Informational 15 Bitcoin Committed Apr 14, 2026 · 04:39 UTC

hashes: use consistent round numbering in sha256 comments

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Public commit record

What the developer wrote

Authored by jrakibi

73/100 · Adequate

hashes: use consistent round numbering in sha256 comments

the 1-way ARM and x86 SHA-NI functions used Rounds 0-3 while
the 2-way ARM function used Rounds 1-4 in the comments.

use this consistently everywhere.

✓ Specific, descriptive subject✓ Names a concrete action or component✓ Provides detailed explanatory context

The short version

What changed, and why it matters

This commit only changes comments in the SHA-256 code. It makes the round-number labels consistent between different versions of the optimized code (ARM and x86). No actual program logic, math, or behavior was changed, so it cannot affect security or correctness.

Recommended action

No security action needed. This is a documentation/comment cleanup commit.

Security signals we found

No strong security signals were identified.

Technical analysis

Evidence from the diff

The diff is a pure comment edit across two hardware-accelerated SHA-256 implementation files (ARM SHA-2 and x86 SHA-NI). Every change is inside a // Rounds X-Y comment, shifting the numbering from 0-based to 1-based to match an existing 2-way ARM implementation. No instructions, constants, control flow, memory access, or arithmetic were modified.

Changed components

hashes/src/sha256/crypto/arm_sha2.rshashes/src/sha256/crypto/x86_shani.rs

Inspect captured patch +32 / −32

diff --git a/hashes/src/sha256/crypto/arm_sha2.rs b/hashes/src/sha256/crypto/arm_sha2.rs
index 812f1c5c..535dee40 100644
--- a/hashes/src/sha256/crypto/arm_sha2.rs
+++ b/hashes/src/sha256/crypto/arm_sha2.rs
@@ -72,7 +72,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
 
     tmp0 = vaddq_u32(msg0, vld1q_u32(K.as_ptr().add(0x00)));
 
-    // Rounds 0-3
+    // Rounds 1-4
     msg0 = vsha256su0q_u32(msg0, msg1);
     tmp2 = state0;
     tmp1 = vaddq_u32(msg1, vld1q_u32(K.as_ptr().add(0x04)));
@@ -80,7 +80,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
     state1 = vsha256h2q_u32(state1, tmp2, tmp0);
     msg0 = vsha256su1q_u32(msg0, msg2, msg3);
 
-    // Rounds 4-7
+    // Rounds 5-8
     msg1 = vsha256su0q_u32(msg1, msg2);
     tmp2 = state0;
     tmp0 = vaddq_u32(msg2, vld1q_u32(K.as_ptr().add(0x08)));
@@ -88,7 +88,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
     state1 = vsha256h2q_u32(state1, tmp2, tmp1);
     msg1 = vsha256su1q_u32(msg1, msg3, msg0);
 
-    // Rounds 8-11
+    // Rounds 9-12
     msg2 = vsha256su0q_u32(msg2, msg3);
     tmp2 = state0;
     tmp1 = vaddq_u32(msg3, vld1q_u32(K.as_ptr().add(0x0c)));
@@ -96,7 +96,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
     state1 = vsha256h2q_u32(state1, tmp2, tmp0);
     msg2 = vsha256su1q_u32(msg2, msg0, msg1);
 
-    // Rounds 12-15
+    // Rounds 13-16
     msg3 = vsha256su0q_u32(msg3, msg0);
     tmp2 = state0;
     tmp0 = vaddq_u32(msg0, vld1q_u32(K.as_ptr().add(0x10)));
@@ -104,7 +104,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
     state1 = vsha256h2q_u32(state1, tmp2, tmp1);
     msg3 = vsha256su1q_u32(msg3, msg1, msg2);
 
-    // Rounds 16-19
+    // Rounds 17-20
     msg0 = vsha256su0q_u32(msg0, msg1);
     tmp2 = state0;
     tmp1 = vaddq_u32(msg1, vld1q_u32(K.as_ptr().add(0x14)));
@@ -112,7 +112,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
     state1 = vsha256h2q_u32(state1, tmp2, tmp0);
     msg0 = vsha256su1q_u32(msg0, msg2, msg3);
 
-    // Rounds 20-23
+    // Rounds 21-24
     msg1 = vsha256su0q_u32(msg1, msg2);
     tmp2 = state0;
     tmp0 = vaddq_u32(msg2, vld1q_u32(K.as_ptr().add(0x18)));
@@ -120,7 +120,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
     state1 = vsha256h2q_u32(state1, tmp2, tmp1);
     msg1 = vsha256su1q_u32(msg1, msg3, msg0);
 
-    // Rounds 24-27
+    // Rounds 25-28
     msg2 = vsha256su0q_u32(msg2, msg3);
     tmp2 = state0;
     tmp1 = vaddq_u32(msg3, vld1q_u32(K.as_ptr().add(0x1c)));
@@ -128,7 +128,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
     state1 = vsha256h2q_u32(state1, tmp2, tmp0);
     msg2 = vsha256su1q_u32(msg2, msg0, msg1);
 
