diff --git a/libs/sharenet-passport/src/infrastructure/crypto/wasm.rs b/libs/sharenet-passport/src/infrastructure/crypto/wasm.rs
index 980fa54..e256b6e 100644
--- a/libs/sharenet-passport/src/infrastructure/crypto/wasm.rs
+++ b/libs/sharenet-passport/src/infrastructure/crypto/wasm.rs
@@ -92,6 +92,7 @@ impl FileEncryptor for XChaCha20FileEncryptor {
         univ_id: &str,
         user_profiles: &[UserProfile],
         date_of_birth: &Option<DateOfBirth>,
+        default_user_profile_id: &Option<String>,
     ) -> Result<PassportFile, Self::Error> {
         // Generate salt and nonce using WASM-compatible RNG
         let mut salt = [0u8; SALT_LENGTH];
@@ -128,6 +129,13 @@ impl FileEncryptor for XChaCha20FileEncryptor {
             .encrypt(&nonce, &*date_of_birth_bytes)
             .map_err(|e| DomainError::CryptographicError(format!("Date of birth encryption failed: {}", e)))?;
 
+        // Serialize and encrypt default user profile ID
+        let default_user_profile_id_bytes = serde_cbor::to_vec(&default_user_profile_id)
+            .map_err(|e| DomainError::CryptographicError(format!("Failed to serialize default user profile ID: {}", e)))?;
+        let enc_default_user_profile_id = cipher
+            .encrypt(&nonce, &*default_user_profile_id_bytes)
+            .map_err(|e| DomainError::CryptographicError(format!("Default user profile ID encryption failed: {}", e)))?;
+
         // Get current timestamp using WASM-compatible time
         let created_at = time::now_seconds()?;
 
@@ -144,6 +152,7 @@ impl FileEncryptor for XChaCha20FileEncryptor {
             version: "1.0.0".to_string(),
             enc_user_profiles,
             enc_date_of_birth,
+            enc_default_user_profile_id,
         })
     }
 
@@ -151,7 +160,7 @@ impl FileEncryptor for XChaCha20FileEncryptor {
         &self,
         file: &PassportFile,
         password: &str,
-    ) -> Result<(Seed, PublicKey, PrivateKey, Vec<UserProfile>, Option<DateOfBirth>), Self::Error> {
+    ) -> Result<(Seed, PublicKey, PrivateKey, Vec<UserProfile>, Option<DateOfBirth>, Option<String>), Self::Error> {
         // Validate file format
         validate_file_format(&file.kdf, &file.cipher)?;
 
@@ -195,7 +204,14 @@ impl FileEncryptor for XChaCha20FileEncryptor {
         let date_of_birth: Option<DateOfBirth> = serde_cbor::from_slice(&date_of_birth_bytes)
             .map_err(|e| DomainError::CryptographicError(format!("Failed to deserialize date of birth: {}", e)))?;
 
+        // Decrypt default user profile ID
+        let default_user_profile_id_bytes = cipher
+            .decrypt(&nonce, &*file.enc_default_user_profile_id)
+            .map_err(|e| DomainError::CryptographicError(format!("Default user profile ID decryption failed: {}", e)))?;
+        let default_user_profile_id: Option<String> = serde_cbor::from_slice(&default_user_profile_id_bytes)
+            .map_err(|e| DomainError::CryptographicError(format!("Failed to deserialize default user profile ID: {}", e)))?;
+
         // Note: univ_id is stored in the PassportFile and will be used when creating the Passport
-        Ok((seed, public_key, private_key, user_profiles, date_of_birth))
+        Ok((seed, public_key, private_key, user_profiles, date_of_birth, default_user_profile_id))
     }
 }
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