Silent Payments

The five-minute read

One action, walked through

1. Open BIP 352 and read the status line before the examples.
2. Write down the rule in one sentence. A fair version of that sentence is: We use the following functions and conventions: ''outpoint'' (36 bytes): the COutPoint of an input (32-byte txid, least significant byte first || 4-byte vout, least significant byte first) '''Why are outpoints little-endian?''' Despite using big endian throughout the rest of the BIP, outpoints are sorted and hashed matching their transaction serialization, which is little-endian.
3. Name the object that changes: SEC1, BIP340, SHA256.
4. Ask what an old client, an old contract, or an offline counterparty does. If the document is silent, the silence is part of the design.

The argument, unpacked

What has to be true

• You are implementing BIP 352 at the status the text itself states: Complete.
• The object that has to change is SEC1, BIP340, SHA256. A neighbouring document with a similar name is not this one.
• Constants in the text can be superseded by a later fork. Cite the EIP number and the fork you mean.

What happened after the paper

The source marks this complete. That is a statement about the text, not a promise that every wallet or node has shipped it. Later documents can narrow, replace, or ignore this one. Cite the number you mean.

What to check before you use the idea

• What does Silent Payments charge, reject, or redefine on the first touch versus a later one?
• Does a reverted subcall roll the change back?
• Can you point at the object in a client: SEC1, BIP340, SHA256?

Terms

BIP 352

The public text titled Silent Payments.

Complete

The document's own label for how finished the text is. It is not a market fact.

The problem the paper names

An underpriced or ambiguous EVM rule is not a feature. It is a block that takes longer than the gas limit claimed, or a client that disagrees about the result.

What the design proposes

• We use the following functions and conventions: ''outpoint'' (36 bytes): the COutPoint of an input (32-byte txid, least significant byte first || 4-byte vout, least significant byte first) '''Why are outpoints little-endian?''' Despite using big endian throughout the rest of the BIP, outpoints are sorted and hashed matching their transaction serialization, which is little-endian.
• This allows a wallet to parse a serialized transaction for use in silent payments without needing to re-order the bytes when computing the input hash.
• Note: despite outpoints being stored and serialized as little-endian, the transaction hash (txid) is always displayed as big-endian.

How the mechanism is specified

• Taken from the specification, the next constraint is: This allows a wallet to parse a serialized transaction for use in silent payments without needing to re-order the bytes when computing the input hash.
• Locate SEC1, BIP340, SHA256 in BIP 352 and apply it to one transaction or call.
• Then check the failure the class of rule always has: a node that did not upgrade, a reverted call, a replayed signature, or a peer that does not speak the message.

What this page does not treat as proven

• A gas or opcode change is not a throughput benchmark. It is a relative price and a validity rule.
• Constants in the text can be superseded by a later fork. Cite the EIP number and the fork you mean.
• The source marks this complete. That is a statement about the text, not a promise that every wallet or node has shipped it.

Why a venture studio still reads it

Use BIP 352 when a pitch says 'Silent Payments' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.