-    // Rounds 28-31
+    // Rounds 29-32
     msg3 = vsha256su0q_u32(msg3, msg0);
     tmp2 = state0;
     tmp0 = vaddq_u32(msg0, vld1q_u32(K.as_ptr().add(0x20)));
@@ -136,7 +136,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
     state1 = vsha256h2q_u32(state1, tmp2, tmp1);
     msg3 = vsha256su1q_u32(msg3, msg1, msg2);
 
-    // Rounds 32-35
+    // Rounds 33-36
     msg0 = vsha256su0q_u32(msg0, msg1);
     tmp2 = state0;
     tmp1 = vaddq_u32(msg1, vld1q_u32(K.as_ptr().add(0x24)));
@@ -144,7 +144,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
     state1 = vsha256h2q_u32(state1, tmp2, tmp0);
     msg0 = vsha256su1q_u32(msg0, msg2, msg3);
 
-    // Rounds 36-39
+    // Rounds 37-40
     msg1 = vsha256su0q_u32(msg1, msg2);
     tmp2 = state0;
     tmp0 = vaddq_u32(msg2, vld1q_u32(K.as_ptr().add(0x28)));
@@ -152,7 +152,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
     state1 = vsha256h2q_u32(state1, tmp2, tmp1);
     msg1 = vsha256su1q_u32(msg1, msg3, msg0);
 
-    // Rounds 40-43
+    // Rounds 41-44
     msg2 = vsha256su0q_u32(msg2, msg3);
     tmp2 = state0;
     tmp1 = vaddq_u32(msg3, vld1q_u32(K.as_ptr().add(0x2c)));
@@ -160,7 +160,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
     state1 = vsha256h2q_u32(state1, tmp2, tmp0);
     msg2 = vsha256su1q_u32(msg2, msg0, msg1);
 
-    // Rounds 44-47
+    // Rounds 45-48
     msg3 = vsha256su0q_u32(msg3, msg0);
     tmp2 = state0;
     tmp0 = vaddq_u32(msg0, vld1q_u32(K.as_ptr().add(0x30)));
@@ -168,25 +168,25 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
     state1 = vsha256h2q_u32(state1, tmp2, tmp1);
     msg3 = vsha256su1q_u32(msg3, msg1, msg2);
 
-    // Rounds 48-51
+    // Rounds 49-52
     tmp2 = state0;
     tmp1 = vaddq_u32(msg1, vld1q_u32(K.as_ptr().add(0x34)));
     state0 = vsha256hq_u32(state0, state1, tmp0);
     state1 = vsha256h2q_u32(state1, tmp2, tmp0);
 
-    // Rounds 52-55
+    // Rounds 53-56
     tmp2 = state0;
     tmp0 = vaddq_u32(msg2, vld1q_u32(K.as_ptr().add(0x38)));
     state0 = vsha256hq_u32(state0, state1, tmp1);
     state1 = vsha256h2q_u32(state1, tmp2, tmp1);
 
-    // Rounds 56-59
+    // Rounds 57-60
     tmp2 = state0;
     tmp1 = vaddq_u32(msg3, vld1q_u32(K.as_ptr().add(0x3c)));
     state0 = vsha256hq_u32(state0, state1, tmp0);
     state1 = vsha256h2q_u32(state1, tmp2, tmp0);
 
-    // Rounds 60-63
+    // Rounds 61-64
     tmp2 = state0;
     state0 = vsha256hq_u32(state0, state1, tmp1);
     state1 = vsha256h2q_u32(state1, tmp2, tmp1);
diff --git a/hashes/src/sha256/crypto/x86_shani.rs b/hashes/src/sha256/crypto/x86_shani.rs
index 87e0d250..676990a0 100644
--- a/hashes/src/sha256/crypto/x86_shani.rs
+++ b/hashes/src/sha256/crypto/x86_shani.rs
@@ -59,7 +59,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         abef_save = state0;
         cdgh_save = state1;
 
-        // Rounds 0-3
+        // Rounds 1-4
         msg = _mm_loadu_si128(block.as_ptr().add(block_offset).cast::<__m128i>());
         msg0 = _mm_shuffle_epi8(msg, MASK);
         msg = _mm_add_epi32(
@@ -70,7 +70,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         msg = _mm_shuffle_epi32(msg, 0x0E);
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
 
-        // Rounds 4-7
+        // Rounds 5-8
         msg1 = _mm_loadu_si128(block.as_ptr().add(block_offset + 16).cast::<__m128i>());
         msg1 = _mm_shuffle_epi8(msg1, MASK);
         msg = _mm_add_epi32(
@@ -82,7 +82,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
         msg0 = _mm_sha256msg1_epu32(msg0, msg1);
 
-        // Rounds 8-11
+        // Rounds 9-12
         msg2 = _mm_loadu_si128(block.as_ptr().add(block_offset + 32).cast::<__m128i>());
         msg2 = _mm_shuffle_epi8(msg2, MASK);
         msg = _mm_add_epi32(
@@ -94,7 +94,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
         msg1 = _mm_sha256msg1_epu32(msg1, msg2);
 
