CocoaShare/Classes/Dropbox/DropboxSDK/MPOAuth/MPOAuthSignatureParameter.m

//
//  MPOAuthSignatureParameter.m
//  MPOAuthConnection
//
//  Created by Karl Adam on 08.12.07.
//  Copyright 2008 matrixPointer. All rights reserved.
//

#import "MPOAuthSignatureParameter.h"
#import "MPOAuthURLRequest.h"
#import "NSString+URLEscapingAdditions.h"
#import "NSURL+MPURLParameterAdditions.h"

#import <openssl/evp.h>
#include <openssl/hmac.h>
#include <openssl/sha.h>
#include "Base64Transcoder.h"

@interface MPOAuthSignatureParameter ()
- (id)initUsingHMAC_SHA1WithText:(NSString *)inText andSecret:(NSString *)inSecret forRequest:(MPOAuthURLRequest *)inRequest;
@end

@implementation MPOAuthSignatureParameter

+ (NSString *)signatureBaseStringUsingParameterString:(NSString *)inParameterString forRequest:(MPOAuthURLRequest *)inRequest {
	return [NSString stringWithFormat:@"%@&%@&%@",	[inRequest HTTPMethod],
			[[inRequest.url absoluteNormalizedString] stringByAddingURIPercentEscapesUsingEncoding:NSUTF8StringEncoding],
			[inParameterString stringByAddingURIPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
}

+ (NSString *)HMAC_SHA1SignatureForText:(NSString *)inText usingSecret:(NSString *)inSecret {
	NSData *secretData = [inSecret dataUsingEncoding:NSUTF8StringEncoding];
	NSData *textData = [inText dataUsingEncoding:NSUTF8StringEncoding];
	OpenSSL_add_all_algorithms();
	unsigned char outbuf[SHA_DIGEST_LENGTH];

	
	
	unsigned int templen;
	HMAC_CTX ctx;
	
	const EVP_MD *digest = EVP_sha1();
	if(!digest) {
		NSLog(@"cannot get digest with name SHA1");
		return nil;
	}
	
	HMAC_CTX_init(&ctx);
	HMAC_Init(&ctx, [secretData bytes], [secretData length], digest);
	HMAC_Update(&ctx, [textData bytes], [textData length]);
	HMAC_Final(&ctx, outbuf, &templen);
	HMAC_CTX_cleanup(&ctx);
	
	//Base64 Encoding
	char base64Result[32];
	size_t theResultLength = 32;
	Base64EncodeData(outbuf, 20, base64Result, &theResultLength);
	NSData *theData = [NSData dataWithBytes:base64Result length:theResultLength];
	NSString *base64EncodedResult = [[[NSString alloc] initWithData:theData encoding:NSUTF8StringEncoding] autorelease];
	
	return base64EncodedResult;
}

- (id)initWithText:(NSString *)inText andSecret:(NSString *)inSecret forRequest:(MPOAuthURLRequest *)inRequest usingMethod:(NSString *)inMethod {
	if ([inMethod isEqual:kMPOAuthSignatureMethodHMACSHA1]) {
		self = [self initUsingHMAC_SHA1WithText:inText andSecret:inSecret forRequest:inRequest];
	} else if ([inMethod isEqualToString:kMPOAuthSignatureMethodPlaintext]) {
		if ((self = [super init])) {
			[self setName:@"oauth_signature"];
			[self setValue:inSecret];
		}
	} else {
		[self release];
		self = nil;
		[NSException raise:@"Unsupported Signature Method" format:@"The signature method \"%@\" is not currently support by MPOAuthConnection", inMethod];
	}
	
	return self;
}

- (id)initUsingHMAC_SHA1WithText:(NSString *)inText andSecret:(NSString *)inSecret forRequest:(MPOAuthURLRequest *)inRequest {
	if ((self = [super init])) {
		NSString *signatureBaseString = [MPOAuthSignatureParameter signatureBaseStringUsingParameterString:inText forRequest:inRequest];

		[self setName:@"oauth_signature"];
		[self setValue:[MPOAuthSignatureParameter HMAC_SHA1SignatureForText:signatureBaseString usingSecret:inSecret]];
	}
	return self;	
}

- (oneway void)dealloc {
	[super dealloc];
}

@end