So I need to generate a Sha256 password in Objective-C, and can't figure out for the life of me how to do it! Is there something easy I'm just missing?
I've tried implementing the following method (which was written for iPhone, but I figured maybe it'd work cross-platform, as some Objective-C code does)
-(NSString*)sha256HashFor:(NSString*)input
{
const char* str = [input UTF8String];
unsigned char result[CC_SHA256_DIGEST_LENGTH];
CC_SHA256(str, strlen(str), result);
NSMutableString *ret = [NSMutableString stringWithCapacity:CC_SHA256_DIGEST_LENGTH*2];
for(int i = 0; i<CC_SHA256_DIGEST_LENGTH; i++)
{
[ret appendFormat:#"%02x",result[i]];
}
return ret;
}
But that just spat out errors about CC_SHA256_DIGEST_LENGTH being an undeclared identifier.
You need to include the appropriate header file:
#include <CommonCrypto/CommonDigest.h>
According to the Cryptographic Services documentation this should be available on both iOS and OS X.
In OS X v10.5 and later and iOS 5.0 and later, Common Crypto provides low-level C support for encryption and decryption. Common Crypto is not as straightforward as Security Transforms, but provides a wider range of features, including additional hashing schemes, cipher modes, and so on.
#import <CommonCrypto/CommonDigest.h>
Objective-C: SHA256 is only two lines:
+ (NSData *)doSha256:(NSData *)dataIn {
NSMutableData *macOut = [NSMutableData dataWithLength:CC_SHA256_DIGEST_LENGTH];
CC_SHA256(dataIn.bytes, dataIn.length, macOut.mutableBytes);
return macOut;
}
Swift 3
func sha256Hex(string: String) -> String? {
guard let messageData = string.data(using:String.Encoding.utf8) else { return nil }
var digestData = Data(count: Int(CC_SHA256_DIGEST_LENGTH))
_ = digestData.withUnsafeMutableBytes {digestBytes in
messageData.withUnsafeBytes {messageBytes in
CC_SHA256(messageBytes, CC_LONG(messageData.count), digestBytes)
}
}
return digestData.map { String(format: "%02hhx", $0) }.joined()
}
// Test
let sha256HexString = sha256Hex(string:"Hello")
print("sha256HexString: \(sha256HexString!)")
sha256HexString: "185f8db32271fe25f561a6fc938b2e264306ec304eda518007d1764826381969"
Objective-C method whose output matches output from random site online
-(NSString*)sha256HashForText:(NSString*)text {
const char* utf8chars = [text UTF8String];
unsigned char result[CC_SHA256_DIGEST_LENGTH];
CC_SHA256(utf8chars, (CC_LONG)strlen(utf8chars), result);
NSMutableString *ret = [NSMutableString stringWithCapacity:CC_SHA256_DIGEST_LENGTH*2];
for(int i = 0; i<CC_SHA256_DIGEST_LENGTH; i++) {
[ret appendFormat:#"%02x",result[i]];
}
return ret;
}
Taken from this Gist.
a modified version of #zaph answer in Objective-C with NSString as input and output:
-(NSString*)sha256HashFor:(NSString*)input
{
NSData* data = [input dataUsingEncoding:NSUTF8StringEncoding];
NSMutableData *sha256Data = [NSMutableData dataWithLength:CC_SHA256_DIGEST_LENGTH];
CC_SHA256([data bytes], (CC_LONG)[data length], [sha256Data mutableBytes]);
return [sha256Data base64EncodedStringWithOptions:0];
}
Check out the NSHash cocoa pod. It has a bunch of different hashing methods including SHA256.
https://github.com/jerolimov/NSHash
Related
My application uses AES 256 encryption to encrypt a string. The same code that was used before is generating a different result. This problem started when iOS 13 was released. And it happens only to applications that are shipped to the store or built with Xcode 11.
