diff --git a/app/Controllers/DoctorDocument.php b/app/Controllers/DoctorDocument.php
index 2a2a8c1..d1573f1 100644
--- a/app/Controllers/DoctorDocument.php
+++ b/app/Controllers/DoctorDocument.php
@@ -314,7 +314,13 @@ class DoctorDocument extends BaseController
             $likeToken = $this->db->escapeLikeString($token);
 
             if (is_numeric($token)) {
-                $whereParts[] = "(p.p_code LIKE '%{$likeToken}' ESCAPE '!' OR p.mphone1 = {$escaped} OR p.udai = {$escaped})";
+                $clause = "(p.p_code LIKE '%{$likeToken}' ESCAPE '!' OR p.mphone1 = {$escaped}";
+                // Aadhaar is stored encrypted; match on its deterministic hash instead.
+                $aadhaarHash = (new \App\Libraries\AadhaarVaultService())->hash($token);
+                if ($aadhaarHash !== '') {
+                    $clause .= ' OR p.udai_hash = ' . $this->db->escape($aadhaarHash);
+                }
+                $whereParts[] = $clause . ')';
                 continue;
             }
 
diff --git a/app/Controllers/Medical.php b/app/Controllers/Medical.php
index 8241554..d21c581 100644
--- a/app/Controllers/Medical.php
+++ b/app/Controllers/Medical.php
@@ -491,7 +491,7 @@ class Medical extends BaseController
         if ($search !== '') {
             $tokens = preg_split('/\s+/', $search) ?: [];
             $searchableFields = [];
-            foreach (['p_code', 'p_fname', 'mphone1', 'udai', 'email1'] as $field) {
+            foreach (['p_code', 'p_fname', 'mphone1', 'email1'] as $field) {
                 if (in_array($field, $fields, true)) {
                     $searchableFields[] = $field;
                 }
diff --git a/app/Controllers/Patient.php b/app/Controllers/Patient.php
index 5762f1f..4e51d4c 100644
--- a/app/Controllers/Patient.php
+++ b/app/Controllers/Patient.php
@@ -144,9 +144,9 @@ class Patient extends BaseController
 			'p_relative' => $this->request->getPost('cbo_relation'),
 			'p_rname' => strtoupper((string) $this->request->getPost('input_relative_name')),
 			'blood_group' => strtoupper($bloodGroup),
-			'udai' => strtoupper((string) $this->request->getPost('input_udai')),
 			'estimate_dob' => $estimate_dob,
 		];
+		$data += (new \App\Libraries\AadhaarVaultService())->buildColumns((string) $this->request->getPost('input_udai'));
 		$this->applyPatientReferbyField($data, $referByName);
 		$this->applyPatientAbhaFieldValues($data, $abhaId, $abhaAddress);
 
@@ -234,7 +234,7 @@ class Patient extends BaseController
 		$abhaField = $this->resolvePatientAbhaIdField();
 
 		$builder = $this->db->table('patient_master');
-		$builder->select("id,p_fname,p_relative,p_rname,gender,add1,city,district,state,zip,mphone1,udai,last_visit,dob,age,age_in_month,estimate_dob");
+		$builder->select("id,p_fname,p_relative,p_rname,gender,add1,city,district,state,zip,mphone1,udai,udai_last4,last_visit,dob,age,age_in_month,estimate_dob");
 		if ($this->db->fieldExists('referby', 'patient_master')) {
 			$builder->select('referby');
 		}
@@ -252,7 +252,8 @@ class Patient extends BaseController
 			}
 
 			if ($inputAadhar !== '') {
-				$builder->orWhere('udai', $inputAadhar);
+				// Aadhaar is stored encrypted, so match on its deterministic hash.
+				$builder->orWhere('udai_hash', (new \App\Libraries\AadhaarVaultService())->hash($inputAadhar));
 				$hasCondition = true;
 			}
 
@@ -528,9 +529,14 @@ class Patient extends BaseController
 		$clauses = [
 			'p.p_code like ' . $this->db->escape('%' . $rowData),
 			'p.mphone1 = ' . $escapedValue,
-			'p.udai = ' . $escapedValue,
 		];
 
