the cloud provider yields ciphertext. The threats are orthogonal; disk encryption does nothing for the second category, file encryption does nothing for the first.
Performance characteristics
Disk encryption is nearly free on modern CPUs. Intel's AES-NI and ARM's Cryptography Extensions handle AES-XTS at memory bandwidth — 5+ GB/s on a decent laptop. You'll never notice BitLocker or FileVault in day-to-day use. File encryption overhead varies by use: 7-Zip re-encrypting a whole archive on every save is slow for large files; Cryptomator's per-file AES-GCM is fast enough to be transparent; GPG public-key operations are milliseconds per file regardless of size because only the session key uses RSA/ECC. For cloud sync, file encryption is the only workable model — disk encryption doesn't help when you upload plaintext.
Granularity and selective access
Disk encryption is all-or-nothing. Anyone with boot credentials reads every file. Multi-user systems need per-user disk encryption (EFS on Windows, or stacked filesystems) to give different users different views — rarely deployed in practice. File encryption gives you per-file, per-recipient access control. Send Alice a file encrypted under her public key; she decrypts with her private key; Bob, sitting next to her with his own key, can't read it even on the same machine. This matters for shared laptops, kiosk systems, and any scenario where multiple people need different views of the same storage.
Recovery and lost-password scenarios
Lost disk encryption credentials usually mean lost data. BitLocker has a 48-digit recovery key that Microsoft stores in your account by default (security tradeoff: they can potentially hand it over to law enforcement). FileVault uses an iCloud recovery or a local recovery key. LUKS offers multiple key slots, so a backup passphrase works. File encryption tools vary: GPG has no recovery if you lose the private key — a deliberate design choice. Cryptomator has no master recovery. 7-Zip archives are permanent ciphertext without the password. The lesson: for file encryption, back up keys in a password manager and keep recovery codes offline.
How they compose
The practical deployment is disk encryption on every device (laptop, phone, backup drive) plus file encryption for anything sensitive that leaves the device. A .pdf tax return sitting in your Dropbox folder gets encrypted with age or Cryptomator before Dropbox syncs it — the file is ciphertext both on your disk (under FileVault) and in Dropbox (under client-side encryption). A thief with your laptop can't read it (disk layer), Dropbox can't read it (file layer), and malware running as your user can't exfiltrate readable copies (file layer). The layers reinforce.
Cloud service considerations
Cloud storage and backup services often advertise "encrypted at rest" which means disk encryption on their servers. The provider holds the key. This protects against a thief stealing their disks, not against the provider themselves. For client-side encryption that keeps the provider out, you need file encryption before upload. Dropbox, Google Drive, iCloud all encrypt at rest but hold keys; Apple's Advanced Data Protection (introduced 2022) makes iCloud client-side-encrypted for most file types. Regular iCloud, OneDrive, and Dropbox don't. If your threat model includes the cloud provider, file encryption is mandatory.
Regulatory treatment of the two
HIPAA 164.312(a)(2)(iv) treats encryption as addressable — both disk and file encryption qualify, but disk-only leaves PHI readable once the machine boots, which fails 164.308(a)(4) access control. PCI DSS 4.0 Requirement 3.5.1 requires the PAN be rendered unreadable anywhere it's stored; file-level encryption with tokenization is the standard pattern because disk encryption doesn't satisfy granular access. GDPR Article 32 accepts either as "appropriate technical measure" depending on risk. CCPA's 1798.150 safe harbor applies to either as long as keys weren't compromised alongside data.
What file transfer services provide
HexaTransfer and similar E2EE file transfer services do a specific kind of file encryption — per-file, per-transfer, with random keys shared through the URL fragment. It's not disk encryption (doesn't protect your laptop) and not persistent file encryption (the file disappears after download). It's transit-stage file encryption: protect this specific transfer from the vendor, the network, and the cloud provider, then let it self-destruct. For permanent storage, pair it with persistent file encryption tools (age, Cryptomator) applied before archiving. Different problems, different tools.
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