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/*Copyright (c) 2010, Zachary Schneirov. All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted
provided that the following conditions are met:
- Redistributions of source code must retain the above copyright notice, this list of conditions
and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright notice, this list of
conditions and the following disclaimer in the documentation and/or other materials provided with
the distribution.
- Neither the name of Notational Velocity nor the names of its contributors may be used to endorse
or promote products derived from this software without specific prior written permission. */
#import "KeyDerivationManager.h"
#import "AttributedPlainText.h"
#import "NotationPrefs.h"
#import "KeyDerivationDelaySlider.h"
#import "NSData_transformations.h"
@implementation KeyDerivationManager
- (id)initWithNotationPrefs:(NotationPrefs*)prefs {
notationPrefs = [prefs retain];
//compute initial test duration for the current iteration number
crapData = [[@"random crap" dataUsingEncoding:NSASCIIStringEncoding] retain];
crapSalt = [[NSData randomDataOfLength:256] retain];
lastHashIterationCount = [notationPrefs hashIterationCount];
lastHashDuration = [self delayForHashIterations:lastHashIterationCount];
if (![self init]) {
[self release];
return nil;
return self;
- (void)awakeFromNib {
//let the user choose a delay between 25 ms and 3 1/2 secs
[slider setMinValue:0.025];
[slider setMaxValue:3.5];
[slider setDelegate:self];
[slider setDoubleValue:lastHashDuration];
[self sliderChanged:slider];
[self updateToolTip];
- (id)init {
if ([super init]) {
if (!view) {
if (![NSBundle loadNibNamed:@"KeyDerivationManager" owner:self]) {
NSLog(@"Failed to load KeyDerivationManager.nib");
return nil;
return self;
- (void)dealloc {
[notationPrefs release];
[crapData release];
[crapSalt release];
[super dealloc];
- (NSView*)view {
return view;
- (int)hashIterationCount {
return lastHashIterationCount;
- (void)updateToolTip {
[slider setToolTip:[NSString stringWithFormat:NSLocalizedString(@"PBKDF2 iterations: %d", nil), lastHashIterationCount]];
- (void)mouseUpForKeyDerivationDelaySlider:(KeyDerivationDelaySlider*)aSlider {
double duration = [aSlider doubleValue];
lastHashIterationCount = [self estimatedIterationsForDuration:duration];
if (duration > 0.7) [iterationEstimatorProgress startAnimation:nil];
lastHashDuration = [self delayForHashIterations:lastHashIterationCount];
if (duration > 0.7) [iterationEstimatorProgress stopAnimation:nil];
//update slider for correction
[slider setDoubleValue:lastHashDuration];
[self updateToolTip];
- (IBAction)sliderChanged:(id)sender {
[hashDurationField setAttributedStringValue:[NSAttributedString timeDelayStringWithNumberOfSeconds:[sender doubleValue]]];
- (double)delayForHashIterations:(int)count {
NSDate *before = [NSDate date];
[crapData derivedKeyOfLength:[notationPrefs keyLengthInBits]/8 salt:crapSalt iterations:count];
return [[NSDate date] timeIntervalSinceDate:before];
- (int)estimatedIterationsForDuration:(double)duration {
//we could compute several hash durations at varying counts and use polynomial interpolation, but that may be overkill
int count = (int)((duration * (double)lastHashIterationCount) / (double)lastHashDuration);
int minCount = MAX(2000, count);
//on a 1GHz machine, don't make them wait more than a minute
return MIN(minCount, 9000000);