TFHE Library

The library exposes utility functions for TFHE operations. The goal of the library is to provide a seamless developer experience for writing smart contracts that can operate on confidential data.

Types

The library provides a type system that is checked both at compile time and at run time. The structure and operations related to these types are described in this sections.

We currently support encrypted integers of bit length up to 32 bits.

Our library provides the following types :

• ebool

• euint8

• euint16

• euint32

These encrypted integers behave as much as possible as Solidity's integer types. However, behaviour such as "revert on overflow" is not supported as this would leak some information of the encrypted integers. Therefore, arithmetic on euint types is unchecked, i.e. there is wrap-around on overlow.

In the back-end, encrypted integers are TFHE ciphertexts. The library abstracts away the ciphertexts and presents pointers to ciphertexts, or ciphertext handles, to the smart contract developer. The euint types are wrappers over these handles.

Operations

The library exposes utility functions for operations on TFHE ciphertexts. The list of supported operations is presented below.

name	function name	type
Add	TFHE.add	Binary
Sub	TFHE.sub	Binary
Mul	TFHE.mul	Binary
BitAnd	TFHE.and	Binary
BitOr	TFHE.or	Binary
BitXor	TFHE.xor	Binary
Shift Right	TFHE.shr	Binary
Shift Left	TFHE.shl	Binary
Equal	TFHE.eq	Binary
Not equal	TFHE.ne	Binary
Greater than or equal	TFHE.ge	Binary
Greater than	TFHE.gt	Binary
Less than or equal	TFHE.le	Binary
Less than	TFHE.lt	Binary
Min	TFHE.min	Binary
Max	TFHE.max	Binary
Neg	TFHE.neg	Unary
Not	TFHE.not	Unary
Cmux	TFHE.cmux	Ternary

More information about the supported operations can be found at the TFHE-rs docs.