License keys are the defacto-standard as an anti-piracy measure. To be honest, this strikes me as (in)Security Through Obscurity, although I really have no idea how license keys are generated. What is a good (secure) example of license key generation? What cryptographic primitive (if any) are they using? Is it a message digest? If so, what data would they be hashing? What methods do developers employ to make it difficult for crackers to build their own key generators? How are key generators made?
It is however very much security by obscurity. Anyone taking the time to disassemble the code would be able to find the graphing function and encryption keys, then mock up a key generator, but its probably quite useful for slowing down casual piracy.
A good software license key/serial number generator consists of more than just a string of random characters or a value from some curve generator. Using a limited alphanumeric alphabet, data can be embedded into a short string (e.g. XXXX-XXXX-XXXX-XXXX) that includes all kinds of useful information such as:
The license key data is then encrypted and then encoded using the limited alphanumeric alphabet. For online validation, the license server holds the secrets for decrypting the information. For offline validation, the decryption secret(s) are included with the software itself along with the decryption/validation code. Obviously, offline validation means the software isn't secure against someone making a keygen.
Probably the hardest part about creating a license key is figuring out how to cram as much data as possible into as few bytes as possible. Remember that users will be entering in their license keys by hand, so every bit counts and users don't want to type extremely long, complex strings in. 16 to 25 character license keys are the most common and balance how much data can be placed into a key vs. user tolerance for entering the key to unlock the software. Slicing up bytes into chunks of bits allows for more information to be included but does increase code complexity of both the generator and validator.
Encryption is a complex topic. In general, standard encryption algorithms like AES have block sizes that don't align with the goal of keeping license key lengths short. Therefore, most developers making their own license keys end up writing their own encryption algorithms (an activity which is frequently discouraged) or don't encrypt keys at all, which guarantees that someone will write a keygen. Suffice it to say that good encryption is hard to do right and a decent understanding of how Feistel networks and existing ciphers work are prerequisites.
Writing a keygen is a matter of knowing what a license key consists of and then producing the same output that the original key generator produces. If the algorithm for license key verification is included in and used by the software, then it is just a matter of creating software that does the reverse of the verification process.
However, despite being broken up into steps, this falls prey to the same methods of cracking used for the normal process. The process used to create an activation key that is checked against the original CD key was quickly discovered, and generators that incorporate both of the keys were made.
Specifically, if you used computed fields or text fields containing only spaces, the Web DataWindow generator now creates a table entry for these fields, making the table display twice as wide. If you see this behavior, delete these placeholder fields and use a more standard layout.
Most buildings require electricity, or power, to function. Power is produced in power generators (see below), stored or discharged from Power Storages, and consumed by buildings. Power is transferred via Power Lines, Power Poles, or Train Stations and Railways. Power is measured in megawatts (MW).
Buildings that consume (or supply) power will only function when connected to a Power grid (see below section) where either the total supply from all power generators is sufficient to meet the total demand from all power consumers or there is still energy in Power Storages. If power demand exceeds supply and all Power Storages are empty, the circuit breaker trips, halting all buildings on that grid until the problem is corrected followed by a breaker reset.
A power grid is a network consisting of power-generating and power-consuming buildings connected through Power Lines, Power Poles, Train Stations, and Railways. A graph of total power capacity, power production, and power consumption can be viewed by interacting E with any Power Pole, generator, Train Station, or Power Switch on that grid.
If power consumption ever exceeds production and there is no energy in Power Storages to use, the power grid will trip. All connected power generators and power consumers in that grid will stop working. The sound effect of the trip can be heard from any part of the map, regardless of the distance between the tripped devices and the pioneer.
The pioneer can reset the circuit breaker by interacting E at any of the connected power generators or Power Poles. In the UI, pull down the lever (refer to the image below) to restore the power. Before resetting it is advised to either attach more power generators to the grid or temporarily remove power cables to some of the areas of the factory. Otherwise, the power grid will simply overload again as soon as it is reactivated.
If there are no connected power generators whatsoever (such as by disconnecting all power generators at once using a switch), the buildings will instead simply switch off and there will be no trip. In this case, the buildings will resume function as soon as an adequate power supply is reconnected, without the need to reset the fuse.
All power generators with the exception of the Biomass Burner always operate at full capacity. Biomass Burners instead scale to power consumption and burn slower at lesser demand. For example, if grid capacity is 105 MW, provided by one Coal Generator producing 75 MW and one Biomass Burner producing 30 MW, and power consumption is 95 MW, the entire capacity of the Coal Generator will be used first followed by two thirds of the Biomass Burner's capacity, meaning fuel will be burned at two thirds of the rate it would at maximum demand. This also renders Biomass Burners unable to charge Power Storages.
When connected to a power grid that is supplied by generators other than Biomass Burners, it will charge using the excess generated power, up to a rate of 100 MW each. Therefore, it will take at least an hour in real-time to fully charge an empty Power Storage, or longer if the spare power is less than to satisfy all Power Storages on the grid (Power Storages that are not fully charged will split the spare power, reducing their charge rate to the available spare power divided by the number of partially charged Power Storages). Charging Power Storage does not add to the grid power consumption or max consumption figures, nor does it diminish capacity since it will slow or stop charging if there are other demands for the available power.
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