package tezos-protocol-014-PtKathma

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package tezos-protocol-014-PtKathma
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Tezos Protocol Implementation - Random number generation

This is not expected to be a good cryptographic random number generator. In particular this is supposed to be used in situations where the seed is a globally known information.

The only expected property is: It should be difficult to find a seed such that the generated sequence is a given one.

Random Generation

type t

The state of the random number generator

type seed

A random seed, to derive random sequences from

type sequence

A random sequence, to derive random values from

A VDF discriminant and challenge

A VDF result, to derive a seed from

val generate_vdf_setup : seed_discriminant:seed -> seed_challenge:seed -> vdf_setup
val vdf_to_seed : seed -> vdf_solution -> seed
val initialize_new : seed -> bytes list -> t

initialize_new state ident returns a new generator

val sequence : t -> int32 -> sequence

sequence state n prepares the n-th sequence of a state

val take : sequence -> bytes * sequence

Generates the next random value in the sequence

val take_int32 : sequence -> int32 -> int32 * sequence

take_int32 s bound generates the next random value as a bounded int32

  • parameter bound

    must be a positive integer

  • raises Invalid_argument

    "Seed_repr.take_int32" if bound <= 0

val take_int64 : sequence -> int64 -> int64 * sequence

take_int64 s bound generates the next random value as a bounded int64

  • parameter bound

    must be a positive integer

  • raises Invalid_argument

    "Seed_repr.take_int64" if bound <= 0

Entropy

type nonce

A nonce for adding entropy to the generator

val update_seed : seed -> nonce -> seed

Add entropy to the seed generator

Use a byte sequence as a nonce

val hash : nonce -> Nonce_hash.t

Compute the hash of a nonce

val check_hash : nonce -> Nonce_hash.t -> bool

check_hash nonce hash is true if the nonce correspond to the hash

val nonce_hash_key_part : Nonce_hash.t -> string list -> string list

For using nonce hashes as keys in the hierarchical database

val deterministic_seed : seed -> seed

Returns a new seed by hashing the one passed with a constant.

val initial_seeds : ?initial_seed:State_hash.t -> int -> seed list

initial_seeds n generates the first n seeds for which there are no nonces. The first seed is a constant value. The kth seed is the hash of seed (k-1) concatenated with a constant. If an initial_seed is provided, the first seed is created using it as the first one.

Predefined nonce

val initial_nonce_0 : nonce
val initial_nonce_hash_0 : Nonce_hash.t

Serializers

type seed_status =
  1. | RANDAO_seed
  2. | VDF_seed
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