# Crate concrete_core[−][src]

Welcome to the concrete-core documentation!

# Fully Homomorphic Encryption

This library contains low-level primitives which can be used to implement fully homomorphically encrypted programs. In a nutshell, fully homomorphic encryption allows you to perform any computation you would normally perform over clear data; but this time over encrypted data. With fhe, you can perform computations without putting your trust on third-party providers. To learn more about the fhe schemes used in this library, you can have a look at the following papers:

If you are not accustomed to cryptography, but are still interested by performing you should check the concrete library, which provides a simpler, higher-level API.

# Quick Example

Despite being low-overhead, concrete-core offers a pretty straightforward interface:

// This examples shows how to multiply a secret value by a public one homomorphically. First
// we import the proper symbols:
use concrete_core::crypto::encoding::{RealEncoder, Cleartext, Encoder, Plaintext};
use concrete_core::crypto::secret::LweSecretKey;
use concrete_core::crypto::LweDimension;
use concrete_core::crypto::lwe::LweCiphertext;
use concrete_core::math::dispersion::LogStandardDev;

// We initialize an encoder that will allow us to turn cleartext values into plaintexts.
let encoder = RealEncoder{offset: 0., delta: 100.};
// Our secret value will be 10.,
let cleartext = Cleartext(10_f64);
let public_multiplier = Cleartext(5);
// We encode our cleartext
let plaintext = encoder.encode(cleartext);

// We generate a new secret key which is used to encrypt the message
let secret_key_size = LweDimension(710);
let secret_key = LweSecretKey::generate(secret_key_size);

// We allocate a ciphertext and encrypt the plaintext with a secure parameter
let mut ciphertext = LweCiphertext::allocate(0u32, secret_key_size.to_lwe_size());
secret_key.encrypt_lwe(
&mut ciphertext,
&plaintext,
LogStandardDev::from_log_standard_dev(-17.)
);

// We perform the homomorphic operation:
ciphertext.update_with_scalar_mul(public_multiplier);

// We decrypt the message
let mut output_plaintext = Plaintext(0u32);
secret_key.decrypt_lwe(&mut output_plaintext, &ciphertext);
let output_cleartext = encoder.decode(output_plaintext);

// We check that the result is as expected !
assert!((output_cleartext.0 - 50.).abs() < 0.01);

The scalar multiplication is only one of the many operations available. For more informations about the operations available, check the crypto module.

## Modules

 crypto Low-overhead homomorphic primitives. math A module containing general mathematical tools. numeric Generic numeric types. utils Utilities for the

## Macros

 zip This macro is used in tandem with the zip_args macro, to allow to zip iterators and access them in an non-nested fashion. This makes large zip iterators easier to write, but also, makes the code faster, as zipped-flatten iterators are hard to optimize for the compiler. zip_args Companion macro to flatten the iterators made with the zip