SSZ ProgressiveContainer

The five-minute read

One action, walked through

1. Open EIP 7495 and read the status line before the examples.
2. Write down the rule in one sentence. A fair version of that sentence is: A new Simple Serialize (SSZ) type to represent containers with forward-compatible Merkleization: A given field is always assigned the same stable generalized index (gindex) even when different container versions append new fields or drop existing fields.
3. Name the object that changes: SSZ, MUST, NOT.
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 EIP 7495 at the status the text itself states: Review.
• The object that has to change is SSZ, MUST, NOT. 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 review. It is not a live consensus rule just because it has a number. 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 SSZ ProgressiveContainer?
• Can the same signature be replayed on another chain, account, or message?
• Which primitive does the text require: SSZ, MUST, NOT?

Terms

EIP 7495

The public text titled SSZ ProgressiveContainer.

Review

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

• A new Simple Serialize (SSZ) type to represent containers with forward-compatible Merkleization: A given field is always assigned the same stable generalized index (gindex) even when different container versions append new fields or drop existing fields.
• SSZ containers are frequently versioned, for example across fork boundaries.
• When the number of fields reaches a new power of two, or a field is removed or replaced with one of a different type, the shape of the underlying Merkle tree changes, breaking verifiers of Merkle proofs for these containers.

How the mechanism is specified

• Taken from the specification, the next constraint is: SSZ containers are frequently versioned, for example across fork boundaries.
• Locate SSZ, MUST, NOT in EIP 7495 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 review. It is not a live consensus rule just because it has a number.

Why a venture studio still reads it

Use EIP 7495 when a pitch says 'SSZ ProgressiveContainer' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.