Module proxy_reencryption 

Proxy re-encryption.

Allows a proxy to transform ciphertext encrypted under Alice’s key into ciphertext decryptable by Bob, WITHOUT the proxy learning the plaintext. Uses ElGamal over P-256.

Protocol

1. Alice computes re-encryption key: rk = bob_sk^-1 * alice_sk
2. Proxy transforms: (c1, c2) → (c1 * rk, c2) [point multiplication]
3. Bob decrypts with his secret key

Structs

Ciphertext

ElGamal ciphertext: (ephemeral point, encrypted point).

ReEncryptionKey

A re-encryption key from Alice to Bob.

Functions

decrypt_point

Decrypt a ciphertext with secret key sk.

encrypt_point

Encrypt a point under public key pk.

generate_rk

Generate a re-encryption key from Alice’s secret to Bob’s public.

re_encrypt

Re-encrypt: transform ciphertext from Alice to Bob.