+		// Aadhaar lives in the vault, so a typed number matches via its hash.
+		$aadhaarHash = (new \App\Libraries\AadhaarVaultService())->hash($rowData);
+		if ($aadhaarHash !== '') {
+			$clauses[] = 'p.udai_hash = ' . $this->db->escape($aadhaarHash);
+		}
+
 		if ($abhaField !== null && $abhaField !== '') {
 			$clauses[] = 'p.' . $abhaField . ' = ' . $escapedValue;
 		}
@@ -995,10 +1001,14 @@ class Patient extends BaseController
 			'p_relative' => strtoupper((string) $this->request->getPost('cbo_relation')),
 			'p_rname' => strtoupper((string) $this->request->getPost('input_relative_name')),
 			'email1' => strtoupper((string) $this->request->getPost('input_email')),
-			'udai' => strtoupper((string) $this->request->getPost('input_Aadhar')),
 			'estimate_dob' => $estimate_dob,
 			'blood_group' => $this->request->getPost('input_blood_group'),
 		];
+		$aadhaarVault = new \App\Libraries\AadhaarVaultService();
+		$aadhaarInput = (string) $this->request->getPost('input_Aadhar');
+		if (! $aadhaarVault->isMasked($aadhaarInput)) {
+			$data += $aadhaarVault->buildColumns($aadhaarInput);
+		}
 		$this->applyPatientReferbyField($data, $referByName);
 
 		if ($isAbhaVerifiedLocked) {
@@ -1101,8 +1111,16 @@ class Patient extends BaseController
 		$pid = (int) $this->request->getPost('p_id');
 		$udai = (string) $this->request->getPost('udai');
 
+		$vault = new \App\Libraries\AadhaarVaultService();
+		if ($vault->isMasked($udai)) {
+			return $this->response->setJSON(['update' => 1, 'showcontent' => 'Aadhaar unchanged']);
+		}
+		if (trim($udai) !== '' && $vault->normalize($udai) === '') {
+			return $this->response->setJSON(['update' => 0, 'error_text' => 'Enter a valid 12-digit Aadhaar number']);
+		}
+
 		$patientModel = new PatientModel();
-		$patientModel->updatePatient(['udai' => $udai], $pid);
+		$patientModel->updatePatient($vault->buildColumns($udai), $pid);
 
