Struct Share 

pub struct Share(/* private fields */);

A cryptographic share that securely wraps a secret for a specific recipient

A Share contains an ephemeral public key and an AES-KW wrapped secret. Only the intended recipient (whose public key was used during creation) can recover the secret.

Wire Format

[ ephemeral_pubkey: 32 bytes ][ wrapped_secret: 40 bytes ]

Examples

// Alice wants to share a bucket secret with Bob
let bucket_secret = Secret::generate();
let bob_pubkey = bob_secret_key.public();

// Alice creates a share for Bob
let share = Share::new(&bucket_secret, &bob_pubkey)?;

// Bob can recover the secret using his private key
let recovered_secret = share.recover(&bob_secret_key)?;
assert_eq!(bucket_secret, recovered_secret);

Implementations

impl Share

pub fn from_hex(hex: &str) -> Result<Self, ShareError>

Parse a share from a hexadecimal string

Accepts both plain hex and “0x”-prefixed hex strings.

pub fn to_hex(&self) -> String

Convert share to hexadecimal string

pub fn new(secret: &Secret, recipient: &PublicKey) -> Result<Self, ShareError>

Create a new share that wraps a secret for a specific recipient

This uses ECDH + AES Key Wrap to securely share the secret:

1. Generates an ephemeral Ed25519 keypair
2. Converts both keys to X25519 for ECDH
3. Performs ECDH to derive a shared secret
4. Uses AES-KW to wrap the secret with the shared secret
5. Returns a Share containing [ephemeral_pubkey || wrapped_secret]

Arguments

• secret - The secret to share (e.g., a bucket encryption key)
• recipient - The public key of the intended recipient

Errors

Returns an error if key conversion or encryption fails.

pub fn recover( &self, recipient_secret: &SecretKey, ) -> Result<Secret, ShareError>

Recover the wrapped secret using the recipient’s private key

This reverses the wrapping process:

1. Extracts the ephemeral public key from the Share
2. Converts keys to X25519 for ECDH
3. Performs ECDH to derive the same shared secret
4. Uses AES-KW to unwrap the secret

Arguments

• recipient_secret - The recipient’s private key (must match the public key used in new)

Errors

Returns an error if:

• Key conversion fails
• AES-KW unwrapping fails (wrong key or corrupted data)
• Unwrapped secret has incorrect size

Security Note

If this function returns an error, it means either the Share was created for a different recipient, the data was corrupted, or an attacker tampered with it.

pub fn bytes(&self) -> &[u8]

Get a reference to the raw share bytes

Trait Implementations

impl Clone for Share

fn clone(&self) -> Share

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Share

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

Formats the value using the given formatter.

impl Default for Share

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Share

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<[u8; 72]> for Share

fn from(bytes: [u8; 72]) -> Self

Converts to this type from the input type.

impl From<Share> for [u8; 72]

fn from(share: Share) -> Self

Converts to this type from the input type.

impl Hash for Share

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Share

fn eq(&self, other: &Share) -> 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 Serialize for Share

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl TryFrom<&[u8]> for Share

type Error = ShareError

The type returned in the event of a conversion error.

fn try_from(bytes: &[u8]) -> Result<Self, Self::Error>

Performs the conversion.

impl Copy for Share

impl Eq for Share

impl StructuralPartialEq for Share