Question

I am using following code to convert string to sha1 string but i am not able to find any solution for reverse of this i.e normal string from sha1 string.

+(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 help me to solve this issue.

Thanks in advance

Answer 1

SHA-1 is a one-way hash algorithm, so there isn’t an algorithm to go from a SHA-1 string to a normal string.