File

util/paseto.lua @ 13182:c48ae06e24d6

util.datamanager: Fix indexing first item if not at the very start If the first item does not start at position 0 then the index function produces a phantom first entry covering position zero until where the real first item starts. When using the index, this would make it either appear as the first item was missing or cause an off-by-one issue with remaining items.
author Kim Alvefur <zash@zash.se>
date Mon, 10 Jul 2023 17:19:05 +0200
parent 12975:d10957394a3c
line wrap: on
line source

local crypto = require "prosody.util.crypto";
local json = require "prosody.util.json";
local hashes = require "prosody.util.hashes";
local base64_encode = require "prosody.util.encodings".base64.encode;
local base64_decode = require "prosody.util.encodings".base64.decode;
local secure_equals = require "prosody.util.hashes".equals;
local bit = require "prosody.util.bitcompat";
local hex = require "prosody.util.hex";
local rand = require "prosody.util.random";
local s_pack = require "prosody.util.struct".pack;

local s_gsub = string.gsub;

local v4_public = {};

local b64url_rep = { ["+"] = "-", ["/"] = "_", ["="] = "", ["-"] = "+", ["_"] = "/" };
local function b64url(data)
	return (s_gsub(base64_encode(data), "[+/=]", b64url_rep));
end

local valid_tails = {
	nil; -- Always invalid
	"^.[AQgw]$"; -- b??????00
	"^..[AQgwEUk0IYo4Mcs8]$"; -- b????0000
}

local function unb64url(data)
	local rem = #data%4;
	if data:sub(-1,-1) == "=" or rem == 1 or (rem > 1 and not data:sub(-rem):match(valid_tails[rem])) then
		return nil;
	end
	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)
	if type(parts) ~= "table" then
		error("bad argument #1 to 'pae' (table expected, got "..type(parts)..")");
	end
	local o = { le64(#parts) };
	for _, part in ipairs(parts) do
		table.insert(o, le64(#part)..part);
	end
	return table.concat(o);
end

function v4_public.sign(m, sk, f, i)
	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, 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)
	local h, sm, f = tok:match("^(v4%.public%.)([^%.]+)%.?(.*)$");
	if not h then
		return nil, "invalid-token-format";
	end
	f = f and unb64url(f) or nil;
	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, 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

v4_public.import_private_key = crypto.import_private_pem;
v4_public.import_public_key = crypto.import_public_pem;
function v4_public.new_keypair()
	return crypto.generate_ed25519_keypair();
end

function v4_public.init(private_key_pem, public_key_pem, options)
	local sign, verify = v4_public.sign, v4_public.verify;
	local public_key = public_key_pem and v4_public.import_public_key(public_key_pem);
	local private_key = private_key_pem and v4_public.import_private_key(private_key_pem);
	local default_footer = options and options.default_footer;
	local default_assertion = options and options.default_implicit_assertion;
	return private_key and function (token, token_footer, token_assertion)
		return sign(token, private_key, token_footer or default_footer, token_assertion or default_assertion);
	end, public_key and function (token, expected_footer, token_assertion)
		return verify(token, public_key, expected_footer or default_footer, token_assertion or default_assertion);
	end;
end

function v4_public.new_signer(private_key_pem, options)
	return (v4_public.init(private_key_pem, nil, options));
end

function v4_public.new_verifier(public_key_pem, options)
	return (select(2, v4_public.init(nil, public_key_pem, options)));
end

local v3_local = { _key_mt = {} };

local function v3_local_derive_keys(k, n)
	local tmp = hashes.hkdf_hmac_sha384(48, k, nil, "paseto-encryption-key"..n);
	local Ek = tmp:sub(1, 32);
	local n2 = tmp:sub(33);
	local Ak = hashes.hkdf_hmac_sha384(48, k, nil, "paseto-auth-key-for-aead"..n);
	return Ek, Ak, n2;
end

function v3_local.encrypt(m, k, f, i)
	assert(#k == 32)
	if type(m) ~= "table" then
		return nil, "PASETO payloads must be a table";
	end
	m = json.encode(m);
	local h = "v3.local.";
	local n = rand.bytes(32);
	local Ek, Ak, n2 = v3_local_derive_keys(k, n);

	local c = crypto.aes_256_ctr_encrypt(Ek, n2, m);
	local m2 = pae({ h, n, c, f or "", i or "" });
	local t = hashes.hmac_sha384(Ak, m2);

	if not f or f == "" then
		return h..b64url(n..c..t);
	else
		return h..b64url(n..c..t).."."..b64url(f);
	end
end

function v3_local.decrypt(tok, k, expected_f, i)
	assert(#k == 32)

	local h, sm, f = tok:match("^(v3%.local%.)([^%.]+)%.?(.*)$");
	if not h then
		return nil, "invalid-token-format";
	end
	f = f and unb64url(f) or nil;
	if expected_f then
		if not f or not secure_equals(expected_f, f) then
			return nil, "invalid-footer";
		end
	end
	local m = unb64url(sm);
	if not m or #m <= 80 then
		return nil, "invalid-token-format";
	end
	local n, c, t = m:sub(1, 32), m:sub(33, -49), m:sub(-48);
	local Ek, Ak, n2 = v3_local_derive_keys(k, n);
	local preAuth = pae({ h, n, c, f or "", i or "" });
	local t2 = hashes.hmac_sha384(Ak, preAuth);
	if not secure_equals(t, t2) then
		return nil, "invalid-token";
	end
	local m2 = crypto.aes_256_ctr_decrypt(Ek, n2, c);
	if not m2 then
		return nil, "invalid-token";
	end

	local payload, err = json.decode(m2);
	if err ~= nil or type(payload) ~= "table" then
		return nil, "json-decode-error";
	end
	return payload;
end

function v3_local.new_key()
	return "secret-token:paseto.v3.local:"..hex.encode(rand.bytes(32));
end

function v3_local.init(key, options)
	local encoded_key = key:match("^secret%-token:paseto%.v3%.local:(%x+)$");
	if not encoded_key or #encoded_key ~= 64 then
		return error("invalid key for v3.local");
	end
	local raw_key = hex.decode(encoded_key);
	local default_footer = options and options.default_footer;
	local default_assertion = options and options.default_implicit_assertion;
	return function (token, token_footer, token_assertion)
		return v3_local.encrypt(token, raw_key, token_footer or default_footer, token_assertion or default_assertion);
	end, function (token, token_footer, token_assertion)
		return v3_local.decrypt(token, raw_key, token_footer or default_footer, token_assertion or default_assertion);
	end;
end

function v3_local.new_signer(key, options)
	return (v3_local.init(key, options));
end

function v3_local.new_verifier(key, options)
	return (select(2, v3_local.init(key, options)));
end

return {
	pae = pae;
	v3_local = v3_local;
	v4_public = v4_public;
};