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+/* This file is part of DarkFi (https://dark.fi)
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+ *
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+ * Copyright (C) 2020-2022 Dyne.org foundation
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+ *
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+ * This program is free software: you can redistribute it and/or modify
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+ * it under the terms of the GNU Affero General Public License as
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+ * published by the Free Software Foundation, either version 3 of the
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+ * License, or (at your option) any later version.
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+ *
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+ * This program is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU Affero General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU Affero General Public License
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+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
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+ */
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+
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+use chacha20poly1305::{AeadInPlace, ChaCha20Poly1305, KeyInit};
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+use darkfi_sdk::crypto::{
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+ diffie_hellman::{kdf_sapling, sapling_ka_agree},
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+ PublicKey, SecretKey,
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+};
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+use darkfi_serial::{Decodable, Encodable, SerialDecodable, SerialEncodable};
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+use rand::rngs::OsRng;
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+
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+use darkfi::{Error, Result};
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+
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+pub const AEAD_TAG_SIZE: usize = 16;
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+
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+pub fn encrypt<T: Encodable>(note: &T, public: &PublicKey) -> Result<EncryptedNote2> {
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+ let ephem_secret = SecretKey::random(&mut OsRng);
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+ let ephem_public = PublicKey::from_secret(ephem_secret);
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+ let shared_secret = sapling_ka_agree(&ephem_secret, public);
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+ let key = kdf_sapling(&shared_secret, &ephem_public);
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+
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+ let mut input = Vec::new();
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+ note.encode(&mut input)?;
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+ let input_len = input.len();
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+
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+ let mut ciphertext = vec![0_u8; input_len + AEAD_TAG_SIZE];
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+ ciphertext[..input_len].copy_from_slice(&input);
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+
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+ ChaCha20Poly1305::new(key.as_ref().into())
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+ .encrypt_in_place([0u8; 12][..].into(), &[], &mut ciphertext)
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+ .unwrap();
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+
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+ Ok(EncryptedNote2 { ciphertext, ephem_public })
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+}
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+
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+#[derive(Debug, Clone, PartialEq, Eq, SerialEncodable, SerialDecodable)]
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+pub struct EncryptedNote2 {
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+ ciphertext: Vec<u8>,
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+ ephem_public: PublicKey,
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+}
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+
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+impl EncryptedNote2 {
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+ pub fn decrypt<T: Decodable>(&self, secret: &SecretKey) -> Result<T> {
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+ let shared_secret = sapling_ka_agree(secret, &self.ephem_public);
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+ let key = kdf_sapling(&shared_secret, &self.ephem_public);
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+
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+ let ciphertext_len = self.ciphertext.len();
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+ let mut plaintext = vec![0_u8; ciphertext_len];
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+ plaintext.copy_from_slice(&self.ciphertext);
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+
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+ match ChaCha20Poly1305::new(key.as_ref().into()).decrypt_in_place(
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+ [0u8; 12][..].into(),
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+ &[],
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+ &mut plaintext,
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+ ) {
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+ Ok(()) => {
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+ Ok(T::decode(&plaintext[..ciphertext_len - AEAD_TAG_SIZE]).map_err(Error::from)?)
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+ }
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+ Err(e) => Err(Error::NoteDecryptionFailed(e.to_string())),
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+ }
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+ }
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+}
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+
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+#[cfg(test)]
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+mod tests {
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+ use super::*;
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+ use darkfi::crypto::types::{DrkCoinBlind, DrkSerial, DrkValueBlind};
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+ use darkfi_sdk::{
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+ crypto::{Keypair, TokenId},
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+ pasta::{group::ff::Field, pallas},
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+ };
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+
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+ #[test]
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+ fn test_note_encdec() {
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+ #[derive(SerialEncodable, SerialDecodable)]
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+ struct MyNote {
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+ serial: DrkSerial,
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+ value: u64,
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+ token_id: TokenId,
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+ coin_blind: DrkCoinBlind,
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+ value_blind: DrkValueBlind,
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+ token_blind: DrkValueBlind,
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+ memo: Vec<u8>,
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+ }
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+ let note = MyNote {
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+ serial: DrkSerial::random(&mut OsRng),
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+ value: 110,
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+ token_id: TokenId::from(pallas::Base::random(&mut OsRng)),
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+ coin_blind: DrkCoinBlind::random(&mut OsRng),
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+ value_blind: DrkValueBlind::random(&mut OsRng),
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+ token_blind: DrkValueBlind::random(&mut OsRng),
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+ memo: vec![32, 223, 231, 3, 1, 1],
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+ };
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+
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+ let keypair = Keypair::random(&mut OsRng);
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+
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+ let encrypted_note = encrypt(¬e, &keypair.public).unwrap();
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+ let note2: MyNote = encrypted_note.decrypt(&keypair.secret).unwrap();
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+ assert_eq!(note.value, note2.value);
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+ assert_eq!(note.token_id, note2.token_id);
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+ assert_eq!(note.token_blind, note2.token_blind);
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+ assert_eq!(note.memo, note2.memo);
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+ }
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+}
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