Human-chosen secrets such as passphrases and PINs are not ideal cryptographic keys by themselves. Where applicable, CipherDrive™ may use a key derivation function to transform a vault secret into key-encryption material suitable for protecting higher-level cryptographic keys.
The CipherDrive whitepaper states that CipherDrive may use PBKDF2-HMAC-SHA-256 for deriving key-encryption material from a user passphrase, PIN, or vault secret where applicable.
PBKDF2 repeatedly applies a pseudorandom function to the secret together with a salt. The goal is to make each password guess more computationally expensive than simply hashing the secret once.
A salt is a random, non-secret value used during derivation. It helps ensure that the same human secret does not necessarily produce the same derived result across unrelated contexts.
The salt can be stored alongside encrypted key material because its security purpose does not depend on secrecy.
PBKDF2 performs many iterations. A higher iteration count makes legitimate derivation more expensive, but also makes large-scale password guessing more expensive for an attacker.
Ackaia may increase KDF parameters over time as hardware improves.
A key derivation function slows guessing; it does not turn a very weak human secret into an unguessable one.
If an attacker obtains encrypted key material and the KDF parameters, a weak PIN or passphrase may still be vulnerable to offline guessing.
Use the strongest vault secret the product supports and avoid short, predictable, reused, or personally obvious secrets.
Conceptually, CipherDrive can use derived key-encryption material to unlock the encrypted master key. The master key can then unwrap per-file keys, and those file keys decrypt actual file content.
This layered structure means the human secret is not simply reused directly for every file.
Hardware gets faster. A work factor that is reasonable today can become cheaper to attack in the future.
CipherDrive's protocol versioning model allows Ackaia to strengthen key-derivation parameters in newer formats while preserving compatibility with older encrypted content where possible.
Important: The whitepaper says CipherDrive may use PBKDF2-HMAC-SHA-256 where applicable. Exact KDF behavior can depend on the active protocol, client, and unlock mechanism.