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Make Offer Signature Structure

To authorize the makeOffer operation within the MNS service, the user (the offeror) must generate a cryptographic signature compliant with the EIP-191 standard.

This signature proves the offeror's intent and authorization to place a specific offer on a target username under the specified terms (amount, expiration).

Signed Message Format​

The message is constructed by concatenating the following components as strings, separated by commas (,):

string.concat(
   "d82e5d8b",
   ",",
   _username,
   ",",
   Strings.toString(_dateExpire),
   ",",
   Strings.toString(_amount),
   ",",
   Strings.toString(_nameServiceNonce)
)

1. MNS Make Offer Identifier (Hex String):

  • Value: d82e5d8b
  • Purpose: A specific identifier used to distinguish MNS makeOffer messages from other types of signed messages.

2. Target Username (String):

  • Value: The _username string itself.
  • Purpose: Specifies the username on which the offer is being placed.

3. Offer Expiration Date (String):

  • Value: The result of Strings.toString(_dateExpire).
  • Purpose: The string representation of the timestamp using Unix epoch seconds indicating when this offer expires.

4. Offer Amount (String):

  • Value: The result of Strings.toString(_amount).
  • Purpose: The string representation of the quantity of MATE tokens (in total) being offered in exchange for the username.

5. MNS Nonce (String):

  • Value: The result of Strings.toString(_nameServiceNonce).
  • Purpose: The string representation of the user's (offeror's) nonce specific to the MNS contract for this makeOffer action. This prevents replay attacks.

Practical Example​

Let's say we want to make an offer with the following parameters:

  • Target Username: "alice"
  • Expiration Date: 1735689600 (Unix timestamp for January 1, 2025)
  • Offer Amount: 1000 (tokens)
  • Name Service Nonce: 5

The message would be constructed as:

"d82e5d8b,alice,1735689600,1000,5"

Message Breakdown:

  • d82e5d8b: Function selector for make offer verification
  • alice: The username being offered on
  • 1735689600: Unix timestamp when the offer expires
  • 1000: Amount of tokens being offered
  • 5: The offeror's name service nonce

This message would then be signed using EIP-191 standard, and the resulting signature would be used to verify the offer request in the verifyMessageSignedForMakeOffer function.

tip
  • The function selector d82e5d8b is the first 4 bytes of the keccak256 hash of the function signature for verifyMessageSignedForMakeOffer
  • Strings.toString converts a number to a string (standard OpenZeppelin utility)
  • The signature verification uses the EIP-191 standard for message signing
  • The _dateExpire parameter should be a Unix timestamp representing when the offer expires
  • The _amount represents the total amount of tokens being offered for the username