sha1加密

#import <CommonCrypto/CommonHMAC.h>

- (NSString *)getSignStr {
    NSString *kApiKey=@"abcdefg";
    NSString *kApiSecret=@"gfedcba";
    int valid_durtion = 100;
    long int current_time = [[NSDate date] timeIntervalSince1970];
    long int expire_time = current_time + valid_durtion;
    long random = labs(arc4random() % 100000000000);
    NSString* str = [NSString stringWithFormat:@"a=%@&b=%ld&c=%ld&d=%ld", kApiKey, expire_time, current_time, random];
    const char *cKey  = [kApiSecret cStringUsingEncoding:NSUTF8StringEncoding];
    const char *cData = [str cStringUsingEncoding:NSUTF8StringEncoding];
    char cHMAC[CC_SHA1_DIGEST_LENGTH];
    CCHmac(kCCHmacAlgSHA1, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
    
    NSData *HMAC = [[NSData alloc] initWithBytes:cHMAC length:sizeof(cHMAC)];
    
    NSData* sign_raw_data = [str dataUsingEncoding:NSUTF8StringEncoding];
    NSMutableData* data = [[NSMutableData alloc] initWithData:HMAC];
    [data appendData:sign_raw_data];
    NSString* sign = [data base64EncodedStringWithOptions:0];
    return sign;
}