diff options
| -rw-r--r-- | util/paseto.lua | 123 |
1 files changed, 123 insertions, 0 deletions
diff --git a/util/paseto.lua b/util/paseto.lua new file mode 100644 index 00000000..5f162ad0 --- /dev/null +++ b/util/paseto.lua @@ -0,0 +1,123 @@ +local crypto = require "util.crypto"; +local json = require "util.json"; +local base64_encode = require "util.encodings".base64.encode; +local base64_decode = require "util.encodings".base64.decode; +local secure_equals = require "util.hashes".equals; +local bit = require "util.bitcompat"; +local s_pack = require "util.struct".pack; + +local s_gsub = string.gsub; + +local pubkey_methods = {}; +local privkey_methods = {}; + +local v4_public_pubkey_mt = { __index = pubkey_methods }; +local v4_public_privkey_mt = { __index = privkey_methods }; +local v4_public = {}; + +local b64url_rep = { ["+"] = "-", ["/"] = "_", ["="] = "", ["-"] = "+", ["_"] = "/" }; +local function b64url(data) + return (s_gsub(base64_encode(data), "[+/=]", b64url_rep)); +end +local function unb64url(data) + return base64_decode(s_gsub(data, "[-_]", b64url_rep).."=="); +end + +local function le64(n) + return s_pack("<I8", bit.band(n, 0x7F)); +end + +local function pae(parts) + local o = { le64(#parts) }; + for _, part in ipairs(parts) do + table.insert(o, le64(#part)..part); + end + return table.concat(o); +end + +function privkey_methods:export() + return self.key:private_pem(); +end + +function pubkey_methods:export() + return self.key:public_pem(); +end + +function v4_public.sign(m, sk, f, i) + if getmetatable(sk) ~= v4_public_privkey_mt then + error("cannot sign v4.public tokens with this key"); + end + if type(m) ~= "table" then + return nil, "PASETO payloads must be a table"; + end + m = json.encode(m); + local h = "v4.public."; + local m2 = pae({ h, m, f or "", i or "" }); + local sig = crypto.ed25519_sign(sk.key, m2); + if not f or f == "" then + return h..b64url(m..sig); + else + return h..b64url(m..sig).."."..b64url(f); + end +end + +function v4_public.verify(tok, pk, expected_f, i) + if getmetatable(pk) ~= v4_public_pubkey_mt then + error("cannot verify v4.public tokens with this key"); + end + local h, sm, f = tok:match("^(v4%.public%.)([^%.]+)%.?(.*)$"); + if not h then + return nil, "invalid-token-format"; + end + if expected_f then + if not f or not secure_equals(expected_f, f) then + return nil, "invalid-footer"; + end + end + local raw_sm = unb64url(sm); + if not raw_sm or #raw_sm <= 64 then + return nil, "invalid-token-format"; + end + local s, m = raw_sm:sub(-64), raw_sm:sub(1, -65); + local m2 = pae({ h, m, f or "", i or "" }); + local ok = crypto.ed25519_verify(pk.key, m2, s); + if not ok then + return nil, "invalid-token"; + end + local payload, err = json.decode(m); + if err ~= nil or type(payload) ~= "table" then + return nil, "json-decode-error"; + end + return payload; +end + +function v4_public.new_keypair() + local key = crypto.generate_ed25519_keypair(); + return { + private_key = setmetatable({ + key = key; + }, v4_public_privkey_mt); + public_key = setmetatable({ + key = key; + }, v4_public_pubkey_mt); + }; +end + +function v4_public.import_public_key(pem) + local key = crypto.import_public_pem(pem); + return setmetatable({ + key = key; + }, v4_public_pubkey_mt); +end + +function v4_public.import_private_key(pem) + local key = crypto.import_private_pem(pem); + return setmetatable({ + key = key; + }, v4_public_privkey_mt); +end + +return { + pae = pae; + v4_public = v4_public; +}; |