hashTypedData

Hashes typed data in EIP-712 format

hashTypedData

Signs typed data and calculates an Ethereum-specific hash in EIP-712 format: keccak256("\x19\x01" || domainSeparator || hashStruct(message)).

Import

import "github.com/ChefBingbong/viem-go/utils/signature"
import "math/big"

Usage

import "github.com/ChefBingbong/viem-go/utils/signature"
import "math/big"

typedData := signature.TypedDataDefinition{
  Domain: signature.TypedDataDomain{
      Name:              "Ether Mail",
      Version:           "1",
      ChainId:           big.NewInt(1),
      VerifyingContract: "0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC",
  },
  Types: map[string][]signature.TypedDataField{
      "Person": {
          {Name: "name", Type: "string"},
          {Name: "wallet", Type: "address"},
      },
      "Mail": {
          {Name: "from", Type: "Person"},
          {Name: "to", Type: "Person"},
          {Name: "contents", Type: "string"},
      },
  },
  PrimaryType: "Mail",
  Message: map[string]any{
      "from": map[string]any{
          "name":   "Cow",
          "wallet": "0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826",
      },
      "to": map[string]any{
          "name":   "Bob",
          "wallet": "0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB",
      },
      "contents": "Hello, Bob!",
  },
}

hash, err := signature.HashTypedData(typedData)
// "0x..."

Returns

Type: (string, error)

The hashed typed data as a hex string with 0x prefix.

Parameters

typedData (required)

Type: signature.TypedDataDefinition

The typed data definition containing domain, types, primary type, and message.

typedData := signature.TypedDataDefinition{
  Domain: signature.TypedDataDomain{
      Name:    "My App",
      Version: "1",
      ChainId: big.NewInt(1),
  },
  Types: map[string][]signature.TypedDataField{
      "Message": {
          {Name: "content", Type: "string"},
      },
  },
  PrimaryType: "Message",
  Message: map[string]any{
      "content": "Hello!",
  },
}

hash, err := signature.HashTypedData(typedData)

domain (required)

Type: signature.TypedDataDomain

The EIP-712 domain parameters. All fields are optional.

domain := signature.TypedDataDomain{
  Name:              "Ether Mail",
  Version:           "1",
  ChainId:           big.NewInt(1),
  VerifyingContract: "0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC",
}

types (required)

Type: map[string][]signature.TypedDataField

The type definitions for the typed data.

types := map[string][]signature.TypedDataField{
  "Person": {
      {Name: "name", Type: "string"},
      {Name: "wallet", Type: "address"},
  },
  "Mail": {
      {Name: "from", Type: "Person"},
      {Name: "to", Type: "Person"},
      {Name: "contents", Type: "string"},
  },
}

primaryType (required)

Type: string

The primary type to extract from types and use in message.

primaryType := "Mail"

message (required)

Type: map[string]any

The structured message to hash. Must match the structure defined in types for primaryType.

message := map[string]any{
  "from": map[string]any{
      "name":   "Cow",
      "wallet": "0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826",
  },
  "to": map[string]any{
      "name":   "Bob",
      "wallet": "0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB",
  },
  "contents": "Hello, Bob!",
}

Hash Format

The typed data hash is computed as:

keccak256("\x19\x01" || domainSeparator || hashStruct(message))

Where:

domainSeparator is the hash of the EIP712Domain struct
hashStruct(message) is the hash of the message struct according to its type definition