Given the message and the salt how can I encode it returning the hashed string?
I need reproduce the php function:
hash_hmac('sha256','message','salt');
Thanks
Found the answer:
#import <CommonCrypto/CommonHMAC.h>
-(NSString *) hashString :(NSString *) data withSalt: (NSString *) salt {
const char *cKey = [salt cStringUsingEncoding:NSUTF8StringEncoding];
const char *cData = [data cStringUsingEncoding:NSUTF8StringEncoding];
unsigned char cHMAC[CC_SHA256_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA256, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
NSString *hash;
NSMutableString* output = [NSMutableString stringWithCapacity:CC_SHA256_DIGEST_LENGTH * 2];
for(int i = 0; i < CC_SHA256_DIGEST_LENGTH; i++)
[output appendFormat:#"%02x", cHMAC[i]];
hash = output;
return hash;
}
Related
Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 8 years ago.
Improve this question
I need to generate HMAC-SHA1 in Objective C. But i didnt find anything that works. I tried with CommonCrypto, using CCHMAC, but didnt works. I need to generate a hmac and after generate HOTP number.
Somebody have any example code in Objective C or C?
Here's how you generate an HMAC using SHA-256:
NSString *key;
NSString *data;
const char *cKey = [key cStringUsingEncoding:NSASCIIStringEncoding];
const char *cData = [data cStringUsingEncoding:NSASCIIStringEncoding];
unsigned char cHMAC[CC_SHA256_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA256, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
NSData *HMAC = [[NSData alloc] initWithBytes:cHMAC
length:sizeof(cHMAC)];
NSString *hash = [HMAC base64Encoding];
I'm not aware of an HOTP library, but the algorithm was quite simple, if I recall correctly.
here is how you can generate HMAC-SHA1 base64.
You need to add Base64.h and Base64.m to your project. You can get it from here.
If you use ARC, it will show some errors in Base64.m. Find the lines who are similar like this
return [[[self alloc] initWithBase64String:base64String] autorelease];
what you need is to delete the autorelease section. The final result should look like:
return [[self alloc] initWithBase64String:base64String];
Now in your general project import "Base64.h"
and the following code
#import "Base64.h"
#include <CommonCrypto/CommonDigest.h>
#include <CommonCrypto/CommonHMAC.h>
- (NSString *)hmacsha1:(NSString *)data secret:(NSString *)key {
const char *cKey = [key cStringUsingEncoding:NSASCIIStringEncoding];
const char *cData = [data cStringUsingEncoding:NSASCIIStringEncoding];
unsigned char cHMAC[CC_SHA1_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA1, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
NSData *HMAC = [[NSData alloc] initWithBytes:cHMAC length:sizeof(cHMAC)];
NSString *hash = [HMAC base64String];
return hash;
}
With
NSLog(#"Hash: %#", hash);
you will get something similar to this:
ghVEjPvxwLN1lBi0Jh46VpIchOc=
This is the complete solution which works without any extra libraries or hacks:
+(NSString *)hmac:(NSString *)plainText withKey:(NSString *)key
{
const char *cKey = [key cStringUsingEncoding:NSASCIIStringEncoding];
const char *cData = [plainText cStringUsingEncoding:NSASCIIStringEncoding];
unsigned char cHMAC[CC_SHA256_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA256, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
NSData *HMACData = [[NSData alloc] initWithBytes:cHMAC length:sizeof(cHMAC)];
const unsigned char *buffer = (const unsigned char *)[HMACData bytes];
NSString *HMAC = [NSMutableString stringWithCapacity:HMACData.length * 2];
for (int i = 0; i < HMACData.length; ++i)
HMAC = [HMAC stringByAppendingFormat:#"%02lx", (unsigned long)buffer[i]];
return HMAC;
}
You don't have to include any third-party base64 library as it is already encoded.
