This document proposes a secure distributed storage system that uses erasure coding and threshold proxy re-encryption. The system allows for robust, confidential storage and forwarding of encrypted data across storage servers without a central authority. It consists of four main modules: 1) System setup which generates keys for users and storage servers, 2) Data storage where a user's message is encrypted and dispersed across storage servers, 3) Data forwarding which allows a user to delegate access to another user via re-encryption of the stored data, and 4) Data retrieval where a user can retrieve their encrypted data from the storage servers.

1. Secure Erasure Code-Based Distributed
Storage System with Secure Data
Forwarding

2. Introduction
 Constructing a secure storage system that supports multiple
functions is challenging when it is distributed and has no
central authority
 The proposed system consist of threshold proxy re-
encryption scheme, integrated with a decentralized erasure
code
 The main focus is on designing a storage system for
robustness, confidentiality, and functionality

4. Modules
 System setup
 Data storage
 Data forwarding
 Data retrieval

5. 1. System setup
 create set of users, n storage servers SS1, SS2, . . .,
SSn, and m key servers KS1, KS2, . . . , KSm.
 Each user A is assigned a public-secret key pair
(PKA, SKA).

6. 2.Data Storage:
 In the data storage phase, user A encrypts his message
M and dispatches it to storage servers.
 A message M is decomposed into k blocks m1, m2..
 User A encrypts each block mi into a ciphertext Ci and
sends it to v randomly chosen storage servers
 Each storage server linearly combines them with
randomly chosen coefficients into a codeword symbol
and stores it.

7. 3.Data Forwarding:
 User A forwards his encrypted message with an identifier
ID stored in storage servers to user B such that B can
decrypt the forwarded message by his secret key.
 compute a re-encryption key RK AB
 Each storage server uses the re-encryption key to re-encrypt
its codeword symbol for later requests by B .
 The re-encrypted codeword symbol is the combination of
cipher texts under B’s public key.

8. 4.Data Retrieval:
 user A requests to retrieve a message from storage
servers
 User A sends a retrieval request to key servers
 user A combines the partially decrypted codeword
symbols to obtain the original message M.

9. Work Done
 Setting servers and users
 Each user has assigned with a key pair
 Selecting a file
 Splitting file into blocks
 Encrypting each block
 Sending cipher text to storage server

10. Work To Be Done
Encoding each block and storing.
Data Forwarding
 Generating re-encryption key
 Re-encrypting codeword
Data Retrieval
 Decrypting each block
 Combing all blocks

11. THANK YOU