Finally works!

Cargo.lock

@@ -5,7 +5,7 @@ version = 3
 [[package]]
 name = "arduino-hal"
 version = "0.1.0"
-source = "git+https://github.com/rahix/avr-hal#fb609ab0d14c5a0a44e2dff3e5e514cb612a529a"
+source = "git+https://github.com/rahix/avr-hal#e29a7be5b1fa9d490ded11e539d345af041ccef6"
 dependencies = [
  "atmega-hal",
  "avr-device",
@@ -19,7 +19,7 @@ dependencies = [
 [[package]]
 name = "atmega-hal"
 version = "0.1.0"
-source = "git+https://github.com/rahix/avr-hal#fb609ab0d14c5a0a44e2dff3e5e514cb612a529a"
+source = "git+https://github.com/rahix/avr-hal#e29a7be5b1fa9d490ded11e539d345af041ccef6"
 dependencies = [
  "avr-device",
  "avr-hal-generic",
@@ -33,9 +33,9 @@ checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
 
 [[package]]
 name = "avr-device"
-version = "0.5.0"
+version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "deb45711b7227cb3f799c40c4e0e8beea1765acff8d06a14bb3479c1a549d8b0"
+checksum = "644690f9699830f0efce38ca9d41c7ad51a6ec1829364dd272638938c953673a"
 dependencies = [
  "avr-device-macros",
  "bare-metal",
@@ -45,9 +45,9 @@ dependencies = [
 
 [[package]]
 name = "avr-device-macros"
-version = "0.5.0"
+version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "87c428a2384981d8460668c48c766ff18e7e91d2d467f7b103151984ee952d38"
+checksum = "ba8b49941a5148cec432d5180d205871f0132f9f15b7225a9f3ad9e2bae026cb"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -57,7 +57,7 @@ dependencies = [
 [[package]]
 name = "avr-hal-generic"
 version = "0.1.0"
-source = "git+https://github.com/rahix/avr-hal#fb609ab0d14c5a0a44e2dff3e5e514cb612a529a"
+source = "git+https://github.com/rahix/avr-hal#e29a7be5b1fa9d490ded11e539d345af041ccef6"
 dependencies = [
  "avr-device",
  "cfg-if 0.1.10",
@@ -76,12 +76,6 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f8fe8f5a8a398345e52358e18ff07cc17a568fbca5c6f73873d3a62056309603"
 
-[[package]]
-name = "binascii"
-version = "0.1.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "383d29d513d8764dcdc42ea295d979eb99c3c9f00607b3692cf68a431f7dca72"
-
 [[package]]
 name = "cfg-if"
 version = "0.1.10"
@@ -107,8 +101,6 @@ dependencies = [
 [[package]]
 name = "ds323x"
 version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "057e63d03a3beb83d3c9b7a19b799c60e203b0c53f1bbec6a715804907f73a2b"
 dependencies = [
  "embedded-hal",
  "rtcc",
@@ -184,9 +176,9 @@ checksum = "dc375e1527247fe1a97d8b7156678dfe7c1af2fc075c9a4db3690ecd2a148068"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.54"
+version = "1.0.56"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e472a104799c74b514a57226160104aa483546de37e839ec50e3c2e41dd87534"
+checksum = "2b63bdb0cd06f1f4dedf69b254734f9b45af66e4a031e42a7480257d9898b435"
 dependencies = [
  "unicode-ident",
 ]
@@ -200,6 +192,12 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "randomize"
+version = "3.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "88c38c99b51f33c9fcc655252bf02ac8048eb70f35244e4697b0de9c473e940a"
+
 [[package]]
 name = "rtcc"
 version = "0.3.0"
@@ -220,9 +218,11 @@ name = "rustytoken"
 version = "0.1.0"
 dependencies = [
  "arduino-hal",
- "binascii",
  "ds323x",
+ "embedded-hal",
+ "nb 1.1.0",
  "panic-halt",
+ "randomize",
  "sha1_smol",
  "ufmt 0.2.0",
 ]

Cargo.toml

@@ -7,14 +7,15 @@ edition = "2021"
 arduino-hal = {  git = "https://github.com/rahix/avr-hal", features = ["arduino-uno"] }
 panic-halt = "0.2.0"
 sha1_smol = "1.0.0"
-binascii = { version = "0.1", default-features = false, features = ["decode"] }
+ds323x = { path = "../ds323x-rs" }
-ds323x = "0.5.0"
-ufmt = "0.2.0"
 embedded-hal = "0.2.7"
+nb = "1.1.0"
+randomize = "3.0.1"
+ufmt = "0.2.0"
 