Here is the code used for the encryption:
- (NSData *)encrypt:(NSData *)plainText key:(NSString *)key iv:(NSString *)iv {
char keyPointer[kCCKeySizeAES256+2],// room for terminator (unused) ref: https://devforums.apple.com/message/876053#876053
ivPointer[kCCBlockSizeAES128+2];
BOOL patchNeeded;
bzero(keyPointer, sizeof(keyPointer)); // fill with zeroes for padding
patchNeeded= ([key length] > kCCKeySizeAES256+1);
if(patchNeeded)
{
NSLog(#"Key length is longer %lu", (unsigned long)[[self md5:key] length]);
key = [key substringToIndex:kCCKeySizeAES256]; // Ensure that the key isn't longer than what's needed (kCCKeySizeAES256)
}
//NSLog(#"md5 :%#", key);
[key getCString:keyPointer maxLength:sizeof(keyPointer) encoding:NSUTF8StringEncoding];
[iv getCString:ivPointer maxLength:sizeof(ivPointer) encoding:NSUTF8StringEncoding];
if (patchNeeded) {
keyPointer[0] = '\0'; // Previous iOS version than iOS7 set the first char to '\0' if the key was longer than kCCKeySizeAES256
}
NSUInteger dataLength = [plainText length];
//see https://developer.apple.com/library/ios/documentation/System/Conceptual/ManPages_iPhoneOS/man3/CCryptorCreateFromData.3cc.html
// For block ciphers, the output size will always be less than or equal to the input size plus the size of one block.
size_t buffSize = dataLength + kCCBlockSizeAES128;
void *buff = malloc(buffSize);
size_t numBytesEncrypted = 0;
//refer to http://www.opensource.apple.com/source/CommonCrypto/CommonCrypto-36064/CommonCrypto/CommonCryptor.h
//for details on this function
//Stateless, one-shot encrypt or decrypt operation.
CCCryptorStatus status = CCCrypt(kCCEncrypt, /* kCCEncrypt, etc. */
kCCAlgorithmAES128, /* kCCAlgorithmAES128, etc. */
kCCOptionPKCS7Padding, /* kCCOptionPKCS7Padding, etc. */
keyPointer, kCCKeySizeAES256, /* key and its length */
ivPointer, /* initialization vector - use random IV everytime */
[plainText bytes], [plainText length], /* input */
buff, buffSize,/* data RETURNED here */
&numBytesEncrypted);
if (status == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buff length:numBytesEncrypted];
}
free(buff);
return nil;
}
- (NSString *) encryptPlainTextWith:(NSString *)plainText key:(NSString *)key iv:(NSString *)iv {
return [[[[CryptLib alloc] init] encrypt:[plainText dataUsingEncoding:NSUTF8StringEncoding] key:[[CryptLib alloc] sha256:key length:32] iv:iv] base64EncodedStringWithOptions:0];
}
/**
* This function computes the SHA256 hash of input string
* #param key input text whose SHA256 hash has to be computed
* #param length length of the text to be returned
* #return returns SHA256 hash of input text
*/
- (NSString*) sha256:(NSString *)key length:(NSInteger) length{
const char *s=[key cStringUsingEncoding:NSASCIIStringEncoding];
NSData *keyData=[NSData dataWithBytes:s length:strlen(s)];
uint8_t digest[CC_SHA256_DIGEST_LENGTH]={0};
CC_SHA256(keyData.bytes, (CC_LONG)keyData.length, digest);
NSData *out=[NSData dataWithBytes:digest length:CC_SHA256_DIGEST_LENGTH];
NSString *hash=[out description];
hash = [hash stringByReplacingOccurrencesOfString:#" " withString:#""];
hash = [hash stringByReplacingOccurrencesOfString:#"<" withString:#""];
hash = [hash stringByReplacingOccurrencesOfString:#">" withString:#""];
if(length > [hash length])
{
return hash;
}
else
{
return [hash substringToIndex:length];
}
}
##
I would like to know if something in the code path has changed in the way it works. The method called to do the encryptions is "encryptPlainTextWith". Thanks in advance.
Inside:
- (NSString*) sha256:(NSString *)key length:(NSInteger) length
I replaced
NSString *hash=[out description];
To
NSString *hash=[out debugDescription];
And everything got back to normal. Cheers Happy coding.
