Trait halo2_gadgets::sinsemilla::SinsemillaInstructions

source · [−]
pub trait SinsemillaInstructions<C: CurveAffine, const K: usize, const MAX_WORDS: usize> {
    type CellValue: Var<C::Base>;
    type Message: From<Vec<Self::MessagePiece>>;
    type MessagePiece: Clone + Debug;
    type RunningSum;
    type X;
    type NonIdentityPoint: Clone + Debug;
    type FixedPoints: FixedPoints<C>;
    type HashDomains: HashDomains<C>;
    type CommitDomains: CommitDomains<C, Self::FixedPoints, Self::HashDomains>;

    fn witness_message_piece(
        &self, 
        layouter: impl Layouter<C::Base>, 
        value: Option<C::Base>, 
        num_words: usize
    ) -> Result<Self::MessagePiece, Error>;
    fn hash_to_point(
        &self, 
        layouter: impl Layouter<C::Base>, 
        Q: C, 
        message: Self::Message
    ) -> Result<(Self::NonIdentityPoint, Vec<Self::RunningSum>), Error>;
    fn extract(point: &Self::NonIdentityPoint) -> Self::X;
}
Expand description

The set of circuit instructions required to use the Sinsemilla gadget. This trait is bounded on two constant parameters: K, the number of bits in each word accepted by the Sinsemilla hash, and MAX_WORDS, the maximum number of words that a single hash instance can process.

Required Associated Types

A variable in the circuit.

A message composed of Self::MessagePieces.

A piece in a message containing a number of K-bit words. A Self::MessagePiece fits in a single base field element, which means it can only contain up to N words, where N*K <= C::Base::CAPACITY.

For example, in the case K = 10, CAPACITY = 254, we can fit up to N = 25 words in a single base field element.

A cumulative sum z is used to decompose a Sinsemilla message. It produces intermediate values for each word in the message, such that z_next = (z_cur - word_next) / 2^K.

These intermediate values are useful for range checks on subsets of the Sinsemilla message. Sinsemilla messages in the Orchard protocol are composed of field elements, and we need to check the canonicity of the field element encodings in certain cases.

The x-coordinate of a point output of Self::hash_to_point.

A point output of Self::hash_to_point.

A type enumerating the fixed points used in CommitDomains.

HashDomains used in this instruction.

CommitDomains used in this instruction.

Required Methods

Witness a message piece given a field element. Returns a Self::MessagePiece encoding the given message.

Panics

Panics if num_words exceed the maximum number of K-bit words that can fit into a single base field element.

Hashes a message to an ECC curve point. This returns both the resulting point, as well as the message decomposition in the form of intermediate values in a cumulative sum.

Extracts the x-coordinate of the output of a Sinsemilla hash.

Implementors