-
Notifications
You must be signed in to change notification settings - Fork 47
/
cm_encryption.rs
119 lines (102 loc) · 3.07 KB
/
cm_encryption.rs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
use pairing::{
PrimeField,
PrimeFieldRepr,
Field,
};
use scrypto::jubjub::{
JubjubEngine,
JubjubParams,
edwards,
PrimeOrder,
FixedGenerators,
ToUniform,
Unknown,
};
use rand::{OsRng, Rng};
use zcrypto::constants::{
PLAINTEXT_SIZE,
CIPHERTEXT_SIZE,
KDF_PERSONALIZATION
};
use blake2_rfc::blake2s::Blake2s;
// Temporary use for enc/dec
use pcrypto::aes::{
encrypt_128_ctr,
decrypt_128_ctr
};
use proofs::primitives::{Diversifier, ValueCommitment};
use byteorder::{
LittleEndian,
WriteBytesExt
};
pub struct Commitments<E: JubjubEngine> (pub ValueCommitment<E>);
impl<E: JubjubEngine> Commitments<E> {
pub fn new (
value: u64,
randomness: E::Fs,
is_negative: bool
) -> Self
{
Commitments (
ValueCommitment {
value,
randomness,
is_negative
}
)
}
pub fn encrypt_cm_to_recipient(
&self,
pk_d: &edwards::Point<E, PrimeOrder>,
diversifier: &Diversifier,
params: &E::Params
) -> Ciphertext<E>
{
let mut rng = OsRng::new().expect("should be able to construct RNG"); // TODO: replace OsRng
let mut buffer = [0u8; 64];
for i in 0..buffer.len() {
buffer[i] = rng.gen();
}
// Generate uniformed random value as ephemeral secret key
let esk = E::Fs::to_uniform(&buffer[..]);
// let p = pk_d.mul_by_cofactor(params); // needs lazy_static for params(JUBJUB)?
// Generate shared secret
let shared_secret = pk_d.mul(esk, params);
// Derive ephemeral public key
let g_d = diversifier.g_d::<E>(params).unwrap();
let epk = g_d.mul(esk, params);
let mut preimage = [0; 64];
shared_secret.write(&mut preimage[0..32]).unwrap();
epk.write(&mut preimage[32..64]).unwrap();
let mut h = Blake2s::with_params(32, &[], &[], KDF_PERSONALIZATION);
h.update(&preimage);
let h = h.finalize();
let mut ciphertext_bytes = [0; CIPHERTEXT_SIZE];
let iv: [u8; 16] = rng.gen();
let mut plaintext = vec![];
// TODO: Ensure the byteorder is correct
(&mut plaintext).write_u64::<LittleEndian>(self.0.value).unwrap();
self.0.randomness.into_repr().write_le(&mut plaintext).unwrap();
encrypt_128_ctr(&h.as_ref()[0..16], &iv, &plaintext, &mut ciphertext_bytes)
.expect("input lengths of key and iv are both 16; qed");
Ciphertext {
encrypted_commitment: ciphertext_bytes,
epk: epk
}
}
}
// #[derive(Clone, Encode, Decode)]
// pub struct EncryptedCommitment([u8; CIPHERTEXT_SIZE]);
#[derive(Clone, Encode, Decode, Default)]
pub struct Ciphertext<E: JubjubEngine> {
encrypted_commitment: [u8; CIPHERTEXT_SIZE],
epk: edwards::Point<E, PrimeOrder>,
}
// impl<E: JubjubEngine> Ciphertext<E> {
// pub fn decrypt(
// &self,
// params: &E::Params
// ) -> Commitments
// {
// }
// }