Cryptanalysis is the study of breaking encrypted data without a key. It is used by both malicious hackers and the military, as well as designers of cryptographic systems to find weaknesses. Different types of attacks can be used, including brute force attacks, but longer keys are less likely to be subject to this type of attack. Cryptanalysis requires mathematics, probability, fast computers, perseverance, intuition, and a general understanding of the target. The Enigma machine, used by the Germans, was eventually cracked by members of the Polish resistance and handed over to the British.
Cryptanalysis is the study of taking encrypted data and trying to decrypt it without the use of the key. The other side of encryption, it is used to break codes by finding weaknesses within them. In addition to being used by malicious hackers, this discipline is also often used by the military. It is also conveniently used by designers of cryptographic systems to find, and subsequently fix, any weaknesses that may exist in the system at the design stage.
There are different types of attacks a cryptanalyst can use to crack a code, depending on how much information he has. A ciphertext-only attack is one where the analyst has a piece of ciphertext (text that has already been encrypted), with no plaintext (plaintext). This is probably the most difficult type of cryptanalysis and requires some guesswork. In a known plaintext attack, the analyst has both a piece of ciphertext and the corresponding piece of plaintext.
Other types of attacks may involve attempting to derive a key through deception or theft, as in the “man-in-the-middle” attack. In this method, the cryptanalyst inserts surveillance software between two communicating parties. When parties’ keys are exchanged for secure communication, they exchange their own keys with the attacker instead of each other.
The ultimate goal of the cryptanalyst is to derive the key so that all ciphertext can be easily deciphered. A brute force attack is one way to do this. In this type of attack, the cryptanalyst tries every possible combination until the correct key is identified. While using longer keys makes derivation statistically less likely to succeed, faster computers still make brute-force attacks feasible. Networking a set of computers in a grid combines their strength, and their cumulative power can be used to break long keys. The longest keys used, 128-bit keys, remain the strongest and are least likely to be subject to this type of attack.
Basically, cryptanalysis is a science of mathematics, probability and fast computers. Cryptanalysts usually also require some perseverance, intuition, guesswork, and a general understanding of the target. The course also has an interesting historical element; the famous Enigma machine, used by the Germans to send secret messages, was eventually cracked by members of the Polish resistance and handed over to the British.
Protect your devices with Threat Protection by NordVPN
