umskt-rs/umskt/src/bink1998.rs

338 lines
10 KiB
Rust

use std::{
cmp::Ordering,
fmt::{Display, Formatter},
};
use anyhow::{bail, Result};
use bitreader::BitReader;
use num_bigint::{BigInt, BigUint, RandomBits};
use num_integer::Integer;
use num_traits::{FromPrimitive, ToPrimitive};
use rand::Rng;
use sha1::{Digest, Sha1};
use crate::{
crypto::{EllipticCurve, PrivateKey},
key::{base24_decode, base24_encode, strip_key},
math::bitmask,
weierstrass_curve::{Point, WeierstrassCurve},
};
const FIELD_BITS: u64 = 384;
const FIELD_BYTES: usize = 48;
const SHA_MSG_LENGTH: usize = 4 + 2 * FIELD_BYTES;
const HASH_LENGTH_BITS: u8 = 28;
const SERIAL_LENGTH_BITS: u8 = 30;
const UPGRADE_LENGTH_BITS: u8 = 1;
const EVERYTHING_ELSE: u8 = HASH_LENGTH_BITS + SERIAL_LENGTH_BITS + UPGRADE_LENGTH_BITS;
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct ProductKey {
upgrade: bool,
channel_id: u32,
sequence: u32,
hash: u32,
signature: u64,
}
impl ProductKey {
pub fn new(
curve: &EllipticCurve,
private_key: &PrivateKey,
channel_id: u32,
sequence: Option<u32>,
upgrade: Option<bool>,
) -> Result<Self> {
// Generate random sequence if none supplied
let sequence = match sequence {
Some(serial) => serial,
None => {
let mut rng = rand::thread_rng();
let random: BigInt = rng.sample(RandomBits::new(32));
let raw = u32::from_be_bytes(random.to_bytes_be().1[0..4].try_into().unwrap());
raw % 999999
}
};
// Default to upgrade=false
let upgrade = upgrade.unwrap_or(false);
// Generate a new random key
let product_key = Self::generate(
&curve.curve,
&curve.gen_point,
&private_key.gen_order,
&private_key.private_key,
channel_id,
sequence,
upgrade,
)?;
// Make sure the key is valid
product_key.verify(&curve.curve, &curve.gen_point, &curve.pub_point)?;
// Ship it
Ok(product_key)
}
pub fn from_key(curve: &EllipticCurve, key: &str) -> Result<Self> {
let key = strip_key(key)?;
let Ok(packed_key) = base24_decode(&key) else {
bail!("Product key is in an incorrect format!")
};
let product_key = Self::from_packed(&packed_key)?;
product_key.verify(&curve.curve, &curve.gen_point, &curve.pub_point)?;
Ok(product_key)
}
fn generate(
e_curve: &WeierstrassCurve,
base_point: &Point,
gen_order: &BigInt,
private_key: &BigInt,
channel_id: u32,
sequence: u32,
upgrade: bool,
) -> Result<Self> {
let serial = channel_id * 1_000_000 + sequence;
let data = serial << 1 | upgrade as u32;
let mut rng = rand::thread_rng();
let product_key = loop {
// Generate a random number c consisting of 384 bits without any constraints.
let c: BigUint = rng.sample(RandomBits::new(FIELD_BITS));
let c: BigInt = c.into();
// Pick a random derivative of the base point on the elliptic curve.
// R = cG;
let r = e_curve.multiply_point(&c, base_point);
// Acquire its coordinates.
// x = R.x; y = R.y;
let (x, y) = match r {
Point::Point { x, y } => (x, y),
Point::Infinity => bail!("Point at infinity!"),
};
let mut msg_buffer: [u8; SHA_MSG_LENGTH] = [0; SHA_MSG_LENGTH];
let x_bin = x.to_signed_bytes_le();
let x_bin = match x_bin.len().cmp(&FIELD_BYTES) {
Ordering::Less => (0..FIELD_BYTES - x_bin.len() - 1)
.map(|_| 0)
.chain(x_bin.into_iter())
.collect(),
Ordering::Greater => continue,
Ordering::Equal => x_bin,
};
let y_bin = y.to_signed_bytes_le();
let y_bin = match y_bin.len().cmp(&FIELD_BYTES) {
Ordering::Less => (0..FIELD_BYTES - y_bin.len() - 1)
.map(|_| 0)
.chain(y_bin.into_iter())
.collect(),
Ordering::Greater => continue,
Ordering::Equal => y_bin,
};
msg_buffer[0..4].copy_from_slice(&data.to_le_bytes());
msg_buffer[4..4 + FIELD_BYTES].copy_from_slice(&x_bin);
msg_buffer[4 + FIELD_BYTES..4 + FIELD_BYTES * 2].copy_from_slice(&y_bin);
let msg_digest = {
let mut hasher = Sha1::new();
hasher.update(msg_buffer);
hasher.finalize()
};
let hash: u32 =
u32::from_le_bytes(msg_digest[0..4].try_into().unwrap()) >> 4 & bitmask(28) as u32;
let mut ek = private_key.clone();
ek *= hash;
let s = (ek + c).mod_floor(gen_order);
let signature = s.to_u64().unwrap_or(0);
if signature <= bitmask(55) {
break Self {
