Expose AEAD ChaCha20 Poly1305 functionality

Note: We expose the modern IETF version but still name it plain
aead_chacha20poly1305.

c_src/enacl_nif.c

@@ -1313,6 +1313,98 @@ ERL_NIF_TERM enif_crypto_pwhash_str_verify(ErlNifEnv *env, int argc, ERL_NIF_TER
   return retVal;
 }
 
+/*
+ * AEAD ChaCha20 Poly1305
+ */
+static
+ERL_NIF_TERM enif_crypto_aead_chacha20poly1305_KEYBYTES(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
+  return enif_make_int64(env, crypto_aead_chacha20poly1305_ietf_KEYBYTES);
+}
+
+static
+ERL_NIF_TERM enif_crypto_aead_chacha20poly1305_NPUBBYTES(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
+  return enif_make_int64(env, crypto_aead_chacha20poly1305_ietf_NPUBBYTES);
+}
+
+static
+ERL_NIF_TERM enif_crypto_aead_chacha20poly1305_ABYTES(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
+  return enif_make_int64(env, crypto_aead_chacha20poly1305_ietf_ABYTES);
+}
+
+static
+ERL_NIF_TERM enif_crypto_aead_chacha20poly1305_MESSAGEBYTES_MAX(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
+  return enif_make_int64(env, crypto_aead_chacha20poly1305_ietf_MESSAGEBYTES_MAX);
+}
+
+static
+ERL_NIF_TERM enif_crypto_aead_chacha20poly1305_encrypt(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
+  ERL_NIF_TERM result;
+  ErlNifBinary key, nonce, ad, message, ciphertext;
+
+  if ((argc != 4) || (!enif_inspect_binary(env, argv[0], &key))
+                  || (!enif_inspect_binary(env, argv[1], &nonce))
+                  || (!enif_inspect_binary(env, argv[2], &ad))
+                  || (!enif_inspect_binary(env, argv[3], &message))
+                  || (key.size != crypto_aead_chacha20poly1305_ietf_KEYBYTES)
+                  || (nonce.size != crypto_aead_chacha20poly1305_ietf_NPUBBYTES)) {
+          return enif_make_badarg(env);
+  }
+
+  do
+  {
+          if (!enif_alloc_binary(message.size + crypto_aead_chacha20poly1305_ietf_ABYTES, &ciphertext)) {
+                  result = nacl_error_tuple(env, "alloc_failed");
+                  continue;
+          }
+
+          if (crypto_aead_chacha20poly1305_ietf_encrypt(ciphertext.data, NULL, message.data, message.size,
+                                                        ad.data, ad.size, NULL, nonce.data, key.data) < 0) {
+                  result = nacl_error_tuple(env, "aead_chacha20poly1305_ietf_encrypt_failed");
+                  continue;
+          }
+
+          result = enif_make_binary(env, &ciphertext);
+  } while (0);
+
+  return result;
+
+}
+
+static
+ERL_NIF_TERM enif_crypto_aead_chacha20poly1305_decrypt(ErlNifEnv *env, int argc, ERL_NIF_TERM const argv[]) {
+  ERL_NIF_TERM result;
+  ErlNifBinary key, nonce, ad, message, ciphertext;
+
+  if ((argc != 4) || (!enif_inspect_binary(env, argv[0], &key))
+                  || (!enif_inspect_binary(env, argv[1], &nonce))
+                  || (!enif_inspect_binary(env, argv[2], &ad))
+                  || (!enif_inspect_binary(env, argv[3], &ciphertext))
+                  || (ciphertext.size < crypto_aead_chacha20poly1305_ietf_ABYTES)
+                  || (key.size != crypto_aead_chacha20poly1305_ietf_KEYBYTES)
+                  || (nonce.size != crypto_aead_chacha20poly1305_ietf_NPUBBYTES)) {
+          return enif_make_badarg(env);
+  }
+
+  do
+  {
+          if (!enif_alloc_binary(ciphertext.size - crypto_aead_chacha20poly1305_ietf_ABYTES, &message)) {
+                  result = nacl_error_tuple(env, "alloc_failed");
+                  continue;
+          }
+
+          if (crypto_aead_chacha20poly1305_ietf_decrypt(message.data, NULL, NULL, ciphertext.data, ciphertext.size,
+                                                        ad.data, ad.size, nonce.data, key.data) < 0) {
+                  result = nacl_error_tuple(env, "aead_chacha20poly1305_ietf_decrypt_failed");
+                  continue;
+          }
+
+          result = enif_make_binary(env, &message);
+  } while (0);
+
+  return result;
+
+}
+
 /*
  * Generic hash
  */
@@ -1624,6 +1716,13 @@ static ErlNifFunc nif_funcs[] = {
 
