Attackers will use a variety of methods to create a functioning codebook. The most common technique, however, is to use an automated system that can generate large amounts of random data, which is then used to create thousands of different encryption algorithms. This process can be extremely time-consuming depending on the size of the file that is being encrypted. For example, if the attacker has stolen a company’s encryption key for their file server and has access to 10 GB of sensitive data, it could take months for them to collect enough random numbers to encrypt all 10 GB using a codebook attack.