Mpesi

mpesi is a standardized protocol used for secure electronic communication, defined by the International Telecommunication Union (ITU) in the early 2000s. Originally created to address the growing need for confidential messaging in international trade, the protocol supports end‑to‑end encryption using public‑key cryptography and offers built‑in authentication mechanisms. The name derives from its key components: Message Processing, Encryption, and Secure Interface.

The protocol was formalized in ITU-T Recommendation X.509/MPESI, which outlines the data formats, key agreement schemes, and integrity checks used by mpesi. Implementation libraries in C, Java and Python have been released as open source, enabling widespread adoption by banks, government agencies and supply‑chain partners. Many national payment systems have integrated mpesi to ensure compliance with the Basel III liquidity requirements.

mpesi is designed to be interoperable with existing internet protocols. It typically operates over Transport Layer Security (TLS) and can be embedded in XMPP or SIP sessions. The standard also defines optional support for elliptic‑curve cryptography, allowing smaller key sizes while maintaining security. Some implementations provide a fallback to legacy symmetric encryption when required.

Criticisms of mpesi focus on its comparatively large packet overhead and complexity of integration. Some vendors argue that newer lightweight protocols offer similar security with less performance impact. Despite these concerns, mpesi remains a reference framework for secure message exchange in high‑assurance contexts.

mpesi has inspired several derivatives, such as the Secure Personal Data Exchange (SPDE) and the Inter‑Organizational Messaging Protocol (IOM), which incorporate parts of the mpesi specification while tailoring it to specific industries. As of 2025, continued updates aim to address post‑quantum cryptography requirements, ensuring the protocol’s relevance in a rapidly evolving security landscape.