 [profile.release]
 lto = true
 panic = "abort"
 strip = true
-opt-level = "z"
+opt-level = "s"
 codegen-units = 1

src/button.rs

@@ -0,0 +1,63 @@
+use embedded_hal::digital::v2::InputPin;
+
+pub struct Button<'a, P> {
+    pin: &'a P,
+    state: bool,
+    is_pullup: bool,
+}
+
+#[derive(PartialEq)]
+pub enum Event {
+    PressDown,
+    PressUp,
+    Pressed,
+    None,
+}
+
+impl<'a, P: InputPin> Button<'a, P> {
+    pub fn new(pin: &'a P, is_pullup: bool) -> Self {
+        let mut state = pin.is_high().map_err(|_| ()).unwrap();
+        if is_pullup {
+            state = !state;
+        }
+
+        Button {
+            pin,
+            state,
+            is_pullup,
+        }
+    }
+
+    fn read_pin(&self) -> bool {
+        let mut inc = 0;
+
+        for _ in 0..100 {
+            let mut state = self.pin.is_high().map_err(|_| ()).unwrap();
+            if self.is_pullup {
+                state = !state;
+            }
+            if state {
+                inc += 1;
+            }
+        }
+
+        inc > 70
+    }
+
+    pub fn update(&mut self) -> Event {
+        let actual_state = self.read_pin();
+
+        match (self.state, actual_state) {
+            (false, false) => Event::None,
+            (true, false) => {
+                self.state = !self.state;
+                Event::PressUp
+            }
+            (false, true) => {
+                self.state = !self.state;
+                Event::PressDown
+            }
+            (true, true) => Event::Pressed,
+        }
+    }
+}

src/crypto.rs

@@ -5,14 +5,8 @@ const BLOCK_SIZE: usize = 64;
 pub fn hmac_sha1(key: &[u8], message: &[u8], output: &mut [u8]) {
     // Preprocess the key.
     let mut key_padded = [0u8; BLOCK_SIZE];
-    if key.len() > BLOCK_SIZE {
+    key_padded[..key.len()].copy_from_slice(key);
-        let mut hash = Sha1::new();
+
-        hash.update(key);
-        let key_digest = hash.digest().bytes();
-        key_padded[..20].copy_from_slice(&key_digest);
-    } else {
-        key_padded[..key.len()].copy_from_slice(key);
-    }
     for byte in &mut key_padded {
         *byte ^= 0x36;
     }

src/datetime.rs

@@ -13,15 +13,7 @@ impl Datetime {
     pub fn unix_epoch(&self) -> u64 {
         let mut year: i64 = self.year as i64 - 1900;
         let mut month: i64 = self.month as i64 - 1;
-        if month >= 12 || month < 0 {
+
-            let mut adj = month / 12;
-            month %= 12;
-            if month < 0 {
-                adj -= 1;
-                month += 12;
-            }
-            year += adj as i64;
-        }
         let (mut t, is_leap) = year_to_secs(year);
         t += month_to_secs(month, is_leap);
         t += 86400 * (self.day as i64 - 1);
@@ -35,21 +27,21 @@ impl Datetime {
         let year = rtc.year().map_err(|_| ()).unwrap();
         let month = rtc.month().map_err(|_| ()).unwrap();
         let day = rtc.day().map_err(|_| ()).unwrap();
-        let hour = match rtc.hours().map_err(|_| ()).unwrap() {
+        let hours = match rtc.hours().map_err(|_| ()).unwrap() {
             ds323x::Hours::AM(val) => val,
             ds323x::Hours::PM(val) => val + 12,
             ds323x::Hours::H24(val) => val,
         };
-        let minute = rtc.minutes().map_err(|_| ()).unwrap();
+        let minutes = rtc.minutes().map_err(|_| ()).unwrap();
-        let second = rtc.seconds().map_err(|_| ()).unwrap();
+        let seconds = rtc.seconds().map_err(|_| ()).unwrap();
 
         Datetime {
-            year: year,
+            year,
-            month: month,
+            month,
-            day: day,
+            day,
-            hours: hour,
+            hours,
-            minutes: minute,
+            minutes,
-            seconds: second,
+            seconds,
         }
     }
 }
@@ -58,64 +50,52 @@ fn year_to_secs(year: i64) -> (i64, bool) {
     let is_leap: bool;
     let res: i64;
 
