Introduction
Cryptocurrency has emerged as a significant technology and financial instrument. For investigators, understanding the fundamentals of cryptocurrency and blockchain technology is essential for investigating crypto-related crimes, tracing transactions, and recovering digital assets.
By the end of this part, you will understand blockchain technology fundamentals, know the major cryptocurrencies, understand wallet types and exchanges, and be aware of the regulatory status in India.
Blockchain Technology
Blockchain is a distributed ledger technology that records transactions across multiple computers in a way that makes it virtually impossible to alter the recorded information without altering all subsequent blocks and gaining consensus from the network.
Core Concepts
Distributed Ledger
A database shared and synchronized across multiple sites, institutions, or geographies.
Blocks
Groups of transactions bundled together and added to the chain in chronological order.
Cryptographic Hashing
Each block contains a hash of the previous block, creating an unbreakable chain.
Consensus Mechanism
Protocol ensuring all nodes agree on the state of the ledger (e.g., Proof of Work, Proof of Stake).
How Blockchain Works
Types of Blockchain
| Type | Access | Example | Use Case |
|---|---|---|---|
| Public | Open to all | Bitcoin, Ethereum | Cryptocurrency, DeFi |
| Private | Restricted | Hyperledger Fabric | Enterprise solutions |
| Consortium | Selected parties | R3 Corda | Banking, supply chain |
| Hybrid | Combination | Dragonchain | Healthcare, government |
Public blockchains like Bitcoin and Ethereum are transparent - all transactions are visible on the public ledger. This transparency is crucial for investigations as it allows tracing of fund flows, though addresses are pseudonymous.
Bitcoin
Bitcoin, created by the pseudonymous Satoshi Nakamoto in 2009, was the first cryptocurrency. It remains the largest by market capitalization and is often the entry point for understanding cryptocurrency.
Key Characteristics
- Supply Cap: Maximum 21 million bitcoins will ever exist
- Divisibility: 1 BTC = 100,000,000 satoshis (smallest unit)
- Consensus: Proof of Work (mining)
- Block Time: Approximately 10 minutes per block
- Halving: Mining reward halves every 210,000 blocks (~4 years)
Bitcoin Address Types
| Type | Prefix | Example Format |
|---|---|---|
| Legacy (P2PKH) | 1 | 1BvBMSEYstWetqTFn5Au4m4GFg7xJaNVN2 |
| Script (P2SH) | 3 | 3J98t1WpEZ73CNmQviecrnyiWrnqRhWNLy |
| Native SegWit | bc1q | bc1qar0srrr7xfkvy5l643lydnw9re59gtzzwf5mdq |
| Taproot | bc1p | bc1p5cyxnuxmeuwuvkwfem96lqzszd02n6xdcjrs20cac6yqjjwudpxqkedrcr |
Bitcoin Transaction Structure
- Inputs: References to previous transaction outputs being spent
- Outputs: New UTXOs (Unspent Transaction Outputs) created
- Transaction Fee: Difference between inputs and outputs (goes to miners)
- Transaction ID (TXID): Unique identifier for each transaction
Ethereum
Ethereum, launched in 2015 by Vitalik Buterin, is a programmable blockchain that enables smart contracts and decentralized applications (dApps). It's the second-largest cryptocurrency by market cap.
Key Differences from Bitcoin
| Feature | Bitcoin | Ethereum |
|---|---|---|
| Purpose | Digital currency | Programmable platform |
| Consensus | Proof of Work | Proof of Stake (since 2022) |
| Block Time | ~10 minutes | ~12 seconds |
| Supply | Capped at 21M | No hard cap |
| Smart Contracts | Limited | Full support |
| Native Currency | BTC | ETH (Ether) |
Smart Contracts
Smart contracts are self-executing programs stored on the blockchain that automatically execute when predetermined conditions are met. They are the basis for:
- DeFi (Decentralized Finance): Lending, borrowing, trading without intermediaries
- NFTs (Non-Fungible Tokens): Unique digital assets
- DAOs (Decentralized Autonomous Organizations): Blockchain-based governance
- Token Standards: ERC-20 (fungible tokens), ERC-721 (NFTs)
Ethereum's smart contracts can be analyzed to understand the flow of funds. Tools like Etherscan allow viewing contract source code, transaction history, and token transfers - invaluable for tracing illicit funds.
Cryptocurrency Wallets
A cryptocurrency wallet doesn't store cryptocurrency directly; instead, it stores the private keys needed to access and transfer cryptocurrency on the blockchain.
