Struct KeySeedFor

pub struct KeySeedFor<Id, Item, Salt, Hash, T> {
    target: Id,
    item: Item,
    salt: Salt,
    _hash: PhantomData<Hash>,
    _marker: PhantomData<T>,
}

A seed structure for deterministic identifier derivation.

KeySeedFor enables the generation of a unique, deterministic identifier (Id) from a combination of:

• a target key type (Id)
• a meta-data value (Item)
• a unique salt (Salt)

within the context of a specific runtime (T) and hashing algorithm (Hash).

Overview

This struct serves as the canonical pre-image for generating new deterministic IDs, based on a source identity (target), a value of interest (item), and a unique salt.

Type Parameters

• Item: The value associated with the derived identifier. May be low entropy or even default.
• Id: The identifier type, used both as the source (key) and the derived output (target).
• Salt: A unique value to ensure uniqueness per (Id, Item) pair.
• Hash: The hashing algorithm used for deterministic ID derivation.
• T: The runtime context.

Constraints & Responsibilities

• target (Id): Must be a high-entropy, globally unique identifier (e.g., account ID, hash, public key).
• item (Item): May be low-entropy; a single Id can be associated with multiple Item types, but each Item type must be uniquely tied to a single Id type.
• salt: Must be unique per (Id, Item) pair; implementers must ensure salts are not reused.

Example Use Cases

• Sub-identities derived from a parent identity
• Capability delegation
• Namespaced object IDs
• Resource handles scoped to specific keys

Fields

target: Id

item: Item

salt: Salt

_hash: PhantomData<Hash>

_marker: PhantomData<T>

Implementations

impl<Id, Item, Salt, Hasher, T> KeySeedFor<Id, Item, Salt, Hasher, T>

where Id: Clone + FullCodec, Item: Clone + FullCodec, Salt: Clone + FullCodec, Hasher: Hash,

Implementation of utility methods for KeySeedFor.

pub fn target(&self) -> Id

Gets the current value of the target key.

pub fn item(&self) -> Item

Gets the current value of the item (metadata for the target key).

pub fn salt(&self) -> Salt

Gets the current value of the salt used for key derivation.

pub fn mut_target(&mut self) -> &mut Id

Provides mutable access to the target key.

pub fn mut_item(&mut self) -> &mut Item

Provides mutable access to the item (metadata).

pub fn mut_salt(&mut self) -> &mut Salt

Provides mutable access to the salt.

pub fn new(target: Id, item: Item, salt: Salt) -> Self

Constructs a new KeySeedFor from the given target, item and salt.

pub fn key_gen(&self) -> Option<Id>

Generates a deterministic identifier (Id) by hashing the encoded target, item, and salt.

Returns Some(Id) if decoding from the hash output succeeds, or None otherwise.

Trait Implementations

impl<Id: Clone, Item: Clone, Salt: Clone, Hash: Clone, T: Clone> Clone for KeySeedFor<Id, Item, Salt, Hash, T>

fn clone(&self) -> KeySeedFor<Id, Item, Salt, Hash, T>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<Id, Item, Salt, Hash, T> Debug for KeySeedFor<Id, Item, Salt, Hash, T>

where Id: Debug, Item: Debug, Salt: Debug, Hash: Debug, T: Debug,

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<Id, Item, Salt, Hash, T> Decode for KeySeedFor<Id, Item, Salt, Hash, T>

where Id: Decode, Item: Decode, Salt: Decode, PhantomData<Hash>: Default, PhantomData<T>: Default,

fn decode<__CodecInputEdqy: Input>( __codec_input_edqy: &mut __CodecInputEdqy, ) -> Result<Self, Error>

Attempt to deserialise the value from input.

fn decode_into<I>( input: &mut I, dst: &mut MaybeUninit<Self>, ) -> Result<DecodeFinished, Error>

where I: Input,

Attempt to deserialize the value from input into a pre-allocated piece of memory.

fn skip<I>(input: &mut I) -> Result<(), Error>

where I: Input,

Attempt to skip the encoded value from input.

fn encoded_fixed_size() -> Option<usize>

Returns the fixed encoded size of the type.

impl<Id, Item, Salt, Hash, T> Encode for KeySeedFor<Id, Item, Salt, Hash, T>

where Id: Encode, Item: Encode, Salt: Encode,

fn size_hint(&self) -> usize

If possible give a hint of expected size of the encoding.

fn encode_to<__CodecOutputEdqy: Output + ?Sized>( &self, __codec_dest_edqy: &mut __CodecOutputEdqy, )

Convert self to a slice and append it to the destination.

fn encode(&self) -> Vec<u8>

Convert self to an owned vector.

fn using_encoded<R, F>(&self, f: F) -> R

where F: FnOnce(&[u8]) -> R,

Convert self to a slice and then invoke the given closure with it.

fn encoded_size(&self) -> usize

Calculates the encoded size.

impl<Id, Item, Salt, Hasher, T> KeyGenFor<Id, Item, Salt, Hasher, T> for KeySeedFor<Id, Item, Salt, Hasher, T>

where Id: Clone + FullCodec, Item: Clone + FullCodec, Salt: Clone + FullCodec, Hasher: Hash,

Blanket implementation of KeyGenFor for KeySeedFor.

This allows any KeySeedFor instance to use the gen_key utility

fn gen_key(target: &Id, item: &Item, salt: Salt) -> Option<Id>

Generates a deterministic identifier (Id) from the given target, item, and salt.

impl<Id, Item, Salt, Hash, T> MaxEncodedLen for KeySeedFor<Id, Item, Salt, Hash, T>

where Id: MaxEncodedLen, Item: MaxEncodedLen, Salt: MaxEncodedLen,

fn max_encoded_len() -> usize

Upper bound, in bytes, of the maximum encoded size of this item.

impl<Id: PartialEq, Item: PartialEq, Salt: PartialEq, Hash: PartialEq, T: PartialEq> PartialEq for KeySeedFor<Id, Item, Salt, Hash, T>

fn eq(&self, other: &KeySeedFor<Id, Item, Salt, Hash, T>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<Id, Item, Salt, Hash, T> TypeInfo for KeySeedFor<Id, Item, Salt, Hash, T>

where Id: TypeInfo + 'static, Item: TypeInfo + 'static, Salt: TypeInfo + 'static, PhantomData<Hash>: TypeInfo + 'static, PhantomData<T>: TypeInfo + 'static, Hash: TypeInfo + 'static, T: 'static,

type Identity = KeySeedFor<Id, Item, Salt, Hash, T>

The type identifying for which type info is provided.

fn type_info() -> Type

Returns the static type identifier for Self.

impl<Id, Item, Salt, Hash, T> EncodeLike for KeySeedFor<Id, Item, Salt, Hash, T>

where Id: Encode, Item: Encode, Salt: Encode,

impl<Id: Eq, Item: Eq, Salt: Eq, Hash: Eq, T: Eq> Eq for KeySeedFor<Id, Item, Salt, Hash, T>

impl<Id, Item, Salt, Hash, T> StructuralPartialEq for KeySeedFor<Id, Item, Salt, Hash, T>