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Security professional with many years of experience with the practical application of cryptographic algorithms and protocols. I'm helping with the design of protocols and API's within international standardization bodies. Lead developer of a common criteria certified product. Over 30 years of general experience with computers.

On crypto I mainly answer less mathematically inclined questions, leaving security proofs to the theoretical cryptographers and analysts.


Nov
19
comment Encryption of big files in Java with AES/GCM
@archie Thanks for the warning. Note that you can always place the BC provider on top of the list of providers and have that take over, or make the provider configurable. I'll take another look at GCM as in Java 8, also because of a few updates regarding bugs with CipherInputStream. This is brand new functionality and is still a bit in movement.
Nov
19
comment AES - Encrypting multiple blocks of files
Explained this in the answer instead of a comment, I apologize if I unnecessarily complicated things, but otherwise the encryption of files is completely standard.
Nov
19
revised AES - Encrypting multiple blocks of files
added 191 characters in body
Nov
19
comment Should I use a key store to keep my symmetric keys
And remember, an AES key consists of bits, not characters. In other words, it is not a String.
Nov
19
comment Should I use a key store to keep my symmetric keys
The key store has one big problem with it, it needs a password to be secure. The question then becomes where to store the password. In the end you require something that is trusted and - according to your description - unique per customer. Key management is however too big a topic to topple here, it all depends on your system.
Nov
19
answered AES - Encrypting multiple blocks of files
Nov
19
comment Encryption of big files in Java with AES/GCM
In general it is better to ask runtime specific questions at stackoverflow. I've not voted to close as your actual question is not directly about the library. I've split my answer up in a theoretical and a Java specific part though (maybe other answers, if any, could do the same).
Nov
19
comment Crypto Challenge.sucked
@Thekwasti If your CPU is fast enough it would find it much quicker, even in Java. My 6 year old laptop would take a bit more time than you've specified. I'm pretty sure of it since my test app is bordering on completion.
Nov
19
comment Encryption of big files in Java with AES/GCM
Beware that the tag size matters with GCM. You could think of EAX or HMAC based authentication if you don't want to look into the security of GCM.
Nov
19
answered Encryption of big files in Java with AES/GCM
Nov
19
comment Simple encoding function mapping integers
@JohnMeacham Yeah, everything is possible but we should close this question and reopen it when that happens.
Nov
19
comment Simple encoding function mapping integers
Although pattern matching could be part of cryptographic analysis, I don't think that it is on topic because of that. Statistics is also used for crypto, but it's still maths in itself
Nov
19
comment DHE key exchange. Is it really secure?
@Larry I look forward to your paper where you ridicule the entire cryptographic community. Please jot me down as the idiot that ridiculed you before you proved that the crypto community is a bunch of asses :)
Nov
19
comment Simple encoding function mapping integers
Voting to close, if it is a cryptographic function, it should be impossible to find the key. As at mathematics instead, after checking if it is on topic there...
Nov
18
revised Is the output of AES-CBC + MAC the same size as the input?
added 25 characters in body
Nov
18
revised Is the output of AES-CBC + MAC the same size as the input?
added 176 characters in body
Nov
18
comment Is the output of AES-CBC + MAC the same size as the input?
That's called overhead and it is in the answer. I've taken the liberty to use the maximum padding size. You may bring it down to 32 bytes if you use a 8 byte tag and 8 byte input to calculate the IV. That is of course if you just concatenate everything, no additional structure specified.
Nov
18
comment Is the output of AES-CBC + MAC the same size as the input?
AES-GCM only requires one key, can use an (8 byte?) nonce directly instead of a full IV and the authentication tag size is configurable. Furthermore, it is much faster. More dangerous in use, but it has some advantages. If you want easy security with less speed advantages, use EAX mode (availability may vary).
Nov
18
answered Is the output of AES-CBC + MAC the same size as the input?
Nov
18
comment Which Encryption Method is used for this stream cipher?
Dunno, there is F9 in hex and then a null terminated string with the ASCII value VrfP. At least, that's likely. Could also be an application ID of some kind.