Wallet Types
Hot Wallets
Connected to internet. Convenient but less secure. Examples: Mobile apps, web wallets, exchange wallets.
Cold Wallets
Offline storage. More secure. Examples: Hardware wallets (Ledger, Trezor), paper wallets.
Desktop Wallets
Software installed on computer. Examples: Electrum, Exodus, Bitcoin Core.
Paper Wallets
Private keys printed on paper. Completely offline but vulnerable to physical damage.
Key Concepts
- Private Key: Secret number that allows spending cryptocurrency (must be kept secret)
- Public Key: Derived from private key, used to generate addresses
- Address: Public identifier for receiving cryptocurrency
- Seed Phrase: 12-24 words that can recover all private keys in a wallet
When seizing cryptocurrency, investigators need access to private keys or seed phrases. Without these, the cryptocurrency cannot be transferred to government custody. Hardware wallets and seed phrases should be carefully documented and preserved.
Cryptocurrency Exchanges
Exchanges are platforms where users can buy, sell, and trade cryptocurrencies. Understanding exchange operations is crucial for investigations as they often maintain user identity records.
Types of Exchanges
| Type | Characteristics | KYC | Examples |
|---|---|---|---|
| Centralized (CEX) | Company-operated, custodial | Required | WazirX, CoinDCX, Binance |
| Decentralized (DEX) | Smart contract-based, non-custodial | Usually not | Uniswap, SushiSwap |
| P2P Platforms | Direct buyer-seller connection | Varies | LocalBitcoins, Paxful |
| OTC Desks | Large volume trades | Required | Genesis, Cumberland |
Exchange Information for Investigation
- KYC Records: User identity documents, photos, addresses
- Transaction History: All deposits, withdrawals, trades
- IP Logs: Access locations and times
- Linked Addresses: Wallet addresses used for deposits/withdrawals
- Bank Account Details: For fiat deposits/withdrawals
Regulatory Status in India
The regulatory landscape for cryptocurrency in India has evolved significantly over the years. Understanding the current legal status is essential for investigators.
Regulatory Timeline
- 2013: RBI first warns about cryptocurrency risks
- 2018: RBI prohibits banks from dealing with crypto entities
- 2020: Supreme Court strikes down RBI ban (Internet and Mobile Association of India v. RBI)
- 2022: 30% tax on crypto income introduced (Finance Act 2022)
- 2022: 1% TDS on crypto transactions (Section 194S)
- 2023-Present: Continued discussions on comprehensive regulation
Current Legal Position
| Aspect | Status |
|---|---|
| Ownership | Legal (not prohibited) |
| Trading | Legal but taxed heavily |
| Payment | Not legal tender |
| Exchanges | Operating with VDA (Virtual Digital Asset) compliance |
| Mining | Not specifically regulated |
| Tax | 30% flat tax on profits, 1% TDS on transfers |
Key Regulatory Bodies
- MeitY: Nodal ministry for digital assets policy
- CBDT: Income tax compliance for crypto
- ED: Investigation of crypto-related money laundering
- CERT-In: Cybersecurity aspects
- FIU-IND: Anti-money laundering compliance (exchanges must register)
From March 2023, all VDA service providers operating in India must register with FIU-IND (Financial Intelligence Unit) and comply with PMLA reporting requirements. Offshore exchanges serving Indian users without registration face penalties.
Other Important Cryptocurrencies
Privacy Coins
Some cryptocurrencies are designed to provide enhanced privacy, making transaction tracing more difficult:
- Monero (XMR): Uses ring signatures, stealth addresses, and RingCT to hide transaction details
- Zcash (ZEC): Offers optional privacy through zero-knowledge proofs (shielded transactions)
- Dash: Optional mixing feature (PrivateSend)
Stablecoins
Cryptocurrencies pegged to fiat currencies or other assets:
- USDT (Tether): Most widely used, pegged to USD
- USDC: US Dollar Coin, regulated
- DAI: Decentralized stablecoin
- Blockchain is a distributed, immutable ledger that records all cryptocurrency transactions
- Bitcoin is the first and largest cryptocurrency; Ethereum enables smart contracts
- Wallets store private keys, not cryptocurrency itself - securing keys is critical
- Centralized exchanges maintain KYC records valuable for investigations
- In India, cryptocurrency is legal but heavily taxed and regulated
- VDA service providers must register with FIU-IND for PMLA compliance
- Privacy coins pose additional challenges for transaction tracing