package octez-libs
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doc/octez-libs.crypto/Tezos_crypto/Timelock/index.html
Module Tezos_crypto.TimelockSource
Timelock is a set of functions to handle time-locking a value and opening time-locked values.
A time-locked value can be opened slowly by anyone doing a fixed number of sequential operations.
In the interface of this module, this fixed number is consistently named time and is represented by an integer.
Once opened via the slow method a proof of opening can be produced to avoid having to do so again. This proof is verifiable in logarithmic time.
In order to time-lock an arbitrary sequence of bytes, we 1. encrypt the bytes with a symmetric key, and then 2. we time-lock the symmetric key itself.
This module implements a scheme inspired by: Time-lock puzzles and timed release - Rivest, Shamir, Wagner https://people.csail.mit.edu/rivest/pubs/RSW96.pdf
We will time-lock symmetric keys to then handle arbitrary bytes
Locked value that can be accessed with a number of sequential operations. It is concretely a member of the RSA group.
Function taking as input a string and returning Some locked_value if the element is in the RSA group with RSA2048 as modulus, None otherwise.
Function taking as input a string and returning a locked_value with no check.
Member of the RSA group that we will lock. In our case it represents a symmetric key.
VDF proof (Wesolowski).
A symmetric ciphertext and message authentication code, containing the bytes we want to protect
type vdf_tuple = {locked_value : locked_value;unlocked_value : unlocked_value;vdf_proof : vdf_proof;
}Tuple of the RSA group comprising the locked and unlocked values as well as a (Wesolowski) proof that the unlocked value indeed corresponds to the locked one.
Proof that the opening of a value is the claimed value. It is concretely a vdf_tuple and a member of the RSA group.
Generates almost uniformly an integer mod n. It is in the RSA group with overwhelming probability. We use this since we want to lock symmetric keys, not pre-determined messages.
Returns None if rsa_public is not RSA2048, otherwise returns Some gen_locked_value_unsafe rsa_public.
Hashes a number mod n to a symmetric key for authenticated encryption, where the number is unlocked_value**nonce mod rsa2048.
Unlock a timelock value and produces a proof certifying that the result is indeed what had been locked.
Produces a proof certifying that the result is indeed what had been locked.
Verifies that locked_value indeed contains unlocked_value with parameters time:int.
val precompute_timelock :
?locked_value:locked_value option ->
?precompute_path:string option ->
time:int ->
unit ->
vdf_tuplePrecomputes a vdf_tuple given a time:int and optionally locked_value. If precompute_path is given, it will instead read vdf_tuple locally and if not found, will write the newly computed vdf_tuple there.
Randomizes a vdf_tuple given a time:int (to verify the vdf_tuple is correct).
encrypt using authenticated encryption, i.e. ciphertext contains a ciphertext and a message authentication code.
Checks the message authentication code. If correct decrypt the ciphertext, otherwise returns None.
Contains a value (the decryption of the ciphertext) that can be provably recovered in time sequential operation.
Provably opens a chest in a short time.
Result of the opening of a chest. The opening can fail in two ways which we distinguish to blame the right party. One can provide a false unlocked_value or unlocked_proof, in which case we return Bogus_opening and the provider of the chest key is at fault. Otherwise we return Correct payload where payload is the content that had originally been put in the chest.
Takes a chest, chest key and time and tries to recover the underlying plaintext. See the documentation of opening_result.
Gives the size of the underlying plaintext in a chest in bytes. Used for gas accounting
val create_chest_and_chest_key :
?precompute_path:string option ->
payload:Bytes.t ->
time:int ->
unit ->
chest * chest_keyHigh level function which given a payload, time and optionally a precomputed_path, generates a chest and chest_key. The payload corresponds to the message to timelock while the time corresponds to the difficulty in opening the chest. Beware, it does not correspond to a duration per se but to the number of iteration needed. The optional precomputation_path is a local path where to read or write some auxiliary information to generate the chest quickly.
High level function to unlock the value and create a proof.
val chest_sampler :
rng_state:Random.State.t ->
plaintext_size:int ->
time:int ->
chest * chest_key----- !!!!! Do not use for wallets: the RNG is not safe !!!!---- Sampler for the gasbenchmarks. Takes an Ocaml RNG state as arg for reproducibility.