Module: Tina4::Auth

Defined in:
lib/tina4/auth.rb

Constant Summary collapse

KEYS_DIR = 
".keys"
BLANK_SECRET_WARNING =

Single source of truth for the blank-secret warning, emitted identically from both the CI/prod boot path (ensure_dev_secret) and the lazy per-call resolver (hmac_secret). Actionable: names exactly what to set.

"Auth: TINA4_SECRET is not set — JWT signing is insecure. Set TINA4_SECRET " \
"to a random value (e.g. `openssl rand -hex 32`) in your environment or " \
".env before serving traffic. " \
"For LOCAL DEV, set TINA4_DEBUG=true and a per-machine secret is generated " \
"automatically into .env.local (gitignored). Seeing this warning means the " \
"run was NOT detected as dev - typically a container or CI without " \
"TINA4_DEBUG set, or TINA4_ENV=production."
HMAC_ALGORITHMS =

Supported JWT algorithms. HMAC only — the whole family ships in OpenSSL, so this stays zero-gem. The header's "alg" is now always the one we actually sign with: the digest is looked up here rather than hardcoded to SHA256. Mirrors the Python master's _HMAC_ALGORITHMS (a name -> digest map); the value is the digest CLASS and a fresh instance is made per signature, so nothing about the digest state is shared between calls or threads.

{
  "HS256" => OpenSSL::Digest::SHA256,
  "HS384" => OpenSSL::Digest::SHA384,
  "HS512" => OpenSSL::Digest::SHA512
}.freeze
RS256_UNAVAILABLE_MESSAGE =

RS256 (RSA-SHA256) is the OPT-IN asymmetric algorithm, and Ruby needs NO gem for it: OpenSSL is a stdlib DEFAULT GEM, so OpenSSL::PKey::RSA#sign/#verify emit and check exactly the RFC 7515 signature the other frameworks do (measured: a token minted here verifies under PHP openssl_verify AND Node crypto.createVerify, and a tampered payload goes INVALID in both). The jwt gem was declared only to wrap the base64url envelope this file already builds for HMAC, so it was dropped.

The contract requires a LOUD, ACTIONABLE failure wherever RS256 is unavailable. In Ruby that branch is UNREACHABLE in practice: the require "openssl" at the top of this file is what supplies OpenSSL::HMAC for the HMAC path too, so an interpreter lacking it cannot load Tina4 at all. The message therefore names the real remedy and deliberately does NOT suggest installing a library — there is none to install.

"RS256 is unavailable: this Ruby has no OpenSSL::PKey::RSA. OpenSSL is a " \
"Ruby stdlib DEFAULT GEM, so this interpreter was built without the openssl " \
"extension — rebuild Ruby with OpenSSL support, or use a build that ships " \
"it. Do NOT install a JWT gem: Tina4 signs and verifies RS256 with stdlib " \
"OpenSSL and needs no third-party library. Tina4's standard algorithms are " \
"HS256/HS384/HS512, which are stdlib OpenSSL too."
JWT_LEEWAY_SECONDS =

Seconds of clock skew tolerated on the "nbf" (not-before) claim. Without this a token minted on one host and validated on another a second behind is rejected for no real reason; RFC 7519 explicitly allows "a small leeway".

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Class Method Summary collapse

Class Method Details

.auth_handler(&block) ⇒ Object 



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# File 'lib/tina4/auth.rb', line 432

def auth_handler(&block)
  if block_given?
    @custom_handler = block
  else
    @custom_handler || method(:default_auth_handler)
  end
end

.authenticate_request(headers, secret: nil, algorithm: nil) ⇒ Object

Extract and validate auth from request headers.

secret: and algorithm: are real overrides. algorithm: used to be accepted with a hardcoded "HS256" default and then dropped on the floor, so an explicit argument silently lost to TINA4_JWT_ALGORITHM — the precedence is now honoured here too (explicit > env > HS256).



