fix(alg): sha2-256 sigma functions were wrong

README.md

@@ -18,3 +18,8 @@ apt install binutils-arm-none-eabi gcc-arm-none-eabi # compiler for the target a
 apt install ruby # ceedling is the used build system for algorithms-c, and needs to be installed with gem, the ruby package manager
 gem install ceedling 
 ```
+
+## Acknowledgements
+
+For implementing the SHA-2-256 Algorithm, [this](https://sha256algorithm.com/) 
+website was very helpful.

crates/algorithms/src/hash/sha2.rs

@@ -76,7 +76,6 @@ impl Sha2_256Context {
         Ok(self.intermediate_hash)
     }
 
-    // BUG: false values at end?
     fn process_block(&mut self) {
         show_internals!({
             self.show_internal_state("start processing");
@@ -93,10 +92,12 @@ impl Sha2_256Context {
                 | (self.block[t4 + 3] as u32);
         }
 
+        // NOTE: The sigma functions used for initializing W and for calculating the alphabet
+        // variables differ.
         for t in 16..SHA2_256_BLOCK_SIZE {
-            w[t] = Self::sha256_sigma1_1(w[t - 2])
+            w[t] = Self::sha256_sigma1_w(w[t - 2])
                 .wrapping_add(w[t - 7])
-                .wrapping_add(Self::sha256_sigma0_1(w[t - 15]))
+                .wrapping_add(Self::sha256_sigma0_w(w[t - 15]))
                 .wrapping_add(w[t - 16]);
         }
 
@@ -134,13 +135,12 @@ impl Sha2_256Context {
                 println!("Iter {t}");
             });
 
-            // BUG: the alphabet values are not being changed correctly?
             temp1 = h
-                .wrapping_add(Self::sha256_sigma1_0(e))
+                .wrapping_add(Self::sha256_sigma1(e))
                 .wrapping_add(Self::sha_ch(e, f, g))
                 .wrapping_add(Self::K[t])
                 .wrapping_add(w[t]);
-            temp2 = Self::sha256_sigma0_0(a).wrapping_add(Self::sha_maj(a, b, c));
+            temp2 = Self::sha256_sigma0(a).wrapping_add(Self::sha_maj(a, b, c));
             h = g;
             g = f;
             f = e;
@@ -151,6 +151,8 @@ impl Sha2_256Context {
             a = temp1.wrapping_add(temp2);
 
             show_internals!({
+                println!("temp1:\t{temp1:032b} {temp1:08x}");
+                println!("temp2:\t{temp2:032b} {temp2:08x}");
                 println!("A:\t{a:032b} {a:08x}");
                 println!("B:\t{b:032b} {b:08x}");
                 println!("C:\t{c:032b} {c:08x}");
@@ -180,7 +182,6 @@ impl Sha2_256Context {
 
         self.block_idx = 0;
 
-        // BUG: something is weird with these hash values, they are almost right?
         show_internals!({
             self.show_internal_state("processing end");
             for (i, h) in self.intermediate_hash.iter().enumerate() {
@@ -255,25 +256,28 @@ impl Sha2_256Context {
 
     #[inline]
     fn sha256_rotr(bits: u32, word: u32) -> u32 {
-        u32::rotate_right(word, bits)
+        word.rotate_right(bits)
     }
 
-    fn sha256_sigma0_0(word: u32) -> u32 {
+    /// This is a different function for W
-        Self::sha256_rotr(2, word) ^ Self::sha256_rotr(13, word) ^ Self::sha256_shr(22, word)
+    fn sha256_sigma0_w(word: u32) -> u32 {
-    }
-
-    fn sha256_sigma1_0(word: u32) -> u32 {
-        Self::sha256_rotr(6, word) ^ Self::sha256_rotr(11, word) ^ Self::sha256_shr(25, word)
-    }
-
-    fn sha256_sigma0_1(word: u32) -> u32 {
         Self::sha256_rotr(7, word) ^ Self::sha256_rotr(18, word) ^ Self::sha256_shr(3, word)
     }
 
-    fn sha256_sigma1_1(word: u32) -> u32 {
+    /// This is a different function for W
+    fn sha256_sigma1_w(word: u32) -> u32 {
         Self::sha256_rotr(17, word) ^ Self::sha256_rotr(19, word) ^ Self::sha256_shr(10, word)
     }
 
+    // NOTE: these do not use shift right for the last internal variable!
+    fn sha256_sigma0(word: u32) -> u32 {
+        Self::sha256_rotr(2, word) ^ Self::sha256_rotr(13, word) ^ Self::sha256_rotr(22, word)
+    }
+
+    fn sha256_sigma1(word: u32) -> u32 {
+        Self::sha256_rotr(6, word) ^ Self::sha256_rotr(11, word) ^ Self::sha256_rotr(25, word)
+    }
+
     #[inline]
     fn sha_ch(x: u32, y: u32, z: u32) -> u32 {
         (x & (y ^ z)) ^ z
@@ -309,7 +313,7 @@ mod debug {
         T: core::fmt::Debug + core::fmt::LowerHex,
     {
         fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
-            write!(f, "[\n")?;
+            writeln!(f, "[")?;
             for (i, t) in self.0.iter().enumerate() {
                 write!(f, "0x{t:02x}")?;
                 if i < self.0.len() - 1 {
@@ -337,6 +341,7 @@ mod debug {
     }
 }
 #[cfg(feature = "show_internals")]
+#[allow(unused)]
 use debug::*;
 
 #[cfg(test)]
@@ -345,6 +350,31 @@ mod test {
     use assert_hex::*;
     use pretty_assertions::{assert_eq, assert_ne};
 
+    macro_rules! assert_eq_bin {
+    ($left:expr, $right:expr $(,)?) => ({
+        match (&$left, &$right) {
+            (left_val, right_val) => {
+                if !(*left_val == *right_val) {
+                    panic!(r#"assertion `left == right` failed
+  left: {:b}
+ right: {:b}"#, &*left_val, &*right_val)
+                }
+            }
+        }
+    });
+    ($left:expr, $right:expr, $($arg:tt)+) => ({
+        match (&($left), &($right)) {
+            (left_val, right_val) => {
+                if !(*left_val == *right_val) {
+                    panic!(r#"assertion `left == right` failed: {}
+  left: {:b}
+ right: {:b}"#, format_args!($($arg)+), &*left_val, &*right_val)
+                }
+            }
+        }
+    });
+}
+
     const TEST_VALUES: &[(&str, Digest256)] = &[
         (
             "AAAA",
@@ -363,7 +393,7 @@ mod test {
     ];
 
     #[test]
-    fn test_check() {
+    fn test_sha256_check() {
         let mut dig;
         for (input, expected_output) in TEST_VALUES.iter().copied() {
             dig = sha2_256_oneshot(input.as_bytes()).unwrap();
@@ -376,4 +406,22 @@ mod test {
             assert_eq_hex!(dig, expected_output)
         }
     }
+
+    #[test]
+    fn test_sha256_sigma0() {
+        let a = 0b01101010000010011110011001100111;
+        assert_eq_bin!(
+            Sha2_256Context::sha256_sigma0(a),
+            0b11001110001000001011010001111110
+        );
+    }
+
+    #[test]
+    fn test_sha256_sigma1() {
+        let a = 0b01010001000011100101001001111111;
+        assert_eq_bin!(
+            Sha2_256Context::sha256_sigma1(a),
+            0b00110101100001110010011100101011
+        );
+    }
 }