Alternative Solution as per #Rob Napier
create separate function for converting NSData to Hex
#pragma mark - String Conversion
-(NSString*)hex:(NSData*)data{
NSMutableData *result = [NSMutableData dataWithLength:2*data.length];
unsigned const char* src = data.bytes;
unsigned char* dst = result.mutableBytes;
unsigned char t0, t1;
for (int i = 0; i < data.length; i ++ ) {
t0 = src[i] >> 4;
t1 = src[i] & 0x0F;
dst[i*2] = 48 + t0 + (t0 / 10) * 39;
dst[i*2+1] = 48 + t1 + (t1 / 10) * 39;
}
return [[NSString alloc] initWithData:result encoding:NSASCIIStringEncoding];
}
After that Inside:
- (NSString*) sha256:(NSString *)key length:(NSInteger) length
I replaced
NSString *hash=[out description];
To
NSString *hash = [self hex:out];
I suspect that your key is longer than 32 UTF-8 bytes. In that case, this code is incorrect. Your patchNeeded conditional is basically creating a garbage key. The contents of buffer aren't promised if this function return returns false, but you're relying on them.
There is no secure way to truncate a key you were given, so I'm not really certain what behavior you want here. It depends on what kinds of strings you're passing.
This code is also incorrect if iv is shorter than 16 UTF-8 bytes. You'll wind up including random values from the stack. That part can be fixed with:
bzero(ivPointer, sizeof(ivPointer));
But if your previous version relied on random values, this will still be different.
Assuming you need to match the old behavior, the best way to debug this is to run your previous version in a debugger and see what keyPointer and ivPointer wind up being.
(Note that this approach to creating a key is very insecure. It's drastically shrinking the AES keyspace. How much depends on what kind of strings you're passing, but it's dramatic. You also should never reuse the same key+iv combination in two messages when using CBC, which this looks like it probably does. If possible, I recommend moving to a correct AES implementation. You can look at RNCryptor for one example of how to do that, or use RNCryptor directly if you prefer.)
For some code challenge used in the oauth2 login process I need to do the following:
code_challenge = BASE64URL-ENCODE(SHA256(ASCII(code_verifier)))
How can I do this from my random string contained in code_verifier?
UPDATE: Can you check if this is correct? Or is some stuff unneccesary/deprecated? I actually have not really an idea what I am doing here, I just copied code from everywhere to solve it...
- (NSString *)createCodeChallengeWithVerifier:(NSString *)codeVerifier {
//Create ASCII
const char *asciiString = [codeVerifier cStringUsingEncoding:NSASCIIStringEncoding];
//Sha256
unsigned char buf[CC_SHA256_DIGEST_LENGTH];
CC_SHA256(asciiString, strlen(asciiString), buf);
NSMutableString * shaString = [NSMutableString stringWithCapacity:(CC_SHA256_DIGEST_LENGTH * 2)];
for (int i = 0; i < CC_SHA256_DIGEST_LENGTH; ++i) {
[shaString appendFormat:#"%02x", buf[i]];
}
//Base 64 encode
NSData *dataFromShaString = [shaString dataUsingEncoding:NSUTF8StringEncoding];
return([dataFromShaString base64EncodedStringWithOptions:0]);
}
I am trying to write some simple code that searches two dictionaries for a string and prints to the console if the string appears in both dictionaries. I want the user to be able to input the string via the console, and then pass the string as a variable into a message. I was wondering how I could go about getting a string from the console and using it as the argument in the following method call.