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# File 'lib/tina4/auth.rb', line 390

def authenticate_request(headers, secret: nil, algorithm: nil)
  auth_header = headers["HTTP_AUTHORIZATION"] || headers["Authorization"] || ""
  return nil unless auth_header =~ /\ABearer\s+(.+)\z/i

  token = Regexp.last_match(1)

  # The JWT is checked FIRST, then the API key — the order Python, PHP and
  # Node all use. Ruby checked the API key first, so the same request could
  # authenticate differently depending on the framework.
  #
  # A custom secret and/or algorithm validates against those directly rather
  # than this process's env-resolved defaults.
  payload = if secret || algorithm
              hmac_decode(token, secret || hmac_secret, algorithm: algorithm)
            elsif valid_token(token)
              get_payload(token)
            end
  return payload if payload

  # API_KEY bypass — timing-safe comparison via validate_api_key
  # (OpenSSL.fixed_length_secure_compare). Parity with Python's
  # authenticate_request (validate_api_key), PHP (hash_equals) and
  # Node (timingSafeEqual). Never use a plain `==` here — that leaks the
  # key length/prefix through comparison timing.
  #
  # "_auth" is the cross-framework key for a non-JWT auth result; PHP and
  # Node already used it, Python used "auth_type" and Ruby "api_key", so the
  # same successful auth read three different ways.
  return { "_auth" => "api_key" } if validate_api_key(token)

  nil
end

.base64url_decode(str) ⇒ Object

Base64url-decode (handles missing padding)



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# File 'lib/tina4/auth.rb', line 146

def base64url_decode(str)
  # Add back padding
  remainder = str.length % 4
  str += "=" * ((4 - remainder) % 4) if remainder != 0
  Base64.urlsafe_decode64(str)
end

.base64url_encode(data) ⇒ Object

Base64url-encode without padding (JWT spec)



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# File 'lib/tina4/auth.rb', line 141

def base64url_encode(data)
  Base64.urlsafe_encode64(data, padding: false)
end

.bearer_auth ⇒ Object 



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# File 'lib/tina4/auth.rb', line 440

def bearer_auth
  lambda do |env|
    auth_header = env["HTTP_AUTHORIZATION"] || ""
    return false unless auth_header =~ /\ABearer\s+(.+)\z/i

    token = Regexp.last_match(1)

    # JWT first, then the API key — same order and same payload shape as
    # authenticate_request above (and as Python/PHP/Node).
    if valid_token(token)
      env["tina4.auth"] = get_payload(token)
      return true
    end

    # API_KEY bypass — timing-safe comparison via validate_api_key
    # (OpenSSL.fixed_length_secure_compare). Parity with Python's
    # authenticate_request (validate_api_key), PHP (hash_equals) and
    # Node (timingSafeEqual). Never use a plain `==` here — that leaks the
    # key length/prefix through comparison timing.
    if validate_api_key(token)
      env["tina4.auth"] = { "_auth" => "api_key" }
      return true
    end

    false
  end
end

.check_password(password, hash) ⇒ Object 



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# File 'lib/tina4/auth.rb', line 344

def check_password(password, hash)
  parts = hash.split('$')
  return false unless parts.length == 4 && parts[0] == 'pbkdf2_sha256'
  iterations = parts[1].to_i
  salt = parts[2]
  expected = parts[3]
  dk = OpenSSL::KDF.pbkdf2_hmac(password, salt: salt, iterations: iterations, length: 32, hash: "sha256")
  actual = dk.unpack1('H*')
  # Timing-safe comparison
  OpenSSL.fixed_length_secure_compare(actual, expected)
rescue
  false
end

.decode_envelope(token, algorithm) ⇒ Object

Read the envelope, PIN the header alg, check the signature via the block, then apply the RFC 7519 claim rules. Returns the payload hash or nil.

The algorithm is PINNED to our configured one rather than trusted from the token: a header asking to be verified as anything else — "none", a different HMAC, or RS256 while we are configured for HMAC — is rejected before any signature work. Making RS256 opt-in must NOT open algorithm substitution, so both paths share this one pin.



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# File 'lib/tina4/auth.rb', line 200

def decode_envelope(token, algorithm)
  parts = token.to_s.split(".")
  return nil unless parts.length == 3
  return nil unless JSON.parse(base64url_decode(parts[0]))["alg"] == algorithm
  return nil unless yield("#{parts[0]}.#{parts[1]}", base64url_decode(parts[2]))

  payload = JSON.parse(base64url_decode(parts[1]))
  now = Time.now.to_i

  # RFC 7519 s4.1.4: "The processing of the 'exp' claim requires that the
  # current date/time MUST be before the expiration date/time". now == exp
  # is therefore ALREADY expired, so the test is >=.
  #
  # key? — NOT a truthiness test on the value. A PRESENT but malformed exp
  # must never read as "no constraint": `payload["exp"] && ...` skipped the
  # check entirely for exp: null / exp: false, turning a broken token into
  # one that never expires.
  if payload.key?("exp")
    exp = numeric_date(payload["exp"])
    return nil if exp.nil? || now >= exp
  end

