diff --git a/firmware/Cargo.lock b/firmware/Cargo.lock
index b821890..3dbe320 100644
--- a/firmware/Cargo.lock
+++ b/firmware/Cargo.lock
@@ -11,6 +11,7 @@ dependencies = [
  "bytemuck",
  "cc",
  "cfg-if",
+ "chrono",
  "const-gen",
  "critical-section",
  "data-encoding-macro",
@@ -45,10 +46,12 @@ dependencies = [
  "panic-rtt-target",
  "password-hash 0.1.0",
  "pastey 0.2.1",
+ "postcard",
  "printf-compat",
  "rand_core 0.9.5",
  "rmk",
  "rtt-target",
+ "serde",
  "sha2",
  "slint",
  "slint-build",
@@ -818,6 +821,7 @@ dependencies = [
  "iana-time-zone",
  "js-sys",
  "num-traits",
+ "serde",
  "wasm-bindgen",
  "windows-link",
 ]
@@ -1836,6 +1840,12 @@ dependencies = [
  "embedded-hal 1.0.0",
 ]
 
+[[package]]
+name = "embedded-io"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ef1a6892d9eef45c8fa6b9e0086428a2cca8491aca8f787c534a3d6d0bcb3ced"
+
 [[package]]
 name = "embedded-io"
 version = "0.6.1"
@@ -5670,6 +5680,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6764c3b5dd454e283a30e6dfe78e9b31096d9e32036b5d1eaac7a6119ccb9a24"
 dependencies = [
  "cobs",
+ "embedded-io 0.4.0",
+ "embedded-io 0.6.1",
  "heapless 0.7.17",
  "postcard-derive",
  "serde",
diff --git a/firmware/acid-firmware/Cargo.toml b/firmware/acid-firmware/Cargo.toml
index 2dc4fe9..267d8dc 100644
--- a/firmware/acid-firmware/Cargo.toml
+++ b/firmware/acid-firmware/Cargo.toml
@@ -80,6 +80,10 @@ password-hash = { path = "../password-hash", default-features = false }
 hmac = "0.12.1"
 data-encoding-macro = "0.1.19"
 embedded-storage-async = "0.4.1"
+postcard = { version = "1.1", default-features = false, features = ["alloc", "postcard-derive"] } # TODO: defmt
+serde = { version = "1.0", default-features = false, features = ["derive"] }
+# serde_with = { version = "3.16", default-features = false, features = ["alloc", "macros"] }
+chrono = { version = "0.4.43", default-features = false, features = ["alloc", "serde"] } # TODO: defmt
 
 # Crates for serial UART CLI
 embedded-cli = { version = "0.2.1", default-features = false, features = ["help", "macros"] }
diff --git a/firmware/acid-firmware/src/db/mod.rs b/firmware/acid-firmware/src/db/mod.rs
index 7b433c9..1a32409 100644
--- a/firmware/acid-firmware/src/db/mod.rs
+++ b/firmware/acid-firmware/src/db/mod.rs
@@ -126,11 +126,11 @@ impl AcidDatabase {
 
         #[cfg(feature = "format-db")]
         {
-            warn!("Formatting EKV database...");
+            log::warn!("Formatting EKV database...");
             db.format()
                 .await
                 .unwrap_or_else(|error| panic!("Failed to format the EKV database: {error:?}"));
-            warn!("EKV database formatted successfully.");
+            log::warn!("EKV database formatted successfully.");
         }
 
         match db.mount().await {
@@ -146,7 +146,7 @@ type DbPathSegment<'a> = Cow<'a, str>;
 type DbPathBuf<'a> = Vec<DbPathSegment<'a>>;
 type DbPath<'a> = [DbPathSegment<'a>];
 
