Authenticated Initial Made Easy

Authenticated initial

a semester presentation we're going to have a look at password authenticated key exchange and look at some of the principles behind peek and see if we can find a better way to be able to authenticate users using passwords so the problem that we harvest this we might have a user Alice there was a password QWERTY our current method of storing our passwords is to be able to define a hashing method and then to be able to avoid rainbow table attacks we add some salt on to Alice's password and then we derive a hash from there unfortunately we must store the hash besides we must all the salt beside the hash which means an intruder eve basically just has to look up a dictionary and then take lots of different passwords from the dictionary and try different permutations because she will not have the salt if she searches through and she'll find the one that might is Alice's password and the salt because she'll be able to find the same hash value so in this case we mostly use our passwords can actually be cracked in some way so what we need is a method that allows Bob the server to be able to store a seer some sort of secret and then for our Alice not to give away her password but to prove that she still knows the password so SRP is one method which is used and the centrality and TLS adults one-to-many Apple products and what happens is that Alice and Bob will exchange some details and at the end of it they'll derive the same encryption key and they can validate serikov our get that Alice knows her secret and we do not release any details of her password from what stored on the server the SRP is a fairly complex protocol until us here so we have an identity and then we also have a password and then we go through various stages of actually proving that Alice knows her password without actually storing it on the system another method that we can use this was called the speak and with this we use our password key exchange so let's look at this scenario here where pollicis the client wants to show Bob that she still knows her password so we don't want to be communicating the password to over the wires but both Bob and Alice will know what the password actually is okay so here's the basic method Alice generates a random value X and takes G a point on the elliptic curve to calculate X which is another point on the curve she then computes W times M plus X X is this value here M is a well-defined point and W is her password converted into an integer this value of T is then passed to Bob Bob then Jairus has random number and we have a point in the left a curve to produce another point here he then calculates s is equal to w x and plus y and again as another point which is fixed and w is the password combated and turn integer value it is not possible even though though eve is less thing to be able to determine what the value of the password actually is so Bob sends that to Alice Alice that calculates the key as the x value times s the vouchers received minus W n she knows an and W is the password competitor integer value Bob calculus s value they should end up with the same key with x times y the to run the various times G every single time we will get a new key and only by knowing the value of W what we'll be able to derive the same key so it's done by this if we take s we get this here WN plus y and then we subtract up your end through that and that cancel so we just get Y and Y is equal to Y G so it's x times y times G so we'll have a look I tell you that really works by looking at speak to okay so we have a password here and then the ID for Bob and Alice and we use elliptic curve and here it's every time that we run this with the same password we should get a different key generated so here's the shared key at the end of it this is the value the hours passes and this is the valley the Bob passes we can use other security levels of if we require and this is the Python code here that were actually using for it obviously Bob and Alice would be communicating over the network but this shows a simple demonstration of it okay so every single time we should end up with the different eye key at the end of it and then if we don't want Bob to actually store the password then what he will do is to be able to has the password and the salt and delete the original password and then that's then used to provide the validation an improved method is a pig and a pig is a fairly new method of a pig and with this there is an original there's a registration of the password which generates I keep here so there's a client secret and there was a server public key Bob will only hold the salt value and Alice will only hold the password value Alice will never determine the salt value and Bob all never determine the password that's what we have is what's called an oblivious pseudo-random function it's also integrated into the diffie-hellman method with this Bob can actually pass the value of the salt value to hours without actually hours her finding out for the salt valuers but she can then use it to be able to derive a key so if we say that the value that we get here a salt - then it's possible to calculate a key based on this new salt value and the password to the Alice knows she then knows that this is the right key because Bob with her six key and has public key passes a ciphered value of the key of what she can decrypt and then determine that she has the right key or not so in this way we divorced both the password and salt and only bread bringing the two of them together can we actually create the right key and validate the user if Alice wants to re-register her key her password again she would go through this registration process and then generate new sets of keys so that she owns her own password and owns the ability to re-create her password okay so that's been an introduction to peek or password authentication key exchange