Crate onepass_seed 

This crate implements arbitrary deterministic secret generation from a fixed seed password.

The core, basic idea here is that a password schema should be enumerable: e.g. the schema [a-z] generates 26 different passwords, the first one is 'a', and the last is 'z'. So then if we can count the size of the universe of passwords generated by a schema, then we can use a cryptographically secure pseudorandom number generator to sample it based on a deterministic secret, yielding a deterministic output.

The other main piece of this password generation scheme entails securely deriving a per-site secret from a single seed password, thereby stretching one secret into an arbitrary number of secrets. We do this by taking a password hash of the seed password against a salt that consists of the full derivation parameters for the site in question; e.g. the site URL, username, and the schema from which the password is generated. Any changes to the derivation should therefore result in securely different secrets, meaning that generally a compromised site password should reveal no information about either the seed password or other site passwords.

Combining these ideas then, usage of this library collapses the state for a password manager from O(n) secret state, where n is the number of sites for which a user has passwords, to O(1) secret state (the seed) plus O(n) non-secret state (the public site derivation parameters.) This makes migration much easier and safer than with traditional password managers; a user may simply upload or copy their site derivation info and write down or memorize their seed password.

A lot of this crate, then, is about canonical serialization of site parameters and schemas such that derivation paths may be deterministically re-derived from configuration. E.g. we normalize URLs and we specify a canonical formatting of password schemas.

This scheme is designed to be user-extensible; crate users may add their own custom secret generators to extend this library into other domains. This is done via Generators. A Generator may extend a password schema with specific extra configuration, e.g. a hash of a word list, to ensure that derivations that are different produce uncorrelated passwords.

The derivation parameters saved per-site are the (mandatory) URL, an optional username, the password schema, and a nonce (called the “increment” in this crate.) The purpose of the nonce is to make it easy to rotate a site password if one is ever compromised, or to comply with rotation policies; simply incrementing the nonce should yield an uncorrelated, new password for that site from the same seed.

use onepass_seed::site::Site;
let site = Site::new("google.com", None, "{words:4:-}", 0).unwrap();
let pw = site.password("seedpass").unwrap();
assert_eq!("jaywalker-diffused-verse-abdominal", pw.expose_secret());

For more information on the schema language see Expr.

Modules

dict

This module re-exports onepass_base::dict and also defines the static EFF_WORDLIST compile-time dictionary.

expr

This module implements the chore schema language for this crate. See Expr::parse for the schema language description, Expr::write_repr for the canonical serialization format, and the Eval and EvalContext instances for the generation scheme.

site

url

Macros

format_tsv

Format the fields passed to this macro as tab-separated values with all inner TSV-meaningful characters escaped; see crate::format_tsv_args.

format_tsv_args

Present the fields passed to this macro as a core::fmt::Arguments that yields tab-separated values.

write_tsv

Write the fields passed to this macro as tab-separated values with all inner TSV-meaningful characters escaped; see crate::format_tsv_args.

Structs

SecretBox

Wrapper type for values that contains secrets, which attempts to limit accidental exposure and ensure secrets are wiped from memory when dropped. (e.g. passwords, cryptographic keys, access tokens or other credentials)

Traits

ExposeSecret

Expose a reference to an inner secret

ExposeSecretMut

Expose a mutable reference to an inner secret

Type Aliases

SecretString

Secret string type.

U256

256-bit unsigned big integer.