-    if year - 2 <= 136 {
+    let mut cycles: i64;
-        let y = year as i32;
+    let centuries: i64;
-        let mut leaps = (y - 68) >> 2;
+    let mut leaps: i64;
-        if !((y - 68) & 3 != 0) {
+    let mut rem: i64;
-            leaps -= 1;
-            is_leap = true;
-        } else {
-            is_leap = false;
-        }
-        res = 31536000 * (y - 70) as i64 + 86400 * leaps as i64;
-    } else {
-        let mut cycles: i64;
-        let centuries: i64;
-        let mut leaps: i64;
-        let mut rem: i64;
 
-        cycles = (year - 100) / 400;
+    cycles = (year - 100) / 400;
-        rem = (year - 100) % 400;
+    rem = (year - 100) % 400;
-        if rem < 0 {
+    if rem < 0 {
-            cycles -= 1;
+        cycles -= 1;
-            rem += 400;
+        rem += 400;
+    }
+    if rem == 0 {
+        is_leap = true;
+        centuries = 0;
+        leaps = 0;
+    } else {
+        if rem >= 200 {
+            if rem >= 300 {
+                centuries = 3;
+                rem -= 300;
+            } else {
+                centuries = 2;
+                rem -= 200;
+            }
+        } else {
+            if rem >= 100 {
+                centuries = 1;
+                rem -= 100;
+            } else {
+                centuries = 0;
+            }
         }
         if rem == 0 {
-            is_leap = true;
+            is_leap = false;
-            centuries = 0;
             leaps = 0;
         } else {
-            if rem >= 200 {
+            leaps = rem / 4;
-                if rem >= 300 {
+            rem %= 4;
-                    centuries = 3;
+            is_leap = rem == 0;
-                    rem -= 300;
-                } else {
-                    centuries = 2;
-                    rem -= 200;
-                }
-            } else {
-                if rem >= 100 {
-                    centuries = 1;
-                    rem -= 100;
-                } else {
-                    centuries = 0;
-                }
-            }
-            if rem == 0 {
-                is_leap = false;
-                leaps = 0;
-            } else {
-                leaps = rem / 4;
-                rem %= 4;
-                is_leap = rem == 0;
-            }
         }
-
-        leaps += 97 * cycles + 24 * centuries - (is_leap as i64);
-
-        res = (year - 100) * 31536000 + leaps * 86400 + 946684800 + 86400;
     }
 
+    leaps += 97 * cycles + 24 * centuries - (is_leap as i64);
+
+    res = (year - 100) * 31536000 + leaps * 86400 + 946684800 + 86400;
+
     (res, is_leap)
 }
 

src/main.rs

@@ -1,53 +1,46 @@
 #![no_std]
 #![no_main]
 
+mod button;
 mod crypto;
 mod datetime;
+mod screen;
+mod storage;
 
 use arduino_hal::default_serial;
 use arduino_hal::delay_ms;
+// use arduino_hal::delay_ms;
+use arduino_hal::prelude::*;
 use crypto::hmac_sha1;
-
+use ds323x::Rtcc;
+use nb::block;
 use panic_halt as _;
+use storage::SECRET_KEY_MAX_LEN;
+use storage::SECRET_KEY_NAME_LEN;
 
 const INTERVAL: u64 = 30;
-const SECRET_KEY_MAX_LEN: usize = 32;
 
-fn process_secret<'a>(secret: &str, output: &mut [u8]) -> usize {
+const ENDL: u8 = 0;
-    // RFC 6238 Doesn't specify a max length for the secret keys, So I chose 32
+const OK: u8 = 1;
-    // You can change the max length by modifying the const
+const ERROR: u8 = 2;
-    let mut result = [0u8; SECRET_KEY_MAX_LEN];
+const HANDSHAKE: u8 = 3;
-    let mut inc = 0;
+const SET_TIMESTAMP: u8 = 10;
-    let offset = match 8 - (secret.len() % 8) {
+const ADD_TOKEN: u8 = 20;
-        8 => 0,
+const DELETE_TOKEN: u8 = 30;
-        n => n,
+const GET_TOKENS: u8 = 40;
-    };
+const WIPE_TOKENS: u8 = 50;
+const EXIT: u8 = 254;
 
