#import "HMACSHA256.h"
#import <CommonCrypto/CommonHMAC.h>
#define SECRET_KEY @"[I]put your secret key here"[/I]
@implementation HMACSHA256
#pragma mark HMACSHA256 et base64Encodage methodes
// The base64Encodage method has been found online, like Petron.
// I use the HMACforString method of Andy.
+ (NSData *)HMACforString:(NSString *)string
{
NSString *secretKey = SECRET_KEY;
NSData *clearTextData = [string dataUsingEncoding:NSUTF8StringEncoding];
NSData *secretKeyData = [secretKey dataUsingEncoding:NSUTF8StringEncoding];
[secretKey release];
uint8_t digest[CC_SHA256_DIGEST_LENGTH] = {0};
CCHmacContext hmacContext;
CCHmacInit(&hmacContext, kCCHmacAlgSHA256, secretKeyData.bytes, secretKeyData.length);
CCHmacUpdate(&hmacContext, clearTextData.bytes, clearTextData.length);
CCHmacFinal(&hmacContext, digest);
NSData *result = [NSData dataWithBytes:digest length:CC_SHA256_DIGEST_LENGTH];
return result;
}
+ (NSString *)base64forData:(NSData *)data
{
static const char encodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
if ([data length] == 0)
return @"";
char *characters = malloc((([data length] + 2) / 3) * 4);
if (characters == NULL)
return nil;
NSUInteger length = 0;
NSUInteger i = 0;
while (i < [data length])
{
char buffer[3] = {0,0,0};
short bufferLength = 0;
while (bufferLength < 3 && i < [data length])
buffer[bufferLength++] = ((char *)[data bytes])[i++];
// Encode the bytes in the buffer to four characters, including padding "=" characters if necessary.
characters[length++] = encodingTable[(buffer[0] & 0xFC) >> 2];
characters[length++] = encodingTable[((buffer[0] & 0x03) << 4) | ((buffer[1] & 0xF0) >> 4)];
if (bufferLength > 1)
characters[length++] = encodingTable[((buffer[1] & 0x0F) << 2) | ((buffer[2] & 0xC0) >> 6)];
else characters[length++] = '=';
if (bufferLength > 2)
characters[length++] = encodingTable[buffer[2] & 0x3F];
else characters[length++] = '=';
}
NSString *encodedString = [[[NSString alloc] initWithBytesNoCopy:characters
length:length
encoding:NSASCIIStringEncoding
freeWhenDone:YES] autorelease];
return encodedString;
}
#pragma mark Arrange the request methods
+ (NSString *)appendTimestamp:(NSString *)undatedUrlString
{
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss'Z'"];
[dateFormatter setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"GMT"]];
NSString *date = [dateFormatter stringFromDate:[NSDate date]];
NSString *datedUrlString = [undatedUrlString stringByAppendingFormat:@"&Timestamp=%@",date];
[dateFormatter release];
dateFormatter = nil;
return datedUrlString;
}
+ (NSString *)sortUrlString:(NSString *)unsortedUrlString
{
// Split and conserve the service address from the request.
NSArray *unsortedUrlStringArrayWithHTTPAddress = [unsortedUrlString componentsSeparatedByString:@"?"];
NSString *serviceAddress =
[NSString stringWithFormat:@"%@", [unsortedUrlStringArrayWithHTTPAddress objectAtIndex:0]];
NSString *unsortedUrlStringWithoutHTTPAddress =
[NSString stringWithFormat:@"%@", [unsortedUrlStringArrayWithHTTPAddress objectAtIndex:1]];
// Free the unsortedUrlStringArrayWithHTTPAddress array.
[unsortedUrlStringArrayWithHTTPAddress release];
// % Escape the request string.
