OVERSEE: Outsourcing Verification to Enable Resource Sharing in Edge - PowerPoint PPT Presentation

OVERSEE: Outsourcing Verification to Enable Resource Sharing in Edge Environment Reporter: Xiaoqing Cai August 2020

From Cloud to Edge Cloud Computing Edge Computing Low Latency

Lack of Resources Cloud Computing Edge Computing No More Edge

Multi-tenant Data Center Tenant C Tenant B Tenant A Task Outsourcing Lessee Lessor 300 300 300 200 200 200 100 100 100 0 0 0 1 3 5 7 9 11 1 3 5 7 9 11 1 3 5 7 9 11 No Simultaneous Peak

Two Basic Properties for Task Outsourcing Reliability Performance The outsourced task can be Verify that the lessor provides executed correctly , i.e., completely sufficient resources to meet and without modification the QoS requirement according If User receives wrong results to the lease agreement between the data center tenants May Bad Traditi- blame Not enough onal resources Innocent Save power to make profit Outso- blame Untrusted QoS urcing information Unaware

OVERSEE Report-Proof Mechanism Reliability After Initialization After Execution O Enclave Enclave V Report Proof E R S Performance Sampling-Challenging Mechanism E E Insert sampling code Sends sampling requests … …

What is SGX Software Guard eXtension is a set of instructions that provide protected memory access control to Intel architectures. DRAM Enclave Local / Remote OS Create Execution Enclave Enclave Local/Remote attestation APP compare measure ❷ load ❸ ❶ Enclave true e

Report-Proof Mechanism Reliability ◆ Verify the correctness ◆ Verify the execution of the task results process I. Exploit TEE provided by I. Redundant calculation Intel SGX Enclave II. Can not guarantee the completeness of task execution II. Non-deterministic results Enclave Ring 3 Report or Ring 0…

Report-Proof Mechanism Insert PK in the report ❷ Generate a pair of ❶ ❸ Initialize the enclave and sign with CPU private key(SK) and Enclave Report public key(PK) PK Code public private … Data CPU Signature ❹ ❺ Sign the proof with SK Execute the task and Proof sampling codes Task Result Hash Sample Array … Private key Signature

Sampling-Challenging Mechanism Performance —— Why not just a monitor process ? Call Gate Trusted Part Untrusted Part CallTrusted (enclave program) (operating system) Process 2 Process 1 1 st SystemCall (QoS monitoring) (task running) Save state (Generate log) Trusted? 1 st OCALL Return Save file I th SystemCall ...... state I th OCALL (Generate log) ...... Return Save n th SystemCall state n th OCALL (Generate log) Return completed Return (The external calling mechanism of SGX)

Sampling-Challenging Mechanism Performance —— Sampling-Challenging Mechanism Call Gate Trusted Part CallTrusted (enclave program) Generate Process 1 Report (task running) (sampling-codes) random sample parameter 1 st sample Proof ...... Task Result Hash I th sample Sample Array ...... Generate … Private key n th sample Signature completed Return

Sampling-Challenging Mechanism Lessee Lessor Enclave Send sampling codes Return execution time Satisfy the If yes, make the requirement ？ lease agreement Send the outsourcing Enclave task with inserted sampling codes Return results Proof Report and certificates compare Proof

Sampling-Challenging Mechanism • Problem Definition Determine the probability that the cheat can be detected given the sampling time, cheating time and the actual execution time of the outsourced task. • Sampling Model 𝒃 𝟑 𝒃 𝟒 𝒃 𝒋 𝒃 𝟐 … … 𝒄 𝟐 𝒄 𝒌 𝒄 𝟑 𝒄 𝟒 𝒄 𝟓 T 𝒃 𝒋 𝒃 𝒋 （ a ） 𝒄 𝒌 𝒄 𝒌 （ b ） （ c ）

Sampling-Challenging Mechanism • Theorem

Evaluation Probability of Detecting QoS Degradation

Evaluation Computational Overhead Environment ： A single machine with 16GB DDR4 RAM and Intel Core i7-9750H 2.6GHz • with 6 hyper-threaded cores • 𝜌 calculation, Bubble Sort and Floyd

Thank You ！