Non-Spend Backup Verification as a Proof Gap
Non-Spend Verification Methods for Seed Backups
This memo is published by CustodyStress, an independent Bitcoin custody stress test that produces reference documents for individuals, families, and professionals.
The Wallet Works But the Backup Remains Unproven
A person sets up a bitcoin wallet. The balance appears on the screen. The backup words are written on paper and stored somewhere. Days pass. Then weeks. Then months. A question forms in the person's mind: how do I know this backup is correct? The person wants to verify the backup without spending any bitcoin. The person wants proof that the words on paper will work when needed. The person does not want to move any coins to get that proof.
What follows covers how the desire to verify a backup without spending exposes a gap between current wallet access and confidence in future recoverability. The backup exists. The wallet works. But the connection between them remains unproven. The proof gap sits between what the person can see now and what the person hopes will work later.
The Wallet Works But the Backup Remains Unproven
When a wallet displays a balance, it proves one thing: the wallet has access to keys that control bitcoin at certain addresses. The wallet works. The person can see the balance. The person can send bitcoin if they choose. These facts describe the present moment.
The backup words on paper describe something different. They describe the ability to recreate keys in the future. The words claim to hold the information needed to rebuild the wallet from nothing. But this claim remains untested until the words are actually used to recreate keys.
The gap exists because the wallet and the backup are separate objects. The wallet holds working keys right now. The backup holds words that can generate keys later. Whether those words generate the same keys depends on whether they were recorded correctly. The wallet cannot show this. The wallet only shows that it works with whatever keys it currently holds.
A person who opens their wallet and sees a balance has confirmed present access. A person who looks at backup words on paper has not confirmed future access. The confirmation requires a different kind of test.
What Verification Without Spending Actually Means
The phrase verify backup without spending contains two separate requests. The first request asks for proof that the backup words are correct. The second request asks that this proof not require moving bitcoin on the blockchain.
These two requests come from different concerns. The proof concern is about correctness. Will these specific words, written on this specific paper, recreate the same keys that control my bitcoin? The spending concern is about evidence. Will confirming correctness create a transaction record that others can see?
The person wants certainty without visibility. The person wants to know the backup works without creating any trace of that knowledge. This combination creates constraints on what kind of evidence can exist.
Some verification methods require spending. A person could send a small amount of bitcoin to a new address and then attempt to recover the wallet using only the backup words. If the balance reappears after recovery, the backup worked. But this method creates a transaction on the blockchain. The transaction exists forever. Anyone analyzing the blockchain can see it happened.
Other verification methods do not require spending. A person could enter the backup words into a different device and check whether the same addresses appear. If the addresses match, the backup words produce the same keys. No transaction occurs. No blockchain record is created. But this method has its own complications.
The Difference Between Address Matching and Recovery Proof
When a person enters backup words into a second device and sees the same addresses, this confirms that the words produce the same keys. The addresses match. The derivation works. The backup words are recorded correctly.
But address matching is not the same as recovery proof. Address matching happens in a controlled moment when both the original wallet and the backup words are available. Recovery happens in an uncontrolled moment when only the backup words are available because something has gone wrong.
A person who matches addresses today knows the backup worked today. The person does not know whether the backup will work in three years when the original wallet is gone and the backup words are the only path back to the bitcoin.
The gap between matching and recovery involves time. It involves storage conditions. It involves the durability of the paper or metal holding the words. It involves the person's ability to find the backup when needed. It involves whether the words remain readable after years of storage.
Verification without spending can confirm the backup was correct at the moment of verification. It cannot confirm the backup will remain correct through all the moments that follow.
Why the Proof Gap Reopens After Verification
A person verifies their backup without spending. The addresses match. The person feels confident. Time passes. The confidence begins to fade.
Did I verify the right backup? The person may have multiple papers with words written on them. Old drafts. Test wallets. Backups for different purposes. Which one was verified? The memory becomes less clear.
Did something change after verification? The person may have created a new wallet since then. The person may have added a passphrase. The person may have moved to a different derivation path. The verification confirmed a state that may no longer be current.
