4.2 Simple Download with GetBlocks Download Sub-Sessions only
Scenario: Peer P1 is trying to download two consecutive blocks, BN and BN + 1, of segment S1 from peer P2.

Figure 3: Simple Download using GetBlocks request/response
Sequence of events:
Since the download involves only two blocks, P1 decides to skip the GetBlockList message (MSG_GETBLKLIST (section 2.2.4.2)). It sends a GetBlocks message (MSG_GETBLKS (section 2.2.4.3)) for BN, and later for BN+1.
Upon receiving the GetBlocks message, P2 replies with a Block message (MSG_BLK (section 2.2.5.3)) containing the encrypted block of data and the initialization vector used during the encryption.
After receiving the Block message, P1 decrypts and stores it, then it asks for the second block by sending a new GetBlocks message.