This works without using custom protocols, using some code from
http://cocoawithlove.com/2009/07/hashvalue-object-for-holding-md5-and.html
HashSHA256.h
#import <Foundation/Foundation.h>
#import <CommonCrypto/CommonDigest.h>
#interface HashSHA256 : NSObject {
}
- (NSString *) hashedValue :(NSString *) key andData: (NSString *) data ;
#end
HashSHA256.m
#import "HashSHA256.h"
#import <CommonCrypto/CommonHMAC.h>
#implementation HashSHA256
- (NSString *) hashedValue :(NSString *) key andData: (NSString *) data {
const char *cKey = [key cStringUsingEncoding:NSUTF8StringEncoding];
const char *cData = [data cStringUsingEncoding:NSUTF8StringEncoding];
unsigned char cHMAC[CC_SHA256_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA256, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
NSString *hash;
NSMutableString* output = [NSMutableString stringWithCapacity:CC_SHA256_DIGEST_LENGTH * 2];
for(int i = 0; i < CC_SHA256_DIGEST_LENGTH; i++)
[output appendFormat:#"%02x", cHMAC[i]];
hash = output;
return hash;
}
#end
Usage:
- (NSString *) encodePassword: (NSString *) myPassword {
HashSHA256 * hashSHA256 = [[HashSHA256 alloc] init];
NSString * result = [hashSHA256 hashedValue:mySecretSalt andData:myPassword];
return result;
}
This is how yo do it without external files returning an hex string:
-(NSString *)hmac:(NSString *)plaintext withKey:(NSString *)key
{
const char *cKey = [key cStringUsingEncoding:NSASCIIStringEncoding];
const char *cData = [plaintext cStringUsingEncoding:NSASCIIStringEncoding];
unsigned char cHMAC[CC_SHA1_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA1, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
NSData *HMACData = [NSData dataWithBytes:cHMAC length:sizeof(cHMAC)];
const unsigned char *buffer = (const unsigned char *)[HMACData bytes];
NSMutableString *HMAC = [NSMutableString stringWithCapacity:HMACData.length * 2];
for (int i = 0; i < HMACData.length; ++i){
[HMAC appendFormat:#"%02x", buffer[i]];
}
return HMAC;
}
It was tested in xCode 5 with iOS 7 and works fine!
I spend a whole day, trying to convert the generated hash (bytes) into readable data. I used the base64 encoded solution from the answer above and it didn´t work at all for me (b.t.w. you need and an external .h to be able to use the base64 encoding, which I had).
So what I did was this (which works perfectly without an external .h):
CCHmac(kCCHmacAlgSHA256, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
// Now convert to NSData structure to make it usable again
NSData *out = [NSData dataWithBytes:cHMAC length:CC_SHA256_DIGEST_LENGTH];
// description converts to hex but puts <> around it and spaces every 4 bytes
NSString *hash = [out description];
hash = [hash stringByReplacingOccurrencesOfString:#" " withString:#""];
hash = [hash stringByReplacingOccurrencesOfString:#"<" withString:#""];
hash = [hash stringByReplacingOccurrencesOfString:#">" withString:#""];
// hash is now a string with just the 40char hash value in it
NSLog(#"%#",hash);
Out of interest, why do you create (unsigned char cHMAC) and then convert into (NSData) and then convert it into (NSMutableString) and then convert finally into (HexString)?
You could do this in a quicker way by cutting the middleman (i.e. without NSData and NSMutableString altogether, quicker and better performance), also changing (unsigned char) into (uint8_t []), after all they are all hex-arrays anyway!, below:
-(NSString *)hmac:(NSString *)plaintext withKey:(NSString *)key
{
const char *cKey = [key cStringUsingEncoding:NSASCIIStringEncoding];
const char *cData = [plaintext cStringUsingEncoding:NSASCIIStringEncoding];
uint8_t cHMAC[CC_SHA1_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA1, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
NSString *Hash1 = #"";
for (int i=0; i< CC_SHA1_DIGEST_LENGTH; i++)
{
Hash1 = [Hash1 stringByAppendingString:[NSString stringWithFormat:#"%02X", cHMAC[i]]];
}
return Hash1;
}
I hope this helps,
Regards
Heider Sati
Have you seen Jens Alfke's new MyCrypto classes?
