# All Questions

1k views

### Sending TLS messages with out encryption using openssl code

Is it possible to send messages over TLS with out encryption? If so which cipher suite is needed for this?
162 views

### Offline app authentication - embedding hashed password inside an encrypted file

I am working on an occasionally connected app. To allow the users to authenticate I created a profile which is encrypted and placed on the users machine. The first byte of the file contains the IV ...
250 views

### Is it possible to cryptographically prove when was the last time a ciphertext was decrypted/encrypted?

I want to provide a service that encrypts and decrypts documents and I want to provide the users with proof that I haven't stolen their secret key and read their documents. I know I can prove when a ...
2k views

### Bcrypt VS Scrypt, Again?

I found this article on SO, but the answer was short, and the subject was closed, What i don't understand, is: Which one of the two limits memory usage to avoid custom Hardware to break the password? ...
497 views

I read that the Encrypt-then-MAC paradigm is provably secure. From what I understand, when using for example AES for encryption and HMAC_SHA256 for MAC generation (and the keys $K_1 \neq K_2$), this ...
426 views

### Requiring a “supervisor” key pair and a “user” key pair to decrypt multiple-recipient messages

I've been toying with some encryption scenarios recently. One of the hard ones I came across is a multi-party system. So we have Bob -- The person who sends the message (and knows it's recipients) ...
350 views

165 views

### Signature scheme with two private keys, neither derivable from the other

Is there any scheme, ideally one widely used or at least widely available, where you can treat both the signing and verifying keys as secret? Basically, the functionality I'm looking for is this: ...
237 views

### Is there a cumulative commitment scheme?

For a certain application I need a commitment scheme where each user could make a commitment, and a single verification operation could verify all the commitments simultaneously, faster than single ...
2k views

### Dictionary attack on pass-phrases on common algorithms

I don't yet perfectly understand the difference between brute-force and dictionary attack since this differentiates one attacking the key and another attacking password: apparently attacking passwords ...
177 views

### ID-Secret Scheme

I have an ID-Secret scheme and I'd like to hear if there are any vulnerabilities present. Party 1 and Party 2 hold some credentials, an ID and a Secret. Party 1 Creates this message: ...