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Implemented SASL SCRAM-SHA-1 Authentication
RFC5802 http://tools.ietf.org/html/rfc5802 Support for SHA-1 but would be easy to support other hashing algorithms in the future. Does not support channel binding.
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‎Authentication/SCRAM-SHA-1/XMPPSCRAMSHA1Authentication.h

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//
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// XMPPSCRAMSHA1Authentication.h
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// iPhoneXMPP
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//
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// Created by David Chiles on 3/21/14.
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//
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//
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#import <Foundation/Foundation.h>
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#import "XMPPSASLAuthentication.h"
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#import "XMPPStream.h"
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@interface XMPPSCRAMSHA1Authentication : NSObject <XMPPSASLAuthentication>
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@end
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@interface XMPPStream (XMPPSCRAMSHA1Authentication)
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- (BOOL)supportsSCRAMSHA1Authentication;
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@end

‎Authentication/SCRAM-SHA-1/XMPPSCRAMSHA1Authentication.m

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//
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// XMPPSCRAMSHA1Authentication.m
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// iPhoneXMPP
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//
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// Created by David Chiles on 3/21/14.
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//
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//
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#import "XMPPSCRAMSHA1Authentication.h"
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#import "XMPP.h"
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#import "XMPPLogging.h"
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#import "XMPPStream.h"
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#import "XMPPInternal.h"
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#import "NSData+XMPP.h"
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#import "XMPPStringPrep.h"
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#import <CommonCrypto/CommonKeyDerivation.h>
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#if ! __has_feature(objc_arc)
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#warning This file must be compiled with ARC. Use -fobjc-arc flag (or convert project to ARC).
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#endif
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// Log levels: off, error, warn, info, verbose
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#if DEBUG
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static const int xmppLogLevel = XMPP_LOG_LEVEL_INFO; // | XMPP_LOG_FLAG_TRACE;
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#else
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static const int xmppLogLevel = XMPP_LOG_LEVEL_WARN;
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#endif
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@interface XMPPSCRAMSHA1Authentication ()
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{
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#if __has_feature(objc_arc_weak)
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__weak XMPPStream *xmppStream;
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#else
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__unsafe_unretained XMPPStream *xmppStream;
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#endif
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}
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@property (nonatomic) BOOL awaitingChallenge;
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@property (nonatomic, strong) NSString *username;
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@property (nonatomic, strong) NSString *password;
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@property (nonatomic, strong) NSString *clientNonce;
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@property (nonatomic, strong) NSString *combinedNonce;
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@property (nonatomic, strong) NSString *salt;
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@property (nonatomic, strong) NSNumber *count;
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@property (nonatomic, strong) NSString *serverMessage1;
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@property (nonatomic, strong) NSString *clientFirstMessageBare;
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@property (nonatomic, strong) NSData *serverSignatureData;
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@property (nonatomic, strong) NSData *clientProofData;
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@property (nonatomic) CCHmacAlgorithm hashAlgorithm;
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@end
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///////////RFC5802 http://tools.ietf.org/html/rfc5802 //////////////
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//Channel binding not yet supported
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@implementation XMPPSCRAMSHA1Authentication
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+ (NSString *)mechanismName
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{
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return @"SCRAM-SHA-1";
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}
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- (id)initWithStream:(XMPPStream *)stream password:(NSString *)password
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{
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if ((self = [super init])) {
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xmppStream = stream;
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self.username = [XMPPStringPrep prepNode:[xmppStream.myJID user]];
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self.password = [XMPPStringPrep prepNode:password];
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self.hashAlgorithm = kCCHmacAlgSHA1;
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}
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return self;
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}
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- (BOOL)start:(NSError **)errPtr
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{
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XMPPLogTrace();
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if(self.username.length || self.password.length) {
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NSXMLElement *auth = [NSXMLElement elementWithName:@"auth" xmlns:@"urn:ietf:params:xml:ns:xmpp-sasl"];
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[auth addAttributeWithName:@"mechanism" stringValue:@"SCRAM-SHA-1"];
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[auth setStringValue:[self clientMessage1]];
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[xmppStream sendAuthElement:auth];
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self.awaitingChallenge = YES;
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return YES;
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}
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else {
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return NO;
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}
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}
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- (XMPPHandleAuthResponse)handleAuth1:(NSXMLElement *)authResponse
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{
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XMPPLogTrace();
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// We're expecting a challenge response.
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// If we get anything else we're going to assume it's some kind of failure response.
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if (![[authResponse name] isEqualToString:@"challenge"])
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{
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return XMPP_AUTH_FAIL;
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}
