Immutable Pointer Encryption for Low-Overhead Memory Safety
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Solution Overview
Problem
Current computing techniques require additional storage and negatively impact performance due to metadata overhead, and existing solutions fail to effectively mitigate memory safety vulnerabilities such as buffer overflows and dangling pointers.
Innovation Solution
Implementing data encryption based on immutable pointers using tag bits associated with memory words, which propagate through the memory hierarchy, and binding data encryption to base addresses to mitigate vulnerabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metadata is used to provide data protection information, then data security is improved, but memory overhead increases and performance deteriorates
Solution Approach 1:
The patent combines data encryption and pointer protection into a unified cryptographic system where the same encryption mechanism serves both purposes. Data is encrypted using a tweakable block cipher where the tweak is derived from the pointer itself, merging the protection of data confidentiality and pointer integrity into a single mechanism that eliminates separate metadata structures.
Solution Approach 2:
The encryption system performs multiple functions simultaneously: it encrypts data to protect confidentiality, binds data to specific pointers through tweak-based encryption, and enables verification of pointer validity. This multi-functional approach replaces multiple separate protection mechanisms with a single universal cryptographic primitive.
2Reliability
If fine-grain metadata is implemented for data protection, then security coverage is improved, but performance deteriorates
Solution Approach 1:
The patent extracts the protection information directly from the pointer structure itself rather than storing it in separate metadata structures. The pointer contains embedded cryptographic material that provides fine-grain protection, eliminating the need for external metadata tables and reducing memory access overhead.
Solution Approach 2:
The pointer structure is designed to be self-sufficient, containing all necessary cryptographic information within itself. The pointer can be verified and used for encryption without requiring external metadata lookups, making the system self-service and eliminating performance-penalizing memory accesses.
3Reliability
If traditional encryption methods are used, then data confidentiality is improved, but memory safety vulnerabilities remain
Solution Approach 1:
The patent uses asymmetric treatment of pointers through tweakable encryption where the encryption tweak is derived from the pointer value itself. This creates an asymmetric relationship where data encrypted with one pointer cannot be accessed with a different pointer, even if the attacker knows the encryption key, providing both confidentiality and pointer validation.
Solution Approach 2:
The system performs preliminary cryptographic binding of data to pointers during the encryption process itself. Before data can be accessed, the pointer must already be valid and authorized, and the encryption process verifies this binding. This preliminary action prevents memory safety vulnerabilities by ensuring pointer validity before access occurs.
Data Source
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AI summary
Technologies disclosed herein provide cryptographic computing. An example processor includes a core to execute an instruction, where the core includes a register to store a pointer to a memory location and a tag associated with the pointer. The tag indicates whether the pointer is at least partially immutable. The core also includes circuitry to access the pointer and the tag associated with the pointer, determine whether the tag indicates that the pointer is at least partially immutable. The circuitry is further, based on a determination that the tag indicates the pointer is at least partially immutable, to obtain a memory address of the memory location based on the pointer, use the memory address to access encrypted data at the memory location, and decrypt the encrypted data based on a key and a tweak, where the tweak including one or more bits based, at least in part, on the pointer.