Eavesdropping experiment with private key I am extremely new to cryptography, still trying to learn basics. I got stuck in the following example of an eavesdropping experiment with a private key.

$$\begin{array} {|r|r r r|r|}
\hline
C &amp; &amp; &amp; &amp; A \\
\hline
k &amp; \leftarrow &amp; Gen(1^{n}) &amp; &amp; \ \\
b &amp; \leftarrow &amp; {0, 1} &amp; \leftarrow [m_0,m_1] \leftarrow &amp; input 1^{n} \\
c &amp; \leftarrow &amp; Enck (m_b) &amp; \rightarrow [c] \rightarrow &amp; output b_0 \\
\hline
\end{array}$$

$A$ succeeds, if $b = b_0$.

Could someone give a basic of what is going on here and point to some resources where I can get the hang of these things?
Here is a simple/laymans explanation of what the example is (most likely) about: 

Suppose you are given a new ciphering scheme (set of encryption and decryption algorithms) and you need to find out if it is secure. In cryptography, the security can be analyzed by issuing a challenge to the eavesdropper or adversary $A$. If the adversary wins the challenge, the cipher is insecure and vice-versa. This exercise consists of the following steps: 


The challenger $C$ (on the left in your figure) generates a random key $k$ of appropriate length: a randomly-generated $n$ bit key would mathematically be represented as $k \leftarrow Gen[1^n]$ or $k \leftarrow \{0,1\}^n$ (I find the latter representation clearer).
The adversary $A$ (on the right in your figure) inputs two messages $m_0$ and $m_1$ to the challenger. Assuming these are $n$ bit messages, one can represent them as $\{0,1\}^n$ too. 
The challenger encrypts only one of these messages $c \leftarrow Enck(k,m)$ with $m$ = $m_0$ or $m_1$. (Think of the challenger tossing a coin; if he gets heads/tails, he encrypts $m_0/m_1$). In the figure, this operation is represented as $c \leftarrow Enck(k,m_b)$ which then depends on the value of a single bit $b$. 
The ciphertext $c$ is handed to the adversary who analyzes it with all possible resources he/she possesses (remember though that they don't know the key) and at the end of the analysis, outputs a bit $b_0$. 
If $b_0 = b$, the adversary has won the challenge. 


Remember the last line is to be interpreted in a statistical sense, i.e., if the challenger-adversary game is played $2N$ times, $b_0 = b$ must be true for $&gt;N$ times.