upgrade,
channel_id,
sequence,
hash,
signature,
};
}
};
Ok(product_key)
}
fn verify(
&self,
e_curve: &WeierstrassCurve,
base_point: &Point,
public_key: &Point,
) -> Result<bool> {
let e = BigInt::from_u32(self.hash).unwrap();
let s = BigInt::from_u64(self.signature).unwrap();
let t = e_curve.multiply_point(&s, base_point);
let mut p = e_curve.multiply_point(&e, public_key);
p = e_curve.add_points(&p, &t);
let (x, y) = match p {
Point::Point { x, y } => (x, y),
Point::Infinity => bail!("Point at infinity!"),
};
let mut msg_buffer: [u8; SHA_MSG_LENGTH] = [0; SHA_MSG_LENGTH];
let x_bin = x.to_signed_bytes_le();
let x_bin = if x_bin.len() < FIELD_BYTES {
(0..FIELD_BYTES - x_bin.len() - 1)
.map(|_| 0)
.chain(x_bin.into_iter())
.collect()
} else {
x_bin
};
let y_bin = y.to_signed_bytes_le();
let y_bin = if y_bin.len() < FIELD_BYTES {
(0..FIELD_BYTES - y_bin.len() - 1)
.map(|_| 0)
.chain(y_bin.into_iter())
.collect()
} else {
y_bin
};
let serial = self.channel_id * 1_000_000 + self.sequence;
let data = serial << 1 | self.upgrade as u32;
msg_buffer[0..4].copy_from_slice(&data.to_le_bytes());
msg_buffer[4..4 + FIELD_BYTES].copy_from_slice(&x_bin);
msg_buffer[4 + FIELD_BYTES..4 + FIELD_BYTES * 2].copy_from_slice(&y_bin);
let msg_digest = {
let mut hasher = Sha1::new();
hasher.update(msg_buffer);
hasher.finalize()
};
let hash: u32 =
u32::from_le_bytes(msg_digest[0..4].try_into().unwrap()) >> 4 & bitmask(28) as u32;
Ok(hash == self.hash)
}
fn from_packed(packed_key: &[u8]) -> Result<Self> {
let mut reader = BitReader::new(packed_key);
// The signature length isn't known, but everything else is, so we can calculate it
let signature_length_bits = (packed_key.len() * 8) as u8 - EVERYTHING_ELSE;
let signature = reader.read_u64(signature_length_bits)?;
let hash = reader.read_u32(HASH_LENGTH_BITS)?;
let serial = reader.read_u32(SERIAL_LENGTH_BITS)?;
let upgrade = reader.read_bool()?;
let sequence = serial % 1_000_000;
let channel_id = serial / 1_000_000;
Ok(Self {
upgrade,
channel_id,
sequence,
hash,
signature,
})
}
fn pack(&self) -> Vec<u8> {
let mut packed_key: u128 = 0;
let serial = self.channel_id * 1_000_000 + self.sequence;
packed_key |= (self.signature as u128) << EVERYTHING_ELSE;
packed_key |= (self.hash as u128) << (SERIAL_LENGTH_BITS + UPGRADE_LENGTH_BITS);
packed_key |= (serial as u128) << UPGRADE_LENGTH_BITS;
packed_key |= self.upgrade as u128;
packed_key
.to_be_bytes()
.into_iter()
.skip_while(|&x| x == 0)
.collect()
}
}
impl Display for ProductKey {
fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
let pk = base24_encode(&self.pack()).unwrap();
let key = pk
.chars()
.enumerate()
.fold(String::new(), |mut acc: String, (i, c)| {
if i > 0 && i % 5 == 0 {
acc.push('-');
}
acc.push(c);
acc
});
write!(f, "{}", key)
}
}
#[cfg(test)]
mod tests {
use std::{fs::File, io::BufReader};
use serde_json::from_reader;
use crate::{bink1998, crypto::EllipticCurve};
#[test]
fn verify_test() {
// Example product key and its BINK ID
let product_key = "D9924-R6BG2-39J83-RYKHF-W47TT";
let bink_id = "2E";
// Load keys.json
let path = "../keys.json";
let file = File::open(path).unwrap();
let reader = BufReader::new(file);
let keys: serde_json::Value = from_reader(reader).unwrap();
let bink = &keys["BINK"][&bink_id];
let p = bink["p"].as_str().unwrap();
let a = bink["a"].as_str().unwrap();
let b = bink["b"].as_str().unwrap();
let gx = bink["g"]["x"].as_str().unwrap();
let gy = bink["g"]["y"].as_str().unwrap();
let kx = bink["pub"]["x"].as_str().unwrap();
let ky = bink["pub"]["y"].as_str().unwrap();
let curve = EllipticCurve::new(p, a, b, gx, gy, kx, ky).unwrap();
assert!(bink1998::ProductKey::from_key(&curve, product_key).is_ok());
assert!(bink1998::ProductKey::from_key(&curve, "11111-R6BG2-39J83-RYKHF-W47TT").is_err());
}
#[test]
fn pack_test() {
let key = super::ProductKey {
upgrade: false,
channel_id: 640,
sequence: 10550,
hash: 39185432,
signature: 6939952665262054,
};
assert_eq!(key.to_string(), "D9924-R6BG2-39J83-RYKHF-W47TT");
}
}