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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/HMACSHA1.h"
#include "Swiften/StringCodecs/PBKDF2.h"
#include "Swiften/IDN/StringPrep.h"
namespace Swift {
static String escape(const String& s) {
String result;
for (size_t i = 0; i < s.getUTF8Size(); ++i) {
if (s[i] == ',') {
result += "=2C";
}
else if (s[i] == '=') {
result += "=3D";
}
else {
result += s[i];
}
}
return result;
}
SCRAMSHA1ClientAuthenticator::SCRAMSHA1ClientAuthenticator(const String& nonce, bool useChannelBinding) : ClientAuthenticator("SCRAM-SHA-1"), step(Initial), clientnonce(nonce), useChannelBinding(useChannelBinding) {
}
boost::optional<ByteArray> SCRAMSHA1ClientAuthenticator::getResponse() const {
if (step == Initial) {
return getGS2Header() + getInitialBareClientMessage();
}
else if (step == Proof) {
ByteArray clientKey = HMACSHA1::getResult(saltedPassword, "Client Key");
ByteArray storedKey = SHA1::getHash(clientKey);
ByteArray clientSignature = HMACSHA1::getResult(storedKey, authMessage);
ByteArray clientProof = clientKey;
for (unsigned int i = 0; i < clientProof.getSize(); ++i) {
clientProof[i] ^= clientSignature[i];
}
ByteArray channelBindData;
if (useChannelBinding && tlsChannelBindingData) {
channelBindData = *tlsChannelBindingData;
}
ByteArray result = ByteArray("c=") + Base64::encode(getGS2Header() + channelBindData) + ",r=" + clientnonce + serverNonce + ",p=" + Base64::encode(clientProof);
return result;
}
else {
return boost::optional<ByteArray>();
}
}
bool SCRAMSHA1ClientAuthenticator::setChallenge(const boost::optional<ByteArray>& challenge) {
if (step == Initial) {
if (!challenge) {
return false;
}
initialServerMessage = *challenge;
std::map<char, String> keys = parseMap(String(initialServerMessage.getData(), initialServerMessage.getSize()));
// Extract the salt
ByteArray salt = Base64::decode(keys['s']);
// Extract the server nonce
String clientServerNonce = keys['r'];
if (clientServerNonce.getUTF8Size() <= clientnonce.getUTF8Size()) {
return false;
}
String receivedClientNonce = clientServerNonce.getSubstring(0, clientnonce.getUTF8Size());
if (receivedClientNonce != clientnonce) {
return false;
}
serverNonce = clientServerNonce.getSubstring(clientnonce.getUTF8Size(), clientServerNonce.npos());
// Extract the number of iterations
int iterations = 0;
try {
iterations = boost::lexical_cast<int>(keys['i'].getUTF8String());
}
catch (const boost::bad_lexical_cast&) {
return false;
}
if (iterations <= 0) {
return false;
}
// Compute all the values needed for the server signature
saltedPassword = PBKDF2::encode(StringPrep::getPrepared(getPassword(), StringPrep::SASLPrep), salt, iterations);
authMessage = getInitialBareClientMessage() + "," + initialServerMessage + "," + "c=" + Base64::encode(getGS2Header()) + ",r=" + clientnonce + serverNonce;
ByteArray serverKey = HMACSHA1::getResult(saltedPassword, "Server Key");
serverSignature = HMACSHA1::getResult(serverKey, authMessage);
step = Proof;
return true;
}
else if (step == Proof) {
ByteArray result = ByteArray("v=") + ByteArray(Base64::encode(serverSignature));
step = Final;
return challenge && challenge == result;
}
else {
return true;
}
}
std::map<char, String> SCRAMSHA1ClientAuthenticator::parseMap(const String& s) {
std::map<char, String> result;
if (s.getUTF8Size() > 0) {
char key;
String value;
size_t i = 0;
bool expectKey = true;
while (i < s.getUTF8Size()) {
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 {
String authenticationID = StringPrep::getPrepared(getAuthenticationID(), StringPrep::SASLPrep);
return ByteArray(String("n=" + escape(authenticationID) + ",r=" + clientnonce));
}
ByteArray SCRAMSHA1ClientAuthenticator::getGS2Header() const {
ByteArray channelBindingHeader("n");
if (tlsChannelBindingData) {
if (useChannelBinding) {
channelBindingHeader = ByteArray("p=tls-server-end-point");
}
else {
channelBindingHeader = ByteArray("y");
}
}
return channelBindingHeader + ByteArray(",") + (getAuthorizationID().isEmpty() ? "" : "a=" + escape(getAuthorizationID())) + ",";
}
void SCRAMSHA1ClientAuthenticator::setTLSChannelBindingData(const ByteArray& channelBindingData) {
this->tlsChannelBindingData = channelBindingData;
}
}
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Swift