Is the backup still readable? The paper may have degraded. The ink may have faded. The storage location may have experienced humidity or temperature changes. The backup was readable when verified. Whether it remains readable years later is a different question.
The proof gap reopens because verification is a point-in-time event. The backup needs to work at a future point in time that cannot be predicted. The distance between the verification moment and the recovery moment creates space for things to change.
Scenarios That Expose the Gap
A person stores their backup in a fireproof safe and verifies it works by matching addresses. Five years later, the person's hardware wallet breaks. The person retrieves the backup from the safe. The paper has yellowed. Some words are harder to read. The person enters what they think they see. The addresses do not match. The verification five years ago confirmed the backup was correct then. The degradation happened after.
A person verifies their backup and writes verified with a date on the paper. The person later creates a second wallet for a different purpose. The person writes down those backup words on a similar paper. Years pass. The person finds two papers, both with backup words, one marked verified. The person cannot remember which wallet each backup belongs to. The verification mark confirms one backup was checked. It does not confirm which bitcoin it controls.
A person verifies their backup by matching addresses on a second device. The person then adds a passphrase to the wallet for additional security. The backup words without the passphrase now produce different addresses. The verification was correct at the time. The wallet configuration changed after. The backup alone no longer leads to the bitcoin.
An executor finds backup words in a deceased person's belongings. The executor does not know if the words were ever verified. The executor does not know if the words are current or old. The executor does not know if additional information like a passphrase is needed. The deceased person may have verified the backup many times. That verification history did not transfer to the executor.
The Record Problem
Verification without spending often means verification without record. The person checks the backup. The addresses match. The person puts the backup away. No evidence of the verification exists outside the person's memory.
Memory fades. The person verified the backup. The person is fairly sure they verified the backup. The person thinks they probably verified the backup at some point. The certainty degrades as time passes.
A verification that leaves no record becomes a verification that cannot be proven. The person knows they did it. But if the person becomes unavailable, through death or incapacity, that knowledge disappears. The next person to encounter the backup has no way to know it was ever tested.
The desire to avoid spending often connects to the desire to avoid records. A transaction creates a record on the blockchain. Some verification methods create records in software logs or on paper. But a person who wants no trace of verification also gets no proof of verification. The goals conflict.
What Third Parties See
When someone other than the original holder needs to evaluate a backup, the absence of verification proof becomes a problem. An executor finds backup words. A spouse finds a paper in a drawer. A trustee receives custody materials. None of them know the verification history.
The third party sees words on paper. The third party does not see whether those words were tested. The third party does not see whether those words are current. The third party does not see whether those words are complete or whether additional information is needed.
The original holder may have verified the backup thoroughly. The original holder may have felt completely confident. That confidence existed in the holder's mind. It did not exist in any transferable form. The third party inherits the backup without inheriting the confidence.
The proof gap that the original holder might have closed through verification remains open for everyone who comes after. The verification happened but left no trace that others can see.
Confidence Versus Proof
Confidence and proof are different things. Confidence is a feeling a person has in a moment. Proof is evidence that can be shown to others and that survives across time.
Verification without spending can create confidence. The person checks the backup. The addresses match. The person feels confident the backup is correct. This confidence is real. It exists in the person's mind.
But confidence does not transfer. When the person is no longer available, the confidence disappears with them. The backup remains. The proof that it was verified does not.
A person who wants to verify backup without spending often wants confidence for themselves in the present moment. The question of whether that confidence can transfer to others or survive into the future is a separate question. The non-spend constraint addresses the first concern. It does not address the second.
Outcome
The desire to verify a backup without spending reflects a gap between current wallet access and confidence in future recoverability. A working wallet proves present access. A backup claims future access. The connection between them remains unproven until the backup is tested.
Verification without spending can confirm that backup words produce the correct addresses at the moment of testing. It cannot confirm that the backup will remain correct, readable, findable, and complete across all the time that follows. The proof gap reopens as circumstances change and memory fades.
The constraint of avoiding spending often means avoiding records. A verification that leaves no trace becomes a verification that cannot be proven to others or remembered with certainty by oneself. The original holder may gain confidence. That confidence does not transfer to executors, heirs, or anyone who encounters the backup later without context.
System Context
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