-    for c in secret.chars() {
+fn decimal_to_packed_bcd(dec: u8) -> u8 {
-        result[inc] = c.to_ascii_uppercase() as u8;
+    ((dec / 10) << 4) | (dec % 10)
-        inc += 1;
-    }
-    for _ in 0..offset {
-        result[inc] = '=' as u8;
-        inc += 1;
-    }
-
-    let decoded = match binascii::b32decode(&result[..inc], output).ok() {
-        Some(bytes) => bytes,
-        None => "".as_bytes(), // TODO: Implement a way to display errors
-    };
-    decoded.len()
 }
 
-fn generate_otp_token(private_key: &str, actual_time: u64) -> u32 {
+fn generate_otp_token(private_key: &[u8], actual_time: u64) -> u32 {
-    let mut output = [0u8; 32];
-    let private_key_len = process_secret(private_key, &mut output);
-
     let interval = actual_time / INTERVAL;
     let msg = interval.to_be_bytes();
 
     let mut hmac_digest = [0u8; 20];
-    hmac_sha1(&output[..private_key_len], &msg, &mut hmac_digest);
+    hmac_sha1(private_key, &msg, &mut hmac_digest);
 
     let start = (hmac_digest[19] & 0xF) as usize;
     let bytes: [u8; 4] = hmac_digest[start..start + 4].try_into().unwrap();
@@ -72,21 +65,170 @@ fn main() -> ! {
     );
     let mut rtc = ds323x::Ds323x::new_ds3231(i2c_clock);
 
+    let mut rs = pins.d12.into_output();
+    let mut en = pins.d11.into_output();
+    let mut d4 = pins.d5.into_output();
+    let mut d5 = pins.d4.into_output();
+    let mut d6 = pins.d3.into_output();
+    let mut d7 = pins.d2.into_output();
+
+    let mut display = screen::StnScreen::new(&mut rs, &mut en, &mut d4, &mut d5, &mut d6, &mut d7);
+    display.clear();
+
     let datetime = datetime::Datetime::from_ds3231(&mut rtc);
 
-    let timestamp = datetime.unix_epoch();
+    let mut eeprom = arduino_hal::Eeprom::new(dp.EEPROM);
-    ufmt::uwriteln!(&mut serial, "Timestamp: {}", timestamp).unwrap();
+    let mut tokens = storage::Tokens::new(&mut eeprom, datetime.unix_epoch());
 
-    let token = generate_otp_token("FS7J22EHLLSOGKUVJKV2XE7FTIX24JAJ", 1680155315);
+    let up = pins.d6.into_pull_up_input();
-    ufmt::uwriteln!(&mut serial, "token: {}", token).unwrap();
+    let mut button = button::Button::new(&up, true);
 
-    delay_ms(5000);
+    // button.update();
-    let token = generate_otp_token("FS7J22EHLLSOGKUVJKV2XE7FTIX24JAJ", 1680155315);
+    // if button.update() == button::Event::Pressed || true {
-    ufmt::uwriteln!(&mut serial, "token: {}", token).unwrap();
+    //     display.write_str("Connected to");
+    //     display.set_cursor(0, 1);
+    //     display.write_str("USB...");
+    //     loop {
+    //         // Waiting from a command since the tool
+    //         let cmd = block!(serial.read()).unwrap_or(u8::MAX);
+    //         display.set_cursor(8, 1);
+    //         display.write_str("---");
+    //         display.set_cursor(8, 1);
+    //         display.write_u32(cmd as u32);
 
