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Feb
15
reviewed Approve suggested edit on alternating-step tag wiki excerpt
Feb
15
reviewed Approve suggested edit on threshold-cryptography tag wiki
Feb
14
revised Encrypting firmware with AES and no IV
Man, there's been a lot of typo's here
Feb
14
revised Encrypting firmware with AES and no IV
More Latex corrections...
Feb
14
answered Encrypting firmware with AES and no IV
Feb
14
revised Why is a 2048-bit public RSA key represented by 540 hexadecimal characters in X.509 Certificates?
Corrected from BER to DER
Feb
14
comment Why is a 2048-bit public RSA key represented by 540 hexadecimal characters in X.509 Certificates?
@HenrickHellström: I was unaware that X.509 used DER, not BER. Thank you for informing me that; I'll fix up my answer accordingly.
Feb
13
answered Why is a 2048-bit public RSA key represented by 540 hexadecimal characters in X.509 Certificates?
Feb
12
comment Prime factorization of RSA modulus
@Moses: look at remark 3.5 in your textbook; that gives an alternate formula that (often) gives a smaller value for the decryption exponent $d$. That's your 'second key'.
Feb
12
comment RFC 3526 - What does pi mean?
@SimonJohnson: Yes; it's there not because we expect it to have some special property, but instead because we don't.
Feb
12
answered RFC 3526 - What does pi mean?
Feb
12
comment Prime factorization of RSA modulus
If your textbook says $e_1d_1 = 1 \bmod \phi(N)$, you might want to consider getting another textbook. Such an $e_1, d_1$ will work as RSA public/private exponents, however not all valid exponents will satisfy the equation; for example, consider the $e_1=337, d_1=1471$ example I gave previously; we have $(x^{337})^{1471} = x \bmod 3953$ for all $x$, but $337 \times 1471 \not\equiv 1 \bmod \phi(3953)$
Feb
12
comment Prime factorization of RSA modulus
An important correction; it is not neccesarily true that $e_1 d_1 = e_2 d_2 - 1 \bmod \phi(N)$. With the $e_1, d_1, e_2, d_2$ you picked, it will be true, however it would not be if we picked (for example) $e_1=337, d_1 = 1471, e_2=23, d_2 = 749$. Instead, the relationship that is guaranteed to hold is $e_1 d_1 = e_2 d_2 = 1 \bmod lcm(p-1,q-1)$, where $p$, $q$ are the prime factors of $N$. This changes how you approach this question.
Feb
12
revised Certificate signature with SHA-1 and RSA: where do 1888 bits come from?
edited tags
Feb
12
answered Certificate signature with SHA-1 and RSA: where do 1888 bits come from?
Feb
11
answered simple multiplication in GF(8)
Feb
11
comment How does RSA signature verification work?
@Pacerier: well, one could devise methods for signing long messages that don't involve hashing, such as splitting up the message into small segments, tie each segment together with an identifier and a segment sequence number, and sign each individually. However, hashing works so much easier that no one ever considers an alternative.
Feb
10
comment If attacker knows salt and hash, how is salt effective?
Question (probably for meta); this question really isn't the same as the "Use of salt to hash a password" (as that question really focused on salt length), however that answer is spot on. Should we dup this question to that question?
Feb
9
comment Needed: signature over a collection of hashes
Also, from a technical point, multiplying all the hashes together in a field won't work; one of the properties of a field is that any nonzero element is divisible by any other nonzero element. That approach will likely need a ring...
Feb
9
comment Needed: signature over a collection of hashes
What is the reason you don't want to distribute the hashes? Is it because of space (for example, we're talking about a lot of hashes), or is it because you don't want anyone else to be able to deduce them (apart from testing the signature against the hash, which they can obviously do)?