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Show HN: InstantCryptor – AES256 Encryption for Dropbox and Google Drive

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Re: Show HN: InstantCryptor – AES256 Encryption for Dropbox and Google Drive

#41

Post by Inflatablewoman »

Grazester wrote: post #24

ooh. I made an app that encrypts files on Android written in Java and has a C# written client for Windows. I have released the java source code. I should post it here on HN to look at it and rip me a new one. What I am sketchy about is how does embedding an unencrypted salt used for the PBKDF2 in the file not potentially make guessing of the passphrase easier

The point is that any salt, even a hard coded salt, would mean that an attacker would need to regenerate the rainbow tables using the known salt.

Re: Show HN: InstantCryptor – AES256 Encryption for Dropbox and Google Drive

#42

Post by jedisct1 »

pjc50 wrote: post #34
wolf550e wrote: post #4

>> The password will be hashed with the SHA256 algorithm, the mode for encryption is 256 Bit Rijndael/AES SHA256 is not a KDF, AES-256 is not a block cipher mode. Where is the source code?

What's the standard for this kind of thing, PBKDF2 / AES-CBC / HMAC-256? (I went and checked NaCl and it has its own primitives, http://nacl.cr.yp.to/secretbox.html )

Scrypt for key derivation, chacha20+poly1305 for authenticated secret-key encryption. In Javascript, https://github.com/jedisct1/libsodium.js provides them.

Re: Show HN: InstantCryptor – AES256 Encryption for Dropbox and Google Drive

#43

Post by moe »

placeybordeaux wrote: post #39
wolf550e wrote: post #4

>> The password will be hashed with the SHA256 algorithm, the mode for encryption is 256 Bit Rijndael/AES SHA256 is not a KDF, AES-256 is not a block cipher mode. Where is the source code?

Looks like they are using CBC block cipher mode. Guess they updated the site since then. This appears to be the source code: https://instantcryptor.com/js/main.js

  var hash = crc.Crypto.Hash.SHA256.hash(password.value)
  crypter = new Crypt.Mode.Licobo(new Crypt.Rijndael256(hash))
And it looks like they didn't bother to use a KDF.

But I guess when your mode is "Crypt.Mode.Licobo" then that is the least of your problems...

Re: Show HN: InstantCryptor – AES256 Encryption for Dropbox and Google Drive

#44

Post by ryanlol »

sarciszewski wrote: post #10

Two things: 1. Cryptor is usually the word used by criminals to describe payload obfuscation to evade antivirus detection. 2. Momma says closed-source crypto is the devil.

1. You're confusing "cryptor" with "crypter"

2. "Closed source" and javascript don't really work together.

Re: Show HN: InstantCryptor – AES256 Encryption for Dropbox and Google Drive

#45

Post by netheril96 »

licobo wrote: post #18

We are using CBC as block cipher mode. I totally understand that open sourcing the complete code is the only way for you to review it and trust it completely. We decided to write a detailed report about the encryption and how we use it and will publish the report soon via Twitter.

How do you generate the initialization vector? CBC mode requires an unpredictable IV, which usually equals cryptographic random number.

> var hash = crc.Crypto.Hash.SHA256.hash(password.value),

> crypter = new Crypt.Mode.Licobo(new Crypt.Rijndael256(hash)),

From the code I cannot see any generation of IV, so I can only assume that the same IV is used every time. A predictable IV leads to many kinds of attacks. In particular, since the key is generated without salting, this means that a combination of the same key and IV will be used for multiple files, completely defeats the confidentiality.

And no integrity protection whatsoever? So vulnerable to bit flipping attacks?

Re: Show HN: InstantCryptor – AES256 Encryption for Dropbox and Google Drive

#46

Post by FlorianWendel »

dreemkilker wrote: post #33
Grazester wrote: post #24

ooh. I made an app that encrypts files on Android written in Java and has a C# written client for Windows. I have released the java source code. I should post it here on HN to look at it and rip me a new one. What I am sketchy about is how does embedding an unencrypted salt used for the PBKDF2 in the file not potentially make guessing of the passphrase easier

To answer your question about the the salt and the PBKDF2: salt ensures that the hash of my password is different from someone else's, even if we use the same password (or I use the same password on another site). Thus, if someone has the hashes, and wants to attack the system, then need to attack each password independently (they can't just run a password dictionary through the PKDF2 (or SHA256 in this case - very b…

Why do you consider unsalted SHA-256 a bad choice here? If neither the password nor its hash are stored and the hash is merely used as a key for the CBC, I don't see how anyone could construct rainbow tables for that. Care to explain?

Re: Show HN: InstantCryptor – AES256 Encryption for Dropbox and Google Drive

#47

Post by sarciszewski »

ryanlol wrote: post #44
sarciszewski wrote: post #10

Two things: 1. Cryptor is usually the word used by criminals to describe payload obfuscation to evade antivirus detection. 2. Momma says closed-source crypto is the devil.

1. You're confusing "cryptor" with "crypter" 2. "Closed source" and javascript don't really work together.

I've seen it spelled both ways. Usually on HackForums (a.k.a. the massive script kiddie honeypot).

Re: Show HN: InstantCryptor – AES256 Encryption for Dropbox and Google Drive

#48

Post by licobo »

@all: thanks a lot for your feedback! It's good to see that so many people care about security. To quickly summarize your questions: We are using the secure CBC mode and have always used it ;) You can have a look on the source code directly on the website (because it's all client side JavaScript), but some parts of it are minified. We are working on a detailed description of the technology behind InstantCryptor and will publish it soon via Twitter (@cloudrail). If you are interested in the technology to easily add cloud storage into your application visit cloudrail.com to get a free copy.

Re: Show HN: InstantCryptor – AES256 Encryption for Dropbox and Google Drive

#49

Post by ryanlol »

sarciszewski wrote: post #47
ryanlol wrote: post #44

Earlier quoted context omitted.

1. You're confusing "cryptor" with "crypter" 2. "Closed source" and javascript don't really work together.

I've seen it spelled both ways. Usually on HackForums (a.k.a. the massive script kiddie honeypot).

site:hackforums.net cryptor About 1,790 results (0.32 seconds)

vs

site:hackforums.net crypter About 62,700 results (0.36 seconds)

Re: Show HN: InstantCryptor – AES256 Encryption for Dropbox and Google Drive

#50

Post by jjarmoc »

licobo wrote: post #48

@all: thanks a lot for your feedback! It's good to see that so many people care about security. To quickly summarize your questions: We are using the secure CBC mode and have always used it ;) You can have a look on the source code directly on the website (because it's all client side JavaScript), but some parts of it are minified. We are working on a detailed description of the technology behind InstantCryptor and w…

CBC mode is not inherently secure. Details matter and can often introduce catastrophic problems.
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