From 1f7c4e6571201d05f5c67e5c709d15ae4a40e059 Mon Sep 17 00:00:00 2001
From: sangge <2251250136@qq.com>
Date: Tue, 7 Oct 2025 22:40:31 +0800
Subject: [PATCH] chore: use "is_multiple_of" method

---
 common/src/lib.rs        | 89 +++++++++++++++++++++++++++++++++++++---
 problems/p21/src/main.rs |  2 +-
 problems/p28/src/main.rs |  1 -
 3 files changed, 85 insertions(+), 7 deletions(-)

diff --git a/common/src/lib.rs b/common/src/lib.rs
index 84f45f4..daf60d2 100644
--- a/common/src/lib.rs
+++ b/common/src/lib.rs
@@ -267,7 +267,7 @@ fn g_func(word: [u8; 4], round: usize) -> [u8; 4] {
 }
 
 pub fn aes_ecb_enc(input: &[u8], key: &[u8; 16]) -> Result<Vec<u8>> {
-    if input.len() % 16 != 0 {
+    if !input.len().is_multiple_of(16) {
         return Err(anyhow!("Invalid input length"));
     }
     let mut cipher: Vec<u8> = Vec::new();
@@ -291,7 +291,7 @@ pub fn aes_ecb_enc(input: &[u8], key: &[u8; 16]) -> Result<Vec<u8>> {
 }
 
 pub fn aes_ecb_dec(input: &[u8], key: &[u8; 16]) -> Result<Vec<u8>> {
-    if input.len() % 16 != 0 {
+    if !input.len().is_multiple_of(16) {
         return Err(anyhow!("Invalid input length"));
     }
 
@@ -317,7 +317,7 @@ pub fn aes_ecb_dec(input: &[u8], key: &[u8; 16]) -> Result<Vec<u8>> {
 }
 
 pub fn aes_cbc_enc(input: &[u8], key: &[u8; 16], iv: &[u8; 16]) -> Result<Vec<u8>> {
-    if input.len() % 16 != 0 {
+    if !input.len().is_multiple_of(16) {
         return Err(anyhow!("Invalid input length"));
     }
     let mut cipher: Vec<u8> = Vec::new();
@@ -350,7 +350,7 @@ pub fn aes_cbc_enc(input: &[u8], key: &[u8; 16], iv: &[u8; 16]) -> Result<Vec<u8
 }
 
 pub fn aes_cbc_dec(input: &[u8], key: &[u8; 16], iv: &[u8; 16]) -> Result<Vec<u8>> {
-    if input.len() % 16 != 0 {
+    if !input.len().is_multiple_of(16) {
         return Err(anyhow!("Invalid input length"));
     }
 
@@ -540,9 +540,88 @@ impl MT19937 {
         for i in 0..624 {
             let y: u32 = (self.mt[i] & 0x80000000) + (self.mt[(i + 1) % 624] & 0x7fffffff);
             self.mt[i] = self.mt[(i + 397) % 624] ^ (y >> 1);
-            if y % 2 != 0 {
+            if !y.is_multiple_of(2) {
                 self.mt[i] ^= 0x9908b0df;
             }
         }
     }
 }
+
+pub fn sha1(input: &[u8]) -> [u8; 20] {
+    let mut h0 = 0x67452301u32;
+    let mut h1 = 0xEFCDAB89u32;
+    let mut h2 = 0x98BADCFEu32;
+    let mut h3 = 0x10325476u32;
+    let mut h4 = 0xC3D2E1F0u32;
+
+    let message_bits_len = input.len() * 8;
+    let mut buffer = input.to_vec();
+    buffer.push(0x80u8);
+
+    while (buffer.len() % 64) != 56 {
+        buffer.push(0x00u8);
+    }
+
+    buffer.extend_from_slice(&(message_bits_len as u64).to_be_bytes());
+
+    for chunk in buffer.chunks(64) {
+        let mut extend_buf = [0u32; 80];
+        for i in 0..16 {
+            let bytes: [u8; 4] = chunk[4 * i..4 * i + 4].try_into().unwrap();
+            extend_buf[i] = u32::from_be_bytes(bytes);
+        }
+        for i in 16..80 {
+            extend_buf[i] =
+                (extend_buf[i - 3] ^ extend_buf[i - 8] ^ extend_buf[i - 14] ^ extend_buf[i - 16])
+                    .rotate_left(1);
+        }
+        let mut a = h0;
+        let mut b = h1;
+        let mut c = h2;
+        let mut d = h3;
+        let mut e = h4;
+        for (i, &w_i) in extend_buf.iter().enumerate() {
+            let f = match i {
+                0..20 => (b & c) | (!b & d),
+                20..40 => b ^ c ^ d,
+                40..60 => (b & c) | (b & d) | (c & d),
+                60..80 => b ^ c ^ d,
+                _ => panic!("Invalid round: {}", i),
+            };
+            let k = match i {
+                0..20 => 0x5A827999,
+                20..40 => 0x6ED9EBA1,
+                40..60 => 0x8F1BBCDC,
+                60..80 => 0xCA62C1D6,
+                _ => panic!("Invalid round: {}", i),
+            };
+            let temp = a
+                .rotate_left(5)
+                .wrapping_add(f)
+                .wrapping_add(e)
+                .wrapping_add(w_i)
+                .wrapping_add(k);
+
+            e = d;
+            d = c;
+            c = b.rotate_left(30);
+            b = a;
+            a = temp;
+        }
+        h0 = h0.wrapping_add(a);
+        h1 = h1.wrapping_add(b);
+        h2 = h2.wrapping_add(c);
+        h3 = h3.wrapping_add(d);
+        h4 = h4.wrapping_add(e);
+    }
+
+    let mut digest = [0u8; 20];
+
+    digest[0..4].copy_from_slice(&h0.to_be_bytes());
+    digest[4..8].copy_from_slice(&h1.to_be_bytes());
+    digest[8..12].copy_from_slice(&h2.to_be_bytes());
+    digest[12..16].copy_from_slice(&h3.to_be_bytes());
+    digest[16..20].copy_from_slice(&h4.to_be_bytes());
+
+    digest
+}
diff --git a/problems/p21/src/main.rs b/problems/p21/src/main.rs
index 6ce3a96..df7c685 100644
--- a/problems/p21/src/main.rs
+++ b/problems/p21/src/main.rs
@@ -77,7 +77,7 @@ impl MT19937 {
         for i in 0..624 {
             let y: u32 = (self.mt[i] & 0x80000000) + (self.mt[(i + 1) % 624] & 0x7fffffff);
             self.mt[i] = self.mt[(i + 397) % 624] ^ (y >> 1);
-            if y % 2 != 0 {
+            if !y.is_multiple_of(2) {
                 self.mt[i] ^= 0x9908b0df;
             }
         }
diff --git a/problems/p28/src/main.rs b/problems/p28/src/main.rs
index 67abde3..2035fe8 100644
--- a/problems/p28/src/main.rs
+++ b/problems/p28/src/main.rs
@@ -100,7 +100,6 @@
 // w[i] = (w[i-6] xor w[i-16] xor w[i-28] xor w[i-32]) leftrotate 2
 // This transformation keeps all operands 64-bit aligned and, by removing the dependency of w[i] on w[i-3], allows efficient SIMD implementation with a vector length of 4 like x86 SSE instructions.
 
-use hex;
 use sha1::{Digest, Sha1};
 
 fn sha1(input: &[u8]) -> [u8; 20] {