Add sha256 hash and ordering.

examples/hashtest.rs

@@ -1,8 +1,6 @@
-use unshell::hash;
-
 macro_rules! hashtest {
     ($input:tt) => {
-        ($input, hash($input))
+        ($input, unshell::hash_32!($input))
     };
 }
 
@@ -17,6 +15,6 @@ const MAP: [(&str, u32); 6] = [
 
 pub fn main() {
     for (a, b) in MAP {
-        println!("unshell::hash(\"{}\") = {}", a, b)
+        println!("unshell::hash_32!(\"{}\") = {}", a, b)
     }
 }

src/crypto/hash.rs

@@ -0,0 +1,137 @@
+// ── Round constants ──────────────────────────────────────────────────────────
+const K: [u32; 64] = [
+    0x428A2F98, 0x71374491, 0xB5C0FBCF, 0xE9B5DBA5, 0x3956C25B, 0x59F111F1, 0x923F82A4, 0xAB1C5ED5,
+    0xD807AA98, 0x12835B01, 0x243185BE, 0x550C7DC3, 0x72BE5D74, 0x80DEB1FE, 0x9BDC06A7, 0xC19BF174,
+    0xE49B69C1, 0xEFBE4786, 0x0FC19DC6, 0x240CA1CC, 0x2DE92C6F, 0x4A7484AA, 0x5CB0A9DC, 0x76F988DA,
+    0x983E5152, 0xA831C66D, 0xB00327C8, 0xBF597FC7, 0xC6E00BF3, 0xD5A79147, 0x06CA6351, 0x14292967,
+    0x27B70A85, 0x2E1B2138, 0x4D2C6DFC, 0x53380D13, 0x650A7354, 0x766A0ABB, 0x81C2C92E, 0x92722C85,
+    0xA2BFE8A1, 0xA81A664B, 0xC24B8B70, 0xC76C51A3, 0xD192E819, 0xD6990624, 0xF40E3585, 0x106AA070,
+    0x19A4C116, 0x1E376C08, 0x2748774C, 0x34B0BCB5, 0x391C0CB3, 0x4ED8AA4A, 0x5B9CCA4F, 0x682E6FF3,
+    0x748F82EE, 0x78A5636F, 0x84C87814, 0x8CC70208, 0x90BEFFFA, 0xA4506CEB, 0xBEF9A3F7, 0xC67178F2,
+];
+
+// ── Initial hash values ──────────────────────────────────────────────────────
+const H: [u32; 8] = [
+    0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A, 0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19,
+];
+// ── Internals ────────────────────────────────────────────────────────────────
+
+/// Returns what byte `pos` should hold in the padded SHA-256 message,
+/// without ever materialising the full padded buffer.
+const fn padded_byte(input: &[u8], pos: usize, padded_len: usize) -> u8 {
+    let bit_len = (input.len() as u64) * 8;
+    if pos < input.len() {
+        input[pos]
+    } else if pos == input.len() {
+        0x80
+    } else if pos >= padded_len - 8 {
+        // Big-endian 64-bit length: byte 0 is the most significant.
+        let byte_index = pos - (padded_len - 8);
+        (bit_len >> (56 - byte_index * 8)) as u8
+    } else {
+        0x00
+    }
+}
+
+/// SHA-256 compression: mixes one 64-byte block into the hash state.
+const fn compress(state: &mut [u32; 8], block: &[u8; 64]) {
+    // Build the 64-word message schedule from the 16-word block.
+    let mut w = [0u32; 64];
+    let mut i = 0;
+    while i < 16 {
+        w[i] = ((block[i * 4] as u32) << 24)
+            | ((block[i * 4 + 1] as u32) << 16)
+            | ((block[i * 4 + 2] as u32) << 8)
+            | (block[i * 4 + 3] as u32);
+        i += 1;
+    }
+    while i < 64 {
+        let s0 = w[i - 15].rotate_right(7) ^ w[i - 15].rotate_right(18) ^ (w[i - 15] >> 3);
+        let s1 = w[i - 2].rotate_right(17) ^ w[i - 2].rotate_right(19) ^ (w[i - 2] >> 10);
+        w[i] = w[i - 16]
+            .wrapping_add(s0)
+            .wrapping_add(w[i - 7])
+            .wrapping_add(s1);
+        i += 1;
+    }
+
+    // Initialise working variables from current hash state.
+    let mut a = state[0];
+    let mut b = state[1];
+    let mut c = state[2];
+    let mut d = state[3];
+    let mut e = state[4];
+    let mut f = state[5];
+    let mut g = state[6];
+    let mut h = state[7];
+
+    // 64 rounds.
+    i = 0;
+    while i < 64 {
+        let sigma1 = e.rotate_right(6) ^ e.rotate_right(11) ^ e.rotate_right(25);
+        let ch = (e & f) ^ ((!e) & g);
+        let temp1 = h
+            .wrapping_add(sigma1)
+            .wrapping_add(ch)
+            .wrapping_add(K[i])
+            .wrapping_add(w[i]);
+
+        let sigma0 = a.rotate_right(2) ^ a.rotate_right(13) ^ a.rotate_right(22);
+        let maj = (a & b) ^ (a & c) ^ (b & c);
+        let temp2 = sigma0.wrapping_add(maj);
+
+        h = g;
+        g = f;
+        f = e;
+        e = d.wrapping_add(temp1);
+        d = c;
+        c = b;
+        b = a;
+        a = temp1.wrapping_add(temp2);
+        i += 1;
+    }
+
+    // Add the compressed chunk back into the hash state.
+    state[0] = state[0].wrapping_add(a);
+    state[1] = state[1].wrapping_add(b);
+    state[2] = state[2].wrapping_add(c);
+    state[3] = state[3].wrapping_add(d);
+    state[4] = state[4].wrapping_add(e);
+    state[5] = state[5].wrapping_add(f);
+    state[6] = state[6].wrapping_add(g);
+    state[7] = state[7].wrapping_add(h);
+}
+
+// ── Public API ───────────────────────────────────────────────────────────────
+
+/// Returns the SHA-256 digest of `input` as 32 raw bytes.
+pub const fn sha256(input: &[u8]) -> [u8; 32] {
+    // Padded length is the next multiple of 64 that fits input + 1 (0x80) + 8 (length).
+    let padded_len = ((input.len() + 9 + 63) / 64) * 64;
+    let mut state = H;
+    let mut block_start = 0;
+
+    while block_start < padded_len {
+        // Assemble the current 64-byte block using the virtual padded view.
+        let mut block = [0u8; 64];
+        let mut j = 0;
+        while j < 64 {
+            block[j] = padded_byte(input, block_start + j, padded_len);
+            j += 1;
+        }
+        compress(&mut state, &block);
+        block_start += 64;
+    }
+
+    // Serialise the 8×u32 state as big-endian bytes.
+    let mut out = [0u8; 32];
+    let mut i = 0;
+    while i < 8 {
+        out[i * 4] = (state[i] >> 24) as u8;
+        out[i * 4 + 1] = (state[i] >> 16) as u8;
+        out[i * 4 + 2] = (state[i] >> 8) as u8;
+        out[i * 4 + 3] = state[i] as u8;
+        i += 1;
+    }
+    out
+}

