securefilestorage

securefilestorage内容摘要：

with a unique File Signature Key (FSK) – To read, user needs FEK – To write, user needs FSK mdfiles Encrypted Key Block (Owner) Encrypted Key Block (User 1) Encrypted Key Block (User n) … FSK Metdata last modified timestamp filename Owner’s hash of metadata MSK used MEK Encrypted Key Blocks Username (or keyID) FEK FSK public key Plaintext Encrypted with MEK of user read/write read Username (or keyID) FEK Plaintext Encrypted with MEK of user Freshness Guarantees • Prevent rollback attacks – Alice replaces new mdfile with an older saved mdfile • mdffile: metadata freshness file – One in each directory of user’s file system – Stamped with unique Master Signing Key (MSK) of user – Contains root of hash tree of all mdfiles in current directory and mdffiles in immediate subdirectories Creating mdffiles 1. Apply SHA1 hash on each mdfile in current directory (verifying mdfile signatures as you go) 2. Concatenate resulting hashes together with mdffiles of immediate subdirectories and apply SHA1 hash to concatenation 3. Place final hash and directory name in mdffile Note: Timestamp used before final ha。