Mono-Signature
A single ECDSA or Schnorr signature controlling an output-typical single-sig scenario versus multisig.
"Mono-signature" is an unusual phrasing for what most people call single-sig: one private key, one signature, controlling one output. It's the default Bitcoin spending pattern.
The vast majority of on-chain Bitcoin transactions today are single-sig. The rest use classical multisig or aggregated schemes for higher-security custody (vaults, exchange cold storage, treasuries) or for protocol reasons (Lightning channels are technically 2-of-2 multisig under the hood, but most other 2-of-2 outputs are now Taproot key-path spends that look like single-sig).
Schnorr (Taproot) single-sig signatures are 64 bytes; ECDSA single-sig signatures are 71-72 bytes after low-R grinding. Both authorize spending with one private key, both look on-chain like one signature, both have the same single-point-of-failure security profile.
The tradeoff is the obvious one: one key, one point of failure. Lose access to the key (lost seed, dead drive, no backup) and the coins are gone. Compromise the key (malware, supply-chain attack on a wallet, careless seed handling) and the coins are stolen. Multisig and aggregated signatures spread that risk across multiple keys or devices, at the cost of operational complexity.
For most users, a single hardware wallet (single-sig) with a properly verified seed backup is dramatically more secure than the alternatives they'd actually execute correctly. Multisig is a real upgrade only if you're willing to use it competently.
Key takeaways
- Standard approach: one private key signs, one signature suffices
- Less secure than multisig if the key is compromised
- Schnorr single-sig can be more compact than ECDSA