Order options in help message

src/bin/headers.rs

@@ -0,0 +1,24 @@
+use std::{env, fs::File, io::{self, Read}};
+use doby::{MAGIC_BYTES, crypto::EncryptionParams};
+
+fn main() -> io::Result<()> {
+    let args: Vec<String> = env::args().collect();
+    let mut file = File::open(&args[1])?;
+
+    let mut magic_bytes = vec![0; MAGIC_BYTES.len()];
+    file.read(&mut magic_bytes)?;
+    if magic_bytes == MAGIC_BYTES {
+        match EncryptionParams::read(&mut file)? {
+            Some(params) => {
+                println!("Argon2 time cost: {}", params.argon2.t_cost);
+                println!("Argon2 memory cost: {}KB", params.argon2.m_cost);
+                println!("Argon2 parallelism: {}", params.argon2.parallelism);
+                println!("Encryption cihpher: {}", params.cipher);
+            }
+            None => eprintln!("Invalid cipher")
+        }
+    } else {
+        eprintln!("Doby format not recognized.");
+    }
+    Ok(())
+}

src/cli.rs

@@ -23,6 +23,7 @@ pub fn parse() -> Option<CliArgs> {
     let app = App::new(crate_name!())
         .version(crate_version!())
         .setting(AppSettings::ColoredHelp)
+        .about("Secure symmetric encryption from the command line.")
         .arg(Arg::with_name("INPUT").help("<PATH> | \"-\" or empty for stdin"))
         .arg(Arg::with_name("OUTPUT").help("<PATH> | \"-\" or empty for stdout"))
         .arg(
@@ -32,14 +33,14 @@ pub fn parse() -> Option<CliArgs> {
                 .help(&format!("Encrypt even if {} format is recognized", crate_name!()))
         )
         .arg(
-            Arg::with_name("password")
+            Arg::with_name("1_password")
                 .short("p")
                 .long("password")
                 .value_name("password")
                 .help("Password used to derive encryption keys")
         )
         .arg(
-            Arg::with_name("t_cost")
+            Arg::with_name("2_t_cost")
                 .short("i")
                 .long("iterations")
                 .value_name("iterations")
@@ -47,7 +48,7 @@ pub fn parse() -> Option<CliArgs> {
                 .default_value("10")
         )
         .arg(
-            Arg::with_name("m_cost")
+            Arg::with_name("3_m_cost")
                 .short("m")
                 .long("memory-cost")
                 .value_name("memory cost")
@@ -55,7 +56,7 @@ pub fn parse() -> Option<CliArgs> {
                 .default_value("4096")
         )
         .arg(
-            Arg::with_name("parallelism")
+            Arg::with_name("4_parallelism")
                 .short("t")
                 .long("threads")
                 .value_name("threads")
@@ -82,9 +83,9 @@ pub fn parse() -> Option<CliArgs> {
         .get_matches();
 
     let params = {
-        let t_cost = number(app.value_of("t_cost").unwrap())?;
-        let m_cost =  number(app.value_of("m_cost").unwrap())?;
-        let parallelism =  number(app.value_of("parallelism").unwrap())?;
+        let t_cost = number(app.value_of("2_t_cost").unwrap())?;
+        let m_cost =  number(app.value_of("3_m_cost").unwrap())?;
+        let parallelism =  number(app.value_of("4_parallelism").unwrap())?;
 
         ArgonParams {
             t_cost,
@@ -129,7 +130,7 @@ pub fn parse() -> Option<CliArgs> {
         })
         .unwrap_or_else(|| Some(Box::new(stdout())))?;
 
-    let password = match app.value_of("password") {
+    let password = match app.value_of("1_password") {
         Some(s) => s.to_string(),
         None => rpassword::read_password_from_tty(Some("Password: ")).unwrap(),
     };

src/crypto.rs

@@ -1,4 +1,8 @@
-use std::{convert::TryFrom, io::{self, Read, Write}};
+use std::{
+    convert::TryFrom,
+    fmt::{self, Display, Formatter},
+    io::{self, Read, Write}
+};
 use num_enum::TryFromPrimitive;
 use chacha20::XChaCha20;
 use aes::{Aes256Ctr, cipher::{NewCipher, StreamCipher}};
@@ -37,13 +41,22 @@ impl CipherAlgorithm {
     }
 }
 
+impl Display for CipherAlgorithm {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        f.write_str(match self {
+            CipherAlgorithm::AesCtr => "AES-CTR",
+            CipherAlgorithm::XChaCha20 => "XChaCha20",
+        })
+    }
+}
+
 #[derive(Debug, PartialEq, Eq)]
 pub struct EncryptionParams {
     password_salt: [u8; SALT_LEN],
-    argon2: ArgonParams,
+    pub argon2: ArgonParams,
     hkdf_salt: [u8; SALT_LEN],
     nonce: Vec<u8>,
-    cipher: CipherAlgorithm,
+    pub cipher: CipherAlgorithm,
 }
 
 impl EncryptionParams {