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-rw-r--r--util/paseto.lua218
1 files changed, 218 insertions, 0 deletions
diff --git a/util/paseto.lua b/util/paseto.lua
new file mode 100644
index 00000000..5a9acafb
--- /dev/null
+++ b/util/paseto.lua
@@ -0,0 +1,218 @@
+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;
+};