 	{"scramble_block_16", 2, enif_scramble_block_16},
 
+        {"crypto_aead_chacha20poly1305_KEYBYTES", 0, enif_crypto_aead_chacha20poly1305_KEYBYTES},
+        {"crypto_aead_chacha20poly1305_NPUBBYTES", 0, enif_crypto_aead_chacha20poly1305_NPUBBYTES},
+        {"crypto_aead_chacha20poly1305_ABYTES", 0, enif_crypto_aead_chacha20poly1305_ABYTES},
+        {"crypto_aead_chacha20poly1305_MESSAGEBYTES_MAX", 0, enif_crypto_aead_chacha20poly1305_MESSAGEBYTES_MAX},
+        erl_nif_dirty_job_cpu_bound_macro("crypto_aead_chacha20poly1305_encrypt", 4, enif_crypto_aead_chacha20poly1305_encrypt),
+        erl_nif_dirty_job_cpu_bound_macro("crypto_aead_chacha20poly1305_decrypt", 4, enif_crypto_aead_chacha20poly1305_decrypt),
+
 	{"crypto_generichash_BYTES", 0, enif_crypto_generichash_BYTES},
 	{"crypto_generichash_BYTES_MIN", 0, enif_crypto_generichash_BYTES_MIN},
 	{"crypto_generichash_BYTES_MAX", 0, enif_crypto_generichash_BYTES_MAX},

src/enacl.erl

@@ -54,6 +54,13 @@
          stream_chacha20/3,
          stream_chacha20_xor/3,
 
+         aead_chacha20poly1305_encrypt/4,
+         aead_chacha20poly1305_decrypt/4,
+         aead_chacha20poly1305_KEYBYTES/0,
+         aead_chacha20poly1305_NONCEBYTES/0,
+         aead_chacha20poly1305_ABYTES/0,
+         aead_chacha20poly1305_MESSAGEBYTES_MAX/0,
+
          stream_key_size/0,
          stream_nonce_size/0,
          stream/3,
@@ -997,7 +1004,62 @@ kx_public_key_size() ->
 kx_secret_key_size() ->
     enacl_nif:crypto_kx_SECRETKEYBYTES().
 
+%% AEAD ChaCha20 Poly1305
+%% ----------------------
+%% @doc aead_chacha20poly1305_encrypt/4 encrypts `Message` with additional data
+%% `AD` using `Key` and `Nonce`. Returns the encrypted message followed by
+%% `aead_chacha20poly1305_ABYTES/0` bytes of MAC.
+%% @end
+-spec aead_chacha20poly1305_encrypt(Key, Nonce, AD, Msg) -> binary() | {error, term()}
+    when Key :: binary(),
+         Nonce :: pos_integer(),
+         AD :: binary(),
+         Msg :: binary().
+aead_chacha20poly1305_encrypt(Key, Nonce, AD, Msg) ->
+    NonceBin = <<0:32, Nonce:64/little-unsigned-integer>>,
+    enacl_nif:crypto_aead_chacha20poly1305_encrypt(Key, NonceBin, AD, Msg).
 
