12,993 reputation
32764
bio website paul-ebermann.tumblr.com
location Berlin, Germany
age
visits member for 3 years
seen 13 hours ago

Don't fear to edit my posts: even if I have more reputation than you, I do make mistakes.

I'm now also a Moderator Pro Tempore (= until the first elections) at Cryptography Stack Exchange: feel free to come around and ask some cryptography questions.


My personal name is spoken as /ˈpawlo/ (IPA), in English this would be written similar to Powlo, I think (i.e. the vowels are ow and o), with an accent on the before-last syllable (which is the first in this case). It's the Esperanto form of my given name.

The photo shows my shadow, taken at night. My camera sometimes seems to forget all the other frequencies and only stores the green ones.

My current main private programming project is the game of fencing, an online abstract turn based strategy game. Implemented as a Java applet, using git as a version control system.


Some more links:


Oct
21
revised What security do Cryptographic Sponges offer against generic quantum attacks?
formatting, keccak tag
Oct
21
revised Is the last step of an iterated cryptographic hash still as resistant to preimage attacks as the original hash?
edited tags
Oct
21
revised Why doesn't preimage resistance imply the second preimage resistance?
formatting, grammar, title, tags
Oct
21
revised Deniable Encryption from simple primitives
formatting, some spelling, deniable-encryption tag
Oct
21
revised Does RSA work for any message M?
use · instead of *
Oct
21
revised How can I improve a password generation scheme based on a shared secret and URL?
typo fixup
Oct
21
comment How can I improve a password generation scheme based on a shared secret and URL?
This entropy loss (which is usually not that large after the initial round, but still existent) can be prevented by rehashing both salt and password in each following round, like PBKDF-2 does.
Oct
21
revised How can I improve a password generation scheme based on a shared secret and URL?
better title (thanks to Ninefingers for the suggestion), some formatting
Oct
20
comment Is there a secret sharing scheme which allows delegation/re-sharing without reconstructing the original secret?
Are the $n$ and $N$ in the last paragraph the same number, or one smaller/bigger than the other?
Oct
20
revised What place do prime numbers have in cryptography?
adding [prime-numbers] tag
Oct
20
revised Is there a secret sharing scheme which allows delegation/re-sharing without reconstructing the original secret?
better title, formatting, tag
Oct
19
awarded  Fanatic
Oct
19
revised Getting the encryption method and key from the encrypted data and the raw data
edited tags
Oct
18
comment How can one break a monoalphbetic substitution chipher at pseudorandom text?
The number of all general monoalphabetic substitution cipher keys is $|\Sigma|!$, where $\Sigma$ is the alphabet. This is still quite a large number ($256! \approx 2^{1684}$ (one byte), $92! \approx 2^{472}$ (printable ASCII), $26! \approx 2^{88}$ (english alphabet)).
Oct
18
comment How can one break a monoalphbetic substitution chipher at pseudorandom text?
For your actual problem, you might want to have a look at format-preserving encryption, and our questions Can you create a strong blockcipher with small blocksize, given a strong blockcipher of conventional blocksize? and How can I encrypt + authenticate short strings into similar short ciphertexts?
Oct
18
comment How can one break a monoalphbetic substitution chipher at pseudorandom text?
Actually, any encryption algorithm which has a corresponding decryption algorithm must guarantee absence of collisions, otherwise decryption would not be possible.
Oct
18
revised How can one break a monoalphbetic substitution chipher at pseudorandom text?
better title, some formatting, tags, adding background information from comment
Oct
18
comment How can one break a monoalphbetic substitution chipher at pseudorandom text?
Welcome to Cryptography Stack Exchange. Your question was migrated here because of being not directly related to software development (the topic of Stack Overflow), and being fully on-topic here. Please register your account here, too, to be able to comment and accept an answer.
Oct
17
comment How can I encrypt + authenticate short strings into similar short ciphertexts?
@eggyal You might want to use some (standard or custom) compression algorithm before adding the zeros (or the MAC) and applying the encryption. deflate (which is used in gzip and zip, for example) can work with a dictionary of common byte sequences to increase compression ratio.
Oct
17
comment How can I encrypt + authenticate short strings into similar short ciphertexts?
Actually, UTF-8 might need more than one byte per character (for all outside of ASCII). So the last paragraph should start with be "if you use an one-byte encoding".