diff --git a/pom.xml b/pom.xml
index 42111a6..2179a39 100644
--- a/pom.xml
+++ b/pom.xml
@@ -6,7 +6,7 @@
 
     <groupId>com.uid2</groupId>
     <artifactId>uid2-e2e</artifactId>
-    <version>4.2.17</version>
+    <version>4.2.18-alpha-96-SNAPSHOT</version>
 
     <properties>
         <maven.compiler.source>21</maven.compiler.source>
diff --git a/src/test/java/app/component/Core.java b/src/test/java/app/component/Core.java
index 27f32cd..ccd794c 100644
--- a/src/test/java/app/component/Core.java
+++ b/src/test/java/app/component/Core.java
@@ -30,6 +30,11 @@ public JsonNode attest(String attestationRequest) throws Exception {
         return OBJECT_MAPPER.readTree(response);
     }
 
+    public JsonNode attestWithApiKey(String attestationRequest, String apiKey) throws Exception {
+        String response = HttpClient.post(getBaseUrl() + "/attest", attestationRequest, apiKey);
+        return OBJECT_MAPPER.readTree(response);
+    }
+
     public JsonNode getWithCoreApiToken(String path) throws Exception {
         return getWithCoreApiToken(path, false);
     }
diff --git a/src/test/java/common/HttpClient.java b/src/test/java/common/HttpClient.java
index 47ab050..739f398 100644
--- a/src/test/java/common/HttpClient.java
+++ b/src/test/java/common/HttpClient.java
@@ -42,6 +42,10 @@ public JsonNode getResponseJson() throws Exception {
             return OBJECT_MAPPER.readTree(response);
         }
 
+        public int getCode() {
+            return code;
+        }
+
         private static String createErrorMessage(HttpMethod method, String url, int code, String message, String response) {
             return "Unsuccessful %s request - URL: %s - Code: %d %s - Response body: %s".formatted(
                     method, url, code, message, response
diff --git a/src/test/java/suite/core/CoreTest.java b/src/test/java/suite/core/CoreTest.java
index 04e95b8..4916c37 100644
--- a/src/test/java/suite/core/CoreTest.java
+++ b/src/test/java/suite/core/CoreTest.java
@@ -30,9 +30,61 @@ public void testAttest_EmptyAttestationRequest(Core core) {
         assertEquals("Unsuccessful POST request - URL: " + coreUrl + "/attest - Code: 400 Bad Request - Response body: {\"status\":\"no attestation_request attached\"}", exception.getMessage());
     }
 
+    /**
+     * Tests that an unknown / mistyped operator key is rejected with HTTP 401 and a body that
+     * names the cause (reason=unrecognized_key).
+     */
+    @ParameterizedTest(name = "/attest unrecognized key - {0}")
+    @MethodSource({
+            "suite.core.TestData#baseArgs"
+    })
+    public void testAttest_UnrecognizedOperatorKey(Core core) {
+        // A well-formed but unknown key - not present in the operators store.
+        String bogusOperatorKey = "UID2-O-L-000-thisKeyDoesNotExist000000000000000000000000=";
+
+        HttpClient.HttpException exception = assertThrows(
+                HttpClient.HttpException.class,
+                () -> core.attestWithApiKey("{\"attestation_request\":\"AA==\"}", bogusOperatorKey)
+        );
+
+        assertEquals(401, exception.getCode(), "unknown operator key should be rejected with 401");
+        JsonNode body = assertDoesNotThrow(exception::getResponseJson);
+        assertAll("401 body should name the rejection cause",
+                () -> assertEquals("unauthorized", body.get("status").asText()),
+                () -> assertEquals("unrecognized_key", body.get("reason").asText()),
+                () -> assertTrue(body.get("message").asText().toLowerCase().contains("not recognized"),
+                        "message should tell the operator the key was not recognized"));
+    }
+
+    /**
+     * Tests that a recognized-but-disabled operator key is rejected with HTTP 401 and reason=key_disabled,
+     * distinguishing it from an unknown key. Relies on the disabled operator key seeded in
+     * uid2-admin localstack (site_id 998, "Disabled Operator (E2E)").
+     */
+    @ParameterizedTest(name = "/attest disabled key - {0}")
+    @MethodSource({
+            "suite.core.TestData#baseArgs"
+    })
+    public void testAttest_DisabledOperatorKey(Core core) {
+        String disabledOperatorKey = "UID2-O-L-998-d1sabledKeyForE2ETestOnly00000000000000000000=";
+
+        HttpClient.HttpException exception = assertThrows(
+                HttpClient.HttpException.class,
+                () -> core.attestWithApiKey("{\"attestation_request\":\"AA==\"}", disabledOperatorKey)
+        );
+
+        assertEquals(401, exception.getCode(), "disabled operator key should be rejected with 401");
+        JsonNode body = assertDoesNotThrow(exception::getResponseJson);
+        assertAll("401 body should identify the key as disabled",
+                () -> assertEquals("unauthorized", body.get("status").asText()),
+                () -> assertEquals("key_disabled", body.get("reason").asText()),
+                () -> assertTrue(body.get("message").asText().toLowerCase().contains("disabled"),
+                        "message should tell the operator the key is disabled"));
+    }
+
     /**
      * Tests valid attestation request with JWT signing.
-     * 
+     *
      * Since LocalStack generates its own RSA key material,
      * we dynamically fetch the public key from LocalStack's
      * KMS using GetPublicKey API to validate JWT signatures.