A secure electronic system for storing and managing receipt and releasing of electronic documents, such as cryptocurrencies, digital currencies, tokens, and smart contracts, includes a platform server, a secure computer, and a non-IP protocol for communication between the secure computer and the platform server. The secure computer includes a plurality of cold memory modules and at least one hot memory module. The secure computer powers up and makes hot one or more of the plurality of the cold memory modules upon detecting and empty condition or a full condition. The secure computer includes a rate limiter that restricts releasing of hot electronic documents, such as cryptocurrencies, digital currencies, tokens, and smart contracts, stored in the at least one hot memory module. The non-IP protocol is known only to authorized administrators or operators of the secure electronic system. The secure computer provides access to the platform server only through the non-IP protocol.