crypt: Switch to using large unsigned integers
- The crate now uses crypto_bigint U128 ints instead of i32. - OsRng instead of thread_rng(), (cryptographically more secure?). - Modular arithmetic methods from crypto_bigint, no more overflows. - Error code for invalid parameters. - Simpler naming.
This commit is contained in:
K Shiva Kiran
parent
b10874e5d6
commit
7ad15fce76
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@ -1 +1,2 @@
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/target
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Cargo.lock
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@ -1,109 +0,0 @@
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# This file is automatically @generated by Cargo.
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# It is not intended for manual editing.
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version = 3
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[[package]]
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checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
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name = "cfg-if"
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[[package]]
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name = "false-bottom"
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version = "0.1.0"
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dependencies = [
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"modinverse",
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"rand",
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]
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[[package]]
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dependencies = [
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"cfg-if",
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"libc",
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"wasi",
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]
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[[package]]
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name = "libc"
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name = "modinverse"
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"num-traits",
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[[package]]
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name = "num-traits"
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"autocfg",
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[[package]]
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name = "ppv-lite86"
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checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
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[[package]]
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name = "rand"
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version = "0.8.5"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
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dependencies = [
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"libc",
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"rand_chacha",
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"rand_core",
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]
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[[package]]
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name = "rand_chacha"
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version = "0.3.1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
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dependencies = [
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"ppv-lite86",
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"rand_core",
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]
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[[package]]
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name = "rand_core"
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version = "0.6.4"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
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dependencies = [
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"getrandom",
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]
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[[package]]
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name = "wasi"
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version = "0.11.0+wasi-snapshot-preview1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
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@ -6,5 +6,5 @@ edition = "2021"
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# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
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[dependencies]
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rand = "^0.8.5"
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modinverse = "0.1.1"
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rand = "0.8.5"
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crypto-bigint = "0.5.5"
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@ -1,6 +1,7 @@
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#[derive(Debug)]
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pub enum FalseBottomError {
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pub enum FBError {
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IntegerTooLarge,
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NoModInverse,
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InvalidKey,
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InvalidParams,
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}
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135
src/lib.rs
135
src/lib.rs
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@ -1,80 +1,85 @@
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pub mod errors;
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use rand::Rng;
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use rand::seq::IteratorRandom;
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use crate::errors::FalseBottomError;
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use modinverse::modinverse;
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use rand::{Rng, seq::IteratorRandom};
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use crate::errors::FBError;
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use crypto_bigint::{U128, RandomMod, NonZero, rand_core::OsRng, Limb};
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#[derive(Debug)]
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pub struct FalseBottom {
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pub k: i32,
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pub r: Vec<i32>,
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pub c: Vec<i32>,
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pub struct FBCrypt {
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k: usize,
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r: Vec<U128>,
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c: Vec<U128>,
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}
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#[derive(Debug)]
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pub struct FalseBottomKey {
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pub key_indices: Vec<i32>,
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pub cipher_indices: Vec<i32>,
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pub struct FBKey {
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r_i: Vec<usize>,
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c_i: Vec<usize>,
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}
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const P: i32 = 9973;
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// Prime number value
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const P: U128 = U128::MAX.wrapping_sub(&U128::from_u32(159 - 1));
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// Our prime is at 159th position to the left of 2^128
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const P_POS: Limb = Limb::from_u32(159);
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impl FalseBottom {
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pub fn init(k: i32) -> FalseBottom {
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let mut rng = rand::thread_rng();
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let mut r: Vec<i32> = Vec::new();
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let mut c: Vec<i32> = Vec::new();
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for _ in 0..k {
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r.push(rng.gen_range(1..k));
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c.push(rng.gen_range(1..P));
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impl FBCrypt {
