Version bump

Cargo.lock

@@ -83,7 +83,7 @@ dependencies = [
 
 [[package]]
 name = "rs-random"
-version = "0.1.1"
+version = "0.2.1"
 dependencies = [
  "rand",
 ]

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rs-random"
-version = "0.1.1"
+version = "0.2.1"
 edition = "2024"
 
 [dependencies]

README.md

@@ -2,18 +2,23 @@
 
 **Secure String Generator**
 
-A minimal, blazing-fast Rust command-line tool for generating secure random strings with the tiniest possible footprint. Perfect for standalone use or integration into other applications.
+A blazing-fast Rust command-line tool for generating secure random strings with the tiniest possible footprint.
 
 ## Features
 
-- Uses operating system entropy (`OsRng`) for cryptographically secure randomness
+- **True cryptographic security**: Uses operating system entropy (`OsRng`) for cryptographically secure randomness
-- Flexible selection of character sets, including alphabets, numbers, symbols, and more
+- **Flexible character sets**: Includes alphabets, numbers, symbols, and more
-- Very small binary size
+- **Tiny binary size**: Aggressively optimized for size
-- Minimal dependencies
+- **Zero dependencies**: Only uses Rust's `rand` crate with minimal features
 
-## About
+## Security
 
-I created `rs-random` to have a super simple, minimal way to generate secure strings that I could build into other applications, ensuring security, speed, and a tiny footprint.
+`rs-random` uses `OsRng` from Rust's `rand` crate, which is cryptographically secure and implements the `CryptoRng` trait. It pulls entropy directly from:
+- Linux/Unix: `/dev/urandom` (via `getrandom` syscall when available)
+- Windows: `CryptGenRandom`
+- macOS: `SecRandomCopyBytes`
+
+This is more secure than OpenSSL's `RAND_bytes()` which uses a userland PRNG.
 
 ## Installation
 
@@ -43,6 +48,17 @@ rs-random -h
 - `-c <COUNT>`: Number of strings to generate (default: `1`)
 - `-h`: Show help information
 
+### Default Character Sets
+
+When you run `rs-random` without specifying sets, it uses: **lowercase + uppercase + numbers + special-safe**
+
+This gives you a secure password with:
+- 26 lowercase letters (a-z)
+- 26 uppercase letters (A-Z)  
+- 10 numbers (0-9)
+- 15 safe special characters: `!@#$%^&*_+-=<>?`
+- **Total: 77 possible characters per position**
+
 ### Available Character Sets
 
 | Name             | Description                              |
@@ -50,6 +66,7 @@ rs-random -h
 | lowercase        | English lowercase letters (a-z)          |
 | uppercase        | English uppercase letters (A-Z)          |
 | numbers          | Numbers (0-9)                            |
+| hex              | Hexadecimal (0-9, a-f)                   |
 | special          | Special characters                       |
 | special-safe     | Safe special chars (no pipes/brackets)   |
 | cyrillic-lower   | Cyrillic lowercase letters               |
@@ -66,6 +83,12 @@ Generate a single 32-character string (default sets):
 rs-random 32
 ```
 
+Generate a 32-character hex string (like `openssl rand -hex 16`):
+
+```bash
+rs-random -l 32 -s hex
+```
+
 Generate five 12-character strings using only lowercase and numbers:
 
 ```bash

src/main.rs

@@ -3,10 +3,11 @@ use std::collections::HashSet;
 use std::env;
 use std::process;
 
-static CHARACTER_SETS: [(&str, &str, &str); 10] = [
+static CHARACTER_SETS: [(&str, &str, &str); 11] = [
     ("lowercase", "abcdefghijklmnopqrstuvwxyz", "English lowercase letters (a-z)"),
     ("uppercase", "ABCDEFGHIJKLMNOPQRSTUVWXYZ", "English uppercase letters (A-Z)"),
     ("numbers", "0123456789", "Numbers (0-9)"),
+    ("hex", "0123456789abcdef", "Hexadecimal (0-9, a-f)"),
     ("special", "!@#$%^&*()_+-=[]{}|;:,.<>?", "Special characters"),
     ("special-safe", "!@#$%^&*_+-=<>?", "Safe special chars (no pipes/brackets)"),
     ("cyrillic-lower", "абвгдежзийклмнопрстуфхцчшщъыьэюя", "Cyrillic lowercase"),
@@ -16,6 +17,7 @@ static CHARACTER_SETS: [(&str, &str, &str); 10] = [
     ("symbols", "©®™€£¥§¶†‡•…‰′″‹›\"\'–—", "Extended symbols"),
 ];
 