[x rangeOfString:"the string goes here" options:NSCaseInsensitiveSearch];
I am unsure as to how to get the string from the user. Do I use scanf(), or fgets(), into a char and then convert it into a NSSstring, or simply scan into an NSString itself. I am then wondering how to pass that string as an argument. Please help:
Here is the code I have so far. I know it is not succinct, but I just want to get the job done:
#import <Foundation/Foundation.h>
#include <stdio.h>
#include "stdlib.h"
int main(int argc, const char* argv[]){
#autoreleasepool {
char *name[100];
printf("Please enter the name you wish to search for");
scanf("%s", *name);
NSString *name2 = [NSString stringWithFormat:#"%s" , *name];
NSString *nameString = [NSString stringWithContentsOfFile:#"/usr/share/dict/propernames" encoding:NSUTF8StringEncoding error:NULL];
NSString *dictionary = [NSString stringWithContentsOfFile:#"/usr/share/dict/words" encoding:NSUTF8StringEncoding error:NULL];
NSArray *nameString2 = [nameString componentsSeparatedByString:#"\n"];
NSArray *dictionary2 = [dictionary componentsSeparatedByString:#"\n"];
int nsYES = 0;
int dictYES = 0;
for (NSString *n in nameString2) {
NSRange r = [n rangeOfString:name2 options:NSCaseInsensitiveSearch];
if (r.location != NSNotFound){
nsYES = 1;
}
}
for (NSString *x in dictionary2) {
NSRange l = [x rangeOfString:name2 options:NSCaseInsensitiveSearch];
if (l.location != NSNotFound){
dictYES = 1;
}
}
if (dictYES && nsYES){
NSLog(#"glen appears in both dictionaries");
}
}
}
Thanks.
Safely reading from standard input in an interactive manner in C is kind of involved. The standard functions require a fixed-size buffer, which means either some input will be too long (and corrupt your memory!) or you'll have to read in a loop. And unfortunately, Cocoa doesn't offer us a whole lot of help.
For reading standard input entirely (as in, if you're expecting an input file over standard input), there is NSFileHandle, which makes it pretty succinct. But for interactively reading and writing like you want to do here, you pretty much have to go with the linked answer for reading.
Once you have read some input into a C string, you can easily turn it into an NSString with, for example, +[NSString stringWithUTF8String:].
I'm trying to create my own custom assert. However, I would like my assertion to automatically include all of the relevant variables. This seems really basic to me, and I've searched around for about an hour but I can't seem to find a way get access to all the relevant stack frame variables. Does anyone know how to get these variables?
FYI - I don't need to access the variables in the debugger, I need to access them programmatically. I would like to upload them along with the crash report to give me more information about the crash. I also know that I can print them out manually...that is exactly what I'm looking to avoid.
You are basically asking to re-invent a good sized chunk of the debugger.
Without symbols, there isn't anything you can interrogate to figure out the layout of the local frame. Even with symbols, it is quite likely that the optimizer will have stomped on any local variables as the optimizer will re-use stack slots at whim once it determines the variable is no longer needed within the frame.
Note that many crashes won't be able to be caught at all or, if caught, the frame within which they occurred will have long since been destroyed.
Since you mention that you are creating a custom assertion, it sounds like you really aren't looking to introspect crashes as much as dump a snap of the local frame when you programatically detect that things have gone off the rails. While there really isn't a means of automatically reporting on local stack state, you could do something like:
{ ... some function ....
... local variables ...
#define reportblock ^{ ... code that summarizes locals ... ; return summary; }
YourAssert( cond, "cond gone bad. summary: %#", reportblock());
}
Note that the #define ensures that each YourAssert() captures the state at the time of the assertion. Note also that the above might have a potentially significant impact on performance.
Note also that I just made that code up. It seems like it is worthy of investigation, but may prove non-viable for a number of reasons.
If you're willing to use Objective-C++, then this is definitely a possibility, as long as you are also willing to declare your variables differently, and understand that you will only be able to grab your own variables with this method.
Also note that it will increase your stack frame size with extra __stack_ variables, which could cause memory issues (although I doubt it, personally).
