Signed Data Standard

The five-minute read

One action, walked through

1. Open ERC 191 and read the status line before the examples.
2. Write down the rule in one sentence. A fair version of that sentence is: We propose the following format for signed_data 0x19 .
3. Name the object that changes: signed_data, RLP, personal_sign.
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 ERC 191 at the status the text itself states: Final.
• The object that has to change is signed_data, RLP, personal_sign. A neighbouring document with a similar name is not this one.
• Wallet support is not the same as consensus validity.

What happened after the paper

The source marks this final. 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 is covered by the signed bytes in Signed Data Standard?
• Can the same signature be replayed on another chain, account, or message?
• Which primitive does the text require: signed_data, RLP, personal_sign?

Terms

ERC 191

The public text titled Signed Data Standard.

Final

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

The problem the paper names

A signature that does not commit to what the user saw can be replayed into a different spend, a different chain, or a different message.

What the design proposes

• We propose the following format for signed_data 0x19 .
• The initial 0x19 byte is intended to ensure that the signed_data is not valid RLP.
• > For a single byte whose value is in the [0x00, 0x7f] range, that byte is its own RLP encoding.

How the mechanism is specified

• Taken from the specification, the next constraint is: The initial 0x19 byte is intended to ensure that the signed_data is not valid RLP.
• Locate signed_data, RLP, personal_sign in ERC 191 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 signature scheme is not a privacy system. It hides the signer only if the protocol says so.
• Wallet support is not the same as consensus validity.
• The source marks this final. 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 ERC 191 when a pitch says 'Signed Data Standard' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.