 		return $this->response->setJSON([
 			'update' => 1,
diff --git a/app/Database/Migrations/2026-08-15-000001_AddAadhaarVaultToPatientMaster.php b/app/Database/Migrations/2026-08-15-000001_AddAadhaarVaultToPatientMaster.php
new file mode 100644
index 0000000..ccdb5b3
--- /dev/null
+++ b/app/Database/Migrations/2026-08-15-000001_AddAadhaarVaultToPatientMaster.php
@@ -0,0 +1,95 @@
+<?php
+
+namespace App\Database\Migrations;
+
+use App\Libraries\AadhaarVaultService;
+use CodeIgniter\Database\Migration;
+
+class AddAadhaarVaultToPatientMaster extends Migration
+{
+    public function up(): void
+    {
+        if (! $this->db->tableExists('patient_master')) {
+            return;
+        }
+
+        $fields = $this->db->getFieldNames('patient_master') ?? [];
+        $add = [];
+
+        if (! in_array('udai_enc', $fields, true)) {
+            $add['udai_enc'] = ['type' => 'TEXT', 'null' => true, 'comment' => 'AES-256-GCM encrypted Aadhaar'];
+        }
+        if (! in_array('udai_hash', $fields, true)) {
+            $add['udai_hash'] = ['type' => 'CHAR', 'constraint' => 64, 'null' => true, 'comment' => 'HMAC-SHA256 of Aadhaar for exact-match search'];
+        }
+        if (! in_array('udai_last4', $fields, true)) {
+            $add['udai_last4'] = ['type' => 'VARCHAR', 'constraint' => 4, 'null' => true, 'comment' => 'Last 4 digits for display'];
+        }
+
+        if ($add !== []) {
+            $this->forge->addColumn('patient_master', $add);
+        }
+
+        if (! $this->indexExists('patient_master', 'idx_patient_udai_hash')) {
+            $this->db->query('CREATE INDEX idx_patient_udai_hash ON patient_master (udai_hash)');
+        }
+
+        $this->migrateExistingAadhaar();
+    }
+
+    public function down(): void
+    {
+        if (! $this->db->tableExists('patient_master')) {
+            return;
+        }
+
+        if ($this->indexExists('patient_master', 'idx_patient_udai_hash')) {
+            $this->db->query('DROP INDEX idx_patient_udai_hash ON patient_master');
+        }
+
+        $fields = $this->db->getFieldNames('patient_master') ?? [];
+        foreach (['udai_enc', 'udai_hash', 'udai_last4'] as $column) {
+            if (in_array($column, $fields, true)) {
+                $this->forge->dropColumn('patient_master', $column);
+            }
+        }
+    }
+
+    /**
+     * Move any plaintext Aadhaar already in udai into the vault and mask the column.
+     */
+    private function migrateExistingAadhaar(): void
+    {
+        $vault = new AadhaarVaultService();
+
+        $rows = $this->db->table('patient_master')
+            ->select('id, udai')
+            ->where('udai IS NOT NULL', null, false)
+            ->where("TRIM(udai) <> ''", null, false)
+            ->where('udai_enc IS NULL', null, false)
+            ->get()
+            ->getResultArray();
+
+        foreach ($rows as $row) {
+            $digits = $vault->normalize((string) ($row['udai'] ?? ''));
+            if ($digits === '') {
+                continue;
+            }
+
+            $this->db->table('patient_master')
+                ->where('id', (int) $row['id'])
+                ->update($vault->buildColumns($digits));
+        }
+    }
+
+    private function indexExists(string $table, string $indexName): bool
+    {
+        foreach ($this->db->query('SHOW INDEX FROM ' . $table)->getResultArray() as $row) {
+            if (($row['Key_name'] ?? '') === $indexName) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}
diff --git a/app/Libraries/AadhaarVaultService.php b/app/Libraries/AadhaarVaultService.php
new file mode 100644
index 0000000..908e5b8
--- /dev/null
+++ b/app/Libraries/AadhaarVaultService.php
@@ -0,0 +1,151 @@
+<?php
+
+namespace App\Libraries;
+
+/**
+ * Aadhaar Vault
+ *
+ * The Aadhaar Act forbids storing the full Aadhaar number in readable form, so
+ * patient_master keeps only a masked value while the number itself is held
+ * encrypted (AES-256-GCM) alongside a deterministic HMAC used for lookups.
+ *
+ * Key configuration — add to .env:
+ *   AADHAAR_ENCRYPTION_KEY = <64-char lowercase hex string — 32 random bytes>
+ *
+ * Generate with:
+ *   php -r "echo bin2hex(random_bytes(32)) . PHP_EOL;"
+ */
+class AadhaarVaultService
+{
+    private const CIPHER  = 'aes-256-gcm';
+    private const IV_LEN  = 12;
+    private const TAG_LEN = 16;
+
+    private string $key;
+
+    public function __construct()
+    {
+        $keyHex = trim((string) getenv('AADHAAR_ENCRYPTION_KEY'));
+        if ($keyHex === '') {
+            $keyHex = trim((string) env('AADHAAR_ENCRYPTION_KEY', ''));
+        }
+        if ($keyHex === '') {
+            $keyHex = trim((string) getenv('ABDM_FHIR_ENCRYPTION_KEY'));
+        }
+
+        if ($keyHex !== '' && ctype_xdigit($keyHex) && strlen($keyHex) >= 64) {
+            $this->key = (string) hex2bin(substr($keyHex, 0, 64));
+        } else {
+            $appKey    = trim((string) env('encryption.key', (string) env('app.key', '')));
+            $this->key = hash_hmac('sha256', 'hms-aadhaar-vault-v1', $appKey, true);
+        }
+    }
+
+    /**
+     * Strip formatting and return the 12 digits, or '' when not a valid Aadhaar.
+     */
+    public function normalize(?string $raw): string
+    {
+        $digits = preg_replace('/\D/', '', (string) $raw) ?? '';
+
+        return strlen($digits) === 12 ? $digits : '';
+    }
+
+    public function last4(?string $raw): string
+    {
+        $digits = $this->normalize($raw);
+
+        return $digits === '' ? '' : substr($digits, -4);
+    }
+
+    /**
+     * Display form kept in patient_master.udai so legacy screens cannot leak the number.
+     */
+    public function mask(?string $raw): string
+    {
+        $last4 = $this->last4($raw);
+
+        return $last4 === '' ? '' : 'XXXXXXXX' . $last4;
+    }
+
+    /**
+     * Deterministic keyed digest so an exact-match search stays possible.
+     */
+    public function hash(?string $raw): string
+    {
+        $digits = $this->normalize($raw);
+
+        return $digits === '' ? '' : hash_hmac('sha256', $digits, $this->key);
+    }
+
+    public function encrypt(?string $raw): string