It won't work with certain constructs such as for-loops, but for 95% of cases, this should work for what you need:
#include <vector>
struct stack_variable;
static std::vector<const stack_variable *> stack_variables;
struct stack_variable {
void **_value;
const char *_name;
const char *_type;
const char *_file;
const char *_line;
private:
template<typename T>
stack_variable(const T& value, const char *type, const char *name, const char *file, const char *line) : _value((void **) &value), _type(type), _name(name), _file(file), _line(line) {
add(*this);
}
static inline void add(const stack_variable &var) {
stack_variables.push_back(static_cast<const stack_variable *>(&var));
}
static inline void remove(const stack_variable &var) {
for (auto it = stack_variables.begin(); it != stack_variables.end(); it++) {
if ((*it) == &var) {
stack_variables.erase(it);
return;
}
}
}
public:
template<typename T>
static inline stack_variable create(const T& value, const char *type, const char *name, const char *file, const char *line) {
return stack_variable(value, type, name, file, line);
}
~stack_variable() {
remove(*this);
}
void print() const {
// treat the value as a pointer
printf("%s:%s - %s %s = %p\n", _file, _line, _type, _name, *_value);
}
static void dump_vars() {
for (auto var : stack_variables) {
var->print();
}
}
};
#define __LINE_STR(LINE) #LINE
#define _LINE_STR(LINE) __LINE_STR(LINE)
#define LINE_STR _LINE_STR(__LINE__)
#define LOCAL_VAR(type, name, value)\
type name = value;\
stack_variable __stack_ ## name = stack_variable::create<type>(name, #type, #name, __FILE__, LINE_STR);\
(void) __stack_ ## name;
Example:
int temp() {
LOCAL_VAR(int, i_wont_show, 0);
return i_wont_show;
}
int main(){
LOCAL_VAR(long, l, 15);
LOCAL_VAR(int, x, 192);
LOCAL_VAR(short, y, 256);
temp();
l += 10;
stack_variable::dump_vars();
}
Output (note the junk extra bytes for the values smaller than sizeof(void *), there isn't much I can do about that):
/Users/rross/Documents/TestProj/TestProj/main.mm:672 - long l = 0x19
/Users/rross/Documents/TestProj/TestProj/main.mm:673 - int x = 0x5fbff8b8000000c0
/Users/rross/Documents/TestProj/TestProj/main.mm:674 - short y = 0xd000000010100
Threads will royally screw this up, however, so in a multithreaded environment this is (almost) worthless.
I decided to add this as a separate answer, as it uses the same approach as my other one, but this time with an all ObjC code. Unfortunately, you still have to re-declare all of your stack variables, just like before, but hopefully now it will work better with your existing code-base.
StackVariable.h:
#import <Foundation/Foundation.h>
#define LOCAL_VAR(p_type, p_name, p_value)\
p_type p_name = p_value;\
StackVariable *__stack_ ## p_name = [[StackVariable alloc] initWithPointer:&p_name\
size:sizeof(p_type)\
name:#p_name\
type:#p_type\
file:__FILE__\
line:__LINE__];\
(void) __stack_ ## p_name;
#interface StackVariable : NSObject
-(id) initWithPointer:(void *) ptr
size:(size_t) size
name:(const char *) name
type:(const char *) type
file:(const char *) file
line:(const int) line;
+(NSString *) dump;
#end
StackVariable.m:
#import "StackVariable.h"
static NSMutableArray *stackVariables;
#implementation StackVariable {
void *_ptr;
size_t _size;
const char *_name;
const char *_type;
const char *_file;
int _line;
}
-(id) initWithPointer:(void *)ptr size:(size_t)size name:(const char *)name type:(const char *)type file:(const char *)file line:(int)line
{
if (self = [super init]) {
if (stackVariables == nil) {
stackVariables = [NSMutableArray new];
}
_ptr = ptr;
_size = size;
_name = name;
_type = type;
_file = file;
_line = line;
[stackVariables addObject:[NSValue valueWithNonretainedObject:self]];
}
return self;
}
-(NSString *) description {
NSMutableString *result = [NSMutableString stringWithFormat:#"%s:%d - %s %s = { ", _file, _line, _type, _name];
const uint8_t *bytes = (const uint8 *) _ptr;
for (size_t i = 0; i < _size; i++) {
[result appendFormat:#"%02x ", bytes[i]];
}
[result appendString:#"}"];
return result;
}
+(NSString *) dump {
NSMutableString *result = [NSMutableString new];
for (NSValue *value in stackVariables) {
__weak StackVariable *var = [value nonretainedObjectValue];
[result appendString:[var description]];
[result appendString:#"\n"];
}
return result;
}
-(void) dealloc {
[stackVariables removeObject:[NSValue valueWithNonretainedObject:self]];
}
#end
Example:
#include "StackVariable.h"
int temp() {
LOCAL_VAR(int, i_wont_show, 0);
return i_wont_show;
}
int main(){
LOCAL_VAR(long, l, 15);
LOCAL_VAR(int, x, 192);
LOCAL_VAR(short, y, 256);
temp();
l += 10;
puts([[StackVariable dump] UTF8String]);
}
Output:
/Users/rross/Documents/TestProj/TestProj/main.m:676 - long l = { 19 00 00 00 00 00 00 00 }
/Users/rross/Documents/TestProj/TestProj/main.m:677 - int x = { c0 00 00 00 }
/Users/rross/Documents/TestProj/TestProj/main.m:678 - short y = { 00 01 }
This requires ARC (and all of it's magic) enabled for any file you want to test this in, or you will manually have to release the __stack_ variables, which won't be pretty.
