On the other hand, when Alice and Bob receive respective ciphertexts from each other, they are able to obtain the same key K through respective modulo functions involving the received ciphertext and their own secrets, as shown below.īelow is a python implementation of the diagram above. Due to the one way nature of modulo functions, even if Eve were to capture the transmission, she would not be able to decrypt the ciphertext easily. Alice and Bob are able to pass secrets 'a' and 'b' in the form of ciphertexts g**a.mod.p and g**b.mod.p, where g and p are publicly known large prime numbers. Implementing Diffie-Hellmanīelow shows a diagrammatic representation of Diffie-Hellman key exchange. You can watch the video below to understand more about PKC. Usher in public key cryptography (PKC), and two of the most popular paradigms - Diffie-Hellman key exchange, invented by Hellman, Diffie, and Merkle and RSA, invented by Rivest, Shamir and Adleman also in 1977. In contrast, Kerckhoffs's principle states that the system should be designed with the assumption that the enemy will immediately gain familiarity, so it must be designed not based on key security, but the algorithm itself. Once the key was compromised, the entire system was comprised. In traditional symmetric encryption, like the dated examples above, robustness of the method depended on the security of the key. Image above: Enigma machine Public Key Cryptography
