4,005 reputation
1621
bio website
location United States
age
visits member for 3 years, 5 months
seen 1 hour ago

Feb
2
comment Definition of ciphertext security
That's not suggesting that security follows from D(k,0)=0; it should be interpreted as "Consider a chosen ciphertext secure encryption system (E,D) where" it happens to be the case that for all keys k, D(k,0)=0. $\hspace{.16 in}$
Feb
2
comment Definition of ciphertext security
Such schemes can't provide plaintext integrity (and thus also can't provide ciphertext integrity), but that has very little to do with IND-CPA. $\;$
Feb
2
comment Existence of encryption schemes where $F_{k}^{-1} \big( F_{k}(A) + R \big) = A + O(R)$
In other words, decryption should be Lipschitz? $\;$
Feb
2
comment Non-repudiation and digital signature of a dishonest participant
(My initial comment shouldn't have said "also". $\:$ The issue raised in your OP is $\hspace{1.5 in}$ hardly "fundamental", it's just an important subtlety.) $\;\;\;\;$
Feb
1
comment Non-repudiation and digital signature of a dishonest participant
... key agreement usually doesn't need nonrepudiation. $\;$
Feb
1
comment Non-repudiation and digital signature of a dishonest participant
The most generic way is a (physically) signed contract stating that, in return for something, Alice will be bound to a certain extent by signed messages that are compatible with [specific public key]. $\:$ One potential alternative is a (video-and-audio) recording of Alice stating that she will be bound to a certain extent by signed messages that are compatible with [specific public key]. $\;\;\;\;$
Feb
1
comment Non-repudiation and digital signature of a dishonest participant
Yes. $\:$ That issue is also fundamental for nonrepudiation, but it's independent $\hspace{1.75 in}$ of the issue raised in your opening post. $\;\;\;\;$
Feb
1
answered Non-repudiation and digital signature of a dishonest participant
Feb
1
comment Parallel Pollard's Rho: Number of distinguished points
Oh, I'd missed that part. $\;$
Feb
1
comment Parallel Pollard's Rho: Number of distinguished points
journals.kantiana.ru/eng/vestnik/860/2408 $\;$
Feb
1
answered One-way function definition
Jan
28
comment RSA: How effective is this keypair-trash attack
There is an even "more annoying scenario" than that: "compute the gcd of" each pair $\hspace{1.32 in}$ of "public keys you can scan over the net." $\;$
Jan
28
answered How do I communicate the value of the initialization vector to the end user? Should it be part of the encrypted message?
Jan
28
comment How do I communicate the value of the initialization vector to the end user? Should it be part of the encrypted message?
From the short description you gave of the assignment, it sounds like you don't need to implement a mode of operation. $\:$ For modes of operation (including CBC), you would store the initialization vector as the beginning of the ciphertext, so that the decryption algorithm can do what you describe. $\;\;\;\;$
Jan
28
comment How do I communicate the value of the initialization vector to the end user? Should it be part of the encrypted message?
"to implement a 32-bit block cipher" for which a specification was given, or one chosen by you? $\hspace{.6 in}$ "a simple block-cipher that uses CBC" is possible, although it seems far more likely that you mean "CBC mode with a simple block cipher", especially since you then jump straight into talking about IVs. $\hspace{.6 in}$
Jan
28
comment Negative exponents in Shoup's threshold RSA?
x^(-n) = x^((-1)*n) = (x^(-1))^n $\;$
Jan
26
answered Will current encryption always remain secure? Is there mathematical proof?
Jan
26
comment Is it a variant of Strong RSA assumption?
What about just outputting $\:(c,\hspace{-0.04 in}1)\;$? $\;\;\;\;$
Jan
25
revised What is contained in a RSA key file?
fixed title's grammar
Jan
24
comment How much work is required to detect multiple collisions for a hash function?
detecting $\mapsto$ finding $\:$ ? $\;\;\;\;$