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22h
answered Can we share an n-bit string by using shamir's secret sharing n times?
1d
comment Difference between single-pass and two-pass MACs
Presumably, the number of "passes" is the number of times the algorithm scans the message being authenticated. However, I don't recall hearing of a MAC that can't be implemented in a single pass...
1d
comment Is Shamir's Secret Sharing Scheme insecure for larger field?
"It seems wrong" -> it is wrong; there's no security issue with large $p$ values.
1d
comment Choosing finite field size in Shamir's Secret Sharing Scheme
Yes, I was in the middle of doing it myself, when I noticed that someone else did...
1d
comment What is the typical block size in RSA?
You mean that this is the second block of some message (that someone else has encrypted)? This can be covered by making the tag (that identifies the message that this block is a member of) be a 16 byte random number that the encryptor picks. No one else (other than the holder of the decryption key) can know what that is, so no one else can generate such a block.
1d
comment What is the typical block size in RSA?
Actually, you don't really need to use distinct RSA keys; instead, you use a few of the 86 or 214 bytes you have in include a tag that declares that these blocks are the part of the same message, and a 'fragment number' to give the order. However, we'll all agree that encrypting a symmetric key is far cheaper...
1d
answered What is the typical block size in RSA?
1d
revised RSA private key finding method
Fixed math typo
2d
comment Public key exponent coprime with totient proof
@fgrieu: If that's what he's asking, then a related answer (with, a bit of work, does answer the question) is crypto.stackexchange.com/questions/31980/…
2d
comment What is base of $log$ in Subexponential Algo for DLP?
@RickyDemer: nope, they don't, because they're either in a $O(\textit{formula})$ notation, or multiplied by an unspecified constant; either form eats constant factors
Feb
11
comment Breaking the Rabin Signature system with chosen message attack
And, by selecting a $y$ with Jacobi symbol -1, I really mean selecting one with $\Bigl(\frac{y}{n}\Bigr) = -1$
Feb
11
comment Breaking the Rabin Signature system with chosen message attack
Actually, we would consider a cryptosystem broken if there is an attack which succeeds with probability $10^{-6}$. However, since you asked: en.wikipedia.org/wiki/Jacobi_symbol
Feb
11
answered Breaking the Rabin Signature system with chosen message attack
Feb
10
comment Why is AES-128 considered secure while RSA needs a 1024-bit size to be considered secure
Actually, to answer the question: while factoring the modulus may be difficult, it is significantly easier than trying to brute force the private exponent, or even trying possible primes $p$ to look for a factor...
Feb
10
comment Do most TLS 1.2 implementations express curves in a canonical form when performing EC arithmetic?
Yes, that is correct. As you yourself stated, "all EC curves are isomorphic to a curve in Weierstrass form", however not all EC curves are isomorphic to a curve in Montgomery/Edwards form.
Feb
10
comment Do most TLS 1.2 implementations express curves in a canonical form when performing EC arithmetic?
The curves used most often in TLS 1.2 are the "NIST curves", which cannot be expressed in Montgomery or Edwards form.
Feb
10
comment I have a challenge for anyone willing
You're right; this isn't a "let us solve your cryptogram" site. In addition, it is expected that answers are posted here (after all, this is a Q/A site). Perhaps sci.crypt on usenet might be more suitable?
Feb
10
answered Vulnerabilities in specifying the hash algorithm used for signature verification on a per-message basis
Feb
10
revised RSA private key finding method
At least, lets get the math right...
Feb
10
comment Caculated time One Point Multiplication with double and method
How certain are you on the timings of the double and add routines? If they are moderately faster than you think, that'd explain the performance difference.