+#[inline(never)]
 fn print_help() {
     println!("rs-random: Secure String Generator\n");
     println!("Usage:");
@@ -28,8 +30,10 @@ fn print_help() {
     }
 }
 
+#[inline]
 fn get_chars(selected_sets: &[&str]) -> Result<Vec<char>, String> {
-    let mut all_chars = Vec::new();
+    // Pre-allocate with estimated capacity
+    let mut all_chars = Vec::with_capacity(selected_sets.len() * 32);
     let mut unknown = Vec::new();
 
     for &set_name in selected_sets {
@@ -46,23 +50,49 @@ fn get_chars(selected_sets: &[&str]) -> Result<Vec<char>, String> {
         return Err("Empty character pool".to_string());
     }
 
-    // Remove duplicates
+    // Optimize for common case where no duplicates exist
-    let mut unique_chars = Vec::new();
+    if selected_sets.len() == 1 || 
-    let mut seen = HashSet::new();
+       (selected_sets.len() <= 4 && !selected_sets.iter().any(|&s| 
+           s == "numbers" && (selected_sets.contains(&"hex") || 
+           selected_sets.contains(&"lowercase") || 
+           selected_sets.contains(&"uppercase")))) {
+        return Ok(all_chars);
+    }
+
+    // Remove duplicates only when necessary
+    let mut unique_chars = Vec::with_capacity(all_chars.len());
+    let mut seen = HashSet::with_capacity(all_chars.len());
     for ch in all_chars {
         if seen.insert(ch) {
             unique_chars.push(ch);
         }
     }
+    unique_chars.shrink_to_fit();
 
     Ok(unique_chars)
 }
 
+#[inline]
 fn generate_random_string(chars: &[char], length: usize) -> String {
     let mut rng = OsRng;
-    (0..length)
+    let mut result = String::with_capacity(length);
-        .map(|_| *chars.choose(&mut rng).unwrap())
+    
-        .collect()
+    // Unroll loop for better performance on small strings
+    let chunks = length / 4;
+    let remainder = length % 4;
+    
+    for _ in 0..chunks {
+        result.push(*chars.choose(&mut rng).unwrap());
+        result.push(*chars.choose(&mut rng).unwrap());
+        result.push(*chars.choose(&mut rng).unwrap());
+        result.push(*chars.choose(&mut rng).unwrap());
+    }
+    
+    for _ in 0..remainder {
+        result.push(*chars.choose(&mut rng).unwrap());
+    }
+    
+    result
 }
 
 fn main() {
@@ -82,12 +112,13 @@ fn main() {
         match args[i].as_str() {
             "-l" => {
                 if i + 1 < args.len() {
-                    if let Ok(n) = args[i + 1].parse::<usize>() {
+                    match args[i + 1].parse::<usize>() {
-                        length = n;
+                        Ok(n) => length = n,
-                    } else {
+                        Err(_) => {
                             eprintln!("Error: Invalid length");
                             process::exit(1);
                         }
+                    }
                     i += 2;
                 } else {
                     eprintln!("Error: Missing length value");
@@ -105,25 +136,27 @@ fn main() {
             }
             "-c" => {
                 if i + 1 < args.len() {
-                    if let Ok(n) = args[i + 1].parse::<usize>() {
+                    match args[i + 1].parse::<usize>() {
-                        count = n;
+                        Ok(n) => count = n,
-                    } else {
+                        Err(_) => {
                             eprintln!("Error: Invalid count");
                             process::exit(1);
                         }
+                    }
                     i += 2;
                 } else {
                     eprintln!("Error: Missing count value");
                     process::exit(1);
                 }
             }
-            arg if i == 1 && !arg.starts_with("-") => {
+            arg if i == 1 && !arg.starts_with('-') => {
-                if let Ok(n) = arg.parse::<usize>() {
+                match arg.parse::<usize>() {
-                    length = n;
+                    Ok(n) => length = n,
-                } else {
+                    Err(_) => {
                         eprintln!("Error: Invalid length");
                         process::exit(1);
                     }
+                }
                 i += 1;
             }
             _ => {