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编号之后。

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 。

您需要将Base64.h和Base64.m添加到项目中。你可以从here获得它。

如果您使用ARC，它将在Base64.m中显示一些错误。找到类似这样的行

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

您需要删除自动释放部分。最终结果应如下所示：

return [[self alloc] initWithBase64String:base64String];

现在在你的一般项目中导入“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;
}

用

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

这不使用自定义协议，使用一些代码 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

用法：

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

Answer 5

我花了一整天时间，尝试将生成的哈希（字节）转换为可读数据。我使用了上面答案中的base64编码解决方案，它对我来说根本不起作用（b.t.w。你需要和外部.h能够使用base64编码，我有）。

所以我做的就是这个（没有外部的.h完美地工作）：

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);

Answer 6

如果没有外部文件返回十六进制字符串，这就是你的做法：

-(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;
}

它在iOS 7的xCode 5中测试过，运行正常！

Answer 7

出于兴趣，为什么要创建（unsigned char cHMAC）然后转换为（NSData）然后将其转换为（NSMutableString）然后最终转换为（HexString）？

你可以通过削减中间人（即完全没有NSData和NSMutableString，更快更好的性能）更快地完成这项工作，同时将（unsigned char）更改为（uint8_t []），毕竟它们都是十六进制数组无论如何！，下面：

-(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;
}

我希望这有帮助，

此致

Heider Sati

Answer 8

你见过Jens Alfke的新MyCrypto课吗？

他有一些sample code on his blog。

Objective-C HMAC-SHA1的示例代码

8 个答案: