Jalaj

875 reputation

bio	website
	location	Waterloo, Canada
	age	28
visits	member for	1 year, 6 months
	seen	Jan 20 at 4:30
stats	profile views	10

I am a PhD student with an interest in theoretical cryptography and mathematical tools used for cryptanalysis.

	875 reputation	bio	website		visits	member for	1 year, 6 months
27 badges		location	Waterloo, Canada		seen	Jan 20 at 4:30

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Sep 21	awarded	Custodian
Apr 9	comment	Does encrypting twice using the same block cipher produce a security weakness? I don't disagree with your comment, but I disagree with the formulation of your answer which for the first time gives an indication that you need to keep the keys independent if you want to use the same cipher text again. I just figured out that I was a bit hasty in making the second comment. You can construct an artificial PKC which is secure on one encryption, but leaks least (most) significant bits when doubly encrypted with the same key.
Apr 9	comment	Does encrypting twice using the same block cipher produce a security weakness? "as long as the keys you chose to encrypt a second time are independent of the keys you use the first time" This is not right, encryption keys are usually long lived keys. In fact, your statement questions the semantic security of the PKC in multiple message model. The second paragraph holds only for information theoretic security and that is because of Shannon's lower bound on the size of the key length.
Apr 4	comment	ECC algorithm pollard's $\rho$ complexity @VineetMenon: Complexity of an algorithm is always measured in terms of input size. In group-theoretic algorithms, the input is group and so it is measured by the order of the group that defines the group. Same for the graph. You define the complexity of a graph-theoretic algorithm in terms of the size of the graph, which is the number of vertices and the number of edges. If you have a sparse graph, then you just specify the number of vertices, edges are considered to be $O(n)$. For a general graph, you need both edges and vertices as for any connected graph, $\Omega(n) \leq E(G) \leq O(n^2).$
Apr 3	comment	ECC algorithm pollard's $\rho$ complexity The Handbook of Applied Cryptography says on Page 92 that it is $O(n^{1/4})$. I am not sure now where this poly-log factor came in to the picture!
Apr 3	comment	ECC algorithm pollard's $\rho$ complexity Can you give more details on why $poly \log$ factor is there? I don't understand what efficiency has to do with it. Thanks in advance!
Apr 3	revised	ECC algorithm pollard's $\rho$ complexity added 135 characters in body
Apr 3	answered	ECC algorithm pollard's $\rho$ complexity
Apr 3	comment	Trouble with diffie-hellman groups $O(2^{256})$ is still $O(1)$.
Mar 31	comment	Can you make a hash out of a stream cipher? The negative vote down, can you state the reason why you are not satisfied with the answer?!
Mar 31	comment	Can you make a hash out of a stream cipher? If you will look at the security requirement in an universal hash function, you will notice the difference from the well-known security requirements of cryptographic hash functions, viz collision resistance. The reason why UOWHF were introduced was to construct much efficient signature scheme without relying on stronger properties like collision resistance.
Mar 29	revised	Can you make a hash out of a stream cipher? added 146 characters in body
Mar 29	comment	SHA3 conference highlights? In addition to Samuel's link, you might refer to the wiki page: ehash.iaik.tugraz.at/wiki/The_SHA-3_Zoo It gets updated almost immediately when there is any worthwhile event.
Mar 29	answered	Can you make a hash out of a stream cipher?
Mar 20	answered	Order Preserving Encryption for Numeric Data Values
Mar 17	revised	Is this fixed length MAC unforgeable? Made it more readable with latex entries instead of text style entry.
Mar 17	suggested	suggested edit on Is this fixed length MAC unforgeable?
Mar 10	revised	Alternatives to FHE for secure function evaluation added 371 characters in body
Mar 10	comment	Alternatives to FHE for secure function evaluation Verifiable homomorphic OT exists, and by the completeness result that existence of secure OT implies existence of secure party computation, I believe we can have verifiability using FHE as well (not sure if composition will work fine or not. As far as I remember, UC model has nothing to say about composobility of homomorphic encryption scheme.) On that note, what is FE?