Objective-C HMAC-SHA1的示例代码

Question

我需要在Objective C中生成HMAC-SHA1.但是我找不到任何有用的东西.我尝试使用CCHMAC使用CommonCrypto,但没有用.我需要生成一个hmac并在生成HOTP号后.

有人在Objective C或C中有任何示例代码吗？

Answer 1

以下是使用SHA-256生成HMAC的方法:

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];

我不知道HOTP库,但如果我没记错的话,算法非常简单.

Answer 2

以下是如何生成HMAC-SHA1 base64的方法.

您需要将Base64.h和Base64.m添加到项目中.你可以从这里得到它.

如果您使用ARC,它将在Ba​​se64.m中显示一些错误.找到类似这样的行

return [[[self alloc] initWithBase64String:base64String] autorelease];

你需要的是删除自动释放部分.最终结果应如下所示:

return [[self alloc] initWithBase64String:base64String];

现在在您的常规项目中导入"Base64.h"和以下代码

#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;
}

同

NSLog(@"Hash: %@", hash);  

你会得到类似的东西:

ghVEjPvxwLN1lBi0Jh46VpIchOc=

 

Answer 3

这是完整的解决方案,无需任何额外的库或黑客即可运行:

+(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;
}

您不必包含任何已编码的第三方base64库.

Answer 4

这可以在不使用自定义协议的情况下工作,使用http://cocoawithlove.com/2009/07/hashvalue-object-for-holding-md5-and.html中的一些代码

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

用法:

- (NSString *) encodePassword: (NSString *) myPassword {
    HashSHA256 * hashSHA256 = [[HashSHA256 alloc] init];   
    NSString * result = [hashSHA256 hashedValue:mySecretSalt andData:myPassword];       
    return result;       
}