gose/jose/jwe_multi

JWE JSON Serialization for multi-recipient encryption and decryption (RFC 7516 Section 7.2.1).

Example

import gleam/json
import gose/algorithm
import gose/jose/jwe_multi
import gose/key

let k1 = key.generate_aes_kw_key(algorithm.Aes256)
let k2 = key.generate_aes_kw_key(algorithm.Aes128)
let plaintext = <<"hello":utf8>>

let message = jwe_multi.new(algorithm.AesGcm(algorithm.Aes256))
let assert Ok(message) =
  jwe_multi.add_recipient(
    message,
    algorithm.AesKeyWrap(algorithm.AesKw, algorithm.Aes256),
    key: k1,
  )
let assert Ok(message) =
  jwe_multi.add_recipient(
    message,
    algorithm.AesKeyWrap(algorithm.AesKw, algorithm.Aes128),
    key: k2,
  )
let assert Ok(encrypted) = jwe_multi.encrypt(message, plaintext:)

let json_str = jwe_multi.serialize_json(encrypted) |> json.to_string
let assert Ok(parsed) = jwe_multi.parse_json(json_str)
let assert Ok(dec) =
  jwe_multi.decryptor(
    algorithm.AesKeyWrap(algorithm.AesKw, algorithm.Aes256),
    algorithm.AesGcm(algorithm.Aes256),
    keys: [k1],
  )
let assert Ok(plaintext) = jwe_multi.decrypt(dec, parsed)

Rejected Algorithms

Direct and EcdhEs(EcdhEsDirect) are rejected because they derive the CEK directly rather than wrapping it, making multi-recipient impossible. Pbes2 is also excluded (requires a password, not a key).

Algorithm Pinning

Each decryptor is pinned to expected key encryption and content encryption algorithms. Mismatches are rejected.

pub opaque type Decryptor

pub type Encrypted

pub opaque type MultiJwe(state)

pub type Unencrypted

pub fn add_recipient(
  message: MultiJwe(Unencrypted),
  alg: algorithm.KeyEncryptionAlg,
  key key: key.Key(String),
) -> Result(MultiJwe(Unencrypted), gose.GoseError)

pub fn decrypt(
  decryptor: Decryptor,
  message: MultiJwe(Encrypted),
) -> Result(BitArray, gose.GoseError)

pub fn decryptor(
  key_alg: algorithm.KeyEncryptionAlg,
  content_alg: algorithm.ContentAlg,
  keys keys: List(key.Key(String)),
) -> Result(Decryptor, gose.GoseError)

pub fn encrypt(
  message: MultiJwe(Unencrypted),
  plaintext plaintext: BitArray,
) -> Result(MultiJwe(Encrypted), gose.GoseError)

pub fn new(enc: algorithm.ContentAlg) -> MultiJwe(Unencrypted)

pub fn parse_json(
  json_str: String,
) -> Result(MultiJwe(Encrypted), gose.GoseError)

pub fn serialize_json(message: MultiJwe(Encrypted)) -> json.Json