TFHE-rs v0.7: Ciphertext Compression, Multi-GPU Support and More

TFHE-rs v0.7 introduces significant advancements in fully homomorphic encryption (FHE) by introducing compressed ciphertexts and support for multi-GPU architectures. With this update, ciphertexts resulting from homomorphic computations can be compressed, reducing their size by up to 1,900 times, a crucial improvement given the typically large size of encrypted data. The release also leverages multi-GPU setups to enhance computational performance without requiring users to modify their code, although it is limited to GPUs with peer access via NVLink. Additionally, the update includes new cryptographic parameter sets, vector and array operations, improved zero-knowledge proofs, and optimized keyswitch operations on GPUs, collectively enhancing the efficiency and functionality of TFHE-rs. These improvements not only reduce the latency of programmable bootstrapping but also expand the capabilities of the tool, promising further enhancements in future updates.