He has some sample code on his blog.
I'm trying to convert a Hex NSString to NSData (I'm using the below attached code). The following is the output:
<00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000>
which looks totally irrelevant to me. Any idea/ suggestions on where its going wrong?
NSString *strData = #"72ff63cea198b3edba8f7e0c23acc345050187a0cde5a9872cbab091ab73e553";
NSLog(#"string Data length is %d",[strData length]);
NSMutableData *commandToSend= [[NSMutableData alloc] init];
unsigned char whole_byte;
char byte_chars[2];
int i;
for (i=0; i < [strData length]/2; i++) {
byte_chars[0] = [strData characterAtIndex:i*2];
byte_chars[1] = [strData characterAtIndex:i*2+1];
whole_byte = strtol(byte_chars, NULL, [strData length]);
[commandToSend appendBytes:&whole_byte length:1];
}
NSLog(#"%#", commandToSend);
NSString *command = #"72ff63cea198b3edba8f7e0c23acc345050187a0cde5a9872cbab091ab73e553";
command = [command stringByReplacingOccurrencesOfString:#" " withString:#""];
NSMutableData *commandToSend= [[NSMutableData alloc] init];
unsigned char whole_byte;
char byte_chars[3] = {'\0','\0','\0'};
int i;
for (i=0; i < [command length]/2; i++) {
byte_chars[0] = [command characterAtIndex:i*2];
byte_chars[1] = [command characterAtIndex:i*2+1];
whole_byte = strtol(byte_chars, NULL, 16);
[commandToSend appendBytes:&whole_byte length:1];
}
NSLog(#"%#", commandToSend);
Here is another method that also handles leading <, trailing > and embedded spaces such as
<9dc69faf a7434ba9 aef57f5c 365d571f 4c3753c4 ae13db42 57d184ca e00246c5>
Code:
+ (NSData *)dataFromHexString:(NSString *)string
{
string = [string lowercaseString];
NSMutableData *data= [NSMutableData new];
unsigned char whole_byte;
char byte_chars[3] = {'\0','\0','\0'};
int i = 0;
int length = string.length;
while (i < length-1) {
char c = [string characterAtIndex:i++];
if (c < '0' || (c > '9' && c < 'a') || c > 'f')
continue;
byte_chars[0] = c;
byte_chars[1] = [string characterAtIndex:i++];
whole_byte = strtol(byte_chars, NULL, 16);
[data appendBytes:&whole_byte length:1];
}
return data;
}
This is based on the answer by #Nikunj R. Jadav
This might be more useful, Apple has shared a NSData category.
NSData+HexString.m
The code is:
#implementation NSData (HexString)
// Not efficent
+(id)dataWithHexString:(NSString *)hex
{
char buf[3];
buf[2] = '\0';
NSAssert(0 == [hex length] % 2, #"Hex strings should have an even number of digits (%#)", hex);
unsigned char *bytes = malloc([hex length]/2);
unsigned char *bp = bytes;
for (CFIndex i = 0; i < [hex length]; i += 2) {
buf[0] = [hex characterAtIndex:i];
buf[1] = [hex characterAtIndex:i+1];
char *b2 = NULL;
*bp++ = strtol(buf, &b2, 16);
NSAssert(b2 == buf + 2, #"String should be all hex digits: %# (bad digit around %d)", hex, i);
}
return [NSData dataWithBytesNoCopy:bytes length:[hex length]/2 freeWhenDone:YES];
}
#end
I see several solution have been post only able to convert string with even length.
