Paŭlo Ebermann

9,765 reputation

21743

bio	website	paul-ebermann.tumblr.com
	location	Berlin, Germany
	age
visits	member for	1 year, 10 months
	seen	18 hours ago
stats	profile views	210

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:

I created an github repository where I'll add interesting code created for responses here.
I lastly created Javadoc for JSch - i.e. I read most of the code, thus I now also can answer some JSch-related questions.
I now have a blog, too. This will feature interesting questions and answers from Stackoverflow (beside other topics).
A link to my google profile for testing this "author" feature.
I got a Job with StackOverflow Careers, and my company's technology department (where I work) has now its own website/blog.

	9,765 reputation	bio	website	paul-ebermann.tumblr.com	visits	member for	1 year, 10 months
21743 badges		location	Berlin, Germany		seen	18 hours ago

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May 5	awarded	Nice Answer
May 2	comment	Encrypt a single file, chunk-by-chunk, each chunk using different key (AES) What is the reasoning for distributing a file on multiple cloud services? So is it lost if any of them fails?
May 2	revised	Have I understood pedersen commitment correctly? formatting
May 1	revised	Why does key generation take an input $1^k$, and how do I represent it in practice? mark the quote as such
May 1	reviewed	Approve suggested edit on Is it generally possible to employ brute force methods when the encryption scheme is not known? Why or why not?
May 1	comment	chaining rsa with ecies If the application doesn't need public key crypto (i.e. there is nobody who needs to encrypt but not to decrypt), there is no point in encrypting a symmetric key itself – just encrypt the data (with as many algorithms/keys as necessarily), and store the symmetric key at another location (where you would store the private keys of your asymmetric algorithms). Storing the TDEA key alongside with the data just adds another breaking point, not another layer of protection.
Apr 30	comment	Interesting game: decipher the following sequence Sorry, that kind of puzzles are off topic here.
Apr 30	comment	chaining rsa with ecies The idea "use TDEA for data, then use AES to encrypt the TDEA key" sounds bogus. Wouldn't you use both symmetric algorithms to encrypt the data, and then the asymmetric algorithms to encrypt the symmetric keys?
Apr 30	comment	Padding of Original Message in MD5 Could you please cite your sources? (i.e. From where did you take this image?)
Apr 30	comment	How can I prove that this encryption scheme from a random oracle is secure? In that paper $Hash$ is a function with fixed length output (and variable length input), while $Gen$ has a fixed length input and arbitrary length output. (Se section 4.1 for the notations.) Normally we name the latter one Random number generator, not hash function, though we want similar security properties for both.
Apr 29	comment	toy hash algorithm Hmm, but attacking the truncated SHA hash is just brute force, not cryptanalysis. Maybe a reduced-round version would be better.
Apr 29	comment	Custom crypto library in C Please note that this site is not so much about software design and the workings of the C library in different platforms (or other programming languages), but more about the theory of cryptography, and maybe implementation concerns of cryptographic algorithms (but certainly not programming language specific stuff).
Apr 27	comment	How can a key pair be derived from an arbitrary hash? That is a kind of PRNG, though :-)
Apr 25	revised	Is this scheme a provably fair random number generation? formatting, tags, slight rewording
Apr 25	revised	repeating-key xor and hamming distance edited tags
Apr 25	comment	Combining AEAD with RSA With a signature, there is no point, yes. Without a signature, AEAD only provides a kind of integrity check (i.e. whoever authored part of the message also authored the whole one). When you include another shared secret in the plaintext, an attacker can't forge the whole message.
Apr 24	comment	Combining AEAD with RSA Yes, but these don't pretend to be "authenticated". We actually have a weak kind of authentication, knowing that whoever sent your message actually knew the whole message, not only part of that. The classic solution would be to add an (asymmetric) signature to your message.
Apr 24	revised	Is it possible to work out the hash algorithm from a list of known message-hash pairs? formatting, rewording
Apr 24	comment	Combining AEAD with RSA What security properties do you want? Anyone who knows your public key can send you a message with a valid authentication tag.
Apr 21	comment	Should I trust CipherCloud? Sorry. While I can understand that you are angry about the takedown, this new question is neither on topic nor constructive.