Struct EncryptionKey

Source

pub struct EncryptionKey(/* private fields */);

Expand description

An ElGamal encryption key (also called a public key in other implementations). To create a new encryption key, see DecryptionKey.

Implementations§

Source §

impl EncryptionKey

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pub fn exp_encrypt<R: RngCore + CryptoRng>( &self, m: Scalar, rng: &mut R, ) -> Ciphertext

Encrypt mG with a randomly-generated blinding factor, where G is the group generator.

This is computationally intensive to decrypt to the original scalar, and not relevant to the majority of users. This function takes advantage of a fast implementation for multiple multiplications in curve25519-dalek.

§Example

use rand::rngs::StdRng;
use rand::SeedableRng;
use rust_elgamal::{DecryptionKey, GENERATOR_TABLE, Scalar};

let mut rng = StdRng::from_entropy();
let dec_key = DecryptionKey::new(&mut rng);
let enc_key = dec_key.encryption_key();

let m = Scalar::from(5u32);
let encrypted = enc_key.exp_encrypt(m, &mut rng);

Source

pub fn exp_encrypt_with(&self, m: Scalar, r: Scalar) -> Ciphertext

Encrypt mG with the blinding factor r, where G is the group generator.

This is computationally intensive to decrypt to the original scalar, and not relevant to the majority of users. This function takes advantage of a fast implementation for multiple multiplications in curve25519-dalek.

§Example

use rand::rngs::StdRng;
use rand::SeedableRng;
use rust_elgamal::{DecryptionKey, GENERATOR_TABLE, Scalar};

let mut rng = StdRng::from_entropy();
let dec_key = DecryptionKey::new(&mut rng);
let enc_key = dec_key.encryption_key();

let m = Scalar::from(5u32);
let r = Scalar::from(10u32);
let encrypted = enc_key.exp_encrypt_with(m, r);

Source

pub fn encrypt<R: RngCore + CryptoRng>( &self, m: RistrettoPoint, rng: &mut R, ) -> Ciphertext

Encrypt the curve point m with a randomly-generated blinding factor.

§Example

use rand::rngs::StdRng;
use rand::SeedableRng;
use rust_elgamal::{DecryptionKey, GENERATOR_TABLE, Scalar};

let mut rng = StdRng::from_entropy();
let dec_key = DecryptionKey::new(&mut rng);
let enc_key = dec_key.encryption_key();

let m = &Scalar::from(5u32) * &GENERATOR_TABLE;
let encrypted = enc_key.encrypt(m, &mut rng);

Source

pub fn encrypt_with(&self, m: RistrettoPoint, r: Scalar) -> Ciphertext

Encrypt the curve point m with the blinding factor r.

§Example

use rand::rngs::StdRng;
use rand::SeedableRng;
use rust_elgamal::{DecryptionKey, GENERATOR_TABLE, Scalar};

let mut rng = StdRng::from_entropy();
let dec_key = DecryptionKey::new(&mut rng);
let enc_key = dec_key.encryption_key();

let m = &Scalar::from(5u32) * &GENERATOR_TABLE;
let r = Scalar::from(10u32);
let encrypted = enc_key.encrypt_with(m, r);

Source

pub fn rerandomise<R: RngCore + CryptoRng>( &self, ct: Ciphertext, rng: &mut R, ) -> Ciphertext

Re-randomise the ciphertext ct with a randomly-generated blinding factor. This will generate a new encryption of the same curve point.

§Example

use rand::rngs::StdRng;
use rand::SeedableRng;
use rust_elgamal::{DecryptionKey, GENERATOR_TABLE, Scalar};

let mut rng = StdRng::from_entropy();
let dec_key = DecryptionKey::new(&mut rng);
let enc_key = dec_key.encryption_key();

let m = &Scalar::from(5u32) * &GENERATOR_TABLE;
let ct1 = enc_key.encrypt(m, &mut rng);
let ct2 = enc_key.rerandomise(ct1, &mut rng);
assert_eq!(dec_key.decrypt(ct1), dec_key.decrypt(ct2));

Source

pub fn rerandomise_with(&self, ct: Ciphertext, r: Scalar) -> Ciphertext

Re-randomise the ciphertext ct with the provided blinding factor. This will generate a new encryption of the same curve point.

§Example

use rand::rngs::StdRng;
use rand::SeedableRng;
use rust_elgamal::{DecryptionKey, GENERATOR_TABLE, Scalar};

let mut rng = StdRng::from_entropy();
let dec_key = DecryptionKey::new(&mut rng);
let enc_key = dec_key.encryption_key();

let m = &Scalar::from(5u32) * &GENERATOR_TABLE;
let ct1 = enc_key.encrypt(m, &mut rng);

let r = Scalar::from(10u32);
let ct2 = enc_key.rerandomise_with(ct1, r);

assert_eq!(dec_key.decrypt(ct1), dec_key.decrypt(ct2));