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NSDictionary *auth = [self dictionaryFromChallenge:authResponse];
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NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init];
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[numberFormatter setNumberStyle:NSNumberFormatterDecimalStyle];
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self.combinedNonce = [auth objectForKey:@"r"];
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self.salt = [auth objectForKey:@"s"];
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self.count = [numberFormatter numberFromString:[auth objectForKey:@"i"]];
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//We have all the necessary information to calculate client proof and server signature
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if ([self calculateProofs]) {
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NSXMLElement *response = [NSXMLElement elementWithName:@"response" xmlns:@"urn:ietf:params:xml:ns:xmpp-sasl"];
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[response setStringValue:[self clientMessage2]];
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[xmppStream sendAuthElement:response];
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self.awaitingChallenge = NO;
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return XMPP_AUTH_CONTINUE;
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}
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else {
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return XMPP_AUTH_FAIL;
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}
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}
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- (XMPPHandleAuthResponse)handleAuth2:(NSXMLElement *)authResponse
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{
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XMPPLogTrace();
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NSDictionary *auth = [self dictionaryFromChallenge:authResponse];
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if ([[authResponse name] isEqual:@"success"]) {
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NSString *receivedServerSignature = [auth objectForKey:@"v"];
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if([self.serverSignatureData isEqualToData:[[receivedServerSignature dataUsingEncoding:NSUTF8StringEncoding] xmpp_base64Decoded]]){
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return XMPP_AUTH_SUCCESS;
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}
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else {
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return XMPP_AUTH_FAIL;
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}
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}
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else {
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return XMPP_AUTH_FAIL;
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}
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}
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- (XMPPHandleAuthResponse)handleAuth:(NSXMLElement *)auth
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{
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XMPPLogTrace();
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if (self.awaitingChallenge) {
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return [self handleAuth1:auth];
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}
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else {
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return [self handleAuth2:auth];
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}
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}
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- (NSString *)clientMessage1
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{
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self.clientNonce = [XMPPStream generateUUID];
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self.clientFirstMessageBare = [NSString stringWithFormat:@"n=%@,r=%@",self.username,self.clientNonce];
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NSData *message1Data = [[NSString stringWithFormat:@"n,,%@",self.clientFirstMessageBare] dataUsingEncoding:NSUTF8StringEncoding];
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return [message1Data xmpp_base64Encoded];
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}
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- (NSString *)clientMessage2
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{
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NSString *clientProofString = [self.clientProofData xmpp_base64Encoded];
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NSData *message2Data = [[NSString stringWithFormat:@"c=biws,r=%@,p=%@",self.combinedNonce,clientProofString] dataUsingEncoding:NSUTF8StringEncoding];
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return [message2Data xmpp_base64Encoded];
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}
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- (BOOL)calculateProofs
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{
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//Check to see that we have a password, salt and iteration count above 4096 (from RFC5802)
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if (!self.password.length || !self.salt.length || self.count.unsignedIntegerValue < 4096) {
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return NO;
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}
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NSData *passwordData = [self.password dataUsingEncoding:NSUTF8StringEncoding];
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NSData *saltData = [[self.salt dataUsingEncoding:NSUTF8StringEncoding] xmpp_base64Decoded];
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NSData *saltedPasswordData = [self HashWithAlgorithm:self.hashAlgorithm password:passwordData salt:saltData iterations:[self.count unsignedIntValue]];
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NSData *clientKeyData = [self HashWithAlgorithm:self.hashAlgorithm data:[@"Client Key" dataUsingEncoding:NSUTF8StringEncoding] key:saltedPasswordData];
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NSData *serverKeyData = [self HashWithAlgorithm:self.hashAlgorithm data:[@"Server Key" dataUsingEncoding:NSUTF8StringEncoding] key:saltedPasswordData];
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NSData *storedKeyData = [clientKeyData xmpp_sha1Digest];
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NSData *authMessageData = [[NSString stringWithFormat:@"%@,%@,c=biws,r=%@",self.clientFirstMessageBare,self.serverMessage1,self.combinedNonce] dataUsingEncoding:NSUTF8StringEncoding];
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NSData *clientSignatureData = [self HashWithAlgorithm:self.hashAlgorithm data:authMessageData key:storedKeyData];
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self.serverSignatureData = [self HashWithAlgorithm:self.hashAlgorithm data:authMessageData key:serverKeyData];
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self.clientProofData = [self xorData:clientKeyData withData:clientSignatureData];
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//check to see that we caclulated some client proof and server signature
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if (self.clientProofData && self.serverSignatureData) {
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return YES;
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}
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else {
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return NO;
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}
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}
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- (NSData *)HashWithAlgorithm:(CCHmacAlgorithm) algorithm password:(NSData *)passwordData salt:(NSData *)saltData iterations:(NSUInteger)rounds
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{
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NSMutableData *mutableSaltData = [saltData mutableCopy];
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UInt8 zeroHex= 0x00;
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UInt8 oneHex= 0x01;
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NSData *zeroData = [[NSData alloc] initWithBytes:&zeroHex length:sizeof(zeroHex)];
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NSData *oneData = [[NSData alloc] initWithBytes:&oneHex length:sizeof(oneHex)];
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[mutableSaltData appendData:zeroData];
