The following shows a detailed step-by-step procedure of the access control system using Calypso. It shows the interaction of the writer (Wanda) and the reader (Ron). To protect the encrypted data, two systems are needed:

• Access Control Blockchain - guarantees that all updates to the access control are correctly authorized
• Secret-Management Committee - executes the decryption (re-encryption) of the document, but only if a correct proof of the access control blockchain is given

The Calypso paper has all the details.

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