module "scram"
--=========================
---SASL SCRAM-SHA-1 according to draft-ietf-sasl-scram-10
+--SASL SCRAM-SHA-1 according to RFC 5802
--[[
Supported Authentication Backends
-scram-{MECH}:
+scram_{MECH}:
+ -- MECH being a standard hash name (like those at IANA's hash registry) with '-' replaced with '_'
function(username, realm)
- return salted_password, iteration_count, salt, state;
+ return stored_key, server_key, iteration_count, salt, state;
end
]]
end
-- hash algorithm independent Hi(PBKDF2) implementation
-local function Hi(hmac, str, salt, i)
+function Hi(hmac, str, salt, i)
local Ust = hmac(str, salt.."\0\0\0\1");
- local res = Ust;
+ local res = Ust;
for n=1,i-1 do
local Und = hmac(str, Ust)
res = binaryXOR(res, Und)
-- check for forbidden char sequences
for eq in username:gmatch("=(.?.?)") do
if eq ~= "2D" and eq ~= "3D" then
- return false
- end
+ return false
+ end
end
-- replace =2D with , and =3D with =
return username;
end
+local function hashprep(hashname)
+ return hashname:lower():gsub("-", "_");
+end
+
+function getAuthenticationDatabaseSHA1(password, salt, iteration_count)
+ if type(password) ~= "string" or type(salt) ~= "string" or type(iteration_count) ~= "number" then
+ return false, "inappropriate argument types"
+ end
+ if iteration_count < 4096 then
+ log("warn", "Iteration count < 4096 which is the suggested minimum according to RFC 5802.")
+ end
+ local salted_password = Hi(hmac_sha1, password, salt, iteration_count);
+ local stored_key = sha1(hmac_sha1(salted_password, "Client Key"))
+ local server_key = hmac_sha1(salted_password, "Server Key");
+ return true, stored_key, server_key
+end
+
local function scram_gen(hash_name, H_f, HMAC_f)
local function scram_hash(self, message)
if not self.state then self["state"] = {} end
+ if type(message) ~= "string" or #message == 0 then return "failure", "malformed-request" end
if not self.state.name then
-- we are processing client_first_message
local client_first_message = message;
-- TODO: fail if authzid is provided, since we don't support them yet
self.state["client_first_message"] = client_first_message;
- self.state["gs2_cbind_flag"], self.state["authzid"], self.state["name"], self.state["clientnonce"] = client_first_message:match("^(%a),(.*),n=(.*),r=([^,]*).*");
+ self.state["gs2_cbind_flag"], self.state["authzid"], self.state["name"], self.state["clientnonce"]
+ = client_first_message:match("^(%a),(.*),n=(.*),r=([^,]*).*");
-- we don't do any channel binding yet
if self.state.gs2_cbind_flag ~= "n" and self.state.gs2_cbind_flag ~= "y" then
-- retreive credentials
if self.profile.plain then
- local password, state = self.profile.plain(self.state.name, self.realm)
+ local password, state = self.profile.plain(self, self.state.name, self.realm)
if state == nil then return "failure", "not-authorized"
elseif state == false then return "failure", "account-disabled" end
log("debug", "Password violates SASLprep.");
return "failure", "not-authorized", "Invalid password."
end
+
self.state.salt = generate_uuid();
self.state.iteration_count = default_i;
- self.state.salted_password = Hi(HMAC_f, password, self.state.salt, default_i);
- elseif self.profile["scram_"..hash_name] then
- local salted_password, iteration_count, salt, state = self.profile["scram-"..hash_name](self.state.name, self.realm);
+
+ local succ = false;
+ succ, self.state.stored_key, self.state.server_key = getAuthenticationDatabaseSHA1(password, self.state.salt, default_i, self.state.iteration_count);
+ if not succ then
+ log("error", "Generating authentication database failed. Reason: %s", self.state.stored_key);
+ return "failure", "temporary-auth-failure";
+ end
+ elseif self.profile["scram_"..hashprep(hash_name)] then
+ local stored_key, server_key, iteration_count, salt, state = self.profile["scram_"..hashprep(hash_name)](self, self.state.name, self.realm);
if state == nil then return "failure", "not-authorized"
elseif state == false then return "failure", "account-disabled" end
- self.state.salted_password = salted_password;
+ self.state.stored_key = stored_key;
+ self.state.server_key = server_key;
self.state.iteration_count = iteration_count;
self.state.salt = salt
end
self.state["server_first_message"] = server_first_message;
return "challenge", server_first_message
else
- if type(message) ~= "string" then return "failure", "malformed-request" end
-- we are processing client_final_message
local client_final_message = message;
- -- TODO: more strict parsing of client_final_message
- self.state["proof"] = client_final_message:match("p=(.+)");
- self.state["nonce"] = client_final_message:match("r=(.+),p=");
- self.state["channelbinding"] = client_final_message:match("c=(.+),r=");
+ self.state["channelbinding"], self.state["nonce"], self.state["proof"] = client_final_message:match("^c=(.*),r=(.*),.*p=(.*)");
if not self.state.proof or not self.state.nonce or not self.state.channelbinding then
return "failure", "malformed-request", "Missing an attribute(p, r or c) in SASL message.";
end
- if self.state.nonce ~= self.state.servernonce then
- return "failure", "malformed-request", "Wrong nonce in client-second-message.";
+ if self.state.nonce ~= self.state.clientnonce..self.state.servernonce then
+ return "failure", "malformed-request", "Wrong nonce in client-final-message.";
end
- local SaltedPassword = self.state.salted_password;
- local ClientKey = HMAC_f(SaltedPassword, "Client Key")
- local ServerKey = HMAC_f(SaltedPassword, "Server Key")
- local StoredKey = H_f(ClientKey)
+ local ServerKey = self.state.server_key;
+ local StoredKey = self.state.stored_key;
+
local AuthMessage = "n=" .. s_match(self.state.client_first_message,"n=(.+)") .. "," .. self.state.server_first_message .. "," .. s_match(client_final_message, "(.+),p=.+")
local ClientSignature = HMAC_f(StoredKey, AuthMessage)
- local ClientProof = binaryXOR(ClientKey, ClientSignature)
+ local ClientKey = binaryXOR(ClientSignature, base64.decode(self.state.proof))
local ServerSignature = HMAC_f(ServerKey, AuthMessage)
- if base64.encode(ClientProof) == self.state.proof then
+ if StoredKey == H_f(ClientKey) then
local server_final_message = "v="..base64.encode(ServerSignature);
self["username"] = self.state.name;
return "success", server_final_message;
function init(registerMechanism)
local function registerSCRAMMechanism(hash_name, hash, hmac_hash)
- registerMechanism("SCRAM-"..hash_name, {"plain", "scram_"..(hash_name:lower())}, scram_gen(hash_name:lower(), hash, hmac_hash));
+ registerMechanism("SCRAM-"..hash_name, {"plain", "scram_"..(hashprep(hash_name))}, scram_gen(hash_name:lower(), hash, hmac_hash));
end
registerSCRAMMechanism("SHA-1", sha1, hmac_sha1);
end
-return _M;
\ No newline at end of file
+return _M;
projects / prosody.git / blobdiff