ORTOA - a family of One Round Trip Oblivious Access protocols that reads or writes data stored on remote storage in one round without revealing the type of access.

The ORTOA-TEE project implements this access protocol leveraging the cryptographic guarantees of trusted execution environments (hardware enclaves) and benchmarks the performance.

This section proposes an alternate one round trip solution to hide the type of access using trusted execution environments (TEEs) such as Intel SGX. Main attributes of TEEs are as follows:

• Secure areas within a main processor that protect the code and data loaded inside it with respect to confidentiality and integrity
• Provide isolation for code and data from the operating system using CPU hardware-level isolation and memory encryption

If a cloud vendor can provide hardware enclaves (i.e., TEEs), an application can deploy its entire system on the cloud, which enables the data and the trusted component to reside together, significantly reducing the communication latency compared to a trusted proxy-based system.

The ORTOA-TEE data flow is as follows:

1. Client sends a request to an untrusted host with the following packet:
   1. Operation type C (GET or PUT)
   2. Key k (an unencrypted integer)
   3. Value v_new (an encrypted string) (for GET requests, the value is randomly generated to maintain uniformity between operation types)
2. Untrusted host retrieves the value, v_old, that corresponds to key k from the database (current implementation uses Redis)
3. Untrusted host sends C, v_old, v_new to enclave
4. The enclave conducts a decryption and encryption based on the following rules:
   • If operation C is GET: decrypt and re-encrypt v_old
   • If operation C is PUT: decrypt and re-encrypt v_new
5. Return the encrypted value v_enclave to untrusted host
6. Untrusted host puts the value v_enclave into database with key k
7. Untrusted host returns the value v_enclave to client

We provide a bash script library srcipts/ortoa-lib.sh that houses a collection of scripts and utilities to manage the ORTOA environment. It can be sourced as follows:

ORTOA/ $ source scripts/ortoa-lib.sh

Details about the project installation process can be found in the docs/ directory as INSTALL.md.

Details about the build can be found in the docs/ directory as BUILD.md. The easiest way to build the C++ projects is to run the ortoa-cbi script.

ORTOA/ $ ortoa-cbi  # requires sourcing scripts & utilities

Runs the ORTOA-TEE client

ORTOA/ $ ortoa-client-run -h

Runs the ORTOA-TEE host. Requires SGX hardware.

ORTOA/ $ ortoa-host -h

Runs the ORTOA-TEE host in simulation mode.

ORTOA/ $ ortoa-simulate -h