diff --git a/packages/backend/src/core/entities/InstanceEntityService.ts b/packages/backend/src/core/entities/InstanceEntityService.ts
index e46bd8b963..1482a22a6c 100644
--- a/packages/backend/src/core/entities/InstanceEntityService.ts
+++ b/packages/backend/src/core/entities/InstanceEntityService.ts
@@ -55,6 +55,7 @@ export class InstanceEntityService {
 			infoUpdatedAt: instance.infoUpdatedAt ? instance.infoUpdatedAt.toISOString() : null,
 			latestRequestReceivedAt: instance.latestRequestReceivedAt ? instance.latestRequestReceivedAt.toISOString() : null,
 			moderationNote: iAmModerator ? instance.moderationNote : null,
+			httpMessageSignaturesImplementationLevel: instance.httpMessageSignaturesImplementationLevel,
 		};
 	}
 
diff --git a/packages/backend/src/models/json-schema/federation-instance.ts b/packages/backend/src/models/json-schema/federation-instance.ts
index 42d98fe523..5da3f87d42 100644
--- a/packages/backend/src/models/json-schema/federation-instance.ts
+++ b/packages/backend/src/models/json-schema/federation-instance.ts
@@ -111,5 +111,9 @@ export const packedFederationInstanceSchema = {
 			type: 'string',
 			optional: true, nullable: true,
 		},
+		httpMessageSignaturesImplementationLevel: {
+			type: 'string',
+			optional: false, nullable: false,
+		},
 	},
 } as const;
diff --git a/packages/misskey-js/src/autogen/types.ts b/packages/misskey-js/src/autogen/types.ts
index 227295fbb8..0e32c91484 100644
--- a/packages/misskey-js/src/autogen/types.ts
+++ b/packages/misskey-js/src/autogen/types.ts
@@ -4492,6 +4492,7 @@ export type components = {
       /** Format: date-time */
       latestRequestReceivedAt: string | null;
       moderationNote?: string | null;
+      httpMessageSignaturesImplementationLevel: string;
     };
     GalleryPost: {
       /**