In-process attacks are a new class of attacks that circumvent protection schemes centered around inter-process isolation. Against these attacks, researchers have proposed fine-grained data isolation schemes that can protect sensitive data from malicious accesses even during the same process. Their proposals based on salient hardware features, such as ARM® processor architecture’s domain protection, are quite successful, but it cannot be applied to a specific architecture, namely AArch64, as this does not provide the same hardware features. In this paper, therefore, we present Sealer, a fine-grained data isolation scheme applicable in AArch64. Sealer achieves its objective by brilliantly harmonizing two hardware features of AArch64: The eXecute-no-Read and the cryptographic extension. Sealer provides application developers with a set of application programming interface (API) so that the developers can enjoy the fine-grained data isolation in their own way.