  # "nbf" (not-before): a post-dated token is not valid yet. Tolerate
  # JWT_LEEWAY_SECONDS of clock skew so a token minted on a host a second
  # ahead is not rejected for nothing. Same malformed-is-rejected rule as
  # exp; NO nbf key at all stays unconstrained (non-breaking).
  if payload.key?("nbf")
    nbf = numeric_date(payload["nbf"])
    return nil if nbf.nil? || now + JWT_LEEWAY_SECONDS < nbf
  end

  payload
rescue ArgumentError, JSON::ParserError, OpenSSL::OpenSSLError
  nil
end

.default_secure_auth ⇒ Object

Default auth handler for secured routes (POST/PUT/PATCH/DELETE) Used automatically unless auth: false is passed



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# File 'lib/tina4/auth.rb', line 470

def default_secure_auth
  @default_secure_auth ||= bearer_auth
end

.encode_envelope(algorithm, claims) ⇒ Object

Write the base64url header.payload.signature envelope. The signature bytes come from the block, so the HMAC and RS256 paths share ONE envelope writer — and one place where "alg" is stamped from whatever actually signed.



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# File 'lib/tina4/auth.rb', line 183

def encode_envelope(algorithm, claims)
  segments = [
    base64url_encode(JSON.generate({ "alg" => algorithm, "typ" => "JWT" })),
    base64url_encode(JSON.generate(claims))
  ]
  segments << base64url_encode(yield(segments.join(".")))
  segments.join(".")
end

.ensure_dev_secret(root_dir = Dir.pwd) ⇒ Object

Boot-time bootstrap (run once after env load, before auth is used).

Mirrors the Python master's tina4_python.auth.ensure_dev_secret:

- If TINA4_SECRET is already set → no-op (returns nil).
- Else if NOT dev, OR CI, OR production → emit the actionable
blank-secret warning and return nil. NEVER generates or persists a
secret in CI or production. (Hard security constraint.)
- Else (dev, not CI, not prod, blank secret) → mint a 32-byte
(64 hex char) random secret, set it in the process env immediately,
then APPEND it to <root_dir>/.env.local (gitignored, created if
missing). On ANY write failure keep the in-memory secret and warn —
never raise (boot must not crash).

root_dir exists only so tests can target a temp dir without chdir; production callers pass nothing (defaults to Dir.pwd).

Returns the generated secret (String) when it mints one, else nil.



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# File 'lib/tina4/auth.rb', line 87

def ensure_dev_secret(root_dir = Dir.pwd)
  existing = ENV["TINA4_SECRET"]
  return nil if existing && !existing.empty?

  unless dev? && !ci? && !production?
    warn_blank_secret
    return nil
  end

  new_secret = SecureRandom.hex(32) # 32 bytes -> 64 hex chars
  ENV["TINA4_SECRET"] = new_secret  # available for this run immediately

  begin
    local_path = File.join(root_dir, ".env.local")
    # If the file exists and does not end in a newline, prepend one so the
    # new key lands on its own line rather than gluing onto the last value.
    prefix = ""
    if File.exist?(local_path)
      content = File.read(local_path)
      prefix = "\n" if !content.empty? && !content.end_with?("\n")
    end
    File.open(local_path, "a") { |f| f.write("#{prefix}TINA4_SECRET=#{new_secret}\n") }
    log_info("Auth: generated a development secret, saved to .env.local (gitignored)")
  rescue StandardError => e
    # Keep the in-memory secret for this run; just warn. Never crash boot.
    log_warning("Auth: generated a development secret but could not write .env.local (#{e.message}); using it for this run only")
  end

  new_secret
end

.get_payload(token) ⇒ Object 



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# File 'lib/tina4/auth.rb', line 359

def get_payload(token)
  parts = token.split(".")
  return nil unless parts.length == 3

  payload_json = base64url_decode(parts[1])
  JSON.parse(payload_json)
rescue ArgumentError, JSON::ParserError
  nil
end

.get_token(payload, expires_in: 60, secret: nil, algorithm: nil) ⇒ Object Also known as: create_token

Mint a signed JWT.

algorithm: selects the HMAC algorithm (else TINA4_JWT_ALGORITHM, else HS256); an unsupported one raises ArgumentError rather than quietly downgrading. It applies to the HMAC path only — the opt-in RS256 path (RSA keys present in .keys/) is unaffected.

BREAKING (deliberate): no "nbf" claim is stamped. It duplicated "iat", added no security, and created clock-skew rejections; RFC 7519 nbf is for deliberately post-dated tokens, which stays fully supported when the caller passes its own "nbf" in the payload. Python/PHP/Node never auto-stamped it, so Ruby doing so was the parity break.



