将sha1字符串解码为普通字符串

我正在使用下面的代码将字符串转换为sha1字符串，但我无法找到任何解决方案，即从sha1字符串中返回正常字符串。将sha1字符串解码为普通字符串

+(NSString *)stringToSha1:(NSString *)str{ 
    const char *s = [str cStringUsingEncoding:NSASCIIStringEncoding]; 
    NSData *keyData = [NSData dataWithBytes:s length:strlen(s)]; 

    // This is the destination 
    uint8_t digest[CC_SHA1_DIGEST_LENGTH] = {0}; 
    // This one function does an unkeyed SHA1 hash of your hash data 
    CC_SHA1(keyData.bytes, keyData.length, digest); 

    // Now convert to NSData structure to make it usable again 
    NSData *out = [NSData dataWithBytes:digest length:CC_SHA1_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:@""]; 

    NSLog(@"Hash is %@ for string %@", hash, str); 

    NSData *dtt = [hash dataUsingEncoding:NSUTF8StringEncoding]; 
    //dtt = [nsda] 
    NSString *unhash = [dtt description]; 

    return hash; 
}

plz帮我解决了这个问题。

在此先感谢

来源

2010-08-16 user130934