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seen Jul 27 at 13:09

Oct
12
suggested suggested edit on Tunnels used in md5
Oct
12
revised Using pairings to verify an extended euclidean relation without leaking the values?
expanded the answer to take into account the comments
Oct
12
comment Encryption algorithm which produces comparable results for substrings
A stream cipher (with the same key and IV as correctly stated) will only provide the same ciphertext for two plaintext strings starting with the same substring, thus a very specific type of substrings (though the one given in the example above). Hence the lack of clarity about what is actually asked.
Oct
12
comment Could the Enigma algorithm be classified as a Feistel network?
@Ethan Heilman: Even the Kriegsmarine's Enigma with four rotors was poor encryption without the Stecker-board. What made it powerful was adding the Stecker-board's configuration to the initial state of the machine.
Oct
12
comment Could the Enigma algorithm be classified as a Feistel network?
@Jon Callas: It's not really a stream cipher (although there is no perfect definition for it, the vast majority of stream ciphers produce a key stream symbols and then combine then with plaintext symbols). The Enigma rather embodies a polyalphabetic cipher with a very large period (as described by Henno Brandsma).
Oct
12
revised Hash function from narrower block cipher operated in CBC-encryption mode?
moved corresponding comment here
Oct
12
comment Hash function from narrower block cipher operated in CBC-encryption mode?
@CodesInChaos: if you assume AES message processing can be DPA protected, then so can AES key schedule, since they are based on the same primitives. In practice, key schedule is also protected.
Oct
12
revised Hash function from narrower block cipher operated in CBC-encryption mode?
taking into account the small block size property
Oct
12
awarded  Revival
Oct
11
answered Hash function from narrower block cipher operated in CBC-encryption mode?
Oct
11
comment Using pairings to verify an extended euclidean relation without leaking the values?
No. As I said in the answer, assuming the output of the extended euclidean algorithm is correct, $\Pi_{i=1}^n e(g^{q_i(s)},g^{P_i(s)}) = e (g,g)$ must also hold. Please note the $\Pi$ in there: it means that you have to multiply with the group law in $G_1$ all of the $e(g^{q_i(s)},g^{P_i(s)})$ together to get the group element $e(g,g)$.
Oct
11
awarded  Citizen Patrol
Oct
11
answered Encryption algorithm which produces comparable results for substrings
Oct
11
comment Using pairings to verify an extended euclidean relation without leaking the values?
No: $e(g,g)$ is just an element of the group $G_1$ since $e$ maps pairs of elements from $G$ to elements of $G_1$. Now, if $e(g,g)=1$, that is, if $e(g,g)$ is the neutral element of $G_1$, then you can basically do nothing with the pairing $e$ using the generator $g$, since then $e(g^a,g^b)=e(g,g)^{a*b}=1^{a*b}=1$. So, to summarize, it can be that $e(g,g)$ for a specific $g$ and $e$, but this case is devoid of interest to build upon for cryptographic purposes (degenerate case).
Oct
11
answered Stream ciphers based on discrete logs
Oct
11
awarded  Editor
Oct
11
revised Using pairings to verify an extended euclidean relation without leaking the values?
$g$ lives in $G$ in this example, not in $G_1$
Oct
11
suggested suggested edit on Using pairings to verify an extended euclidean relation without leaking the values?
Oct
11
answered Using pairings to verify an extended euclidean relation without leaking the values?
Oct
11
answered RSA keys finding when messages are known