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pub fn init(n: usize, k: usize) -> Result<FBCrypt, FBError> {
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if n < k || k < 2 {
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return Err(FBError::InvalidParams)
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}
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FalseBottom {k, r, c}
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const MODULUS: NonZero<U128> = NonZero::<U128>::const_new(P).0;
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let r: Vec<U128> = (0..k)
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.map(|_| U128::random_mod(&mut OsRng, &MODULUS))
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.collect();
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let c: Vec<U128> = (0..n)
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.map(|_| U128::random_mod(&mut OsRng, &MODULUS))
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.collect();
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Ok(FBCrypt {k, r, c})
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}
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pub fn add(&mut self, m: i32) ->
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Result<FalseBottomKey, FalseBottomError>
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{
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if m > P as i32 {
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return Err(FalseBottomError::IntegerTooLarge)
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pub fn add(&mut self, m: &U128) -> Result<FBKey, FBError> {
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if m.ge(&P) {
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return Err(FBError::IntegerTooLarge);
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}
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let mut rng = rand::thread_rng();
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let n = rng.gen_range(2..=self.k);
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let (r, c) = (&mut self.r, &mut self.c);
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let n = OsRng.gen_range(2..=self.k);
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let mut c_i: Vec<usize> = (0..c.len())
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.choose_multiple(&mut OsRng, n-1);
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let r_i: Vec<usize> = (0..self.k)
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.choose_multiple(&mut OsRng, n);
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let mut cipher_indices: Vec<i32> = (0..self.c.len() as i32)
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.choose_multiple(&mut rng, n as usize - 1);
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let key_indices: Vec<i32> = (0..self.k)
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.choose_multiple(&mut rng, n as usize);
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let mut sum = 0;
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for (j, rho) in cipher_indices.iter()
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.zip(key_indices.iter())
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let mut sum: U128 = U128::ZERO;
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for (&ci, &ri) in c_i.iter()
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.zip(r_i.iter())
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{
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sum += self.c[*j as usize] * self.r[*rho as usize];
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sum %= P;
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sum = sum.add_mod(
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&c[ci].mul_mod_special(&r[ri], P_POS),
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&P);
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}
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let key_last_el = *key_indices.last().unwrap() as usize;
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let mod_inv = modinverse(self.r[key_last_el], P)
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.ok_or(FalseBottomError::NoModInverse)?;
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let cipher_new_element = ((m - sum) * mod_inv)
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.rem_euclid(P);
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self.c.push(cipher_new_element);
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cipher_indices.push(self.c.len() as i32 - 1);
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Ok(FalseBottomKey {key_indices, cipher_indices})
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let r_last = *r_i.last().unwrap();
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let (mod_inv, inv_exists) = r[r_last].inv_mod(&P);
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let inv_exists: bool = inv_exists.into();
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if !inv_exists {
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return Err(FBError::NoModInverse);
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}
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let c_new = m.sub_mod(&sum, &P)
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.mul_mod_special(&mod_inv, P_POS);
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c.push(c_new);
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c_i.push(c.len()-1);
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Ok(FBKey {r_i, c_i})
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}
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pub fn decrypt(&self, indices: &FalseBottomKey) -> Result<i32, FalseBottomError> {
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let keyi = &indices.key_indices;
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let cipheri = &indices.cipher_indices;
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if keyi.len() > self.r.len() || cipheri.len() > self.c.len() {
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return Err(FalseBottomError::InvalidKey)
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pub fn decrypt(&self, indices: &FBKey) -> Result<U128, FBError> {
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let (r_i, c_i) = (&indices.r_i, &indices.c_i);
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if r_i.len() > self.r.len() || c_i.len() > self.c.len() {
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return Err(FBError::InvalidKey)
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}
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let mut m: i32 = 0;
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for (ki, ci) in keyi.iter().zip(cipheri.iter()) {
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m += self.c[*ci as usize] * self.r[*ki as usize];
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m %= P;
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let mut m: U128 = U128::ZERO;
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for (&ri, &ci) in r_i.iter().zip(c_i.iter()) {
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m = m.add_mod(
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&self.c[ci].mul_mod_special(&self.r[ri], P_POS),
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&P);
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}
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Ok(m)
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}
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@ -83,12 +88,20 @@ impl FalseBottom {
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn encrypt_decrypt_100() {
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let msg = 100;
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let mut fb = FalseBottom::init(9);
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let key = fb.add(msg).unwrap();
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let msg: U128 = U128::from_u32(100);
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let mut fb = FBCrypt::init(20, 12).unwrap();
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let key = fb.add(&msg).unwrap();
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let decrypted = fb.decrypt(&key).unwrap();
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assert_eq!(decrypted, msg);
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assert_eq!(msg, decrypted);
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}
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#[test]
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fn many_runs() {
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for _ in 0..1000 {
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encrypt_decrypt_100();
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}
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}
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}
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