-    delay_ms(5000);
+    //         match cmd {
-    let token = generate_otp_token("FS7J22EHLLSOGKUVJKV2XE7FTIX24JAJ", 1680155315);
+    //             EXIT => {}
-    ufmt::uwriteln!(&mut serial, "token: {}", token).unwrap();
+    //             HANDSHAKE => serial.write(OK).unwrap(),
+    //             SET_TIMESTAMP => {
+    //                 serial.write(OK).unwrap();
+    //                 let year = loop {
+    //                     let y = block!(serial.read()).unwrap();
+    //                     serial.write(y).unwrap();
+    //                     if block!(serial.read()).unwrap() == OK {
+    //                         break y;
+    //                     }
+    //                 };
+    //                 let month = loop {
+    //                     let m = block!(serial.read()).unwrap();
+    //                     serial.write(m).unwrap();
+    //                     if block!(serial.read()).unwrap() == OK {
+    //                         break m;
+    //                     }
+    //                 };
+    //                 let day = loop {
+    //                     let d = block!(serial.read()).unwrap();
+    //                     serial.write(d).unwrap();
+    //                     if block!(serial.read()).unwrap() == OK {
+    //                         break d;
+    //                     }
+    //                 };
+    //                 let hours = loop {
+    //                     let h = block!(serial.read()).unwrap();
+    //                     serial.write(h).unwrap();
+    //                     if block!(serial.read()).unwrap() == OK {
+    //                         break h;
+    //                     }
+    //                 };
+    //                 let minutes = loop {
+    //                     let m = block!(serial.read()).unwrap();
+    //                     serial.write(m).unwrap();
+    //                     if block!(serial.read()).unwrap() == OK {
+    //                         break m;
+    //                     }
+    //                 };
+    //                 let seconds = loop {
+    //                     let s = block!(serial.read()).unwrap();
+    //                     serial.write(s).unwrap();
+    //                     if block!(serial.read()).unwrap() == OK {
+    //                         break s;
+    //                     }
+    //                 };
+    //                 rtc.set_year(year as u16 + 2000).unwrap();
+    //                 rtc.set_month(month).unwrap();
+    //                 rtc.set_day(day).unwrap();
+    //                 rtc.set_hours(ds323x::Hours::H24(hours)).unwrap();
+    //                 rtc.set_minutes(minutes).unwrap();
+    //                 rtc.set_seconds(seconds).unwrap();
+    //                 serial.write(OK).unwrap();
+    //             }
+    //             ADD_TOKEN => match tokens.search_free() {
+    //                 Some(index) => {
+    //                     serial.write(OK).unwrap();
+    //                     let mut name_buff = [0u8; SECRET_KEY_NAME_LEN as usize];
+    //                     for i in 0..name_buff.len() {
+    //                         let ch = block!(serial.read()).unwrap();
+    //                         if ch == ENDL {
+    //                             break;
+    //                         } else {
+    //                             name_buff[i] = ch;
+    //                         }
+    //                     }
+
+    //                     let mut key_buff = [0u8; SECRET_KEY_MAX_LEN as usize];
+    //                     for i in 0..key_buff.len() {
+    //                         let ch = block!(serial.read()).unwrap();
+    //                         if ch == ENDL {
+    //                             break;
+    //                         } else {
+    //                             key_buff[i] = ch;
+    //                         }
+    //                     }
+    //                     match tokens.write(index, &name_buff, &key_buff) {
+    //                         Some(_) => serial.write(OK).unwrap(),
+    //                         None => serial.write(ERROR).unwrap(),
+    //                     }
+    //                 }
+    //                 None => serial.write(ERROR).unwrap(),
+    //             },
+    //             WIPE_TOKENS => {
+    //                 serial.write(OK).unwrap();
+    //                 tokens.wipe_all_tokens();
+    //                 serial.write(OK).unwrap();
+    //             }
+    //             _ => {}
+    //             u8::MAX => {}
+    //         }
+    //     }
+    // }
+    // loop {}
+
+    match tokens.current {
+        Some(index) => {
+            let mut buff_name = [0u8; SECRET_KEY_NAME_LEN as usize];
+            let mut buff_key = [0u8; SECRET_KEY_MAX_LEN as usize];
+            match tokens.read(index, &mut buff_name, &mut buff_key) {
+                Some((len_name, len_key)) => {
+                    let name = core::str::from_utf8(&buff_name[..len_name]).unwrap();
+                    let key = &buff_key[..len_key];
+                    let dt = datetime::Datetime::from_ds3231(&mut rtc);
+
+                    let datetime::Datetime {
+                        year,
+                        month,
+                        day,
+                        hours,
+                        minutes,
+                        seconds,
+                    } = dt;
+
+                    let timestamp = dt.unix_epoch();
+
+                    let token = generate_otp_token(key, timestamp);
+
+                    display.set_cursor(0, 0);
+                    display.write_str(name);
+                    display.set_cursor(0, 1);
+                    display.write_u32(token);
+                }
+                _ => {
+                    // display.clear();
+                    // display.set_cursor(0, 0);
+                    // display.write_str("ERROR");
+                }
+            }
+        }
+        _ => {}
+    }
 
     loop {
         led.toggle();

src/screen.rs

@@ -2,11 +2,23 @@ use arduino_hal::delay_ms;
 use arduino_hal::delay_us;
 use embedded_hal::digital::v2::OutputPin;
 
+// The CMDs codes are documented here:
+// https://www.openhacks.com/uploadsproductos/eone-1602a1.pdf
 const INIT_CMD: u8 = 0x03; // 0b00000011
 const MODE_4_BITS_CMD: u8 = 0x02; // 0b00000010
-const DISPLAY_MODE_CMD: u8 = 0x28; // 0b00101000
+const DISPLAY_MODE_16X2_CMD: u8 = 0x28; // 0b00101000
 const ENABLE_SCREEN_CMD: u8 = 0x0C; // 0b00001100
 const CLEAN_SCREEN_CMD: u8 = 0x01; // 0b00000001
+const SHIFT_LEFT_CMD: u8 = 0x10; // 0b10000
+const SHIFT_RIGHT_CMD: u8 = 0x14; // 0b10100
+const MOVE_CURSOR_CMD: u8 = 0x80; // 0b10000000
+
+const ROW_OFFSETS: [u8; 2] = [0x00, 0x40];
+
+pub enum Direction {
+    Left = SHIFT_LEFT_CMD as isize,
+    Right = SHIFT_RIGHT_CMD as isize,
+}
 
 pub struct StnScreen<'a, RS, EN, D4, D5, D6, D7> {
     rs: &'a mut RS,
@@ -55,8 +67,9 @@ impl<
         delay_us(100);
         display.write_nibble(MODE_4_BITS_CMD, false);
         delay_us(100);
-        display.send_cmd(DISPLAY_MODE_CMD, false);
+        display.send_cmd(DISPLAY_MODE_16X2_CMD, false);
         display.send_cmd(ENABLE_SCREEN_CMD, false);
+        display.clear();
 
         display
     }
@@ -85,8 +98,19 @@ impl<
         self.pulse_enable();
     }
 
-    fn clear(&mut self) {
+    pub fn clear(&mut self) {
-        display.send_cmd(CLEAN_SCREEN_CMD, false);
+        self.send_cmd(CLEAN_SCREEN_CMD, false);
+    }
+
+    pub fn shift(&mut self, dir: Direction) {
+        let cmd = dir as u8;
+        self.send_cmd(cmd, false);
+    }
+
+    pub fn set_cursor(&mut self, col: u8, row: u8) {
+        let row_offset = ROW_OFFSETS[row as usize];
+        let address_position = row_offset | col;
+        self.send_cmd(MOVE_CURSOR_CMD | address_position, false);
     }
 
     pub fn write_char(&mut self, c: char) {
@@ -102,8 +126,36 @@ impl<
             self.write_char(c);
         }
     }
+
+    pub fn write_u32(&mut self, num: u32) {
+        // The max number in an u32 is: 4,294,967,295
+        let mut buff = [0; 10];
+        let len = num_chars(num, &mut buff);
+        self.write_str(&core::str::from_utf8(&buff[..len]).unwrap());
+    }
 }
 
 fn last_bit(n: u8) -> bool {
     (n & 1) != 0
 }
+
+fn num_rev(mut num: u32) -> u32 {
+    let mut rev_num = 0;
+    while num > 0 {
+        let digit = num % 10;
+        rev_num = rev_num * 10 + digit;
+        num /= 10;
+    }
+    rev_num
+}
+
+fn num_chars(n: u32, output: &mut [u8]) -> usize {
+    let mut n = num_rev(n);
+    let mut i = 0;
+    while n > 0 {
+        output[i] = (n % 10) as u8 + '0' as u8;
+        n = n / 10;
+        i += 1;
+    }
+    i
+}

