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cleaned code a bit

pull/8/head
Nanak Nihal Singh Khalsa 1 year ago
parent
commit
63ab2f26f3
1 changed files with 4 additions and 27 deletions
  1. +4
    -27
      src/lib.rs

+ 4
- 27
src/lib.rs

@ -206,34 +206,12 @@ impl Point {
false
}
// Use a variation of the Koblitz method
pub fn from_msg_vartime(msg: BigInt/*msg: &[u8; 28]*/) -> Point {
// This is the largest point that can fit BabyJubJub curve while still allowing 8 extra bytes, as long as those bytes are less than f0000001
// Babyjubjub r parameter is 0x30644e72e131a029b85045b68181585d2833e84879b9709143e1f593f0000001
// assert!(
// BigInt::from_bytes_be(Sign::Plus, msg)
// <
// BigInt::parse_bytes(b"30644e72e131a029b85045b68181585d2833e84879b9709143e1f593f00000",16).unwrap()
// );
// let mut acc: u32 = 0;
// let mut pt: Point;
// let mut is_residue: bool = false;
// let mut on_curve: bool = false;
// while (acc <= 0xf0000001) && !on_curve {
// let acc_bytes: [u8; 4] = acc.to_be_bytes();
// // let mut buff: ArrayVec::<[u8; 32]> = concat_bytes!()[msg, acc_bytes]);
// let mut buf = BytesMut::with_capacity(32);
// buf.put_slice(msg);
// buf.put_u32(acc);
// Fr::from_str("123").unwrap().legendre()
// println!("bytes {:?}", buf);
// }
// Koblitz decoding method, adapted for this curve:
// Koblitz decoding method, adapted for this curve:
// message m must be < r/10000
// Try finding a point with y value m*10000+0, m*10000+1, .... m*10000+5617 (5617 are last four digits of prime r)
// There is an approximately 1/(2^1000) chance no point will be encodable,
// since each y value has probability of about 1/2 of being on the curve
pub fn from_msg_vartime(msg: BigInt) -> Point {
let MAX_MSG: BigInt = BigInt::parse_bytes(
b"2188824287183927522224640574525727508854836440041603434369820418657580849",10 // Prime r but missing last 4 digits
).unwrap();
@ -245,9 +223,8 @@ impl Point {
let mut x: Fr = Fr::from_str(&msg.to_str_radix(10)).unwrap();
let mut y: Option<Fr> = None;
x.mul_assign(&Fr::from_str("10000").unwrap());
let one = Fr::one();
// let m10000 = 1000.to_bigint().unwrap() * msg;
while (acc < ACC_UNDER) && !on_curve {
// If x is on curve, calculate what y^2 should be, by (ax^2 - 1) / (dx^2 - 1)
let mut x2 = x.clone();
@ -270,7 +247,7 @@ impl Point {
y = numerator.sqrt();
} else {
acc += 1;
x.add_assign(&Fr::one());
x.add_assign(&one);
}
}
// Unwrap y since we can't be 100% sure at compile-time it will have been found; it may still be a None value!

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