-        // Rounds 12-15
+        // Rounds 13-16
         msg3 = _mm_loadu_si128(block.as_ptr().add(block_offset + 48).cast::<__m128i>());
         msg3 = _mm_shuffle_epi8(msg3, MASK);
         msg = _mm_add_epi32(
@@ -109,7 +109,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
         msg2 = _mm_sha256msg1_epu32(msg2, msg3);
 
-        // Rounds 16-19
+        // Rounds 17-20
         msg = _mm_add_epi32(
             msg0,
             _mm_set_epi64x(0x240CA1CC0FC19DC6u64 as i64, 0xEFBE4786E49B69C1u64 as i64),
@@ -122,7 +122,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
         msg3 = _mm_sha256msg1_epu32(msg3, msg0);
 
-        // Rounds 20-23
+        // Rounds 21-24
         msg = _mm_add_epi32(
             msg1,
             _mm_set_epi64x(0x76F988DA5CB0A9DCu64 as i64, 0x4A7484AA2DE92C6Fu64 as i64),
@@ -135,7 +135,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
         msg0 = _mm_sha256msg1_epu32(msg0, msg1);
 
-        // Rounds 24-27
+        // Rounds 25-28
         msg = _mm_add_epi32(
             msg2,
             _mm_set_epi64x(0xBF597FC7B00327C8u64 as i64, 0xA831C66D983E5152u64 as i64),
@@ -148,7 +148,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
         msg1 = _mm_sha256msg1_epu32(msg1, msg2);
 
-        // Rounds 28-31
+        // Rounds 29-32
         msg = _mm_add_epi32(
             msg3,
             _mm_set_epi64x(0x1429296706CA6351u64 as i64, 0xD5A79147C6E00BF3u64 as i64),
@@ -161,7 +161,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
         msg2 = _mm_sha256msg1_epu32(msg2, msg3);
 
-        // Rounds 32-35
+        // Rounds 33-36
         msg = _mm_add_epi32(
             msg0,
             _mm_set_epi64x(0x53380D134D2C6DFCu64 as i64, 0x2E1B213827B70A85u64 as i64),
@@ -174,7 +174,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
         msg3 = _mm_sha256msg1_epu32(msg3, msg0);
 
-        // Rounds 36-39
+        // Rounds 37-40
         msg = _mm_add_epi32(
             msg1,
             _mm_set_epi64x(0x92722C8581C2C92Eu64 as i64, 0x766A0ABB650A7354u64 as i64),
@@ -187,7 +187,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
         msg0 = _mm_sha256msg1_epu32(msg0, msg1);
 
-        // Rounds 40-43
+        // Rounds 41-44
         msg = _mm_add_epi32(
             msg2,
             _mm_set_epi64x(0xC76C51A3C24B8B70u64 as i64, 0xA81A664BA2BFE8A1u64 as i64),
@@ -200,7 +200,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
         msg1 = _mm_sha256msg1_epu32(msg1, msg2);
 
-        // Rounds 44-47
+        // Rounds 45-48
         msg = _mm_add_epi32(
             msg3,
             _mm_set_epi64x(0x106AA070F40E3585u64 as i64, 0xD6990624D192E819u64 as i64),
@@ -213,7 +213,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
         msg2 = _mm_sha256msg1_epu32(msg2, msg3);
 
-        // Rounds 48-51
+        // Rounds 49-52
         msg = _mm_add_epi32(
             msg0,
             _mm_set_epi64x(0x34B0BCB52748774Cu64 as i64, 0x1E376C0819A4C116u64 as i64),
@@ -226,7 +226,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
         msg3 = _mm_sha256msg1_epu32(msg3, msg0);
 
-        // Rounds 52-55
+        // Rounds 53-56
         msg = _mm_add_epi32(
             msg1,
             _mm_set_epi64x(0x682E6FF35B9CCA4Fu64 as i64, 0x4ED8AA4A391C0CB3u64 as i64),
@@ -238,7 +238,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         msg = _mm_shuffle_epi32(msg, 0x0E);
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
 
-        // Rounds 56-59
+        // Rounds 57-60
         msg = _mm_add_epi32(
             msg2,
             _mm_set_epi64x(0x8CC7020884C87814u64 as i64, 0x78A5636F748F82EEu64 as i64),
@@ -250,7 +250,7 @@ pub(super) unsafe fn process_block(state: &mut [u32; 8], block: &[u8]) {
         msg = _mm_shuffle_epi32(msg, 0x0E);
         state0 = _mm_sha256rnds2_epu32(state0, state1, msg);
 
-        // Rounds 60-63
+        // Rounds 61-64
         msg = _mm_add_epi32(
             msg3,
             _mm_set_epi64x(0xC67178F2BEF9A3F7u64 as i64, 0xA4506CEB90BEFFFAu64 as i64),

Risk score

Why this scored 15/100

Our methodology →

Potential impact 0/30

Exploitability 0/25

Stealth signal 0/15

Affected reach 0/15

Confidence 10/10

Evidence quality 5/5

Human-validated context

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What the developer wrote

What changed, and why it matters

Security signals we found

Evidence from the diff

Changed components

Why this scored 15/100

Community notes

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