Struct SaplingWitness

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

A cryptographic witness proving that a Sapling note commitment exists in the note commitment tree.

SaplingWitness is a specialized form of incremental Merkle tree witness for the Sapling protocol. It proves that a specific note commitment is included in the global Sapling note commitment tree, which is necessary when spending a note.

Zcash Concept Relation

In Zcash’s Sapling protocol:

• Note Commitment Tree: A Merkle tree containing all Sapling note commitments
• Merkle Path: The path from a leaf (note commitment) to the root of the tree
• Witness: The authentication path proving a leaf exists in the tree
• Anchors: Root hashes of the note commitment tree at specific blockchain heights

When spending a Sapling note, a zero-knowledge proof must demonstrate that the note’s commitment exists in the tree at a specific anchor (root hash), without revealing which specific commitment is being spent. The witness provides the necessary path information to create this proof.

Data Preservation

During wallet migration, complete witness data must be preserved for all unspent notes. This includes:

• The authentication path (sequence of hashes forming the Merkle path)
• The position of the note commitment in the tree
• The tree depth used (32 for Sapling)

Without this witness data, unspent notes cannot be spent as it would be impossible to prove their inclusion in the note commitment tree.

Trait Implementations

impl Clone for SaplingWitness

fn clone(&self) -> SaplingWitness

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for SaplingWitness

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

Formats the value using the given formatter.

impl From<SaplingWitness> for Envelope

fn from(value: SaplingWitness) -> Self

Converts to this type from the input type.

impl PartialEq for SaplingWitness

fn eq(&self, other: &SaplingWitness) -> 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 TryFrom<Envelope> for SaplingWitness

type Error = Error

The type returned in the event of a conversion error.

fn try_from(envelope: Envelope) -> Result<Self, Self::Error>

Performs the conversion.

impl Eq for SaplingWitness

impl StructuralPartialEq for SaplingWitness