Introduction to Cryptography in Blockchain
Cryptography forms the backbone of blockchain security, which is why we refer to tokens as "cryptocurrencies." This article delves into the role of public/private keys and the principles behind encryption technologies that power decentralized systems.
Symmetric vs. Asymmetric Encryption
Symmetric Encryption
Uses the same key for encryption and decryption (e.g., Morse Code). While efficient, it requires secure key distribution—a vulnerability exploited if intercepted.
Example: Morse Code in WWII
- Featured in films like The Message, its wartime use highlighted both utility and risks of shared codebooks.
- Decryption relies on standardized cipher tables (easily searchable today).
Asymmetric Encryption
Employs paired keys:
- Public Key: Shared openly to encrypt data or verify signatures.
- Private Key: Kept secret to decrypt or sign transactions.
- Wallet addresses derive from public keys, while private keys authenticate ownership.
RSA Encryption: A Foundational Example
Key Generation
- Select primes p and q (e.g., 17 and 19).
Compute:
- N = p × q = 323
- L = LCM(p-1, q-1) = 144
- Choose E (public key exponent) coprime with L (e.g., 5).
- Derive D (private key) where (E × D) mod L = 1 (here, D = 29).
Encryption Process
- Public Key: (5, 323)
- Private Key: (29, 323)
- Encrypt plaintext (e.g., "123") as ciphertext = (123^5) mod 323.
Security Strength
- Factoring large N (e.g., RSA-768) remains computationally prohibitive.
- Modern blockchains use Elliptic Curve Cryptography (ECC) for shorter keys with equivalent security (detailed in future articles).
FAQs
1. Why is asymmetric encryption preferred in blockchain?
It eliminates key-sharing risks—users transact securely without pre-exchanging secrets.
2. How does Morse Code relate to modern cryptography?
Both rely on agreed ciphers, but symmetric methods like Morse lack scalability for digital systems.
3. Can quantum computers break RSA?
Theoretical threats exist, but current implementations (like ECC) are evolving to resist quantum attacks.
👉 Discover advanced cryptographic tools for blockchain
Blockchain’s trustless security stems from these elegant mathematical principles—bridging wartime espionage to today’s decentralized finance.