Password Authenticated Key AgreementRomuald Franck - MSc, Scrum Master
Password Authenticated Key Agreement (PAKE) is a cryptographic protocol that enables two parties to establish a shared secret key over an insecure network without the need for a pre-shared key. PAKE protocols have gained popularity in recent years, especially in the context of secure communication over the internet.
PAKE protocols are designed to overcome the limitation of traditional key agreement protocols, where the security of the shared key is dependent on the security of the pre-shared key. In contrast, PAKE protocols use a password or a passphrase as input, eliminating the need for a pre-shared key.
One of the most popular PAKE protocols is the Secure Remote Password (SRP) protocol, which was first introduced by Thomas Wu in 1998. The SRP protocol uses a combination of symmetric-key cryptography and public-key cryptography to provide a secure and efficient way to establish a shared secret key between two parties.
The SRP protocol works by first generating a verifier from the user`s password, which is stored securely on the server. When a user wants to authenticate, they send their username to the server, which responds with the verifier. The user then generates a random number, known as the ephemeral private key, and uses it to generate a public key. The user then sends their public key to the server, along with some additional information.
The server then generates its own ephemeral private key and public key, and uses these to calculate the shared secret key. The server then sends its public key to the user, along with some additional information. The user can then use the server`s public key and additional information to calculate the shared secret key, without ever revealing their password or their ephemeral private key.
PAKE protocols offer several advantages over traditional key agreement protocols. For one, they provide a way to establish a shared secret key over an insecure network without the need for a pre-shared key. They also eliminate the need for users to store pre-shared keys securely, which can be a challenge in practice. Finally, PAKE protocols can be used in conjunction with other security measures, such as secure channels and authentication protocols, to provide even greater security.
In conclusion, PAKE protocols offer a secure and efficient way to establish a shared secret key between two parties over an insecure network. With the rise of internet-based communication and the increasing need for secure communication, PAKE protocols are likely to play an increasingly important role in the years to come.