-struct DbKey {
+pub struct DbKey {
     /// Segments separated by `0x00`, with the whole thing suffixed with `[0x00, 0xFF]`.
     bytes: Vec<u8>,
 }
@@ -160,12 +160,12 @@ impl Deref for DbKey {
 }
 
 impl DbKey {
-    fn from_raw(mut key: Vec<u8>) -> Self {
+    pub fn from_raw(mut key: Vec<u8>) -> Self {
         key.extend_from_slice(&[0x00, 0xFF]);
         Self { bytes: key }
     }
 
-    fn new<'a>(path: impl IntoIterator<Item = DbPathSegment<'a>>) -> Self {
+    pub fn new<'a>(path: impl IntoIterator<Item = DbPathSegment<'a>>) -> Self {
         // Null bytes are not allowed within path segments, and will cause a panic.
         // Bytes of `0xFF` cannot appear in valid UTF-8.
         // The byte vector stored in a `DbKey` is formed by interspersing the segments with `0x00`, and suffixing the key with `[0x00, 0xFF]`.
@@ -188,20 +188,17 @@ impl DbKey {
             bytes.push(0x00);
         }
 
-        if let Some(last_byte) = bytes.last_mut() {
-            bytes.push(0xFF);
-        } else {
-            panic!("An empty path is not a valid path.");
-        }
+        assert!(!bytes.is_empty(), "An empty path is not a valid path.");
+        bytes.push(0xFF);
 
         DbKey { bytes }
     }
 
-    fn range_of_children(&self) -> Range<&[u8]> {
+    pub fn range_of_children(&self) -> Range<&[u8]> {
         (&self.bytes[0..(self.bytes.len() - 1)])..(&self.bytes[..])
     }
 
-    fn segments(&self) -> impl Iterator<Item = DbPathSegment<'_>> {
+    pub fn segments(&self) -> impl Iterator<Item = DbPathSegment<'_>> {
         struct SegmentIterator<'a> {
             rest: &'a [u8],
         }
diff --git a/firmware/acid-firmware/src/ui/mod.rs b/firmware/acid-firmware/src/ui/mod.rs
index 1f4ab69..6f870e7 100644
--- a/firmware/acid-firmware/src/ui/mod.rs
+++ b/firmware/acid-firmware/src/ui/mod.rs
@@ -5,7 +5,15 @@ use core::{
     ops::{Deref, DerefMut, Range},
 };
 
-use alloc::{borrow::Cow, boxed::Box, ffi::CString, vec::Vec};
+use alloc::{
+    borrow::Cow,
+    boxed::Box,
+    ffi::CString,
+    string::{String, ToString},
+    vec,
+    vec::Vec,
+};
+use chrono::{DateTime, NaiveDateTime};
 use ekv::{Database, MountError, flash::PageID};
 use embassy_embedded_hal::{adapter::BlockingAsync, flash::partition::Partition};
 use embassy_sync::blocking_mutex::raw::{CriticalSectionRawMutex, RawMutex};
@@ -16,14 +24,17 @@ use esp_storage::FlashStorage;
 use itertools::Itertools;
 use log::{info, warn};
 use rmk::futures::TryFutureExt;
+use serde::{Deserialize, Serialize};
 use slint::SharedString;
-use spectre_api_sys::{SpectreAlgorithm, SpectreCounter, SpectreKeyPurpose, SpectreUserKey};
+use spectre_api_sys::{
+    SpectreAlgorithm, SpectreCounter, SpectreKeyPurpose, SpectreResultType, SpectreUserKey,
+};
 
 #[cfg(feature = "limit-fps")]
 use crate::FRAME_DURATION_MIN;
 use crate::{
     SIGNAL_LCD_SUBMIT, SIGNAL_UI_RENDER,
-    db::{AcidDatabase, PartitionAcid},
+    db::{AcidDatabase, DbKey, DbPathSpectreUsers, PartitionAcid},
     ui::backend::SlintBackend,
     util::DurationExt,
 };
@@ -33,10 +44,131 @@ pub mod window_adapter;
 
 slint::include_modules!();
 
