zebra/zebra-chain/src/note_encryption/sapling.rs

use std::{fmt, io};

#[cfg(test)]
use proptest::{arbitrary::Arbitrary, collection::vec, prelude::*};

use crate::serialization::{SerializationError, ZcashDeserialize, ZcashSerialize};

use super::*;

/// A _Diversifier_, an 11 byte value used to randomize the
/// recipient's final public shielded payment address to create a
/// _diversified payment address_.
///
/// When used, this value is mapped to an affine JubJub group element.
#[derive(Copy, Clone, Debug, PartialEq)]
pub struct Diversifier(pub [u8; 11]);

pub struct Note {
    diversifier: Diversifier,
    // TODO: refine as a type, derived from a scalar mult of the
    // diversifier as a jubjub group element and the incoming view key
    // scalar.
    transmission_key: [u8; 32],
    value: u64,
    note_commitment_randomness: NoteCommitmentRandomness,
}

/// The decrypted form of encrypted Sapling notes on the blockchain.
pub struct NotePlaintext {
    diversifier: Diversifier,
    value: u64,
    // TODO: refine as jub-jub appropriate in the base field.
    note_commitment_randomness: NoteCommitmentRandomness,
    memo: memo::Memo,
}

/// A ciphertext component for encrypted output notes.
pub struct EncryptedCiphertext(pub [u8; 580]);

impl fmt::Debug for EncryptedCiphertext {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_tuple("EncryptedCiphertext")
            .field(&hex::encode(&self.0[..]))
            .finish()
    }
}

// These impls all only exist because of array length restrictions.

impl Copy for EncryptedCiphertext {}

impl Clone for EncryptedCiphertext {
    fn clone(&self) -> Self {
        let mut bytes = [0; 580];
        bytes[..].copy_from_slice(&self.0[..]);
        Self(bytes)
    }
}

impl PartialEq for EncryptedCiphertext {
    fn eq(&self, other: &Self) -> bool {
        self.0[..] == other.0[..]
    }
}

impl Eq for EncryptedCiphertext {}

impl ZcashSerialize for EncryptedCiphertext {
    fn zcash_serialize<W: io::Write>(&self, mut writer: W) -> Result<(), io::Error> {
        writer.write_all(&self.0[..])?;
        Ok(())
    }
}

impl ZcashDeserialize for EncryptedCiphertext {
    fn zcash_deserialize<R: io::Read>(mut reader: R) -> Result<Self, SerializationError> {
        let mut bytes = [0; 580];
        reader.read_exact(&mut bytes[..])?;
        Ok(Self(bytes))
    }
}

#[cfg(test)]
impl Arbitrary for EncryptedCiphertext {
    type Parameters = ();

    fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy {
        (vec(any::<u8>(), 580))
            .prop_map(|v| {
                let mut bytes = [0; 580];
                bytes.copy_from_slice(v.as_slice());
                return Self(bytes);
            })
            .boxed()
    }

    type Strategy = BoxedStrategy<Self>;
}

/// A ciphertext component for encrypted output notes.
pub struct OutCiphertext(pub [u8; 80]);

impl fmt::Debug for OutCiphertext {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_tuple("OutCiphertext")
            .field(&hex::encode(&self.0[..]))
            .finish()
    }
}

// These impls all only exist because of array length restrictions.

impl Copy for OutCiphertext {}

impl Clone for OutCiphertext {
    fn clone(&self) -> Self {
        let mut bytes = [0; 80];
        bytes[..].copy_from_slice(&self.0[..]);
        Self(bytes)
    }
}

impl PartialEq for OutCiphertext {
    fn eq(&self, other: &Self) -> bool {
        self.0[..] == other.0[..]
    }
}

impl Eq for OutCiphertext {}

impl ZcashSerialize for OutCiphertext {
    fn zcash_serialize<W: io::Write>(&self, mut writer: W) -> Result<(), io::Error> {
        writer.write_all(&self.0[..])?;
        Ok(())
    }
}

impl ZcashDeserialize for OutCiphertext {
    fn zcash_deserialize<R: io::Read>(mut reader: R) -> Result<Self, SerializationError> {
        let mut bytes = [0; 80];
        reader.read_exact(&mut bytes[..])?;
        Ok(Self(bytes))
    }
}

#[cfg(test)]
impl Arbitrary for OutCiphertext {
    type Parameters = ();

    fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy {
        (vec(any::<u8>(), 80))
            .prop_map(|v| {
                let mut bytes = [0; 80];
                bytes.copy_from_slice(v.as_slice());
                return Self(bytes);
            })
            .boxed()
    }

    type Strategy = BoxedStrategy<Self>;
}

#[cfg(test)]
proptest! {

    #[test]
    fn encrypted_ciphertext_roundtrip(ec in any::<EncryptedCiphertext>()) {

        let mut data = Vec::new();

        ec.zcash_serialize(&mut data).expect("EncryptedCiphertext should serialize");

        let ec2 = EncryptedCiphertext::zcash_deserialize(&data[..]).expect("randomized EncryptedCiphertext should deserialize");

        prop_assert_eq![ec, ec2];
    }

    #[test]
    fn out_ciphertext_roundtrip(oc in any::<OutCiphertext>()) {

        let mut data = Vec::new();

        oc.zcash_serialize(&mut data).expect("OutCiphertext should serialize");

        let oc2 = OutCiphertext::zcash_deserialize(&data[..]).expect("randomized OutCiphertext should deserialize");

        prop_assert_eq![oc, oc2];
    }
}