This document proposes a lightweight cryptography solution for secure communication in mobile ad hoc networks (MANETs). It describes creating a distributed public key infrastructure (PKI) using Shamir's secret sharing to decentralize the certificate authority role among MANET nodes. Each node holds a share of the private key. It then proposes using Tiny Encryption Algorithm (TEA), an efficient symmetric-key cipher, along with elliptic curve Diffie-Hellman key exchange to establish secure communication between nodes with limited resources. The system initializes by having founding MANET nodes act as dealers to distribute secret shares. Nodes then use Diffie-Hellman to independently derive a secret key to encrypt communications.