## ITC == Introduction To Cryptography

## Some ...

# ITC == Introduction To Cryptography

# Some notes about the Homework #2

# 1. Generator

## (a) Generator

## (b) Diffie-Hellman Key Exange Protocol

- allows two parties to agree a secret key over an insecure channel without having met before.
- Its security is based on the discrete logarithm problem in a finite abelian group G.

## (c) Man-in-the-Middle attack

## (d) ElGamal cryptosystem

#### Modular multiplicative inverse

# 2. Euler’s Theorem is the extension of Fermat’s Theorem.

## (a) Euler’s totient function

## (b) Euler’s Theorem

## (c) the last 3 digits of 8^803

```
8^{803} \mod 1000 \equiv 8 \times 64^{400+1} \mod 1000 \equiv 8 \times 64 \equiv 512
```

# 3.

## multiplicative inverse

## finite field

# 4. RSA

## p, q, e, n, d

use Extended Euclidean algorithm

# 5. system of equations

Still don't get it...

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