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[mutableSaltData appendData:zeroData];
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[mutableSaltData appendData:zeroData];
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[mutableSaltData appendData:oneData];
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NSData *result = [self HashWithAlgorithm:algorithm data:mutableSaltData key:passwordData];
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NSData *previous = [result copy];
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for (int i = 1; i < rounds; i++) {
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previous = [self HashWithAlgorithm:algorithm data:previous key:passwordData];
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result = [self xorData:result withData:previous];
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}
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return result;
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}
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- (NSData *)HashWithAlgorithm:(CCHmacAlgorithm) algorithm data:(NSData *)data key:(NSData *)key
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{
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unsigned char cHMAC[CC_SHA1_DIGEST_LENGTH];
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CCHmac(algorithm, [key bytes], [key length], [data bytes], [data length], cHMAC);
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return [[NSData alloc] initWithBytes:cHMAC length:sizeof(cHMAC)];
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}
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- (NSData *)xorData:(NSData *)data1 withData:(NSData *)data2
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{
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NSMutableData *result = data1.mutableCopy;
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char *dataPtr = (char *)result.mutableBytes;
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char *keyData = (char *)data2.bytes;
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char *keyPtr = keyData;
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int keyIndex = 0;
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for (int x = 0; x < data1.length; x++) {
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*dataPtr = *dataPtr ^ *keyPtr;
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dataPtr++;
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keyPtr++;
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if (++keyIndex == data2.length) {
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keyIndex = 0;
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keyPtr = keyData;
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}
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}
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return result;
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}
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- (NSDictionary *)dictionaryFromChallenge:(NSXMLElement *)challenge
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{
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// The value of the challenge stanza is base 64 encoded.
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// Once "decoded", it's just a string of key=value pairs separated by commas.
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NSData *base64Data = [[challenge stringValue] dataUsingEncoding:NSASCIIStringEncoding];
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NSData *decodedData = [base64Data xmpp_base64Decoded];
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self.serverMessage1 = [[NSString alloc] initWithData:decodedData encoding:NSUTF8StringEncoding];
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XMPPLogVerbose(@"%@: Decoded challenge: %@", THIS_FILE, self.serverMessage1);
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NSArray *components = [self.serverMessage1 componentsSeparatedByString:@","];
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NSMutableDictionary *auth = [NSMutableDictionary dictionaryWithCapacity:5];
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for (NSString *component in components)
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{
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NSRange separator = [component rangeOfString:@"="];
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if (separator.location != NSNotFound)
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{
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NSMutableString *key = [[component substringToIndex:separator.location] mutableCopy];
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NSMutableString *value = [[component substringFromIndex:separator.location+1] mutableCopy];
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if(key) CFStringTrimWhitespace((__bridge CFMutableStringRef)key);
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if(value) CFStringTrimWhitespace((__bridge CFMutableStringRef)value);
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if ([value hasPrefix:@"\""] && [value hasSuffix:@"\""] && [value length] > 2)
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{
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// Strip quotes from value
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[value deleteCharactersInRange:NSMakeRange(0, 1)];
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[value deleteCharactersInRange:NSMakeRange([value length]-1, 1)];
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}
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if(key && value)
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{
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[auth setObject:value forKey:key];
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}
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}
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}
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return auth;
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}
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@end
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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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#pragma mark -
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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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@implementation XMPPStream (XMPPSCRAMSHA1Authentication)
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- (BOOL)supportsSCRAMSHA1Authentication
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{
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return [self supportsAuthenticationMechanism:[XMPPSCRAMSHA1Authentication mechanismName]];
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}
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@end

‎Core/XMPP.h

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#import "XMPPSASLAuthentication.h"
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#import "XMPPDigestMD5Authentication.h"
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#import "XMPPSCRAMSHA1Authentication.h"
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#import "XMPPPlainAuthentication.h"
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#import "XMPPXFacebookPlatformAuthentication.h"
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#import "XMPPAnonymousAuthentication.h"

‎Core/XMPPStream.m

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// P.S. - This method is deprecated.
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id <XMPPSASLAuthentication> someAuth = nil;
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if ([self supportsDigestMD5Authentication])
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if ([self supportsSCRAMSHA1Authentication])
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{
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someAuth = [[XMPPSCRAMSHA1Authentication alloc] initWithStream:self password:password];
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result = [self authenticate:someAuth error:&err];
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}
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else if ([self supportsDigestMD5Authentication])
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{
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someAuth = [[XMPPDigestMD5Authentication alloc] initWithStream:self password:password];
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result = [self authenticate:someAuth error:&err];

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