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Oct
25
comment Hypothetical unknown cipher - security in obscurity?
Your question reads like a Choose Your Own Adventure book. They're valid questions - but I suggest you break them up into smaller, more answerable questions. I also suggest you read on up Kerckhoffs's principle.
Oct
25
suggested suggested edit on Hypothetical unknown cipher - security in obscurity?
Oct
24
comment Knowing pre-encryption data, can we find the private key CryptoLocker used?
Read up on known plaintext attacks. If the files have been encrypted with a modern symmetric cipher (likely) such as AES, you're out of luck.
Oct
23
answered Would it be possible to generate the original data from a SHA-512 checksum?
Oct
22
comment Implementing OpenSSL padding
@user4982 - PCKS5 padding is recognizable in the ciphertext by comparing its length with that of the cleartext.
Oct
22
comment Implementing OpenSSL padding
I'm no openssl expert here, but the documentation states: "All the block ciphers normally use PKCS#5 padding also known as standard block padding". I tried your code from the command line and padding was indeed used. Keep in mind that padding might just be a single byte, depending on the length of the input.
Oct
20
comment Serpent block cipher : S0 to S7 functions unclear
@archie - fair point - although Cryptix is now defunct, and besides, the Cryptix dev team is already credited in the JSerpent source (along with the original authors of the algorithm).
Oct
18
comment Serpent block cipher : S0 to S7 functions unclear
Have you had a look at this bitslice implementation in java?
Oct
18
comment Order of cascaded ciphers
@fgrieu - would you mind clarifying "truly independent keys" as opposed to ciphers that "share their key"? How would you classify two "statistically independent" keys derived from a KDF with the same input?
Oct
15
comment Decrypting encrypted files if i have the original files(Plain Text attack)
Off-topic because: Requests for analyzing or decyphering a block of data are off-topic here, as the results are rarely useful to anyone else.
Oct
14
answered Is scrypt a hashing function, encryption, or PBKDF?
Oct
13
comment How does GCM (Galois/Counter Mode) work?
While I appreciate the effort - copying and pasting large portions of an RFC is not really appropriate as an answer - and is not helpful to the community. But then again, neither is asking a question which could be answered by simply reading the RFC.
Oct
13
comment How does GCM (Galois/Counter Mode) work?
I don't understand what you're asking... you understand the authentication part, but not the encryption? The encryption is based on counter mode (CTR). Directly from wikipedia: "As the name suggests, GCM mode combines the well-known counter mode of encryption with the new Galois mode of authentication".
Oct
13
comment How does GCM (Galois/Counter Mode) work?
Is the wikipedia page dedicated to this topic not adequate?
Oct
9
comment AES file encryption with PBKDF2. Safe parameters?
@CodesInChaos I'm pretty sure we're on the same page: perform as many iterations of PBKDF2 as tolerable requesting output equal to the native size of the underlying hash, and then a final single iteration requesting however many bytes are required.
Oct
9
comment AES file encryption with PBKDF2. Safe parameters?
@CodesInChaos - yup, hence 512 bits of output only for the final round (256 bits for every other round). I'm a big fan of HKDF too - but seeing as though PBKDF2 is required here anyway, it seems cleaner to me to use it for the final step.
Oct
9
comment what are the uses of tweaks in block ciphers?
Related: crypto.stackexchange.com/questions/6185/…
Oct
9
comment AES file encryption with PBKDF2. Safe parameters?
"HMAC-SHA256 with the content's encryption key" - naughty. Never use the same key for two different crypto primitives. Upon completion of your PBKDF2 rounds, perform a final round, but ask for 512 bits of output. Use the first 256 bits for the encryption key, and the rest for the HMAC key. More info here. As mentioned, if it's available, authenticated encryption such as CCM, EAX, GCM or OCB is also a good option.
Oct
2
comment NIST temporarily closed — will that have a negative impact on the future of cryptography?
i.imgur.com/LO4yypb.png
Sep
28
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