So here is my solution which also able return correct data if the string is odd length like this "DBA" became data like this this "\x0D\xBA"
+ (NSData *)dataFromHexString:(NSString *) string {
if([string length] % 2 == 1){
string = [#"0"stringByAppendingString:string];
}
const char *chars = [string UTF8String];
int i = 0, len = (int)[string length];
NSMutableData *data = [NSMutableData dataWithCapacity:len / 2];
char byteChars[3] = {'\0','\0','\0'};
unsigned long wholeByte;
while (i < len) {
byteChars[0] = chars[i++];
byteChars[1] = chars[i++];
wholeByte = strtoul(byteChars, NULL, 16);
[data appendBytes:&wholeByte length:1];
}
return data;
}
I'm working with a partner and we're not able to get C# and Objective-C to produce the same hashes using what we think are the same tools in the respective languages. In C#, I'm doing this:
byte[] noncebytes=new byte[32];
//We seed the hash generator with a new 32 position array. Each position is 0.
//In prod code this would be random, but for now it's all 0s.
HMACSHA256 hmac256 = new HMACSHA256(noncebytes);
string plaintext = "hello";
string UTFString = Convert.ToBase64String(
System.Text.Encoding.UTF8.GetBytes(plaintext));
string HashString = Convert.ToBase64String(
hmac256.ComputeHash(System.Text.Encoding.UTF8.GetBytes(plaintext))); //Convert that hash to a string.
This produces the following base64string hash:
Q1KybjP+DXaaiSKmuikAQQnwFojiasyebLNH5aWvxNo=
What is the equivalent Objective-C code to do this? We need the client and the server to be able to generate matching hashes for matching data.
Here is the Objective-C code we are currently using:
...
NSData *zeroNumber = [self zeroDataWithBytes:32]; //empty byte array
NSString *nonceTest = [zeroNumber base64String]; // using MF_Base64Additions.h here
NSData *hashTest = [self hmacForKeyAndData:nonceTest withData:#"hello"]; //creating hash
NSString *hashTestText = [hashTest base64String];
NSLog(#"hello hash is %#", hashTestText);
...
//functions for zeroing out the byte. I'm sure there's a better way
- (NSData *)zeroDataWithBytes: (NSUInteger)length {
NSMutableData *mutableData = [NSMutableData dataWithCapacity: length];
for (unsigned int i = 0; i < length; i++) {
NSInteger bits = 0;
[mutableData appendBytes: (void *) &bits length: 1];
} return mutableData;
}
//hash function
-(NSData *) hmacForKeyAndData:(NSString *)key withData:(NSString *) data {
const char *cKey = [key cStringUsingEncoding:NSASCIIStringEncoding];
const char *cData = [data cStringUsingEncoding:NSASCIIStringEncoding];
unsigned char cHMAC[CC_SHA256_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA256, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
return [[NSData alloc] initWithBytes:cHMAC length:sizeof(cHMAC)];
}
UPDATE:
There is a pretty good project on GitHub that seems to accomplish everything you want, plus a lot more encryption related options; includes unit tests.