+    {
+        $digits = $this->normalize($raw);
+        if ($digits === '') {
+            return '';
+        }
+
+        $iv  = random_bytes(self::IV_LEN);
+        $tag = '';
+
+        $ciphertext = openssl_encrypt($digits, self::CIPHER, $this->key, OPENSSL_RAW_DATA, $iv, $tag, '', self::TAG_LEN);
+        if ($ciphertext === false) {
+            throw new \RuntimeException('Aadhaar encryption failed.');
+        }
+
+        return base64_encode($iv . $tag . $ciphertext);
+    }
+
+    /**
+     * Returns '' when the payload is empty or cannot be authenticated.
+     */
+    public function decrypt(?string $payload): string
+    {
+        $payload = trim((string) $payload);
+        if ($payload === '') {
+            return '';
+        }
+
+        $binary = base64_decode($payload, true);
+        if ($binary === false || strlen($binary) <= self::IV_LEN + self::TAG_LEN) {
+            return '';
+        }
+
+        $iv         = substr($binary, 0, self::IV_LEN);
+        $tag        = substr($binary, self::IV_LEN, self::TAG_LEN);
+        $ciphertext = substr($binary, self::IV_LEN + self::TAG_LEN);
+
+        $plain = openssl_decrypt($ciphertext, self::CIPHER, $this->key, OPENSSL_RAW_DATA, $iv, $tag);
+
+        return $plain === false ? '' : $plain;
+    }
+
+    /**
+     * True when the value is the masked form we render back into edit forms,
+     * which must never be treated as a new Aadhaar number.
+     */
+    public function isMasked(?string $value): bool
+    {
+        return preg_match('/^X{8}\d{4}$/i', trim((string) $value)) === 1;
+    }
+
+    /**
+     * Column values for a patient_master insert/update.
+     *
+     * @return array{udai:string,udai_enc:string,udai_hash:string,udai_last4:string}
+     */
+    public function buildColumns(?string $raw): array
+    {
+        $digits = $this->normalize($raw);
+        if ($digits === '') {
+            return ['udai' => '', 'udai_enc' => '', 'udai_hash' => '', 'udai_last4' => ''];
+        }
+
+        return [
+            'udai'       => $this->mask($digits),
+            'udai_enc'   => $this->encrypt($digits),
+            'udai_hash'  => $this->hash($digits),
+            'udai_last4' => $this->last4($digits),
+        ];
+    }
+}
diff --git a/app/Views/billing/Person_Edit_V.php b/app/Views/billing/Person_Edit_V.php
index fd30741..bcca1b1 100644
--- a/app/Views/billing/Person_Edit_V.php
+++ b/app/Views/billing/Person_Edit_V.php
@@ -95,9 +95,11 @@
                         <div class="col-md-3">
                             <div class="form-group">
                                 <label>Aadhar No.</label>
+                                <?php $aadhaarLast4 = trim((string) ($data[0]->udai_last4 ?? '')); ?>
                                 <input class="form-control input-sm" name="input_Aadhar" id="input_Aadhar"
-                                    value="<?=$data[0]->udai ?>" placeholder="Aadhar Number" type="text"
+                                    value="<?= $aadhaarLast4 !== '' ? 'XXXXXXXX' . esc($aadhaarLast4) : '' ?>" placeholder="Aadhar Number" type="text"
                                     autocomplete="off">
+                                <small class="text-muted">Stored encrypted. Leave masked value to keep it unchanged.</small>
                             </div>
                         </div>
                         <div class="col-md-3">
diff --git a/app/Views/billing/Person_profile_V.php b/app/Views/billing/Person_profile_V.php
index dd195e0..9b6f97e 100644
--- a/app/Views/billing/Person_profile_V.php
+++ b/app/Views/billing/Person_profile_V.php
@@ -140,7 +140,10 @@
                                 </div>
                                 <div class="row">
                                     <div class="col-lg-3 col-md-4 label">Aadhar No.</div>
-                                    <div class="col-lg-9 col-md-8"><?=$data[0]->udai?></div>
+                                    <div class="col-lg-9 col-md-8">
+                                        <?php $aadhaarLast4 = trim((string) ($data[0]->udai_last4 ?? '')); ?>
+                                        <?= $aadhaarLast4 !== '' ? 'XXXX-XXXX-' . esc($aadhaarLast4) : 'Not available' ?>
+                                    </div>
                                 </div>
                                 <div class="row">
                                     <div class="col-lg-3 col-md-4 label">ABHA ID</div>
@@ -253,7 +256,7 @@
                                     <div class="col-lg-6">
                                         <label class="form-label">Aadhar No.</label>
                                         <div class="input-group input-group-sm">
-                                            <input class="form-control" type="text" name="input_Aadhar" id="input_Aadhar" value="<?=$data[0]->udai ?>">
+                                            <input class="form-control" type="text" name="input_Aadhar" id="input_Aadhar" value="<?= trim((string) ($data[0]->udai_last4 ?? '')) !== '' ? 'XXXXXXXX' . esc((string) $data[0]->udai_last4) : '' ?>">
                                             <button type="button" id="btn_update_aadhar" class="btn btn-info">Update</button>
                                         </div>
                                     </div>
diff --git a/app/Views/billing/search_adv_data.php b/app/Views/billing/search_adv_data.php
index a284da5..a378c3a 100644
--- a/app/Views/billing/search_adv_data.php
+++ b/app/Views/billing/search_adv_data.php
@@ -51,18 +51,20 @@ $normalize = static function ($value): string {
 $filters = $filters ?? [];
 $filterPhone = trim((string) ($filters['input_mphone1'] ?? ''));
 $filterAadhaar = $normalize($filters['input_udai'] ?? '');
+// Aadhaar is stored masked/encrypted, so rows can only be compared on the last 4 digits.
+$filterAadhaarLast4 = substr(preg_replace('/\D/', '', (string) ($filters['input_udai'] ?? '')) ?? '', -4);
 $filterAbha = trim((string) ($filters['input_abha_id'] ?? ''));
 $filterName = $normalize($filters['input_name'] ?? '');
 $filterRelativeName = $normalize($filters['input_relative_name'] ?? '');
 
