Crate hotboot

hotboot

hotboot allows to secure private data with a weak secret, using as a protection access control of the system and defense especially designed against cold-boot attacks.

Usage

let data: Vec<u8> = very_private_data();
let secret: Vec<u8> = get_secret_from_user();
let hidden = hotboot::hide(data, secret, 100000).unwrap();

// `data` and `secret` no longer exist in memory
// A cold boot attack is highly unlikely to succeed in retrieving `data`, even
// if `secret` is known

let secret: Vec<u8> = get_secret_from_user();
let recovered = hotboot::recover(hidden, secret).unwrap();
// `recovered` is the same as `data` was

Threat model

The threat model is that of a physical attacker who attacks a weak-secret-protected data using a cold boot attack.

The special use case this was designed for is screenlockers: the screen unlocking password may not be strong, but there are timing delays that make brute-force impractical. The use of hotboot to protect the secure data in memory with the unlocking password allows to also be secure against a cold boot attack.

Design

During a cold boot attack, some bits get corrupted. The aim of hotboot is to minimize the ratio of bits that have to get corrupted to make it impossible to recover the private data.

In order to do so, it encrypts the data with a random key, then encrypts the random key with another random key, iterates a number of times, and then encrypts the last random key with a key derived from the password.

If any bit in this chain is corrupted, garbage will be found at the end, without being able to know which bit caused the issue.

The choice of cryptographic primitives is AES256-CTR for the encryption (with a random 128-bits IV and a random 256-bits key, making for 384 bits that have not to be corrupted to decrypt one step), and PBKDF2-SHA256 with 10000 iterations for initial key derivation.

Troubleshooting

Be it a support request, a bug, a lack in documentation or anything else that doesn't just work as expected, please report it as a GitHub issue.

History

• 2017-03-04: Project launch

License

hotboot is licensed under GPLv3, please see the file called LICENSE.md.

Structs

HiddenData

Opaque struct encapsulating data encrypted with a secret.

Enums

Error

Error that can be raised by a failed hide or recover call.

Functions

hide	Hides data so that it cannot be recovered by a cold boot attack without the secret secret.
recover	Recovers data hidden with secret secret.