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seen Apr 5 '13 at 6:59

Mar
26
awarded  Popular Question
Apr
5
accepted How is ElGamal not secure under chosen ciphertext attack, but semantically secure in some cases?
Apr
5
comment How is ElGamal not secure under chosen ciphertext attack, but semantically secure in some cases?
Oh- that helps clear up a lot of things I misinterpreted. Thanks!
Apr
5
revised How is ElGamal not secure under chosen ciphertext attack, but semantically secure in some cases?
edited body
Apr
5
asked How is ElGamal not secure under chosen ciphertext attack, but semantically secure in some cases?
Apr
5
comment Chosen ciphertext insecurity in an ElGamal variant
Is it the same result for (g^a(mod p))^k as it is for (g^a)^k(mod p)?
Apr
4
asked Chosen ciphertext insecurity in an ElGamal variant
Apr
4
accepted Attack on DSA with signatures made with k, k+1, k+2
Apr
4
comment Attack on DSA with signatures made with k, k+1, k+2
Just to be clear, if all operations are performed in Z_q, does that mean that if I have something like a - b(mod q), that necessarily means (a-b)(mod q), NOT subtract b(mod q) from a? For example, in the equation from step 3, and some of the other equations along the way
Apr
4
comment Attack on DSA with signatures made with k, k+1, k+2
Ok- that helps a lot. Another question: in 1.2, I can't understand why (mod q) is still in the equation. If I use the rule you've provided in the edit, I eliminate the entire term x*r2(mod q) and am left with only h2-(h1(r2/r1)) so I'm trying to understand why the (mod q) part of the term is still there rather than having the whole term eliminated
Apr
4
awarded  Custodian
Apr
4
reviewed Approve suggested edit on Attack on DSA with signatures made with k, k+1, k+2
Apr
4
comment Attack on DSA with signatures made with k, k+1, k+2
Thanks! There are a few lines I don't understand- might just be that I'm unfamiliar with some modular arithmetic. In step 1, #2, what is the operation being performed? Are we subtracting (1)*[r2/r1]? If so, I don't completely understand where the x gets eliminated. Also, in step 2, #1, it looks like you've rearranged (1) from step 1- is there some property of modulus that allows you to just "swap" the x and the h1/r1 like you did? Would you be able to include exactly what you're adding/subtracting to get each equation so I can follow the math?
Apr
4
accepted Solving congruences using PARI
Apr
4
asked Attack on DSA with signatures made with k, k+1, k+2
Mar
18
comment Solving congruences using PARI
That works- thanks! Both of your answers have been really helpful to me even though you don't use PARI/GP
Mar
18
comment Solving congruences using PARI
I've edited the comment to show how I've attempted to solve the example system of congruence you gave in my last question
Mar
18
awarded  Editor
Mar
18
revised Solving congruences using PARI
added 244 characters in body
Mar
17
awarded  Scholar