Secure E-Voting System

This repository contains the implementation of a Secure Electronic Voting System leveraging advanced cryptographic techniques to ensure privacy, security, and transparency. The system is based on a multi-authority election scheme and incorporates features such as homomorphic encryption, digital signatures, and threshold decryption for a robust voting process.

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Features

1. Homomorphic Encryption

• Each voter encrypts their choice (e.g., Yes/No) using a homomorphic encryption algorithm.
• The encryption guarantees that the tally of votes can be computed without decrypting individual votes, ensuring vote secrecy.

2. Digital Signatures

• Voters sign the cryptogram (encrypted vote) using digital signatures.
• This signature proves that the vote originates from an authorized voter, maintaining the system's integrity.

3. Multi-Authority Setup

• To mitigate risks of vote decryption by a dishonest authority, the decryption key is distributed across multiple parties using a Shamir (t, n)-threshold scheme.
• At least t out of n parties must collaborate to reveal the vote tally, ensuring no single authority can compromise the system.

4. Trusted Setup and Decentralization

• Initially, a trusted center is assumed to set up the system by choosing necessary cryptographic parameters (e.g., primes p and q).
• However, the system can also operate without a trusted center by employing a secure communication protocol executed by the parties involved.

5. Public-Key Infrastructure

• A public-key infrastructure (PKI) is used to authenticate messages and guarantee the origin of all posted data.
• This ensures that only legitimate participants can interact with the system.

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Communication Model

• The system uses a bulletin board as a shared, publicly accessible memory for posting encrypted votes and related cryptographic data.
• The bulletin board allows transparency and verifiability:
  • Every member has a designated section to post messages.
  • No one can delete or modify any information once posted.
  • The complete board is viewable by all members, including external observers.

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Workflow

1. Voter Registration
   Each voter receives a cryptographic key pair for encryption and digital signatures.

2. Vote Casting

   • The voter encrypts their choice using homomorphic encryption.
   • The encrypted vote is signed and posted to the bulletin board.

3. Vote Collection

   • All encrypted votes are stored on the bulletin board.
   • Votes remain confidential as they are not decrypted during this stage.

4. Tallying

   • The authorities compute the tally directly on the encrypted votes.
   • Decryption is performed collaboratively by at least t out of n authorities, ensuring security.

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Advantages

• Privacy: Individual votes remain confidential throughout the process.
• Security: Threshold decryption prevents any single authority from compromising the system.
• Transparency: The bulletin board model allows public verifiability of the election process.
• Efficiency: The system is optimized for low time and communication complexity.

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Technologies and Concepts Used

• Cryptography: Homomorphic Encryption, Digital Signatures, Shamir Threshold Scheme.
• Public-Key Infrastructure (PKI): For message authentication.
• Distributed Systems: Multi-authority setup for decentralized decryption.

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Future Enhancements

• Replace the trusted center with a decentralized protocol for setting up cryptographic parameters.
• Optimize the communication model for larger-scale elections.
• Implement advanced user interfaces for ease of use by voters and authorities.

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References

This system is based on the theoretical framework introduced in the research paper by [CraGenSch97], which outlines the secure multi-authority election scheme.

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