-$getMatchScore = static function ($row) use ($normalize, $filterPhone, $filterAadhaar, $filterAbha, $filterName, $filterRelativeName): int {
+$getMatchScore = static function ($row) use ($normalize, $filterPhone, $filterAadhaarLast4, $filterAbha, $filterName, $filterRelativeName): int {
     $score = 0;
 
     if ($filterPhone !== '' && trim((string) ($row->mphone1 ?? '')) === $filterPhone) {
         $score++;
     }
 
-    if ($filterAadhaar !== '' && $normalize($row->udai ?? '') === $filterAadhaar) {
+    if ($filterAadhaarLast4 !== '' && trim((string) ($row->udai_last4 ?? '')) === $filterAadhaarLast4) {
         $score++;
     }
 
@@ -133,7 +135,7 @@ if (! empty($search_result) && is_array($search_result)) {
             if ($filterPhone !== '' && trim((string) ($row->mphone1 ?? '')) === $filterPhone) {
                 $matchReasons[] = 'Phone';
             }
-            if ($filterAadhaar !== '' && $normalize($row->udai ?? '') === $filterAadhaar) {
+            if ($filterAadhaarLast4 !== '' && trim((string) ($row->udai_last4 ?? '')) === $filterAadhaarLast4) {
                 $matchReasons[] = 'Aadhaar';
             }
             if ($filterAbha !== '' && trim((string) ($row->abha_id ?? '')) === $filterAbha) {
diff --git a/app/Views/partials/abha_create_panel.php b/app/Views/partials/abha_create_panel.php
index 0bb2c2a..d4933e5 100644
--- a/app/Views/partials/abha_create_panel.php
+++ b/app/Views/partials/abha_create_panel.php
@@ -13,7 +13,7 @@
 $_pid  = (int) ($data[0]->id ?? 0);
 $_abha = esc($patientAbhaId ?? '');
 $_mob  = esc($data[0]->mphone1 ?? '');
-$_aadh = esc($data[0]->udai ?? '');
+$_aadh = '';
 ?>
 
 <h5 class="card-title mb-0">ABHA Number Create and Verify</h5>