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Feb
12
comment Is the complexity of Caesar (shift) ciphers “n * n!”?
Please note that "decryption" usually means an algorithm which knows the key. And knowing the key, you should be able to decrypt a text in O(length of text).
Feb
8
comment Is $f(x)\oplus x$ a one-way function?
Of course, this is only a counter-example if one-way functions exist at all.
Feb
6
awarded  Notable Question
Jan
13
revised How to find the factors of the modulus?
edited tags
Jan
9
revised Are there any known inverse hash lookups for the zero string?
null → zero
Jan
9
revised Which block cipher mode does the experts use?
you also need the key to encrypt ;-)
Jan
7
comment Loss of data due to encryption
@yyyyyyy While we are not sure that block ciphers are actually pseudorandom, the "permutation" part is usually uncontested. And this is what matters in the context of this question.
Jan
7
awarded  Notable Question
Dec
27
revised Why shouldn't I use ECB encryption?
edited tags
Dec
27
comment Can I simulate iterated AES-ECB with other block cipher modes?
And maybe also how to decrypt?
Dec
27
comment What is Initialization vector (IV)
Hi Haochen, welcome to Cryptography Stack Exchange. We (at Stack Exchange in general) prefer answers with a bit more explanation in the answer itself, instead of mainly a link to somewhere else on the Internet. If you could add some sentences about the function of the IV, this would improve your answer.
Dec
27
comment Why would an Initialization Vector be supplied externally?
I think if the caller of that library has to know the details of CBC to use it with larger plaintext, it is not abstracted enough. It should provide a stream-like API, where the caller can pass chunks of data in several steps, and the stream takes care of the details.
Dec
26
comment how to let other people respond to emails only decrypt-able with my private key
Do you have some examples of (public key) encryption schemes which allow this (with a reencryption key which is not just the pair $(d_A, e_B)$, i.e. decryption followed by encryption)?
Dec
26
revised how to let other people respond to emails only decrypt-able with my private key
typos
Dec
22
comment Find private exponent in RSA
@Mac The $1/e$ means the multiplicative inverse of $e$ modulo $\phi(n)$ (i.e. in $\mathbb Z/_{\phi(n)\mathbb Z}$), not the inverse in $\mathbb{Q}$ (or $\mathbb{R}$ or your computer's floating point numbers).
Dec
22
revised Find private exponent in RSA
formatting
Dec
21
revised How can a cryptosystem be unconditional secure?
make the image a link
Dec
20
comment Is it safe to AES-CBC and AES-CMAC both using the same key?
@binta I did think this too, but the effective IV here is not the predictable "last 16 bytes of previous ciphertext", but the AES-encryption of those, which should not be predictable by an attacker, assuming no time-rollback.
Nov
27
comment Diceware word list for six dice
@Ed: I'm not sure that there are that many "relative easy words" in any language.
Nov
18
comment Is it possible to determine a PGP public key from encrypted data?
@Ricky I have to concur to e-sushi's comment ... could you write at least some excerpt of that answer here, maybe with some emphasis on the crypto-related stuff?