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# File 'lib/tina4/auth.rb', line 295

def get_token(payload, expires_in: 60, secret: nil, algorithm: nil)
  now = Time.now.to_i
  claims = payload.merge(
    "iat" => now,
    "exp" => now + (expires_in * 60).to_i
  )

  if secret
    hmac_encode(claims, secret, algorithm: algorithm)
  elsif use_hmac?
    hmac_encode(claims, hmac_secret, algorithm: algorithm)
  else
    ensure_keys
    rs256_encode(claims)
  end
end

.hash_password(password, salt = nil, iterations = 260000) ⇒ Object 



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# File 'lib/tina4/auth.rb', line 338

def hash_password(password, salt = nil, iterations = 260000)
  salt ||= SecureRandom.hex(16)
  dk = OpenSSL::KDF.pbkdf2_hmac(password, salt: salt, iterations: iterations, length: 32, hash: "sha256")
  "pbkdf2_sha256$#{iterations}$#{salt}$#{dk.unpack1('H*')}"
end

.hmac_decode(token, secret, algorithm: nil) ⇒ Object

Decode and verify an HMAC-signed JWT. Returns the payload hash or nil.



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# File 'lib/tina4/auth.rb', line 245

def hmac_decode(token, secret, algorithm: nil)
  # Resolved OUTSIDE decode_envelope's rescue: an unsupported algorithm is a
  # configuration error that must surface, not become a nil "invalid token".
  alg = resolve_algorithm(algorithm)

  decode_envelope(token, alg) do |input, signature|
    expected = hmac_signature(alg, secret, input)
    # Constant-time comparison to prevent timing attacks. Lengths must match
    # first — fixed_length_secure_compare RAISES on a length mismatch, which
    # a forged signature of the wrong digest size would trigger.
    expected.bytesize == signature.bytesize &&
      OpenSSL.fixed_length_secure_compare(expected, signature)
  end
end

.hmac_encode(claims, secret, algorithm: nil) ⇒ Object

Build a JWT with Ruby's OpenSSL::HMAC (no gem needed). The algorithm is the explicit argument, else TINA4_JWT_ALGORITHM, else HS256 — and the header advertises exactly the algorithm that signed.



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# File 'lib/tina4/auth.rb', line 239

def hmac_encode(claims, secret, algorithm: nil)
  alg = resolve_algorithm(algorithm)
  encode_envelope(alg, claims) { |input| hmac_signature(alg, secret, input) }
end

.hmac_secret ⇒ Object

Lazy per-call secret resolver. When the secret is blank, emit the actionable blank-secret warning (the same text the CI/prod bootstrap path uses) before returning. Parity with Python's _resolve_secret.



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# File 'lib/tina4/auth.rb', line 134

def hmac_secret
  secret = ENV["TINA4_SECRET"]
  warn_blank_secret if secret.nil? || secret.empty?
  secret
end

.hmac_signature(algorithm, secret, signing_input) ⇒ Object

HMAC the signing input with the digest the algorithm actually names, so the header's "alg" can never disagree with the bytes we produced.



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# File 'lib/tina4/auth.rb', line 176

def hmac_signature(algorithm, secret, signing_input)
  OpenSSL::HMAC.digest(HMAC_ALGORITHMS.fetch(algorithm).new, secret.to_s, signing_input)
end

.private_key ⇒ Object 



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# File 'lib/tina4/auth.rb', line 478

def private_key
  @private_key ||= OpenSSL::PKey::RSA.new(File.read(private_key_path))
end

.public_key ⇒ Object 



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# File 'lib/tina4/auth.rb', line 482

def public_key
  @public_key ||= OpenSSL::PKey::RSA.new(File.read(public_key_path))
end

.refresh_token(token, expires_in: 60) ⇒ Object

Validate and re-issue a token with the same claims.

Only "iat"/"exp" are dropped (they are re-stamped). A caller-supplied "nbf" is PRESERVED — matching the Python master, and keeping the promise made when auto-nbf was removed: a deliberately post-dated claim is the issuer's, and a refresh must not quietly erase it.



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# File 'lib/tina4/auth.rb', line 375

def refresh_token(token, expires_in: 60)
  return nil unless valid_token(token)

  payload = get_payload(token)
  return nil unless payload
  payload = payload.reject { |k, _| %w[iat exp].include?(k) }
  get_token(payload, expires_in: expires_in)
end

.resolve_algorithm(algorithm = nil) ⇒ Object

Pick the JWT algorithm: explicit argument, else TINA4_JWT_ALGORITHM, else HS256. A blank value counts as unset (parity with Python, where an empty env string is falsy and falls through).

