Circom-tfhe-rs

Circom-tfhe-rs enables users to generate a TFHE circuit that corresponds to the arithmetization of a Circom circuit. In simpler terms, it translates Circom circuits into their TFHE equivalents. Circom code is compiled into an arithmetic circuit using circom-2-arithc and then translated gate by gate to the corresponding tfhe-rs operators.

NOTE: Now circom-2-arithc also conveniently outputs the Bristol format with corresponding circuit_info (hence the json_arbistol is not necessary anymore).

Supported Circom Op

Op	FheUint	FheInt
+ Addition	✅	✅
/ Division	✅	✅
== Equality	✅	✅
> Greater Than	✅	✅
>= Greater Than or Equal	✅	✅
< Less Than	✅	✅
<= Less Than or Equal	✅	✅
* Multiplication	✅	✅
!= Not Equal	✅	✅
- Subtraction	✅	✅
** Exponentiation	❌	❌
<< Shift Left	✅	❌
>> Shift Right	✅	❌
^ Bitwise XOR	✅	✅
| Bitwise OR	✅	✅
& Bitwise AND	✅	✅
% Modulo	✅	✅

Structure

• circom-2-arithc - we are using the latest version.
• tfhe-rs - supports the arithmetization on tfhe
• main.py - the main script to run the circom-tfhe. It does the following:
  • Compiles the Circom code to the arithmetic circuit with circom-2-arithc.
  • Generates tfhe-rs program by converting bristol fashion circuit.
  • Performs the computation using tfhe-rs.
• examples - example circuits to run with circom-tfhe.

Installation

Clone the repo

git clone https://github.com/Vishalkulkarni45/circom-tfhe-rs
git clone https://github.com/namnc/circom-2-arithc

Build circom-2-arithc

Go to the circom-2-arithc submodule directory:

cd circom-2-arithc

Initialize the .env file:

touch .env
vim .env

Build the compiler:

cargo build --release

How to run

We have two examples available:

• ops_tests - a benchmark of supported operations
• naive_search - a benchmark of naive search

For both the examples ,We successfully executed them for FheUint8, FheUint16, and FheUint64 on a 4-core machine with 16GB of RAM, but encountered memory limitations when attempting FheUint128.

In both examples, you will find the following files in each example directory:

• circuit.circom - the circom code representing the circuit
• {circuit_name}.py - automated generator for input files and raw_circuit tfhe-rs program

You can run these examples by following the instructions in the root directory.

#Before running this you need to change the raw tfhe code plain and cipher text data type manunal
python main.py {circuit_name} {plain_text_data_type} 

• {circuit_name} is the name of the circuit you want to run. Can either be ops_tests or naive_search.
• Intermediate files will be stored in the outputs/{circuit_name} directory.
• Outputs are directly printed to the console.

How it works

1. Generate Rust directory in the outputs folder; outputs/{circuit_name} and outputs/{circuit_name}_raw

   • If the directory exists, it deletes the directory and makes new directory.

2. Add the necessary dependencies in Cargo.toml in each Rust directory.

3. For existing circom circuit, run circom-2-arithc.

4. Run python script in examples/{circuit_name}/

   • It generates raw_circuit tfhe-rs code, input.json
   • After generating input.json, make a new file input_struct.json which has different format.
   • After generating raw_circuit tfhe-rs code, copy it into outputs/{circuit_name}_raw
   • Copy input.json and input_struct.json in outputs/{circuit_name} and outputs/{circuit_name}_raw

5. Using bristol fashion circuit, generate tfhe-rs code.

   • It divides the operation into two folder: client and server.
   • Client code is responside for encrypting the inputs and decrypting the output
   • Server code handles performing operations on the encrypted inputs.

6. Run converted tfhe-rs code, and compare it with model tfhe-rs code.

   • It compares the output of the generated TFHE circuit with that of the manually created TFHE circuit.
   • It also compares the output of the generated TFHE circuit with the functionality executed using unencrypted methods (via native Rust , which is present in circuit_name_raw folder)