Developed a Multiple Ratchet Group Key Agreement Protocol

Secure and scalable group key agreements provide end-to-end encryption in instant messaging applications and adapt to the frequently dynamic changes during chat life while maintaining the security features provided by the double ratchet protocol in one-on-one communication, represents a challenge. Using the Double Ratchet Algorithm approach and the core principles of confidentiality, integrity, and authenticity based on Chacha20/Poly1305, SHA256, and XEdDSA, respectively in addition to Curve2559 as an asymmetric system, this study introduces a secure, scalable, and flexible multiple ratchet group key agreement (MRGKA) protocol. MRGKA innovatively divides users into subgroups (SG), each with a maximum capacity of 15 members, and each subgroup is endowed with a unique Identity Key (SGIK) and Signed Pre-shared Keys (SGSPK), facilitating secure and private intra-group communications as if each subgroup were a single user entity. MRGKA provides an efficient 70 subgroup with a 20MB data size without any compression or cache mechanisms. Invite Authentication Code (IAC) was introduced in this protocol to provide robust subsequent sessions and more security strength for the symmetric rachet approach. finally, the protocol supports asynchronous communication and is capable of dynamically adapting to group changes such as user additions or removals, making it highly suitable for real-world applications where group dynamics are fluid.