NSString *escapedUnsortedUrlString =
(NSString *) CFURLCreateStringByAddingPercentEscapes(
NULL, (CFStringRef)unsortedUrlStringWithoutHTTPAddress,
NULL, (CFStringRef)@"!*'();:@+$,/?%#[]",
kCFStringEncodingUTF8);
// Split all items from the requestin an array and sort the array insensitive to the case.
NSArray *arrayUrlString = [escapedUnsortedUrlString componentsSeparatedByString:@"&"];
arrayUrlString = [arrayUrlString sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)];
// Join all items.
int i,itemCount = [arrayUrlString count];
NSString *enumString;
NSString *appendStringArray;
// Find and place the AWSAccessKeyId=XXXX field first.
for (enumString in arrayUrlString) {
if ([enumString rangeOfString:@"AWSAccessKeyId="].location != NSNotFound) {
appendStringArray = [NSString stringWithFormat:@"%@",enumString];
}
}
// Append the other fields to the first field, voiding recopying it a second times.
for (i = 0; i < itemCount;i++) {
if([[arrayUrlString objectAtIndex:i] rangeOfString:@"AWSAccessKeyId="].location == NSNotFound) {
appendStringArray = [appendStringArray stringByAppendingFormat:
@"&%@",[arrayUrlString objectAtIndex:i]];
}
}
// Join the serviceAddress string to the request.
appendStringArray = [NSString stringWithFormat:@"%@?%@", serviceAddress, appendStringArray];
return appendStringArray;
}
+ (NSString *)transformServiceAddress:(NSString *)serviceAddress
{
// Transform the serviceAddress string to fit for the signature calculation.
NSString *tSA = [serviceAddress stringByReplacingOccurrencesOfString:@"http://" withString:@"GET\n"];
tSA = [tSA stringByReplacingOccurrencesOfString:@"/onca/xml" withString:@"\n/onca/xml\n"];
return tSA;
}
+ (NSString *)signUrlString:(NSString *)unsignedUrlString
{
// Split and conserve the service address from the request.
NSArray *splitRequest = [unsignedUrlString componentsSeparatedByString:@"?"];
NSString *serviceAddress =
[NSString stringWithFormat:@"%@", [splitRequest objectAtIndex:0]];
NSString *canonicalRequestForm =
[NSString stringWithFormat:@"%@", [splitRequest objectAtIndex:1]];
// Free the array.
// [splitRequest release];
// Getting the canonical form of the service address.
NSString *sACanonicalForm = [HMACSHA256 transformServiceAddress:serviceAddress];
NSString *fullCanonicalFormRequest = [NSString
stringWithFormat:@"%@%@", sACanonicalForm, canonicalRequestForm];
// Calcul the signature from the canonical request and % escape it.
NSString *signatureUncoded = [HMACSHA256 base64forData:[HMACSHA256 HMACforString:fullCanonicalFormRequest]];
NSString *signature = (NSString *)CFURLCreateStringByAddingPercentEscapes(
NULL,(CFStringRef) signatureUncoded,
NULL, (CFStringRef)@"+/=",
kCFStringEncodingUTF8);
[signature autorelease];
// Rejoin service address string, canonical request string and the signature field.
NSString *signedUrlString = [NSString stringWithFormat:
@"%@?%@&Signature=%@", serviceAddress, canonicalRequestForm,signature];
return signedUrlString;
}
+ (NSString *)getSignedRequest:(NSString *)undatedUnsortedUnsignedUrlString
{
// Append "&Timestamp=XXXX" field.
NSString *datedUnsortedUnsignedUrlString = [HMACSHA256 appendTimestamp:undatedUnsortedUnsignedUrlString];
// Sort and % escape the request fields.
NSString *datedSortedUnsignedUrlString = [HMACSHA256 sortUrlString:datedUnsortedUnsignedUrlString];
// Calcul and append the "&Signature=XXXX" field to the rest of the request.
NSString *datedSortedSignedUrlString = [HMACSHA256 signUrlString:datedSortedUnsignedUrlString];
return datedSortedSignedUrlString;
}
@end