Raises ArgumentError naming the supported set when asked for one we cannot sign — Ruby's idiomatic equivalent of the master's ValueError. The env var was registered in the CLI's known_vars and then silently ignored here, so a user could set HS512 and still get HS256 tokens.



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# File 'lib/tina4/auth.rb', line 161

def resolve_algorithm(algorithm = nil)
  candidate = [algorithm, ENV["TINA4_JWT_ALGORITHM"]]
              .find { |value| !value.nil? && !value.to_s.strip.empty? }
  chosen = (candidate || "HS256").to_s.strip
  unless HMAC_ALGORITHMS.key?(chosen)
    raise ArgumentError,
          "Unsupported JWT algorithm #{chosen.inspect}. Tina4 signs with " \
          "#{HMAC_ALGORITHMS.keys.sort.join(', ')} (HMAC only, zero-dependency). " \
          "Set TINA4_JWT_ALGORITHM to one of those."
  end
  chosen
end

.rs256_available? ⇒ Boolean

Does this runtime provide RSA natively? Ruby ships OpenSSL as a stdlib DEFAULT GEM, so this is true on every normal build — there is nothing to install and nothing to opt into at the library level.

Returns:

  • (Boolean) 


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# File 'lib/tina4/auth.rb', line 265

def rs256_available?
  defined?(OpenSSL::PKey::RSA) ? true : false
end

.rs256_decode(token) ⇒ Object 



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# File 'lib/tina4/auth.rb', line 276

def rs256_decode(token)
  require_rs256!
  decode_envelope(token, "RS256") { |input, sig| public_key.verify(OpenSSL::Digest::SHA256.new, sig, input) }
end

.rs256_encode(claims) ⇒ Object

RSA-SHA256, with a FRESH digest instance per call so nothing about the digest state is shared between calls or threads (same rule as HMAC).



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# File 'lib/tina4/auth.rb', line 271

def rs256_encode(claims)
  require_rs256!
  encode_envelope("RS256", claims) { |input| private_key.sign(OpenSSL::Digest::SHA256.new, input) }
end

.setup(root_dir = Dir.pwd) ⇒ Object 



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# File 'lib/tina4/auth.rb', line 64

def setup(root_dir = Dir.pwd)
  @keys_dir = File.join(root_dir, KEYS_DIR)
  FileUtils.mkdir_p(@keys_dir)
  ensure_keys
end

.use_hmac? ⇒ Boolean

Returns true when SECRET env var is set and no RSA keys exist in .keys/

Returns:

  • (Boolean) 


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# File 'lib/tina4/auth.rb', line 121

def use_hmac?
  secret = ENV["TINA4_SECRET"]
  return false if secret.nil? || secret.empty?

  # If RSA keys already exist on disk, prefer RS256 for backward compat
  @keys_dir ||= File.join(Dir.pwd, KEYS_DIR)
  !(File.exist?(File.join(@keys_dir, "private.pem")) &&
    File.exist?(File.join(@keys_dir, "public.pem")))
end

.valid_token(token) ⇒ Object

Verify a JWT signature + expiry.

3.13.0: return type changed from Boolean to Hash | nil. The decoded payload is returned on success, nil on failure. Matches Python's Auth.valid_token in 3.13.0.

Legacy if Tina4::Auth.valid_token(t) patterns keep working because a non-empty Hash is truthy and nil is falsy.



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# File 'lib/tina4/auth.rb', line 320

def valid_token(token)
  if use_hmac?
    hmac_decode(token, hmac_secret) # returns Hash payload or nil
  else
    ensure_keys
    rs256_decode(token)
  end
end

.valid_token_detail(token) ⇒ Object Also known as: validate_token

BREAKING (deliberate): the RS256 branch used to surface the jwt gem's own wording ("Signature has expired", or a raw decode message). Both paths now report the single HMAC-path wording, so the detail shape no longer depends on which algorithm signed.



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# File 'lib/tina4/auth.rb', line 333

def valid_token_detail(token)
  payload = valid_token(token)
  payload ? { valid: true, payload: payload } : { valid: false, error: "Invalid or expired token" }
end

.validate_api_key(provided, expected: nil) ⇒ Object 



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# File 'lib/tina4/auth.rb', line 423

def validate_api_key(provided, expected: nil)
  expected ||= ENV["TINA4_API_KEY"]
  return false if expected.nil? || expected.empty?
  return false if provided.nil? || provided.empty?
  return false if provided.length != expected.length

  OpenSSL.fixed_length_secure_compare(provided, expected)
end