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/*
* Copyright (c) 2010 Remko Tronçon
* Licensed under the GNU General Public License v3.
* See Documentation/Licenses/GPLv3.txt for more information.
*/
#include <Swiften/SASL/SCRAMSHA1ClientAuthenticator.h>
#include <cassert>
#include <map>
#include <boost/lexical_cast.hpp>
#include <Swiften/StringCodecs/SHA1.h>
#include <Swiften/StringCodecs/Base64.h>
#include <Swiften/StringCodecs/HMAC_SHA1.h>
#include <Swiften/StringCodecs/PBKDF2.h>
#include <Swiften/IDN/StringPrep.h>
#include <Swiften/Base/Concat.h>
namespace Swift {
static std::string escape(const std::string& s) {
std::string result;
for (size_t i = 0; i < s.size(); ++i) {
if (s[i] == ',') {
result += "=2C";
}
else if (s[i] == '=') {
result += "=3D";
}
else {
result += s[i];
}
}
return result;
}
SCRAMSHA1ClientAuthenticator::SCRAMSHA1ClientAuthenticator(const std::string& nonce, bool useChannelBinding) : ClientAuthenticator(useChannelBinding ? "SCRAM-SHA-1-PLUS" : "SCRAM-SHA-1"), step(Initial), clientnonce(nonce), useChannelBinding(useChannelBinding) {
}
boost::optional<SafeByteArray> SCRAMSHA1ClientAuthenticator::getResponse() const {
if (step == Initial) {
return createSafeByteArray(concat(getGS2Header(), getInitialBareClientMessage()));
}
else if (step == Proof) {
ByteArray clientKey = HMAC_SHA1()(saltedPassword, createByteArray("Client Key"));
ByteArray storedKey = SHA1::getHash(clientKey);
ByteArray clientSignature = HMAC_SHA1()(createSafeByteArray(storedKey), authMessage);
ByteArray clientProof = clientKey;
for (unsigned int i = 0; i < clientProof.size(); ++i) {
clientProof[i] ^= clientSignature[i];
}
ByteArray result = concat(getFinalMessageWithoutProof(), createByteArray(",p="), createByteArray(Base64::encode(clientProof)));
return createSafeByteArray(result);
}
else {
return boost::optional<SafeByteArray>();
}
}
bool SCRAMSHA1ClientAuthenticator::setChallenge(const boost::optional<ByteArray>& challenge) {
if (step == Initial) {
if (!challenge) {
return false;
}
initialServerMessage = *challenge;
std::map<char, std::string> keys = parseMap(byteArrayToString(initialServerMessage));
// Extract the salt
ByteArray salt = Base64::decode(keys['s']);
// Extract the server nonce
std::string clientServerNonce = keys['r'];
if (clientServerNonce.size() <= clientnonce.size()) {
return false;
}
std::string receivedClientNonce = clientServerNonce.substr(0, clientnonce.size());
if (receivedClientNonce != clientnonce) {
return false;
}
serverNonce = createByteArray(clientServerNonce.substr(clientnonce.size(), clientServerNonce.npos));
// Extract the number of iterations
int iterations = 0;
try {
iterations = boost::lexical_cast<int>(keys['i']);
}
catch (const boost::bad_lexical_cast&) {
return false;
}
if (iterations <= 0) {
return false;
}
// Compute all the values needed for the server signature
try {
saltedPassword = PBKDF2::encode<HMAC_SHA1>(StringPrep::getPrepared(getPassword(), StringPrep::SASLPrep), salt, iterations);
}
catch (const std::exception&) {
}
authMessage = concat(getInitialBareClientMessage(), createByteArray(","), initialServerMessage, createByteArray(","), getFinalMessageWithoutProof());
ByteArray serverKey = HMAC_SHA1()(saltedPassword, createByteArray("Server Key"));
serverSignature = HMAC_SHA1()(serverKey, authMessage);
step = Proof;
return true;
}
else if (step == Proof) {
ByteArray result = concat(createByteArray("v="), createByteArray(Base64::encode(serverSignature)));
step = Final;
return challenge && challenge == result;
}
else {
return true;
}
}
std::map<char, std::string> SCRAMSHA1ClientAuthenticator::parseMap(const std::string& s) {
std::map<char, std::string> result;
if (s.size() > 0) {
char key = 0;
std::string value;
size_t i = 0;
bool expectKey = true;
while (i < s.size()) {
if (expectKey) {
key = s[i];
expectKey = false;
i++;
}
else if (s[i] == ',') {
result[key] = value;
value = "";
expectKey = true;
}
else {
value += s[i];
}
i++;
}
result[key] = value;
}
return result;
}
ByteArray SCRAMSHA1ClientAuthenticator::getInitialBareClientMessage() const {
std::string authenticationID;
try {
authenticationID = StringPrep::getPrepared(getAuthenticationID(), StringPrep::SASLPrep);
}
catch (const std::exception&) {
}
return createByteArray(std::string("n=" + escape(authenticationID) + ",r=" + clientnonce));
}
ByteArray SCRAMSHA1ClientAuthenticator::getGS2Header() const {
ByteArray channelBindingHeader(createByteArray("n"));
if (tlsChannelBindingData) {
if (useChannelBinding) {
channelBindingHeader = createByteArray("p=tls-unique");
}
else {
channelBindingHeader = createByteArray("y");
}
}
return concat(channelBindingHeader, createByteArray(","), (getAuthorizationID().empty() ? ByteArray() : createByteArray("a=" + escape(getAuthorizationID()))), createByteArray(","));
}
void SCRAMSHA1ClientAuthenticator::setTLSChannelBindingData(const ByteArray& channelBindingData) {
this->tlsChannelBindingData = channelBindingData;
}
ByteArray SCRAMSHA1ClientAuthenticator::getFinalMessageWithoutProof() const {
ByteArray channelBindData;
if (useChannelBinding && tlsChannelBindingData) {
channelBindData = *tlsChannelBindingData;
}
return concat(createByteArray("c=" + Base64::encode(concat(getGS2Header(), channelBindData)) + ",r=" + clientnonce), serverNonce);
}
}
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Swift