#Flowjo serial number generator pc serial numbers#
#Flowjo serial number generator pc verification#
#Flowjo serial number generator pc software#

With an alphabet of 34 characters (digits and uppercase letters except 'O' and 'I'), a 64-bit block requires 13 letters, which is probably acceptable (a typical Microsoft serial number has 25 letters).

#Flowjo serial number generator pc serial numbers#

This is not really more secure than the plain counter, but at least the serial numbers will be random-looking. The checker knows the key, and verifies the serial number by decrypting it (with the same hardcoded symmetric key) and looking at the final zeros. Encrypt that block with some hardcoded symmetric key, using a block cipher. Use the counter from the previous scheme (the one with ends with three zeros).The classical not-really-secure scheme would look like this: Rather, it will go as: 'my scheme is secure until a sufficiently witty and bored student comes along, reverse-engineers the checker code, and publishes the result on Facebook'. At that point, you will not get quantified security: you will not be able to say: 'my scheme is secure up to a budget of 3.8 billion dollars'. If you do not use a signature scheme, then you must be aware that a reasonably determined attacker will be able, through some disassembly, to circumvent the checker, or even to learn enough to be able to produce his own serial numbers (which the checker will happily accept). Along with the payload, you will end up with serial numbers of length 35 or so, which is probably too much for an average user to type in (but not by a large margin an 80-bit signature would fit nicely). There is some work on signature systems with shorter signatures ( Quartz, or McEliece-Niederreiter) but there is quite some controversy on their security.Įven with both uppercase letters and digits (36 possible characters, and there you have both 'I' and '1', and also 'O' and '0'), a 160-bit signature will use 31 characters. However, the smallest signatures among the 'assumed to be secure schemes' are closer to 160 bits (with BLS, which uses a pairing, which is kind of complex to implement) or 320 bits (with DSA or ECDSA). The minimal theoretical size for a cryptographically secure signature is about 80 bits (since signatures can be verified with only the public key, an attacker could try all possible bit sequences, and we usually require a security level of at least 2 80). I assume that the serial number will be, at some point, typed by a user.

#Flowjo serial number generator pc verification#

The trouble with this setup is not really about verification time, even in Javascript rather, it is the size of the signature which is a problem. The generator has a private key, which it uses to compute the signatures the checker only knows the corresponding public key. a counter of all serial numbers that you have generated) and a signature over the payload. The cryptographically secure solution is to have signed serial numbers: the serial number is the encoding of some payload (e.g. If this solution does not please you, then you do have a need for security, and this calls for cryptography. Only one of every 1000 numbers will be accepted by the checker. The checker works like this: a serial number is valid if it ends with three zeros. When you want a new serial number, increment your counter by 1000 the new counter value is the serial number. If there is no real need for security, then here is a very fast serial number generator, with a checker:

Salt: I don't know whether salt is the right word, but the algorithm should have at least one parameter, whose choice alters the generated keys (so that multiple people can use the same algorithm and needn't fear collisions). And only a small fraction of all the possible keys of a given length are actually valid so it's hard to guess keys. I'm also pretty sure that the keys were all generated algorithmically rather than by hand.

#Flowjo serial number generator pc software#

If you type it in, the software verifies it algorithmically (by checking whether it fulfills certain properties), rather than looking up a huge database. To clarify: If you buy commercial software, it is sometimes protected with a serial number/a key. Rather, it should be very easy to implement (in javascript) and it should be very fast. The algorithm needn't be cryptographically secure. Those numbers should only account for a small fraction of all the possible numbers of the given length. The generator should only produce serial numbers that pass the test of the checker. I would like to be able to set a salt (and maybe a length). I need a serial number generator and accompanying checker.