src/crypto/mod.rs

@@ -0,0 +1,54 @@
+use alloc::string::String;
+
+mod hash;
+mod ordering;
+
+pub use hash::sha256;
+pub use ordering::feistel_shuffle;
+
+#[macro_export]
+macro_rules! hash_256 {
+    ($s:literal) => {{
+        // string literal arm
+        const HASH: [u8; 32] = $crate::crypto::sha256($s.as_bytes());
+        HASH
+    }};
+    ($n:expr) => {{
+        // integer/expression arm
+        const BYTES: [u8; 8] = ($n as u64).to_be_bytes();
+        const HASH: [u8; 32] = $crate::crypto::sha256(&BYTES);
+        HASH
+    }};
+}
+
+#[macro_export]
+macro_rules! hash_32 {
+    ($s:literal) => {{
+        // string literal arm
+        const HASH: [u8; 32] = $crate::crypto::sha256($s.as_bytes());
+        const RESULT: u32 = u32::from_be_bytes([HASH[0], HASH[8], HASH[16], HASH[24]]);
+        RESULT
+    }};
+    ($n:expr) => {{
+        // integer/expression arm
+        const BYTES: [u8; 8] = ($n as u64).to_be_bytes();
+        const HASH: [u8; 32] = $crate::crypto::sha256(&BYTES);
+        const RESULT: u32 = u32::from_be_bytes([HASH[0], HASH[8], HASH[16], HASH[24]]);
+        RESULT
+    }};
+}
+
+pub fn hash_string_32(input: String) -> u32 {
+    let hash: [u8; 32] = sha256(input.as_bytes());
+    u32::from_be_bytes([hash[0], hash[8], hash[16], hash[24]])
+}
+
+pub fn hash_str_32(input: &str) -> u32 {
+    let hash: [u8; 32] = sha256(input.as_bytes());
+    u32::from_be_bytes([hash[0], hash[8], hash[16], hash[24]])
+}
+
+pub fn hash_32(input: u32) -> u32 {
+    let hash: [u8; 32] = sha256(&input.to_be_bytes());
+    u32::from_be_bytes([hash[0], hash[8], hash[16], hash[24]])
+}

