SignChain

Sign, Don’t Type—Decentralized Verification for Fintech Security

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SignChain – Blockchain-Based OTP Replacement for Fintech Transactions

Secure your transactions with cryptographic signatures, not SMS-based OTPs.
SignChain offers a modern, decentralized alternative to traditional authentication.

Team Details

Karan Mishra
Role: Solo Developer / Team Leader
Email: karanmishra9820@gmail.com

Project Description

Problem

Traditional OTPs (One-Time Passwords), commonly used for securing financial transactions, are:

  • Vulnerable to phishing, SIM swap attacks, and malware
  • Dependent on centralized SMS/email infrastructure
  • Frequently delayed or undelivered
  • Lacking cryptographic proof of user consent

As digital financial activity grows, reliance on insecure OTP systems exposes users and businesses to increasing risk.

Solution

SignChain eliminates OTPs by using Ethereum-based cryptographic digital signatures for transaction verification.

Users sign a transaction ID using MetaMask. The signature is then verified both:

  • Off-chain using Ethers.js
  • On-chain using a Solidity smart contract with ecrecover

This system is:

  • Decentralized and transparent
  • Cryptographically verifiable
  • Resistant to phishing, SIM swap, and MITM attacks
  • Fast and seamless for users

Target Users

  • Fintech platforms seeking secure transaction authorization
  • Developers building modern authentication flows
  • E-commerce businesses implementing secure checkouts
  • End users who prioritize security, privacy, and usability

How It Works

  1. User submits a mock transaction on the frontend
  2. MetaMask prompts the user to sign the transaction ID (txId)
  3. A signature is generated using the user’s private key
  4. The frontend sends the txId, signature, and address to the backend API
  5. The backend verifies the signature off-chain using Ethers.js
  6. If valid:
    • Transaction is saved to MongoDB
    • Signature is submitted to the smart contract
    • Smart contract uses ecrecover to verify the signer
    • Result is returned to the backend and frontend
  7. If invalid:
    • Backend responds with an error

Why It Matters

  • Removes reliance on insecure and centralized OTP systems
  • Provides verifiable cryptographic proof of user consent
  • Improves user experience by eliminating delays and manual entry
  • Enables full transparency and auditability through smart contracts

Tech Stack

Layer Technologies
Smart Contract Solidity, Hardhat
Wallet MetaMask
Frontend React.js, Ethers.js
Backend Node.js (Express)
Database MongoDB
Blockchain Ethereum (EVM-compatible)

Features

  • OTP-less transaction authorization
  • MetaMask-based digital signing
  • Smart contract verification using ecrecover
  • MongoDB-backed transaction logging
  • Modular architecture with separate frontend, backend, and smart contract layers

GitHub Repository

Repository: https://github.com/KaranMishra3610/SignChain

Includes structured code, setup instructions, documentation, and visuals.

Demo

Live Demo:
https://subtle-gelato-4d93e4.netlify.app/

Walkthrough Video:
https://vimeo.com/1102466789

Technical PPT https://drive.google.com/file/d/1iRr7lm0Y_O2XEk6y-kmB00chzeLH4vDC/view?usp=sharing

Pitch Video

Watch on Vimeo:
https://vimeo.com/1102569375?share=copy

Pitch PPT https://drive.google.com/file/d/1Lgz3L6ZGoR5AvWyzMZz1Fbal5r5cPdn-/view?usp=sharing

Business Potential

SignChain offers:

  • Fintech-grade transaction security through decentralized infrastructure
  • Operational cost reduction by eliminating SMS/email OTP gateways
  • A scalable model for millions of users via Ethereum and L2 networks
  • A modern, user-friendly experience built on web3 standards

Why You Should Invest

The need for secure, scalable, and user-friendly authentication is growing rapidly. OTPs are outdated, insecure, and inefficient. SignChain replaces them with verifiable, cryptographic signatures—bringing transparency, privacy, and resilience to transaction workflows.

SignChain is not just a solution—it’s a step toward a more secure digital economy.

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