diff --git a/services/identity/src/database.rs b/services/identity/src/database.rs
--- a/services/identity/src/database.rs
+++ b/services/identity/src/database.rs
@@ -25,8 +25,8 @@
   USERS_TABLE_USERNAME_INDEX, USERS_TABLE_USER_PUBLIC_KEY_ATTRIBUTE,
   USERS_TABLE_WALLET_ADDRESS_ATTRIBUTE, USERS_TABLE_WALLET_ADDRESS_INDEX,
 };
-use comm_opaque::Cipher;
 use crate::token::{AccessTokenData, AuthType};
+use comm_opaque::Cipher;
 
 #[derive(Clone)]
 pub struct DatabaseClient {
@@ -138,6 +138,49 @@
       .map_err(|e| Error::AwsSdk(e.into()))
   }
 
+  pub async fn add_user_to_users_table(
+    &self,
+    user_id: String,
+    device_id: String,
+    registration: ServerRegistration<Cipher>,
+    username: String,
+    user_public_key: String,
+  ) -> Result<PutItemOutput, Error> {
+    let item = HashMap::from([
+      (
+        USERS_TABLE_PARTITION_KEY.to_string(),
+        AttributeValue::S(user_id),
+      ),
+      (
+        USERS_TABLE_USERNAME_ATTRIBUTE.to_string(),
+        AttributeValue::S(username),
+      ),
+      (
+        USERS_TABLE_REGISTRATION_ATTRIBUTE.to_string(),
+        AttributeValue::B(Blob::new(registration.serialize())),
+      ),
+      (
+        USERS_TABLE_DEVICES_ATTRIBUTE.to_string(),
+        AttributeValue::M(HashMap::from([(
+          device_id,
+          AttributeValue::M(HashMap::from([(
+            USERS_TABLE_USER_PUBLIC_KEY_ATTRIBUTE.to_string(),
+            AttributeValue::S(user_public_key),
+          )])),
+        )])),
+      ),
+    ]);
+
+    self
+      .client
+      .put_item()
+      .table_name(USERS_TABLE)
+      .set_item(Some(item))
+      .send()
+      .await
+      .map_err(|e| Error::AwsSdk(e.into()))
+  }
+
   pub async fn get_access_token_data(
     &self,
     user_id: String,
diff --git a/services/identity/src/service.rs b/services/identity/src/service.rs
--- a/services/identity/src/service.rs
+++ b/services/identity/src/service.rs
@@ -1,5 +1,6 @@
 use aws_sdk_dynamodb::Error as DynamoDBError;
 use chrono::Utc;
+use comm_opaque::Cipher;
 use constant_time_eq::constant_time_eq;
 use futures_core::Stream;
 use opaque_ke::{
@@ -16,7 +17,6 @@
 use tokio_stream::{wrappers::ReceiverStream, StreamExt};
 use tonic::{Request, Response, Status};
 use tracing::{error, info, instrument};
-use comm_opaque::Cipher;
 
 use crate::constants::MPSC_CHANNEL_BUFFER_CAPACITY;
 use crate::database::DatabaseClient;