src/crypto/ordering.rs

@@ -0,0 +1,35 @@
+/// Performs a deterministic pseudo-random shuffle of a 16-bit index.
+///
+/// # Arguments
+/// * `index` - The input value (0..65536).
+/// * `seed` - The 32-bit seed acting as the encryption key.
+///
+/// # Returns
+/// A unique 16-bit shuffled value.
+pub fn feistel_shuffle(index: u16, seed: u32) -> u16 {
+    // Split 16-bit index into two 8-bit halves
+    let mut l = ((index >> 8) & 0xFF) as u8;
+    let mut r = (index & 0xFF) as u8;
+
+    // Perform 4 rounds of Feistel mixing
+    for round in 0..4 {
+        // Derive sub-key: Rotate seed and add golden ratio constant
+        let rot_amount = (round * 5) % 32;
+        let sub_key = seed
+            .rotate_left(rot_amount)
+            .wrapping_add(round.wrapping_mul(0x9E3779B9));
+
+        // Round function F: Simple multiplicative hash mixing R and sub_key
+        // We cast to u32 for multiplication to avoid overflow, then mask back to 8 bits
+        let r_u32 = r as u32;
+        let hash_val = ((r_u32.wrapping_mul(sub_key)) ^ (r_u32 >> 4)) as u8 & 0xFF;
+
+        // Feistel step: New L = Old R, New R = Old L XOR F(R, key)
+        let temp = l;
+        l = r;
+        r = temp ^ hash_val;
+    }
+
+    // Recombine halves
+    ((l as u16) << 8) | (r as u16)
+}

src/hash.rs

@@ -1,57 +0,0 @@
-//! Temporary hash function
-
-const fn hash_recursive(state: &mut [u8; 4], input: &[u8]) {
-    match input.len() {
-        3 => {
-            state[0] ^= input[0];
-            state[1] ^= input[1];
-            state[2] ^= input[2];
-        }
-        2 => {
-            state[0] ^= input[0];
-            state[1] ^= input[1];
-        }
-        1 => {
-            state[0] ^= input[0];
-        }
-        0 => {}
-        _ => {
-            state[0] ^= input[0];
-            state[1] ^= input[1];
-            state[2] ^= input[2];
-            state[3] ^= input[3];
-
-            // Mess with the state quite a bit
-            state[0] = u8::reverse_bits(state[0]) ^ state[2];
-            state[2] = state[0].wrapping_add(state[2]).wrapping_add(state[3]) ^ state[0];
-            state[3] = state[2].wrapping_add(state[3] << 2) ^ state[1];
-            state[1] = state[3] ^ 0xa3;
-
-            hash_recursive(state, &input[1..]);
-        }
-    }
-}
-
-pub const fn hash(input: &'static str) -> u32 {
-    let mut data = [0xDE, 0xED, 0xBE, 0xEF];
-    hash_recursive(&mut data, input.as_bytes());
-
-    // throw the data back into itself because why not
-    let input2 = [
-        u8::reverse_bits(data[1]),
-        data[2],
-        data[2],
-        data[1],
-        u8::reverse_bits(data[0]),
-        data[2],
-        u8::reverse_bits(data[3]),
-        u8::reverse_bits(data[2]),
-        data[3],
-        u8::reverse_bits(data[3]),
-        u8::reverse_bits(data[2]),
-        data[0],
-    ];
-    hash_recursive(&mut data, &input2);
-
-    u32::from_be_bytes(data)
-}

src/lib.rs

@@ -11,14 +11,12 @@
 //! The library requires `alloc` for path and payload management.
 
 #![no_std]
-#![feature(const_index)]
-#![feature(const_trait_impl)]
 
 pub extern crate alloc;
 
-mod hash;
+pub mod crypto;
 pub mod interface;
 pub mod logger;
 pub mod protocol;
 
-pub use hash::hash;
+// pub use hash::hash;

unshell-leaves/leaf-pty/src/constants.rs

@@ -1,8 +1,10 @@
+use unshell::hash_32;
+
 /// Leaf id used by the generated fake PTY wrapper.
-pub const LEAF_FAKE_PTY: u32 = unshell::hash("dev.unshell.v1.pty");
+pub const LEAF_FAKE_PTY: u32 = hash_32!("dev.unshell.v1.pty");
 
 /// Outer procedure id used by all fake PTY session packets.
-pub const PROC_PTY: u32 = unshell::hash("dev.unshell.v1.pty.pty");
+pub const PROC_PTY: u32 = hash_32!("dev.unshell.v1.pty.pty");
 
 /// Downward opcode that opens one PTY session.
 pub const OP_OPEN: u8 = 0;