Vanity Address

A vanity address is a Bitcoin address whose prefix has been chosen for vanity reasons rather than left to chance. The generation method is brute force: derive random keypairs and check if the resulting address starts with the desired pattern. The search cost grows exponentially with the prefix length.

Rough orders of magnitude for bech32 (bc1q... / bc1p...) addresses:

• 4 custom characters: ~1 million tries (seconds on a laptop)
• 6 custom characters: ~1 billion tries (minutes to an hour on a laptop)
• 8 custom characters: ~1 trillion tries (multiple GPU-hours)
• 10+ custom characters: realistically requires GPU clusters and days of compute

Famous examples include the 1BitcoinEater... burn-address vanities and various exchange "branded" addresses.

The security trap is letting someone else do the work. If a vanity service generates the key and emails you the seed, they have the private key (and so does anyone who breaks into their database). Best practice is one of:

• Local generation with an open-source tool (Vanitygen, bitcoin-vanity-search, etc.) on hardware you control. The private key never leaves your machine.
• Split-key vanity generation. A two-party protocol where one party brute-forces a partial key matching the prefix, and the other party adds a secret scalar offset. Neither party ever sees the full private key. Useful when you want to outsource the compute without trusting the compute provider.

Vanity addresses are a privacy mistake by default. Reusing one address for vanity-branding purposes destroys the wallet's transactional privacy by aggregating activity onto one identifier. If you really want a vanity address, generate one and use it as a vanity receive address that you then sweep into normal HD-wallet addresses for actual custody.