腾讯云V3签名方法之iOS

// 计算签名
-(NSDictionary *)calculationSignature{
    
    NSString *SECRET_ID = @"AKIDz8krbsJ5yKBZQpn74WFkmLPx3EXAMPLE";
    NSString *SECRET_KEY = @"Gu5t9xGARNpq86cd98joQYCN3EXAMPLE";
    NSString *CType = @"application/json; charset=utf-8";
    NSString *service = @"cvm";
    NSString *host = @"cvm.tencentcloudapi.com";
    NSString *hostn = [host stringByAppendingString:@"\n"];
    NSString *region = @"ap-guangzhou";
    NSString *action = @"DescribeInstances";
    NSString *version = @"2017-03-12";
    NSString *algorithm = @"TC3-HMAC-SHA256";
    NSString *timestamp = @"1551113065"; //此处用官方文档中的时间戳
    NSString *date = [self getUTCStr];
    
    // ************* 步骤 1：拼接规范请求串 *************
    NSString *httpRequestMethod = @"POST";
    NSString *canonicalUri = @"/";
    NSString *canonicalQueryString = @"";
    NSString *canonicalHeaders = [@"content-type:application/json; charset=utf-8\nhost:" stringByAppendingString:hostn];
    NSString *signedHeaders = @"content-type;host";
    NSString *bodyStr = @"{\"Limit\": 1, \"Filters\": [{\"Values\": [\"\\u672a\\u547d\\u540d\"], \"Name\": \"instance-name\"}]}";
    NSString *hashedRequestPayload = [self sha256HashFor:bodyStr];
    NSString *canonicalRequest= [[NSString alloc] initWithFormat:@"%@%@%@%@%@%@%@%@%@%@%@", httpRequestMethod,@"\n",canonicalUri,@"\n", canonicalQueryString,@"\n", canonicalHeaders,@"\n", signedHeaders,@"\n", hashedRequestPayload];
    
    NSLog(@"第一步结果:%@%@",@"\n",canonicalRequest);
    // ************* 步骤 2：拼接待签名字符串 *************
    NSString *credentialScope = [[NSString alloc]initWithFormat: @"%@%@%@%@", date,@"/",service,@"/tc3_request"];
    NSString *hashedCanonicalRequest = [self sha256HashFor:canonicalRequest];
    NSString *stringToSign = [[NSString alloc] initWithFormat:@"%@%@%@%@%@%@%@", algorithm,@"\n",timestamp,@"\n",credentialScope,@"\n",hashedCanonicalRequest];
    NSLog(@"第二步结果:%@%@",@"\n",stringToSign);
    // ************* 步骤 3：计算签名 *************
    
   
    NSString * key1 = [self hexStringFromString:[@"TC3" stringByAppendingString:SECRET_KEY]];
    NSString *secretDate = [self hmacForHexKey:key1 andStringData:date];
//    NSLog(@"secretDate:%@", secretDate);
    NSString *secretService = [self hmacForHexKey:secretDate andStringData:service];
//    NSLog(@"secretService:%@", secretService);
    NSString *secretSigning = [self hmacForHexKey:secretService andStringData:@"tc3_request"];
//    NSLog(@"secretSigning:%@", secretSigning);
    NSString *signature = [self hmacForHexKey:secretSigning andStringData:stringToSign];
    NSLog(@"第三步结果:%@%@",@"\n",signature);
    // ************* 步骤 4：拼接 Authorization *************
    NSString *authorization = [[NSString alloc] initWithFormat: @"%@ Credential=%@/%@, SignedHeaders=%@, Signature=%@",algorithm,SECRET_ID,credentialScope, signedHeaders, signature];
    NSLog(@"第四步结果:%@%@",@"\n",authorization);
    NSDictionary *dic = @{
        @"URL": [@"https://" stringByAppendingString:host],
        @"Authorization": authorization,
        @"ContentType": CType,
        @"Host": host,
        @"X-TC-Action": action,
        @"X-TC-Version": version,
        @"X-TC-Timestamp": timestamp,
        @"X-TC-Region": region,
    };
    NSLog(@"最终完整的调用信息:%@%@",@"\n",dic);
    return dic;
}

//SHA256加密
-(NSString*)sha256HashFor:(NSString*)input{
    const char* str = [input UTF8String];
    unsigned char result[CC_SHA256_DIGEST_LENGTH];
    CC_SHA256(str, (CC_LONG)strlen(str), result);
    
    NSMutableString *ret = [NSMutableString stringWithCapacity:CC_SHA256_DIGEST_LENGTH*2];
    for(int i = 0; i<CC_SHA256_DIGEST_LENGTH; i++)
    {
        [ret appendFormat:@"%02x",result[i]];
    }
    ret = (NSMutableString *)[ret uppercaseString];
    return [ret lowercaseString];
}

// hmac256加密
- (NSString *)hmacForHexKey:(NSString *)hexkey andStringData:(NSString *)data
{
    NSData *keyData = [self dataFromHexString:hexkey];
    const char *cKey  = [keyData bytes];
    const char *cData = [data cStringUsingEncoding:NSUTF8StringEncoding];
    unsigned char cHMAC[CC_SHA256_DIGEST_LENGTH];
    CCHmac(kCCHmacAlgSHA256, cKey, keyData.length, cData, strlen(cData), cHMAC);
    return  [self convertDataToHexStr: [[NSData alloc] initWithBytes:cHMAC length:sizeof(cHMAC)]];
}

- (NSString *)convertDataToHexStr:(NSData *)data{
    if (!data || [data length] == 0) {
        return @"";
    }
    NSMutableString *string = [[NSMutableString alloc] initWithCapacity:[data length]];
    [data enumerateByteRangesUsingBlock:^(const void *bytes, NSRange byteRange, BOOL *stop) {
        unsigned char *dataBytes = (unsigned char*)bytes;
        for (NSInteger i = 0; i < byteRange.length; i++) {
            NSString *hexStr = [NSString stringWithFormat:@"%x", (dataBytes[i]) & 0xff];
            if ([hexStr length] == 2) {
                [string appendString:hexStr];
            } else {
                [string appendFormat:@"0%@", hexStr];
            }
        }
    }];
    return string;
}

// 获取UTC时间
-(NSString *)getUTCStr{
    NSTimeInterval time = 1551113065;//此处使用腾讯云文档中的时间戳，实际请求时需要获取当前时间
    NSDate *currentDate = [NSDate dateWithTimeIntervalSince1970:(NSTimeInterval)time];
    //转为字符串
    NSDateFormatter *format = [[NSDateFormatter alloc]init];
    NSTimeZone* timeZone = [NSTimeZone timeZoneForSecondsFromGMT:0];
    [format setTimeZone:timeZone];
    [format setDateFormat:@"yyyy-MM-dd"];
    return [format stringFromDate:currentDate];
}

// string 转data
- (NSData *)dataFromHexString:(NSString *)sHex {
    const char *chars = [sHex UTF8String];
    int i = 0;
    NSUInteger len = sHex.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;
}

// 普通转为16进制
- (NSString *)hexStringFromString:(NSString *)string{
    NSData *myD = [string dataUsingEncoding:NSUTF8StringEncoding];
    Byte *bytes = (Byte *)[myD bytes];
    //下面是Byte 转换为16进制。
    NSString *hexStr=@"";
    for(int i=0;i<[myD length];i++)
    {
        NSString *newHexStr = [NSString stringWithFormat:@"%x",bytes[i]&0xff];///16进制数
        if([newHexStr length]==1)
            hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];
        else
            hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];
    }
    return hexStr;
}