src/storage.rs

@@ -0,0 +1,131 @@
+use arduino_hal::eeprom::Eeprom;
+use randomize::PCG32;
+
+pub const SECRET_KEY_MAX_LEN: u16 = 32;
+pub const SECRET_KEY_NAME_LEN: u16 = 16;
+pub const SECRET_KEY_FULL_LEN: u16 = SECRET_KEY_MAX_LEN + SECRET_KEY_NAME_LEN;
+
+pub struct Tokens<'a> {
+    mem: &'a mut Eeprom,
+    pub current: Option<u16>,
+    capacity: u16,
+    rand: PCG32,
+}
+
+impl<'a> Tokens<'a> {
+    pub fn new(mem: &'a mut Eeprom, rand_seed: u64) -> Self {
+        let capacity = mem.capacity() / SECRET_KEY_FULL_LEN;
+
+        let mut tokens = Tokens {
+            mem,
+            capacity,
+            rand: PCG32::seed(rand_seed, 1),
+            current: None,
+        };
+        tokens.current = tokens.first();
+
+        tokens
+    }
+
+    pub fn search_free(&self) -> Option<u16> {
+        for n in 0..self.capacity {
+            let index = SECRET_KEY_FULL_LEN * n;
+            if self.mem.read_byte(index) == 255 {
+                return Some(n);
+            }
+        }
+
+        None
+    }
+
+    fn first(&self) -> Option<u16> {
+        for n in 0..self.capacity {
+            let index = SECRET_KEY_FULL_LEN * n;
+            if self.mem.read_byte(index) != 255 {
+                return Some(n);
+            }
+        }
+        return None;
+    }
+
+    pub fn next(&mut self) -> Option<u16> {
+        let mut index = self.current.unwrap();
+        for _ in 0..self.capacity {
+            index = (index + 1) % self.capacity;
+            if self.mem.read_byte(index * SECRET_KEY_FULL_LEN) != 255 {
+                self.current = Some(index);
+                return Some(index);
+            }
+        }
+        None
+    }
+
+    pub fn prev(&mut self) -> Option<u16> {
+        todo!();
+    }
+
+    pub fn read(&self, index: u16, name: &mut [u8], key: &mut [u8]) -> Option<(usize, usize)> {
+        name.fill(0);
+        key.fill(0);
+        let index_name = index * SECRET_KEY_FULL_LEN;
+        let index_key = (index * SECRET_KEY_FULL_LEN) + SECRET_KEY_NAME_LEN;
+        match self.mem.read(index_name, name) {
+            Ok(n) => {}
+            Err(_) => return None,
+        }
+        match self.mem.read(index_key, key) {
+            Ok(n) => {}
+            Err(_) => return None,
+        }
+        let mut len_name = name
+            .iter()
+            .position(|&n| n == 0)
+            .unwrap_or(SECRET_KEY_NAME_LEN as usize);
+        let mut len_key = key
+            .iter()
+            .position(|&n| n == 0)
+            .unwrap_or(SECRET_KEY_MAX_LEN as usize);
+        Some((len_name, len_key))
+    }
+
+    pub fn write(&mut self, index: u16, name: &[u8], key: &[u8]) -> Option<u16> {
+        let index_name = index * SECRET_KEY_FULL_LEN;
+        let index_key = (index * SECRET_KEY_FULL_LEN) + SECRET_KEY_NAME_LEN;
+        match self.mem.write(index_name, name) {
+            Ok(_) => {}
+            Err(_) => return None,
+        }
+        match self.mem.write(index_key, key) {
+            Ok(_) => {}
+            Err(_) => return None,
+        }
+        Some(index)
+    }
+
+    pub fn delete(&mut self, index: u16) -> Option<u16> {
+        // The Arduino's EEPROM memory has a maximum number of write cycles.
+        // To keep writes to a minimum, only the first byte of the token name is set to 0
+        // and a byte of the key is randomly chosen to be overwritten with
+        // another random value, so that it's unrecoverable.
+        let index_name = index * SECRET_KEY_FULL_LEN;
+        let index_key = (index * SECRET_KEY_FULL_LEN) + SECRET_KEY_NAME_LEN;
+        let index_key = index_key + (self.rand.next_u32() % SECRET_KEY_MAX_LEN as u32) as u16;
+        let rand_byte = (self.rand.next_u32() % 255) as u8;
+        self.mem.write_byte(index_name, 255);
+        self.mem.write_byte(index_key, rand_byte);
+        Some(index)
+    }
+
+    pub fn wipe_all_tokens(&mut self) -> u8 {
+        let mut inc = 0;
+
+        for n in 0..self.capacity {
+            let index = SECRET_KEY_FULL_LEN * n;
+            if self.mem.read_byte(index) != 255 {
+                self.delete(index);
+                inc += 1;
+            }
+        }
+        inc
+    }
+}

