# All Questions

601 views

### Sending KCV (key check value) with cipher text

I was wondering why it is not more common to send the KCV of a secret key together with the cipher text. I see many systems that send cipher text and properly prepend the IV to e.g. a CBC mode ...
217 views

### secure multiparty computation for multiplication

Suppose there are $N$ parties $p_j$, each with a binary $b_j\in{\{0,1\}}$. The problem needs to compute the multiplication of number of ones times that of zeros, that is, ...
1k views

### Which one of the Block Cipher modes is the best?

I have two questions regarding the Block Cipher Modes: First: Which one of the modes is considered the best? I know CBC has a problem of IV since the next block of the plain text is XORed with the ...
5k views

### How should I calculate the entropy of a password?

If part of the password is a whole regular English word, does the entropy of that part depend on the number of English words in existence, the number of English words known by the choosing algorithm, ...
301 views

### How to generate one-time password

Through my reading about the generation of one-time password (OTP) I found that there are many algorithms that generate OTP and they are either based on time such as TOTP or based on mathematical ...
133 views

### How can I store a combination of multiple pass phrases?

Let's assume we have 2 phrases, one is the real password from a user, and the other is generated from the real password and almost impossible to guess. You would need both to authenticate a user. What ...
230 views

### Can I secure my key by XORing it with a hashed password?

I'd like to build a simple password-protected symmetric key system. The key-creation process in my system operates as follows: The system creates a 256-bit key purely at random. The user chooses a ...
264 views

### Are derived hashes weakening the root?

Given a root hash root = H(plaintext) and two (or more) derived hashes h1 = H(salt1 + root) h2 = H(salt2 + root) would the ...
324 views

326 views

### Can md5 be used for encrypting data?

I know that md5 shouldn't be used for password hashing because of collisions and possibility of making dictionary attacks e.g. using rainbow tables. But what about ...
745 views

### Converting a DER ECDSA signature to ASN.1

I having trouble verifying an ECDSA signature signed using client side javascript with Java/BouncyCastle. The javascript signing function source ...