Very simple implementation of sha3_256 (doesn't work for very long inputs)

.gitignore

@@ -0,0 +1 @@
+/target

Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "sha3"
+version = "0.1.0"

Cargo.toml

@@ -0,0 +1,4 @@
+[package]
+name = "sha3"
+version = "0.1.0"
+edition = "2024"

src/lib.rs

@@ -0,0 +1,37 @@
+pub mod sha3;
+
+#[cfg(test)]
+mod tests {
+    // use super::*;
+
+    use crate::sha3::Sha3_256;
+
+    #[test]
+    fn it_works() {
+        let mut sha = Sha3_256::default();
+
+        let text = "";
+
+        let arr = text.as_bytes();
+
+        let mut data = [0_u8; 136];
+        data.clone_from_slice(arr);
+
+        // sha.absorb([0, 1, 2, 3, 4, 5, 6, 7]);
+        sha.absorb(&data);
+        let res = sha.squeeze();
+        // a7ffc6f8bf1ed76651c14756a061d662f580ff4de43b49fa82d80a4b80f8434a
+        let expected_res: [u8; 32] = [
+            0xa7, 0xff, 0xc6, 0xf8, 0xbf, 0x1e, 0xd7, 0x66, 0x51, 0xc1, 0x47, 0x56, 0xa0, 0x61,
+            0xd6, 0x62, 0xf5, 0x80, 0xff, 0x4d, 0xe4, 0x3b, 0x49, 0xfa, 0x82, 0xd8, 0x0a, 0x4b,
+            0x80, 0xf8, 0x43, 0x4a,
+        ];
+
+        for i in 0..32 {
+            print!("{:#001x}", res[i]);
+        }
+        println!();
+
+        assert!(res == expected_res);
+    }
+}

src/main.rs

@@ -0,0 +1,26 @@
+use sha3::sha3::Sha3_256;
+
+fn main() {
+    let mut sha = Sha3_256::default();
+
+    // println!("{:?}", (0x01 as u64).to_ne_bytes());
+
+    let text = "hola";
+
+    sha.absorb(text.as_bytes());
+    let res = sha.squeeze();
+
+    let expected_res: [u8; 32] = [
+        0x8a, 0xf1, 0x3d, 0x92, 0x44, 0x61, 0x8e, 0xee, 0x87, 0x6d, 0x04, 0x31, 0xf3, 0x44, 0x9a,
+        0xa4, 0xff, 0x95, 0x27, 0x4c, 0xa3, 0xe7, 0xe5, 0xc6, 0x54, 0x19, 0x79, 0x49, 0x9f, 0x5b,
+        0x85, 0xde,
+    ];
+
+    for i in 0..32 {
+        print!("{:#001x} ", res[i]);
+    }
+    println!();
+
+    assert!(res == expected_res);
+    println!("FUNCIONAAAAA");
+}

