Architectural Support for Copy and Tamper Resistant Software

Abstract

Although there have been attempts to develop code transformations that yield tamper-resistant software, no reliable software-only methods Jire known. This paper studies the hardware implementation of a form of execute-only memory (XOM) that allows instructions stored in memory to be executed but not otherwise manipulated. To support XOM code we use a machine that supports internal compartments-a process in one compartment cannot read data firom another compartment. All data that leaves the machine is encrypted, since we assume external memory is not secure. The design of this machine poses some interesting trade-offs between security, efficiency, and flexibiUty. We explore some of the potential security issues as one pushes the machine to become more efficient and flexible. Although security carries a performance penalty, our analysis indicates that it is possible to create a normal multi-tcisking max;hine where nearly all applications can be run in XOM mode. While a virtual XOM machine is possible, the underlying hardware needs to support a unique private key, private memory, and traps on cache misses. For efficient operation, hardware assist to provide fcist symmetric ciphers is also required.

Watermarking, tamper-proofing, and obfuscation - tools for software protection

“…It should be noted that there is a vast body of practical research and development on hardware assisted software protection. The available art for hardware-assisted security is based on memory devices such as floppy disks [31], CDROMs [97], modern removable storage media (hard disk, recordable DVD, secure digital memory card), and video playback units [1]: secure processors [50], smart cards [10], and hardware dongles [15], [58], [83]. 1 Many of these schemes are trade secrets, although some are the subject of patent disclosures.…”

Automated software attack recovery using rollback and huddle

“…Several of these focus on providing architectural support for encrypted execution and storage. In [16], the authors introduce the concept of eXecute-Only Memory, or XOM, which provides a mechanism for cryptographic separation of instruction and data-memory space. The prohibitive performance impact of XOM was later improved in [32] by using a "one-time pad" encryption scheme to reduce encryption latencies.…”

“…Once rollback takes place, the HPU would identify and decrypt the encrypted instructions so that they can be executed upon rollback and re-execution. Using the HPU as an accelerated encryption engine could also be extended to create an execution environment similar to XOM [16]. Instead of decrypting placeholder instructions upon rollback, the HPU would encrypt the entire instruction space.…”

Efficient scheme of verifying integrity of application binaries in embedded operating systems

“…Among them, regarding software integrity problems, there have been efforts to solve the problems such as XOM [8,26], off-chip memory security solution [45], and secure single chip processors [2,40] from a hardware perspective.…”