Diffie-Hellman Key Exchange was one of the most important developments in public key cryptography and is still frequently implemented in various security protocols today.
It allows two parties who have not previously met to securely establish a key that they can use to protect their communications.
What is the Diffie-Hellman Algorithm?
Diffie-Hellman is a key exchange algorithm that allows two parties to establish a shared secret key over an insecure communications channel that only the two parties know, even without having shared anything beforehand. The shared key is asymmetric, but like all asymmetric encryption key systems, it is inherently slow and impractical for bulk encryption. Therefore, the key is used to securely exchange a symmetric key, such as AES (Advanced Encryption Standard), which encrypts subsequent communications more quickly and efficiently.
The goal of the Diffie-Hellman encryption algorithm is to achieve the exchange of a secret key over an insecure channel such as the Internet. For this algorithm to work, computer data must be translated into numbers, which is possible by employing systems such as ASCII code combined with others.
When to use the Diffie-Hellman Algorithm?
Diffie-Hellman is used for data communication but not as often for data stored or archived for long periods. It is commonly implemented in protocols such as TLS, IPsec, SSH, and PGP (Pretty Good Privacy). It is used in PFS due to its fast key generation capabilities. Diffie-Hellman is often used to access another computer and send encrypted emails remotely.
Vulnerabilities of this crucial exchange system
It should be noted that the Diffie-Hellman algorithm is not entirely infallible. A man-in-the-middle attack is a common attack used again this encryption process. In such attacks, an attacker could place himself between the two computers and act as an intruder, agreeing on a key with each party.
In other words, he would impersonate person A to person B and vice versa. The attacker would then act as a bridge or intermediary between the two people and, knowing the keys, could decrypt the information and then re-encrypt it to send it to the other team without either team realizing that their communication is being intercepted.
The fact that it is a crucial exchange algorithm still in use 45 years after its creation is a testament to its effectiveness and how far ahead of its time its creators were. This long-standing technology inspired the creation of the RSA algorithm. It paved the way for other recent innovations, such as elliptic curve cryptography.
