From a7469975aded00b32b9a1fde9ad3aa16d998b25c Mon Sep 17 00:00:00 2001
From: Michael Starke <michael.starke@hicknhack-software.com>
Date: Thu, 31 Jan 2019 15:52:50 +0100
Subject: [PATCH] Updated entropy calculation to account for required
 characters

---
 MacPass/MPPasswordCreatorViewController.m |  8 +++--
 MacPass/NSString+MPPasswordCreation.m     | 41 ++++++++++++++++++-----
 2 files changed, 38 insertions(+), 11 deletions(-)

diff --git a/MacPass/MPPasswordCreatorViewController.m b/MacPass/MPPasswordCreatorViewController.m
index 5c23850e..b68c5ac6 100644
--- a/MacPass/MPPasswordCreatorViewController.m
+++ b/MacPass/MPPasswordCreatorViewController.m
@@ -175,7 +175,7 @@ typedef NS_ENUM(NSUInteger, MPPasswordRating) {
                                                length:self.passwordLength];
 }
 
-- (NSString*)_customCharacters{
+- (NSString *)_customCharacters{
   if(self.useCustomString && self.customCharactersTextField.stringValue.length > 0) {
     return self.customCharactersTextField.stringValue;
   }
@@ -319,6 +319,7 @@ typedef NS_ENUM(NSUInteger, MPPasswordRating) {
 - (void)controlTextDidChange:(NSNotification *)obj {
   if([obj object] == self.customCharactersTextField) {
     self.setDefaultButton.enabled = YES;
+    [self _resetCharacters];
     [self _generatePassword:nil];
   }
 }
@@ -394,7 +395,10 @@ typedef NS_ENUM(NSUInteger, MPPasswordRating) {
 
   // ensure minimum character lenght
   if(self.ensureOccurance) {
-    
+    NSUInteger minimumLength = [NSString minimumPasswordLengthWithCharacterSet:self.characterFlags customCharacters:[self _customCharacters] ensureOccurance:self.ensureOccurance];
+    if(self.passwordLength < minimumLength) {
+      self.passwordLength = minimumLength;
+    }
   }
   
 }
diff --git a/MacPass/NSString+MPPasswordCreation.m b/MacPass/NSString+MPPasswordCreation.m
index 17b96cd7..a834e8e7 100644
--- a/MacPass/NSString+MPPasswordCreation.m
+++ b/MacPass/NSString+MPPasswordCreation.m
@@ -84,7 +84,7 @@ static NSString *mergeWithoutDuplicates(NSString* baseCharacters, NSString* cust
                         ensureOccurence:(BOOL)ensureOccurence
                                  length:(NSUInteger)length {
   if(ensureOccurence) {
-    length = MAX(length, [NSString minimumPasswordLengthWithCharacterSet:allowedCharacters customCharacters:customCharacters ensureOccurance:ensureOccurence]);    
+    length = MAX(length, [NSString minimumPasswordLengthWithCharacterSet:allowedCharacters customCharacters:customCharacters ensureOccurance:ensureOccurence]);
   }
   NSMutableString *password = [NSMutableString stringWithCapacity:length];
   NSString *characters = mergeWithoutDuplicates(
@@ -160,16 +160,39 @@ static NSString *mergeWithoutDuplicates(NSString* baseCharacters, NSString* cust
 
 
 - (CGFloat)entropyWhithCharacterSet:(MPPasswordCharacterFlags)characterSet customCharacters:(NSString *)customCharacters ensureOccurance:(BOOL)ensureOccurance {
+  CGFloat passwordLength = self.composedCharacterLength;
+  CGFloat entropy = 0;
   if(ensureOccurance) {
-    return 0;
-  }
-  else {
-    NSString *characters = nil;
-    characters = mergeWithoutDuplicates(allowedCharactersString(characterSet), customCharacters);
-    CGFloat alphabetCount = characters.composedCharacterLength;
-    CGFloat passwordLength = self.composedCharacterLength;
-    return passwordLength * ( log10(alphabetCount) / log10(2) );
+    CGLError alphabetCount = 0;
+    if(characterSet & MPPasswordCharactersLowerCase) {
+      alphabetCount = (CGFloat)characterClassMap()[@(MPPasswordCharactersLowerCase)].length;
+      entropy += log2(alphabetCount);
+    }
+    if(characterSet & MPPasswordCharactersUpperCase) {
+      alphabetCount = (CGFloat)characterClassMap()[@(MPPasswordCharactersUpperCase)].length;
+      entropy += log2(alphabetCount);
+    }
+    if(characterSet & MPPasswordCharactersNumbers) {
+      alphabetCount = (CGFloat)characterClassMap()[@(MPPasswordCharactersNumbers)].length;
+      entropy += log2(alphabetCount);
+      
+    }
+    if(characterSet & MPPasswordCharactersSymbols){
+      alphabetCount = (CGFloat)characterClassMap()[@(MPPasswordCharactersSymbols)].length;
+      entropy += log2(alphabetCount);
+      
+    }
+    if(customCharacters.composedCharacterLength > 0) {
+      entropy += log2(customCharacters.composedCharacterLength);
+    }
+    NSUInteger minLenght = [NSString minimumPasswordLengthWithCharacterSet:characterSet customCharacters:customCharacters ensureOccurance:ensureOccurance];
+    passwordLength -= minLenght;
   }
+  NSString *characters = mergeWithoutDuplicates(allowedCharactersString(characterSet), customCharacters);
+  CGFloat alphabetCount = characters.composedCharacterLength;
+  entropy += passwordLength * log2(alphabetCount);
+  
+  return entropy;
 }
 
 - (NSString *)shuffledString {