tools/menu.py

@@ -0,0 +1,157 @@
+from datetime import datetime
+from time import sleep
+from typing import Any
+import base64
+import serial
+import sys
+
+ENDL = bytes([0])
+OK = bytes([1])
+ERROR = bytes([2])
+HANDSHAKE = bytes([3])
+SET_TIMESTAMP = bytes([10])
+ADD_TOKEN = bytes([20])
+DELETE_TOKEN = bytes([30])
+GET_TOKENS = bytes([40])
+WIPE_TOKENS = bytes([50])
+EXIT = bytes([254])
+
+def loop_input(msg: str, valid_values: Any) -> str:
+    valid_values = list(map(str, valid_values))
+
+    while True:
+        data = input(msg)
+
+        if data not in valid_values:
+            print(f"'{data}' isn't a valid value, please enter a value in {valid_values}")
+        else:
+            break
+    return data
+
+def b(n: int) -> bytes:
+    return bytes([n])
+
+def process_secret(secret: str) -> bytes:
+    offset = 8 - (len(secret) % 8)
+    if offset != 8:
+        secret += "=" * offset
+    return base64.b32decode(secret, casefold=True)
+
+def send_and_validate(value: bytes, conn):
+    while True:
+        print(f"Send {list(value)}")
+        conn.write(value)
+        resp = conn.read()
+        print(f"Received {list(resp)}")
+        if resp == value:
+            conn.write(OK)
+            break
+        else:
+            conn.write(ERROR)
+
+def get_datetime_items() -> dict[str, bytes]:
+    now = datetime.utcnow()
+
+    return {
+        "year": b(now.year - 2000),
+        "month": b(now.month),
+        "day": b(now.day),
+        "hours": b(now.hour),
+        "minutes": b(now.minute),
+        "seconds": b(now.second)
+    }
+
+def main(argv: list[str]):
+    port = argv[-1]
+
+    conn = serial.Serial(port=port, baudrate=9600)
+    print("UP + Reset to enable the USB connection")
+    input("Press Enter if the device in the USB mode...")
+
+    conn.write(HANDSHAKE)
+    sleep(0.1)
+    res = conn.read()
+    if res != OK:
+        print("A handshake could not be performed")
+        print("Check the connection with your Arduino")
+        return 1
+    else:
+        print("Handshake successfully performed")
+
+    while True:
+        print("What do you want to do?")
+        print("1) Update timestamp")
+        print("2) Add a new token")
+        print("3) Remove a token")
+        print("4) WIPE ALL THE TOKENS")
+        print("5) EXIT")
+
+        opt = loop_input(">>> ", range(1, 6))
+
+        # Update Timestamp
+        if opt == "1":
+            conn.write(SET_TIMESTAMP)
+            sleep(0.1)
+            resp = conn.read()
+            sleep(0.1)
+            if resp == ERROR:
+                print(f"Error in the communication: Error {resp}")
+                continue
+            date_items = get_datetime_items();
+            send_and_validate(date_items["year"], conn)
+            send_and_validate(date_items["month"], conn)
+            send_and_validate(date_items["day"], conn)
+            send_and_validate(date_items["hours"], conn)
+            send_and_validate(date_items["minutes"], conn)
+            send_and_validate(date_items["seconds"], conn)
+            resp = conn.read()
+            if resp != OK:
+                print(f"Error in the communication: Error {resp}")
+            else:
+                print("Timestamp updated successfully!")
+        # Add token
+        elif opt == "2":
+            conn.write(ADD_TOKEN)
+            sleep(0.1)
+            resp = conn.read()
+            if resp == ERROR:
+                print("The memory of the device is full")
+                continue
+            name = input("Enter the name of the new token (16 chars max):\n>>> ")
+            name = name.strip()[:16].encode("ascii")
+
+            key = input("Enter the OTP secret key (32 chars max):\n>>> ")
+            key = process_secret(key.strip()[:32])
+
+            for ch in name:
+                conn.write(b(ch))
+            conn.write(ENDL)
+            for ch in key:
+                conn.write(b(ch))
+            conn.write(ENDL)
+
+            resp = conn.read()
+            if resp == ERROR:
+                print("Error trying to add the token, try again")
+            else:
+                print("Token added successfully!")
+        # Wipe tokens
+        elif opt == "4":
+            conn.write(WIPE_TOKENS)
+            sleep(0.1)
+            _ = conn.read()
+            resp = conn.read()
+            if resp == OK:
+                print("All the tokens wipped successfully!")
+        elif opt == "5":
+            return 0
+
+if __name__ == "__main__":
+    attrs = sys.argv
+    if len(attrs) == 1:
+        print("You need to specify the Arduino's serial port")
+        print("Example:")
+        print(f"python {attrs[0]} /dev/ttyUSB0")
+        sys.exit(1)
+
+    sys.exit(main(attrs[1:]))

upload.sh

@@ -1 +1,2 @@
-avrdude -p atmega328p -c arduino -P /dev/ttyACM0 -U flash:w:target/avr-atmega328p/release/rustytoken.elf:e
+# avrdude -p atmega328p -c arduino -P /dev/ttyACM0 -U flash:w:target/avr-atmega328p/release/rustytoken.elf:e
+avrdude -p atmega328p -c arduino -P /dev/ttyUSB0 -U flash:w:target/avr-atmega328p/release/rustytoken.elf:e