Methods For Splitting and Recovering Key, Program Product, Storage Medium, and System

A method for splitting a transaction key in a key management system, wherein the key management system comprises a management device for managing user devices of users in a user group and a hardware security module connected to the management device, and the method comprises:

• at the hardware security module,
• acquiring a number of the users of the user group and a first predetermined value, wherein the first predetermined value indicates a minimum number of users for recovering the transaction key, and the user group is configured to manage the transaction key;
• randomly generating the transaction key associated with processing authority of this transaction based on messages about other users except for a splitting user determined for splitting the transaction key in the user group, wherein the messages about other users at least indicate public keys of the other users;
• splitting the transaction key into a plurality of sub-keys of the same number as the number of the users, wherein each sub-key in the plurality of sub-keys corresponds to one user in the user group;
• and
• encrypting the plurality of sub-keys respectively with public keys of the users corresponding to the plurality of sub-keys.