Add setup instructions

Cargo.lock

@@ -20,10 +20,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
 
 [[package]]
-name = "base64"
+name = "base32"
-version = "0.13.0"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "904dfeac50f3cdaba28fc6f57fdcddb75f49ed61346676a78c4ffe55877802fd"
+checksum = "23ce669cd6c8588f79e15cf450314f9638f967fc5770ff1c7c1deb0925ea7cfa"
 
 [[package]]
 name = "bitflags"
@@ -260,7 +260,7 @@ checksum = "b1141d4d61095b28419e22cb0bbf02755f5e54e0526f97f1e3d1d160e60885fb"
 name = "totp_generator"
 version = "0.1.0"
 dependencies = [
- "base64",
+ "base32",
  "clap",
  "totp_rfc6238",
 ]

Cargo.toml

@@ -7,5 +7,5 @@ edition = "2018"
 
 [dependencies]
 totp_rfc6238 = "0.5.0"
-base64 = "0.13.0"
+base32 = "0.4.0"
 clap = { version = "3.1.6", features = ["derive"] }

src/main.rs

@@ -1,10 +1,31 @@
-use clap::Parser;
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use base32::Alphabet;
+use clap::{Parser, Subcommand};
 use totp_rfc6238::{HashAlgorithm, TotpGenerator};
 
+/// Get the current time since epoch
+pub fn time() -> u64 {
+    SystemTime::now().duration_since(UNIX_EPOCH).unwrap().as_secs()
+}
+
+
 /// TOTP - One Time Password generator
 #[derive(Parser, Debug)]
 #[clap(author, version, about, long_about = None)]
 struct Args {
+    #[clap(subcommand)]
+    command: SubCommands
+}
+
+#[derive(Subcommand, Debug)]
+enum SubCommands {
+    /// Setup configuration
+    Setup,
+
+    /// Get a TOTP code
+    #[clap(arg_required_else_help = true)]
+    Code {
         /// The secret to use
         #[clap(short, long)]
         secret: String,
@@ -16,19 +37,41 @@ struct Args {
         /// Size of generated secret
         #[clap(short, long, default_value_t = 6)]
         len: usize,
+    },
 }
 
 fn main() {
     let args: Args = Args::parse();
 
+    match args.command {
+        SubCommands::Setup => {
+            println!("To configure TOPT :");
+            println!("1. Please open https://mysignins.microsoft.com/security-info");
+            println!("2. Click on \"Add method\"");
+            println!("3. On the popup that appears, choose \"Authenticator app\" and click \"Add\".");
+            println!("4. Click on \"I want to use a different authenticator app\" and click \"Next\"");
+            println!("5. Click on \"Can't save image ?\" and copy the \"Secret key\"");
+            println!("6. Re-run this program running {} code --secret <SECRET>", std::env::args().next().unwrap());
+            println!("7. Back on the browser, click Next and paste copied code");
+        }
+
+        SubCommands::Code { secret, topt_step, len } => {
             let totp_generator = TotpGenerator::new()
-        .set_digit(args.len).unwrap()
+                .set_digit(len).unwrap()
-        .set_step(args.topt_step).unwrap()
+                .set_step(topt_step).unwrap()
                 .set_hash_algorithm(HashAlgorithm::SHA1)
                 .build();
 
-    let key = base64::decode(args.secret).unwrap();
+            let key = base32::decode(
-    let code = totp_generator.get_code(&key);
+                Alphabet::RFC4648 { padding: true },
+                &secret,
+            ).unwrap();
 
-    println!("Secret len = {}", code);
+            let code = totp_generator.get_code(&key);
+            let next_update = totp_generator.get_next_update_time().unwrap();
+
+            println!("Secret = {}", code);
+            println!("Next update = {} seconds", next_update - time());
+        }
+    }
 }