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seen Mar 3 '13 at 20:01

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Mar
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accepted Can active attacks really decrypt a particular AES-256, CBC, PKCS#7 encrypted file?
Feb
28
comment Can active attacks really decrypt a particular AES-256, CBC, PKCS#7 encrypted file?
Do you think these concerns of active attacks against local CBC encrypted files are more theoretical than practical? Could you provide some information about the practicality of such attacks, how long time they could take, etc.? Would you urge everyone to dump CBC and switch ASAP to something like EAX?
Feb
28
revised Can active attacks really decrypt a particular AES-256, CBC, PKCS#7 encrypted file?
added 4 characters in body
Feb
28
accepted How less secure is an encryption if we know something about the original data?
Feb
28
asked Can active attacks really decrypt a particular AES-256, CBC, PKCS#7 encrypted file?
Feb
28
awarded  Commentator
Feb
28
comment How less secure is an encryption if we know something about the original data?
Another question I have is that if I use HMAC SHA-1 in PBKDF2 to generate the key <-- this HMAC is totally unrelated to the one you mention in the context of CBC,GCM,EAX?
Feb
28
comment How less secure is an encryption if we know something about the original data?
Can you elaborate on whether what you mention is just theoretical or has actually been successfully carried out in practice? For instance, if given an encryption program that encrypts files with AES-256, CBC mode, and a file encrypted with this program, are there active attacks against that file? (the cracker have access to the program that created the file of course). If this is the case, wouldn't this imply that AES-256 CBC is in fact a non-secure crackable algorithm that shouldn't be used anymore? Why do people use it?
Feb
28
comment How less secure is an encryption if we know something about the original data?
Aren't active attacks used against "streaming" data such as through an active network connection? How useful are active attacks against a given encrypted file (assuming still that we know the "abcdef" of the original)?
Feb
28
asked How less secure is an encryption if we know something about the original data?
Feb
27
accepted How does PKCS#7 padding work with AES-256, CBC mode?
Feb
27
comment How does PKCS#7 padding work with AES-256, CBC mode?
I still don't get how padding can be done before encryption, because often we are encrypting the whole data in small pieces at a time, until we hit the end. At the end there is usually a "finalize" function that is supposed to take care of the padding. So how did it happen before encryption? Can you please elaborate?
Feb
27
asked How does PKCS#7 padding work with AES-256, CBC mode?
Feb
26
accepted Key length and hash function in PBKDF2
Feb
26
asked Key length and hash function in PBKDF2