# All Questions

175 views

### 3DES Modes EED orEDE?

Can we use EED with 2 keys (K1 K1 K3) rather than EDE (k1,k2,k1) ? We measure the strength of DES by the effort (in term of number of tries) in finding some K1 & K2 to match a known plaintext and ...
126 views

### Attacking multi block MAC constructions

For variable-length messages, there are three different ways to generate the tags. $Tag = MAC_k(\Sigma_i m_i)$. $t_i = MAC_k(m_i)$ and $Tag = (t_1, ..., t_l)$. $t_i = MAC_k(i||m_i)$ ...
147 views

### Strategies for securing public key storage on software

I´m kind of new in this so I apologize in advance for any noob mistakes (feel free to point it out) We are developing a licensing mechanism on our software, and I would like some advice. The ...
115 views

### Generic name for (?hash) functions of form $\{0,1\}^n \rightarrow \{0,1\}^{poly(n)}$

Consider a function $$f: \{0,1\}^n \rightarrow \{0,1\}^{poly(n)}$$ with the following properties: hard to invert, i.e. given $f(x)$, hard to find $x$ hard to find a collision, i.e given $f(x)$, ...
164 views

### Deriving a decryption equation

Consider a very simple symmetric block encryption algorithm, in which 32-bits blocks of plaintext are encrypted using a 64-bit key. Encryption is defined as C = (P⊕KL)⊗KR where C = ciphertext; K = ...
134 views

### FIPS-Compliant SHA2

I want to use SHA-512 for hashing in a system that must be FIPS-compliant. When I look at the FIPS 140 list of approved providers, I don't see SHA from any provider as being an approved algorithm, I ...
211 views

### Diffie-Hellman Application

Alice and Bob want to perform a Diffie-Hellman key exchange using the group $G$, a primitive root $g$, Alice’s secret key $k_A$ and Bob’s secret key $k_B$. In each case below compute the element of ...
119 views

### Is the idea of a known plaintext attack really that new?

As you can probably guess, I just watched The Imitation Game, which hasn't really gotten points for historical accuracy... During World War II, Turing and his team fret that they can't know the ...
122 views

### Prime modulus for RSA and sharing a secret?

According to this paper entitled "Using Commutative Encryption to Share a Secret" they define their modulus to be a large prime p, which is public. Both exponents are private in this case. According ...