Erlang SDK

The Erlang account client is in erlang/mesgd_auth_client.erl in mesgd-sdk. Use it to enroll an account, obtain a session, and manage public keys independently of the PKI layer. The examples use an existing account named alice; passwords and authenticator codes come from the application rather than literals in source.

Support status

Completeness position: 1 of 18. Verified HTTPS, peer-key helpers, and hybrid seal/open with a tested full public-key registration round trip. The language matrix explains the ranking criteria and comparable tiers. WSS readiness is listed separately; no SDK currently provides a complete, validated encrypted messaging workflow against this server.

Setup and transport

Compile mesgd_auth_client.erl and make the mesgd json module available on the code path. The examples use binaries for usernames, passwords, tokens, and authenticator codes. Load the SDK's pki module explicitly when testing cryptography: mesgd also has a module with that name.

mesgd_auth_client:https/1 creates an httpc transport and starts inets and ssl as needed. https/2 accepts a list of DER CA certificates while preserving certificate and hostname verification.

A custom transport must serialize JSON, attach Authorization: Bearer TOKEN only when a token is supplied, verify the certificate and hostname, reject redirects, and use a finite timeout. Its origin is an HTTPS URL, such as https://mesgd.example.com, rather than a WebSocket URL.

Log in, read keys, and log out

Pass the current authenticator code as a six-digit string, preserving leading zeroes. This example reads the account's published keys and ends the session on its successful path. Applications that retain a session can keep the bearer until logout or expiry instead.

T = mesgd_auth_client:https("https://mesgd.example.com"),
{ ok, Session } = mesgd_auth_client:login(T, <<"alice">>, Password, OTP),
Token = maps:get(<<"access_token">>, Session),
{ ok, Keys } = mesgd_auth_client:keys(T, Token),
{ ok, _ } = mesgd_auth_client:logout(T, Token).

Calls return {ok, Object} or {error, {http, Status}}. Invalid input and transport failures raise errors. The SDK PKI implementation binds keys to the calling process dictionary; initialize it in the process performing the cryptographic operations.

Enroll a new account

The following fragment uses an existing client or transport from the example above. Signup returns a pending enrollment. Display qr_png_base64 or otpauth_uri, let the person configure the authenticator, then collect a code to confirm it. These calls are separate application steps, with user interaction between them.

{ ok, Enrollment } = mesgd_auth_client:signup(
    T, <<"alice">>, <<"alice@example.com">>, Password, []),
% Display the enrollment information before obtaining EnrollmentOTP.
{ ok, Session } = mesgd_auth_client:confirm(
    T, <<"alice">>, maps:get(<<"enrollment_token">>, Enrollment), EnrollmentOTP),
RecoveryCodes = maps:get(<<"recovery_codes">>, Session).

Confirmation returns the first session and eight recovery codes. Display the recovery codes for separate safekeeping. A code accepted for confirmation cannot be reused for login or a key update; wait for a new authenticator step before another operation that consumes a code.

Account operations

A key update takes the session token, current password, a fresh authenticator code, and an array containing only public JWKs. An empty array clears the linked keys. A password reset takes the username, a saved recovery code, a new password, and a fresh authenticator code; success replaces the recovery codes and revokes existing sessions without returning a new session.

The shared authentication reference documents argument order, response fields, and transport behavior. Session refresh is available through the HTTP API but is not wrapped by these seven SDK operations.

Local signing and encryption

This example exercises the local PKI implementation without opening a network connection. It signs a short message, verifies it with the same identity, and encrypts and decrypts it locally. It demonstrates the primitives rather than a complete peer-to-peer exchange.

pki:init("pki_keys.json"),
Message = <<"hello">>,
Signature = pki:sign(Message),
true = pki:verify(Message, Signature),
Ciphertext = pki:encrypt(Message),
Message = pki:decrypt(Ciphertext).

For a different recipient, use that recipient's public encryption key rather than the local identity's encryption key. Public-key export and interoperability coverage vary by implementation; see Keys and Languages. Private key files are not account credentials and must not be sent to PUT /auth/keys.

Message connections

Account login does not establish a message connection. The current server accepts JSON WebSocket frames and can authenticate an upgrade with a login session or an issued grant token. Login sessions carry identity without path restrictions; grants limit routing to assigned patterns. See WebSocket and Routing.

The encrypted registration handshake in the ping/pong samples is not implemented by the current mesgd listener. Treat those samples as experimental cryptographic examples, with compatibility limits described in Samples.

Validation

From the mesgd-sdk repository root, run the account contract suite for this language:

python3 tests/test_auth.py --language erlang

This is an offline request-contract check. Missing toolchains are reported as skips. See Languages for live HTTPS and PKI test coverage.