+#[derive(Deserialize, Serialize, Clone, Debug, PartialEq, Eq)]
+struct SpectreUsersConfig {
+    users: Vec<SpectreUserConfig>,
+}
+
+#[derive(Deserialize, Serialize, Clone, Debug, PartialEq, Eq)]
+struct SpectreUserConfig {
+    username: String,
+}
+
+trait ReprConvert: Copy {
+    type Repr: Copy;
+
+    fn into_repr(self) -> Self::Repr;
+    fn from_repr(repr: Self::Repr) -> Self;
+}
+
+impl ReprConvert for SpectreAlgorithm {
+    type Repr = u32;
+
+    fn from_repr(repr: Self::Repr) -> Self {
+        unsafe { core::mem::transmute::<Self::Repr, Self>(repr) }
+    }
+
+    fn into_repr(self) -> Self::Repr {
+        self as Self::Repr
+    }
+}
+
+impl ReprConvert for SpectreResultType {
+    type Repr = u32;
+
+    fn from_repr(repr: Self::Repr) -> Self {
+        unsafe { core::mem::transmute::<Self::Repr, Self>(repr) }
+    }
+
+    fn into_repr(self) -> Self::Repr {
+        self as Self::Repr
+    }
+}
+
+mod with_repr {
+    use serde::{Deserialize, Deserializer, Serializer};
+
+    use super::ReprConvert;
+
+    pub fn serialize<T, S>(value: &T, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        T: ReprConvert<Repr = u32>,
+        S: Serializer,
+    {
+        serializer.serialize_u32(value.into_repr())
+    }
+
+    pub fn deserialize<'de, T, D>(deserializer: D) -> Result<T, D::Error>
+    where
+        T: ReprConvert<Repr = u32>,
+        D: Deserializer<'de>,
+    {
+        <u32 as Deserialize>::deserialize(deserializer).map(T::from_repr)
+    }
+}
+
+#[derive(Deserialize, Serialize, Clone, Debug, PartialEq, Eq)]
+struct SpectreSiteConfig {
+    #[serde(with = "with_repr")]
+    algorithm: SpectreAlgorithm,
+    counter: SpectreCounter::Type,
+    #[serde(rename = "type")]
+    #[serde(with = "with_repr")]
+    result_type: SpectreResultType,
+    password: Option<String>,
+    #[serde(with = "with_repr")]
+    login_type: SpectreResultType,
+    login_name: Option<String>,
+    uses: u32,
+    last_used: NaiveDateTime,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+struct SpectreSite {
+    username: String,
+    site_name: String,
+    config: SpectreSiteConfig,
+}
+
 #[embassy_executor::task]
 pub async fn run_renderer_task(backend: SlintBackend, flash_part_acid: PartitionAcid) {
     let db = AcidDatabase::mount(flash_part_acid).await;
-    let write = db.write_transaction().await;
+
+    let value = SpectreUsersConfig {
+        users: vec![SpectreUserConfig {
+            username: "test".to_string(),
+        }],
+    };
+
+    {
+        let mut write = db.write_transaction().await;
+        write
+            .write(
+                &DbKey::new(DbPathSpectreUsers),
+                &postcard::to_allocvec(&value).unwrap(),
+            )
+            .await
+            .unwrap();
+        write.commit().await.unwrap();
+    }
+
+    let read_value = {
+        let read = db.read_transaction().await;
+        // TODO: https://github.com/embassy-rs/ekv/issues/20
+        let mut buffer = Vec::new();
+        let length = read
+            .read(&DbKey::new(DbPathSpectreUsers), &mut buffer)
+            .await
+            .unwrap();
+        buffer.resize(length, 0);
+        read.read(&DbKey::new(DbPathSpectreUsers), &mut buffer)
+            .await
+            .unwrap();
+
+        postcard::from_bytes::<SpectreUsersConfig>(&buffer).unwrap()
+    };
+
+    assert_eq!(value, read_value, "values do not match");
 
     // TODO:
     // * Store a config as a versioned postcard-serialized struct