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8h
revised How does ROTL work?
Give example uses including those given as tag in the question
11h
revised How does ROTL work?
Notable CPUs that use the ROTL mnemonic. Explain how that's done from C.
13h
answered How does ROTL work?
13h
revised Non adjacent form of an integer is unique
add missing tilde
15h
comment How to securely map an element from an smaller domain to the other element in a large domain
The previous comment makes a convincing argument that if $e$ can be guessed, and $Enc_{pk}(r \cdot e)$ known, and $Enc_{pk}$ is homomorphic, and $e^{-1}$ in the sense of the homomorphism can be computed from $e$, then $Enc_{pk}(r)$ can be successfully guessed. While this is far from the question as written (which does not mention anything like homomorphic, or multiplication by $r$, or that this is random), my conclusion is that what's asked in question and comments can't be achieved.
15h
comment How to securely map an element from an smaller domain to the other element in a large domain
I have trouble relating the above comment to the question. $\;$ In particular, is the " small sized domain " of the question that of $r$, $e$, or $v$ in the comment? Is the " public encoding " of the question the " Paillier encryption " of the comment? Also, what is meant by " eliminate $e$ " in that comment? I suggest reformulation the question, incorporating the comment in a unified framework.
16h
revised Non adjacent form of an integer is unique
Bounds of the number of digits in the NAF; polish
16h
comment Non adjacent form of an integer is unique
@Vi Jay: Yes, your summary is correct. The answer now gives more details on the general method, called infinite descent , a special form of proof by contradiction. $\;$ Also I revised the proof. Formerly I used $b=(a−1)/4$ in the second case of the second proof, in order to match the first proof, but that left a gap because I assumed without proof that small $a$ had a single NAF. Now I'm first proving that $0$ has a single NAF, and in the second case of the second proof use $b=a−1$, which is simplest. $b=(a−1)/2$ also works.
16h
revised Non adjacent form of an integer is unique
Explain relevance of NAF to crypto
17h
revised Non adjacent form of an integer is unique
Spacing
17h
revised Non adjacent form of an integer is unique
Simpler definition of NAF as a tuple. Make the proofs more detailed and rigorous. In particular, get rid of the "Clearly, a>3" which was clear as mud in the second proof, and required extensive rework.
1d
answered Non adjacent form of an integer is unique
1d
comment Which one these alternatives using authentication and encryption will solve this multiple-user database problem?
@Ricky Demer: We also need that " different users " bit.
1d
comment How to securely map an element from an smaller domain to the other element in a large domain
With the requirements as I understand them, and the addition that the encoding/mapping is a deterministic function (in addition to public), there is no solution, for precisely the reason given in mikeazo's comment.
1d
comment How to securely map an element from an smaller domain to the other element in a large domain
Anything wrong with simply: each user $j$ secretly chooses a 256-bit random secret key $K_j$, then computes the 256-bit $\operatorname{HMAC-SHA-256}(K_j,x)$ where $x$ is a $s$-bit element of the small domain? $\;$ Perhaps that does not match the "public encoding" requirement, even though the method is public?
1d
revised Has human-generated entropy ever been a real problem?
polish
1d
answered Has human-generated entropy ever been a real problem?
1d
comment Which one these alternatives using authentication and encryption will solve this multiple-user database problem?
There's a solution to the problem even if $E_{pk_D}$ is secure, thus randomized, which is assumed in any sound application of public-key encryption. That seems to be the intend in the textbook: no mention is made of RSA; much less of textbook RSA, which would not be able to directly encipher or sign a sizable database query, sign an RSA cryptogram, or encipher a message comprising an RSA signature, assuming $k_A$ and $k_D$ have the same size. $\;$ $\;$ Additional hint: the policy is worded with "A user" rather than "Anyone".
1d
comment Which one these alternatives using authentication and encryption will solve this multiple-user database problem?
Hint: assume that an answer counts as information about what was asked. $\;$ Note: one method clearly beats the other, but both have the pitfall that the length of $R$ (and of the answer) is not masked, which is information about what was asked. $\;$ Note: You should probably retype and reword the question more concisely, in particular because there is a chance that you'll find the solution doing so; at least, give credit to the textbook (the question is interesting), and verify that you have the right to repost this extract.
1d
comment what is number of invertible matrix m*m on$ z_n$?
The question is in fact a duplicate of this one, which has a satisfactory solution (if not answer in the sense of the CSE website logic) in comment, and as an edit of the question.