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2d
comment Generate RSA-2048 private key for a VERY fast decryption (don't care if it will be unsecure)
@SEJPM: $d=1$ if for every prime factor $p$ of $n$, we have $e \equiv 1 \bmod p-1$. So, I picked an $e$ where $e−1$ is divisible by a lot of numbers, and then tested all those divisors to find which ones were one less than a prime, and then made sure that the product of all those primes was $>2^{2048}$
2d
revised Generate RSA-2048 private key for a VERY fast decryption (don't care if it will be unsecure)
edited body
2d
answered Generate RSA-2048 private key for a VERY fast decryption (don't care if it will be unsecure)
Aug
28
comment Calculating $\mathbb F_{p^2}$-rational points of an elliptic curve defined over $\mathbb F_p$
@111: In the field $GF(p^2)$, we often use a representation $ai + b$, where $i$ is one of the field elements with $i^2 = -1$ (and it turns out not to matter which, as they are isomorphic). In your representation, $i$ is one of two values $4z+3$ and $7z+8$.
Aug
28
awarded  Enlightened
Aug
28
awarded  Nice Answer
Aug
27
comment Does Curve25519 only provide 112 bit security?
@RichieFrame: actually, 4 of those bits are already accounted for by the fact that the full order size is 255 (not 256) bits, and that the cofactor is 8. DJB does leave one addition bit fixed (however, that's not inherent in the Curve25519; that's how Dan suggests it be used); however even with that change, that reduces the strength to 125.5 bits...
Aug
27
answered Does Curve25519 only provide 112 bit security?
Aug
27
comment What was the NSA's reasoning for making their bitwise combination functions in SHA-1 the way they did?
Well, one obvious distinction between their F1 and yours is that their F1 has evenly distributed output (assuming the inputs are evenly distributed); yours has a distinct bias towards 1 bits.
Aug
26
comment Inverse public-key encryption
What are you actually worried about? Is it that someone can figure out how to fake a response from your server (and if so, a good signature algorithm would fix that)? Or, is it that someone would modify your Java application so that it no longer cares whether it can talk to the server? The latter is a much tougher problem.
Aug
26
comment Possible to determine equivalence of hash codes from different hashing functions?
@P.Anderson: actually, after I wrote this, I realized that if $i$ and $j$ were relatively prime, you could reconstuct $SHA256(x)$ from $H_i(x)$ and $H_j(x)$. This isn't fatal, though; one way to make this work is to make our 'indicies' values which aren't relatively prime; for $H_i$, we use the exponent $3 \times 5 \times 7 \times ... \times p_n / p_i$, where $p_i$ is the ith odd prime (and where $n$ is the total number of indicies). That way, even with all the values $H_i$ other than $H_j$, we still can't recover $H_j$
Aug
25
reviewed Close Complement of information on software usage
Aug
25
reviewed Close Email: Degrees of Security
Aug
25
comment Complement of information on software usage
Are you looking for shareware to generate such images? If not, what precisely are you asking for?
Aug
24
comment What is the difference between a random oracle and a probabilistic algorithm?
One important distinction is that the random oracle is generally considered public (that is, the adversary is free to make queries to it); for a probabilistic algorithm, we don't expect that the adversary has special insight into the choices we make (he might be able to deduce them from the ciphertext)
Aug
24
comment How can I handle the situation if key size is less than 64 bits in DES?
Actually, it's not historic; instead, a DES key is defined to be 64 bits. Yes, 8 of those bits do not actually contribute for the transform (and so are typically ignored for cryptographical purposes), but as far as the API is concerned, all 64 bits need to be there.
Aug
24
revised Ensuring integrity and confidentiality together with symmetric encryption
edited body
Aug
24
reviewed Close how to do AES decryption knowing the key (matasano)
Aug
24
reviewed Close Is double encryption using AES using different key lengths (128 bit and then 256 bit) vulnerable?