+%% @doc aead_chacha20poly1305_decrypt/4 decrypts ciphertext `CT` with additional
+%% data `AD` using `Key` and `Nonce`. Note: `CipherText` should contain
+%% `aead_chacha20poly1305_ABYTES/0` bytes that is the MAC. Returns the decrypted
+%% message.
+%% @end
+-spec aead_chacha20poly1305_decrypt(Key, Nonce, AD, CT) -> binary() | {error, term()}
+    when Key :: binary(),
+         Nonce :: pos_integer(),
+         AD :: binary(),
+         CT :: binary().
+aead_chacha20poly1305_decrypt(Key, Nonce, AD, CT) ->
+    NonceBin = <<0:32, Nonce:64/little-unsigned-integer>>,
+    enacl_nif:crypto_aead_chacha20poly1305_decrypt(Key, NonceBin, AD, CT).
+
+%% @doc aead_chacha20poly1305_KEYBYTES/0 returns the number of bytes
+%% of the key used in AEAD ChaCha20 Poly1305 encryption/decryption.
+%% @end
+-spec aead_chacha20poly1305_KEYBYTES() -> pos_integer().
+aead_chacha20poly1305_KEYBYTES() ->
+    enacl_nif:crypto_aead_chacha20poly1305_KEYBYTES().
+
+%% @doc aead_chacha20poly1305_NONCEBYTES/0 returns the number of bytes
+%% of the Nonce in AEAD ChaCha20 Poly1305 encryption/decryption.
+%% @end
+-spec aead_chacha20poly1305_NONCEBYTES() -> pos_integer().
+aead_chacha20poly1305_NONCEBYTES() ->
+    enacl_nif:crypto_aead_chacha20poly1305_NPUBBYTES().
+
+%% @doc aead_chacha20poly1305_ABYTES/0 returns the number of bytes
+%% of the MAC in AEAD ChaCha20 Poly1305 encryption/decryption.
+%% @end
+-spec aead_chacha20poly1305_ABYTES() -> pos_integer().
+aead_chacha20poly1305_ABYTES() ->
+    enacl_nif:crypto_aead_chacha20poly1305_ABYTES().
+
+%% @doc aead_chacha20poly1305_MESSAGEBYTES_MAX/0 returns the max number of bytes
+%% allowed in a message in AEAD ChaCha20 Poly1305 encryption/decryption.
+%% @end
+-spec aead_chacha20poly1305_MESSAGEBYTES_MAX() -> pos_integer().
+aead_chacha20poly1305_MESSAGEBYTES_MAX() ->
+    enacl_nif:crypto_aead_chacha20poly1305_MESSAGEBYTES_MAX().
 
 %% Obtaining random bytes
 

src/enacl_nif.erl

@@ -67,6 +67,13 @@
          crypto_stream_xor/3,
          crypto_stream_xor_b/3,
 
+         crypto_aead_chacha20poly1305_encrypt/4,
+         crypto_aead_chacha20poly1305_decrypt/4,
+         crypto_aead_chacha20poly1305_KEYBYTES/0,
+         crypto_aead_chacha20poly1305_NPUBBYTES/0,
+         crypto_aead_chacha20poly1305_ABYTES/0,
+         crypto_aead_chacha20poly1305_MESSAGEBYTES_MAX/0,
+
          crypto_auth_BYTES/0,
          crypto_auth_KEYBYTES/0,
 
@@ -240,6 +247,13 @@ crypto_stream_b(_Bytes, _Nonce, _Key) -> erlang:nif_error(nif_not_loaded).
 crypto_stream_xor(_M, _Nonce, _Key) -> erlang:nif_error(nif_not_loaded).
 crypto_stream_xor_b(_M, _Nonce, _Key) -> erlang:nif_error(nif_not_loaded).
 
+crypto_aead_chacha20poly1305_encrypt(_Key, _Nonce, _AD, _Message) -> erlang:nif_error(nif_not_loaded).
+crypto_aead_chacha20poly1305_decrypt(_Key, _Nonce, _AD, _Message) -> erlang:nif_error(nif_not_loaded).
+crypto_aead_chacha20poly1305_KEYBYTES()                           -> erlang:nif_error(nif_not_loaded).
+crypto_aead_chacha20poly1305_NPUBBYTES()                          -> erlang:nif_error(nif_not_loaded).
+crypto_aead_chacha20poly1305_ABYTES()                             -> erlang:nif_error(nif_not_loaded).
+crypto_aead_chacha20poly1305_MESSAGEBYTES_MAX()                   -> erlang:nif_error(nif_not_loaded).
+
 crypto_auth_BYTES() -> erlang:nif_error(nif_not_loaded).
 crypto_auth_KEYBYTES() -> erlang:nif_error(nif_not_loaded).
 crypto_auth(_Msg, _Key) -> erlang:nif_error(nif_not_loaded).