src/sha3.rs

@@ -0,0 +1,171 @@
+// Rate: 1088
+// Capacity: 512
+
+// use std::arch::x86_64::_mm256_xor_epi64;
+
+use std::array;
+
+const RATE_256: usize = 136;
+const TOTAL_STATE_SIZE: usize = 200;
+const ROUNDS: usize = 24;
+const DELIMITER_SUFFIX: u8 = 0x06; // delimiter suffix for sha3
+
+#[derive(Debug)]
+pub struct Sha3_256 {
+    state: [u8; TOTAL_STATE_SIZE],
+}
+
+impl Default for Sha3_256 {
+    fn default() -> Self {
+        Self {
+            state: [0; TOTAL_STATE_SIZE],
+        }
+    }
+}
+
+impl Sha3_256 {
+    pub fn absorb(&mut self, input: &[u8]) {
+        // Xor input with rate
+        let mut remaining = input.len();
+        let mut off = 0;
+        let mut in_len = 0;
+        while remaining > 0 {
+            in_len = remaining.min(RATE_256);
+            println!("{}", in_len);
+            for i in 0..in_len {
+                self.state[i] ^= input[i + off];
+            }
+            off += in_len - 1;
+            remaining -= in_len;
+
+            if in_len == RATE_256 {
+                keccak_permute(&mut self.state);
+                in_len = 0;
+            }
+        }
+
+        self.state[in_len] ^= DELIMITER_SUFFIX;
+
+        if (DELIMITER_SUFFIX & 0x80) != 0 && in_len == RATE_256 - 1 {
+            keccak_permute(&mut self.state);
+        }
+
+        self.state[RATE_256 - 1] ^= 0x80;
+    }
+
+    pub fn squeeze<const S: usize>(&mut self) -> [u8; S] {
+        keccak_permute(&mut self.state);
+        let mut res = [0_u8; S];
+        let mut out_len;
+        let mut remaining = S;
+        let mut off = 0;
+        while remaining > 0 {
+            out_len = remaining.min(RATE_256);
+            res[off..off + out_len].copy_from_slice(&self.state[0..out_len]);
+            off += out_len;
+            remaining -= out_len;
+
+            if out_len > 0 {
+                keccak_permute(&mut self.state);
+            }
+        }
+        // *self.state.first_chunk().unwrap()
+        res
+    }
+}
+
+fn keccak_permute(input: &mut [u8; TOTAL_STATE_SIZE]) {
+    let (lanes, _) = input.as_chunks_mut::<8>();
+    let mut lfsr_state = 0x01_u8;
+    for _ in 0..ROUNDS {
+        // θ step
+        let c: [u64; 5] = array::from_fn(|x| {
+            get_lane(lanes, x, 0)
+                ^ get_lane(lanes, x, 1)
+                ^ get_lane(lanes, x, 2)
+                ^ get_lane(lanes, x, 3)
+                ^ get_lane(lanes, x, 4)
+        });
+
+        let mut d: u64;
+        for x in 0..5 {
+            d = c[(x + 4) % 5] ^ rol64(c[(x + 1) % 5], 1);
+            for y in 0..5 {
+                xor_lane(d, lanes, x, y);
+            }
+        }
+
+        // ρ and π steps
+        let (mut x, mut y) = (1, 0);
+        let mut current = get_lane(lanes, x, y);
+        let mut temp: u64;
+
+        for t in 0..24 {
+            let r = ((t + 1) * (t + 2) / 2) % 64;
+            let y2 = (2 * x + 3 * y) % 5;
+            x = y;
+            y = y2;
+
+            temp = get_lane(lanes, x, y);
+            set_lane(rol64(current, r), x, y, lanes);
+            current = temp;
+        }
+
+        // χ step
+        let mut temp2 = [0_u64; 5];
+        for y in 0..5 {
+            for x in 0..5 {
+                temp2[x] = get_lane(lanes, x, y);
+            }
+            for x in 0..5 {
+                set_lane(
+                    temp2[x] ^ ((!temp2[(x + 1) % 5]) & temp2[(x + 2) % 5]),
+                    x,
+                    y,
+                    lanes,
+                );
+            }
+        }
+
+        // ι step
+
+        for j in 0..7 {
+            let bit_pos: usize = (1 << j) - 1;
+            if lfsr86540(&mut lfsr_state) {
+                xor_lane((1 as u64) << bit_pos, lanes, 0, 0);
+            }
+        }
+    }
+}
+
+#[inline]
+fn get_lane(lanes: &[[u8; 8]], x: usize, y: usize) -> u64 {
+    u64::from_ne_bytes(lanes[x + 5 * y])
+}
+
+#[inline]
+fn set_lane(lane: u64, x: usize, y: usize, lanes: &mut [[u8; 8]]) {
+    lanes[x + 5 * y] = lane.to_ne_bytes();
+}
+
+#[inline]
+fn rol64(v: u64, off: usize) -> u64 {
+    ((v) << off) ^ ((v) >> (64 - off))
+}
+
+#[inline]
+fn xor_lane(lane: u64, lanes: &mut [[u8; 8]], x: usize, y: usize) {
+    set_lane(get_lane(lanes, x, y) ^ lane, x, y, lanes);
+}
+
+// Function that computes the linear feedback shift register (LFSR)
+// I have absolutely no idea wtf is this shit. Copied from a github repo lol.
+fn lfsr86540(lfsr: &mut u8) -> bool {
+    let res = (*lfsr & 0x01) != 0;
+    if (*lfsr & 0x80) != 0 {
+        *lfsr = (*lfsr << 1) ^ 0x71;
+    } else {
+        *lfsr <<= 1;
+    }
+    res
+}