However, it now gives you a hex dump of the variable (rather than the weird pointer one), and if you really tried hard enough (using __builtin_types_compatible), it could detect whether the result was an object, and print that.
Once again, threads will mess this up, but a simple way to fix that would be to create a NSDictionary of NSArrays, with a NSThread as the key. Makes it a bit slower, but let's be honest, if you're using this over the C++ version, you aren't going for performance.
How to find the Mac OSX serial number.
Sometimes it is required to get serial number of a mac, and you validate on that.
I needed the same, few years back, when I developed a plugin for OsiriX. I was asked to release it in such a way, only few systems can use that plugin.
If we get any better solution than this, that will be quite helpful for all of us.
The following code is mainly copied from Technical Note TN1103,
with small modifications to return an NSString and to make it compile with ARC:
#include <IOKit/IOKitLib.h>
- (NSString *)getSerialNumber
{
NSString *serial = nil;
io_service_t platformExpert = IOServiceGetMatchingService(kIOMasterPortDefault,
IOServiceMatching("IOPlatformExpertDevice"));
if (platformExpert) {
CFTypeRef serialNumberAsCFString =
IORegistryEntryCreateCFProperty(platformExpert,
CFSTR(kIOPlatformSerialNumberKey),
kCFAllocatorDefault, 0);
if (serialNumberAsCFString) {
serial = CFBridgingRelease(serialNumberAsCFString);
}
IOObjectRelease(platformExpert);
}
return serial;
}
You have to add the IOKit.framework to your build settings.
This is the Swift version of the solution:
var serialNumber: String? {
let platformExpert = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice") )
guard platformExpert > 0 else {
return nil
}
guard let serialNumber = (IORegistryEntryCreateCFProperty(platformExpert, kIOPlatformSerialNumberKey as CFString, kCFAllocatorDefault, 0).takeUnretainedValue() as? String) else {
return nil
}
IOObjectRelease(platformExpert)
return serialNumber
}
This is a C++ version based on the TN1103 that Martin mention above.
C++ example:
#include <CoreFoundation/CoreFoundation.h>
#include <IOKit/IOKitLib.h>
std::string example_class::getSerialNumber()
{
CFStringRef serial;
char buffer[64] = {0};
std::string seriaNumber("");
io_service_t platformExpert = IOServiceGetMatchingService(kIOMasterPortDefault,
IOServiceMatching("IOPlatformExpertDevice"));
if (platformExpert)
{
CFTypeRef serialNumberAsCFString = IORegistryEntryCreateCFProperty(platformExpert,
CFSTR(kIOPlatformSerialNumberKey),
kCFAllocatorDefault, 0);
if (serialNumberAsCFString) {
serial = (CFStringRef)serialNumberAsCFString;
}
if (CFStringGetCString(serial, buffer, 64, kCFStringEncodingUTF8)) {
seriaNumber = buffer;
}
IOObjectRelease(platformExpert);
}
return seriaNumber;
}