Digital Signatures

Digital signatures are cryptographic primitives that provide three essential security properties:

Authentication - Verifies the identity of the signer
Non-repudiation - The signer cannot deny having signed the message
Integrity - The message has not been altered since signing

How Digital Signatures Work

Digital signatures typically involve two main operations:

Signing: Using a private key to generate a signature for a message
- Input: Message + Private Key
- Output: Signature
Verification: Using a public key to verify the signature matches the message
- Input: Message + Signature + Public Key
- Output: True/False (valid/invalid)

Types of Digital Signatures

Traditional Signatures (e.g. ECDSA)

Based on elliptic curve cryptography
Widely used in Bitcoin and other blockchains
Each signature is independent
Size grows linearly with number of signers

BLS Signatures

Based on bilinear pairings on elliptic curves
Allows signature aggregation
Multiple signatures can be combined into one
Constant size regardless of number of signers
More computationally intensive than ECDSA

Use Cases

Document signing
Software authentication
Blockchain transactions
Secure messaging
Identity verification

Security Considerations

Private keys must be kept secure
Use cryptographically secure random number generators
Implement proper key management
Be aware of potential attacks (e.g. replay attacks)
Use standardized implementations when possible