CodesInChaos

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bio	website	github.com/CodesInChaos
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GitHub: github.com/CodesInChaos
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	5,954 reputation	bio	website	github.com/CodesInChaos	visits	member for	1 year, 10 months
1927 badges		location	Munich, Germany		seen	yesterday

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Apr 22	comment	How to perform file encryption using 128-Bit AES? Then why don't you just put the file in an encrypted TrueCrypt container? Or use some other existing crypto program that satisfies your requirements?
Apr 22	comment	How to perform file encryption using 128-Bit AES? Isn't this more of a programming problem, than a crypto problem? Your question is also pretty vague. For example you didn't specify where the key comes from(A password? Randomly generated per file?, ...), if you need authentication, if you need random access(just reading, or read+write?)... And do you want transparent encryption, or just a program that takes a file, and spits out a new file that's encrypted?
Apr 22	suggested	suggested edit on blind-signature tag wiki excerpt
Apr 22	wiki	created blind-signature excerpt
Apr 22	revised	Which blind signature schemes exist, and how do they compare? edited tags
Apr 22	awarded	Citizen Patrol
Apr 22	asked	Which blind signature schemes exist, and how do they compare?
Apr 22	comment	How secure is the Vigenère cipher in file encryption if you encrypt the password first? @Ephraim no it won't help. This kind of cipher can be easily attacked as long as the length of the key is short compared to the ciphertext, and the plaintext has any recognizable structure. And it's trivially broken in a known plaintext scenario.
Apr 21	comment	Is this authenticated one-way communication protocol secure? crypto.SE is clearly the better choice
Apr 21	comment	Can a digital money system exist, that's secure, anonymous and allows offline transactions? One problem with the first kind of scheme is that it sacrifices a lot anonymity even for honest users. The accounts are not anonymous, the amount of cash flowing in/out of an account can be observed by the bank. I was considering some escrow based systems, but couldn't make it work. Escrow can punish double-spend, but it's not enough once the multi-spend factor is large enough.
Apr 21	comment	Can a digital money system exist, that's secure, anonymous and allows offline transactions? "have all hardware that's in their possession completely under control" i.e. if the users have the MintChip, I assume that they can extract any secret keys embedded by the bank.
Apr 20	revised	Can a digital money system exist, that's secure, anonymous and allows offline transactions? added 53 characters in body
Apr 20	asked	Can a digital money system exist, that's secure, anonymous and allows offline transactions?
Apr 20	comment	Offline anonymous electronic money systems and their cryptographical base Are you sure such a system can even exist? I think that out of secure, anonymous and offline, you can only have two at the same time.
Apr 18	comment	How can I do a brute force (ciphertext only) attack on an CBC-encrypted message? Do you know which padding mode was used, and how long the plaintext and/or ciphertext are?
Apr 18	comment	Is RSA of a random nonce with no padding safe? @ThomasPornin Your argument doesn't show that per-encryption randomness is required. For example you don't show why padding based on `hash(m,e,n)` is a problem. Such a scheme is still deterministic, and doesn't suffer from this specific problem.
Apr 18	comment	Why is elliptic curve cryptography not widely used, compared to RSA? For me the primary selling point of RSA is that it doesn't leak the private key if your PRNG happens to be badly seeded while signing. While it's possible to avoid this issue, most implementations don't.
Apr 18	awarded	Scholar
Apr 18	accepted	Can one reduce the size of ECDSA-like signatures?
Apr 16	comment	Deterministic nonces in CTR mode There is already a question about the first scheme, so this question is mainly about the second scheme. In particular how it compares to the first scheme.