NSData *hmacForKeyAndData(NSString *key, NSString *data)
{
const char *cKey = [key cStringUsingEncoding:NSASCIIStringEncoding];
const char *cData = [data cStringUsingEncoding:NSASCIIStringEncoding];
unsigned char cHMAC[CC_SHA256_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA256, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
return [[NSData alloc] initWithBytes:cHMAC length:sizeof(cHMAC)];
}
(Source)
With the above, I think you will have import <CommonCrypto/CommonHMAC.h>. The next step for encoding to Base64:
+ (NSString *)Base64Encode:(NSData *)data
{
//Point to start of the data and set buffer sizes
int inLength = [data length];
int outLength = ((((inLength * 4)/3)/4)*4) + (((inLength * 4)/3)%4 ? 4 : 0);
const char *inputBuffer = [data bytes];
char *outputBuffer = malloc(outLength);
outputBuffer[outLength] = 0;
//64 digit code
static char Encode[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
//start the count
int cycle = 0;
int inpos = 0;
int outpos = 0;
char temp;
//Pad the last to bytes, the outbuffer must always be a multiple of 4
outputBuffer[outLength-1] = '=';
outputBuffer[outLength-2] = '=';
/* http://en.wikipedia.org/wiki/Base64
Text content M a n
ASCII 77 97 110
8 Bit pattern 01001101 01100001 01101110
6 Bit pattern 010011 010110 000101 101110
Index 19 22 5 46
Base64-encoded T W F u
*/
while (inpos < inLength){
switch (cycle) {
case 0:
outputBuffer[outpos++] = Encode[(inputBuffer[inpos]&0xFC)>>2];
cycle = 1;
break;
case 1:
temp = (inputBuffer[inpos++]&0x03)<<4;
outputBuffer[outpos] = Encode[temp];
cycle = 2;
break;
case 2:
outputBuffer[outpos++] = Encode[temp|(inputBuffer[inpos]&0xF0)>> 4];
temp = (inputBuffer[inpos++]&0x0F)<<2;
outputBuffer[outpos] = Encode[temp];
cycle = 3;
break;
case 3:
outputBuffer[outpos++] = Encode[temp|(inputBuffer[inpos]&0xC0)>>6];
cycle = 4;
break;
case 4:
outputBuffer[outpos++] = Encode[inputBuffer[inpos++]&0x3f];
cycle = 0;
break;
default:
cycle = 0;
break;
}
}
NSString *pictemp = [NSString stringWithUTF8String:outputBuffer];
free(outputBuffer);
return pictemp;
}
Note the second line of code in the objective-c portion of the question.
NSString *nonceTest = [zeroNumber base64String];
but it should be this:
NSString *nonceTest = [[NSString alloc] initWithData:zeroNumber encoding:NSASCIIStringEncoding];
It was a case of converting the string to base64 when we didn't need to for the hmac seeeding.
We now get: Q1KybjP+DXaaiSKmuikAQQnwFojiasyebLNH5aWvxNo= as the hash on both platforms.
I have this:
NSString *string1 = ...;
NSString *string2 = ...;
NSMutableArray *array = [NSMutableArray alloc]inithWithObjects:string1, string2]autorelease];
How do I calculate the MD5 hash (or other more appropriate hash) for each content of the array, for further comparisons?
Thanks!
You can use this method on every string of your array:
- (NSString*)md5HexDigest:(NSString*)input {
const char* str = [input UTF8String];
unsigned char result[CC_MD5_DIGEST_LENGTH];
CC_MD5(str, strlen(str), result);
NSMutableString *ret = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH*2];
for(int i = 0; i<CC_MD5_DIGEST_LENGTH; i++) {
[ret appendFormat:#"%02x",result[i]];
}
return ret;
}
Do not forget to include:
#import <CommonCrypto/CommonDigest.h>
I have an unsigned char array and I want to convert it to hex NSString, currently I do it in the following way:
unsigned char result[16];
// Fill the array
NSString *myHexString = [NSString stringWithFormat: #"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",
result[0], result[1], result[2], result[3],
result[4], result[5], result[6], result[7],
result[8], result[9], result[10], result[11],
result[12], result[13], result[14], result[15]
]];
Is there a better way to built-in function that achieves that?
How about this?
NSMutableString *hex = [NSMutableString string];
for (int i=0; i<16; i++)
[hex appendFormat:#"%02x", result[i]];
// And if you insist on having the hex in an immutable string:
NSString *immutableHex = [NSString stringWithString:hex];
You can also turn the code into a category to keep things nice:
#implementation NSString (Hex)
+ (NSString*) hexStringWithData: (unsigned char*) data ofLength: (NSUInteger) len
{
NSMutableString *tmp = [NSMutableString string];
for (NSUInteger i=0; i<len; i++)
[tmp appendFormat:#"%02x", data[i]];
return [NSString stringWithString:tmp];
}
#end
Then your code boils down to:
unsigned char result[16] = {…};
NSString *hexString = [NSString hexStringWithData:result ofLength:16];
I think that’s about as nice as it gets.