Singlesignature

Single-signature refers to a digital signature scheme in which a single private key is used by a signer to generate a signature on a message, verifiable with the corresponding public key. It is the standard model for most digital signatures and is distinct from multi-signature systems, which require two or more signers to authorize a signature.

Common single-signature schemes include RSA, DSA, ECDSA, and EdDSA. RSA-based signatures rely on the difficulty of factoring large integers, while DSA and ECDSA rely on the hardness of discrete logarithms in chosen groups. EdDSA, such as Ed25519, emphasizes high performance and deterministic signing to avoid nonce-related vulnerabilities. In practice, messages are typically hashed before signing to produce a fixed-length digest that the signer authenticates.

Single-signatures underpin many digital trust mechanisms, including X.509 certificates, code signing, email signing (S/MIME, PGP), and document authentication. In blockchain systems, most transactions use single-signature schemes, with the public key or a hash of it providing verifiable ownership of blockchain assets.

Security considerations center on safeguarding the private key and ensuring proper implementation. Key management practices, secure storage (hardware security modules or wallets), key rotation, and robust verification procedures are essential. Some signature schemes are vulnerable to nonce reuse or side-channel attacks if not implemented correctly; deterministic schemes or well-vetted libraries mitigate these risks. Public-key infrastructure, certificate revocation, and algorithm agility are important for maintaining long-term trust.

Limitations of single-signature systems include the reliance on a single private key, creating a potential single point of failure. For higher assurance, organizations may use multi-signature or threshold-signature schemes to distribute trust and reduce the impact of key compromise.