When we want to convert sensitive information to gibberish, we encrypt the data. To convert it back, we decrypt it.To do this, w use an algorithm. The word “algorithm” is a scientific term for a recipe or step-by-step procedure. It is a list of instructions or things to do in a particular order. An algorithm might have a rigid list of commands to follow, or it might contains a series of questions and depending on the answers, describe the appropriate steps to follow. A mathematical algorithm might list the operation to perform in a particular order to “find x”. For example, an automobile diagnostic algorithmmay ask questions about oil pressure, torque, fluid levels, temperature, and so on, to determine what’s wrong. A computer program can also implement an algorithm, meaning the program converts the algorithm’s list of commands, questions, and operations into the computer’s language, enabling it to perform the steps in appropriate order. In computer cryptography, algorithms are sometimes complex mathematical operations or simply bit manipulations.Many encryptions algorithm exist, and each one has its own particular list of commands or steps. Just as you can have a program that plays solitaire or one that computes the trajectory of satellites, you can have a program that implements an encryption algorithm that takes your data and converts it to gibberish.
The data that you want to keep secret is called plaintext ( some call it cleartext). Your plaintext could be a human-readable text file, such as the memo. Or it could be a binary file, which looks like nonsense for human eyes but makes perfect sense for computer program. For example, if you open a PowerPoint file using windows text editor, the file looks like gibberish because the program cannot convert the PowerPoint formatting informations; but if you open the same file in PowerPoint, it appears as intended. Whether or not your information is readable by a human or a given program, it’s called plaintext.
After data is encrypted, it’s known as ciphertext.
The algorithm encrypts our plaintext into ciphertext, but it need one more thing-a key.
We have also met attacker, someone trying to steal information. Actually, an attacker may try to do more than simply uncover someone else’s secrets. Some attackers try to pose as people they are not, disable website, delete someone’s information, prevent customers from buyingat a particular onine merchant, slow down systems, and on and on and on.The term attacker is simply a catchall for the individual from whom we must protect our digital assets.
The study of breaking cryprographic systems is known as cryptanalysis. Similar to the attacker, the cryrptanalyst looks for weaknesses in algorithm. All algorithm can be “broken”; the good ones are simply the algorithms strong enough to withstand an attack for so long the break comes ‘too late”. So a cryptanalyst ‘s job is to find weaknesses that may help someone break the algorithm faster. Attacker may use cryptanalitical techniques to damage the cryptography algorithm, but yhey also use other tools.
The cryptographer develops crypto systems: the cryptanalyst looks for weaknesses. It’s important for the crypto communityto know about the weaknesses, because the attackers are looking for them as well.Attackers are almost certainlynot going to announcetheir discoveries to the world, so cryptanalysts perform a service, letting us all know what attackers probably know but won’t tell us.