TxSeismic

Core Seismic transaction type (0x4A)

The core Seismic transaction type, identified by type code 0x4A. Extends a legacy-style Ethereum transaction with encryption metadata for privacy-preserving contract interactions.

Overview

TxSeismic represents a complete Seismic transaction with encrypted calldata. It contains standard EVM fields (chain ID, nonce, gas, recipient, value, input) plus a TxSeismicElements struct carrying all encryption and expiry parameters. The input field holds encrypted calldata after the filler pipeline processes it.

Definition

pub struct TxSeismic {
    pub chain_id: ChainId,
    pub nonce: u64,
    pub gas_price: u128,
    pub gas_limit: u64,
    pub to: TxKind,
    pub value: U256,
    pub input: Bytes,
    pub seismic_elements: TxSeismicElements,
}

Type Constant

pub const TX_TYPE: u8 = 0x4A;

Fields

Field	Type	Description
chain_id	ChainId (u64)	Numeric chain identifier (e.g., 5124 for Seismic testnet)
nonce	u64	Sender's transaction count
gas_price	u128	Gas price in wei
gas_limit	u64	Maximum gas allowed for execution
to	TxKind	TxKind::Call(Address) for calls, TxKind::Create for deployment
value	U256	Amount of wei to transfer
input	Bytes	Calldata -- encrypted after filler processing
seismic_elements	TxSeismicElements	Encryption metadata, block hash, expiry, and read flag

Trait Implementations

TxSeismic implements the following Alloy traits:

Trait	Description
Transaction	Standard transaction interface (chain_id, nonce, gas, etc.)
SignableTransaction	Provides signing hash and signature methods
Typed2718	EIP-2718 typed transaction encoding (type 0x4A)
InputDecryptionElements	Access decryption metadata for the TEE
Encodable / Decodable	RLP encoding and decoding

Methods

EIP-712 Support

Method	Signature	Description
is_eip712()	fn is_eip712(&self) -> bool	Returns true if message_version >= 2
eip712_to_type_data()	fn eip712_to_type_data(&self) -> TypedData	Converts to EIP-712 typed data for structured signing

Conversion

Method	Signature	Description
to_legacy_tx()	fn to_legacy_tx(&self) -> TxLegacy	Converts to a standard TxLegacy for gas estimation
legacy_fields()	fn legacy_fields(&self) -> TxLegacyFields	Extracts the legacy subset (chain_id, nonce, to, value)

Metadata

Method	Signature	Description
tx_metadata(sender)	fn tx_metadata(&self, sender: Address) -> TxSeismicMetadata	Builds the full metadata struct for AAD construction

Encryption

Method	Signature	Description
encrypt_input_aead(sk, plaintext, sender)	fn encrypt_input_aead(&self, sk: &SecretKey, plaintext: &Bytes, sender: Address) -> Result<Bytes, anyhow::Error>	Encrypts calldata using AEAD with transaction metadata as AAD
decrypt_input_aead(sk, ciphertext, sender)	fn decrypt_input_aead(&self, sk: &SecretKey, ciphertext: &Bytes, sender: Address) -> Result<Vec<u8>, anyhow::Error>	Decrypts calldata using AEAD with transaction metadata as AAD

Validation

Method	Signature	Description
validate_recent_block_hash(recent_blocks)	fn validate_recent_block_hash(&self, recent_blocks: &[B256]) -> bool	Verifies that recent_block_hash exists in the provided block list
validate_expiration(current_block)	fn validate_expiration(&self, current_block: u64) -> bool	Checks that the transaction has not expired
validate_block(current_block, recent_blocks)	fn validate_block(&self, current_block: u64, recent_blocks: &[B256]) -> Result<(), SeismicValidationError>	Combined freshness and expiration validation

Examples

Constructing a TxSeismic

In practice, you rarely construct TxSeismic directly. The filler pipeline builds it from a SeismicTransactionRequest. However, for reference:

use seismic_prelude::foundry::*;
use alloy::primitives::{Bytes, U256, TxKind, Address, B256};

let tx = TxSeismic {
    chain_id: 5124,
    nonce: 0,
    gas_price: 20_000_000_000, // 20 gwei
    gas_limit: 100_000,
    to: TxKind::Call("0x1234567890123456789012345678901234567890".parse()?),
    value: U256::ZERO,
    input: Bytes::from(encrypted_calldata),
    seismic_elements: TxSeismicElements {
        encryption_pubkey: tee_pubkey,
        encryption_nonce: U96::from(rand_nonce),
        message_version: 2, // EIP-712
        recent_block_hash: latest_block_hash,
        expires_at_block: current_block + 100,
        signed_read: false,
    },
};

Using the Builder Pattern (Recommended)

use seismic_prelude::foundry::*;
use alloy::primitives::{U256, TxKind};
use alloy::sol_types::SolCall;

sol! {
    interface IMyContract {
        function setValue(suint256 x) public;
    }
}

let calldata = IMyContract::setValueCall {
    x: U256::from(42),
}.abi_encode();

// Build and mark as seismic
let tx: SeismicTransactionRequest = seismic_foundry_tx_builder()
    .with_input(calldata.into())
    .with_kind(TxKind::Call(contract_address))
    .into()
    .seismic();

// The filler pipeline converts this into a TxSeismic internally
let pending = provider.send_transaction(tx.into()).await?;

Converting to Legacy for Gas Estimation

let seismic_tx = TxSeismic { /* ... */ };

// Convert to legacy for gas estimation
let legacy_tx = seismic_tx.to_legacy_tx();
// legacy_tx can be used with standard gas estimation RPCs

EIP-712 Typed Data

let tx = TxSeismic { /* ... */ };

if tx.is_eip712() {
    let typed_data = tx.eip712_to_type_data();
    // Use typed_data for EIP-712 signing workflows
}

Accessing Metadata for AAD

let tx = TxSeismic { /* ... */ };
let sender: Address = "0xSENDER...".parse()?;

let metadata = tx.tx_metadata(sender);
let aad_bytes = metadata.encode_as_aad();
// aad_bytes is used as Additional Authenticated Data in AES-GCM

RLP Encoding

TxSeismic uses RLP encoding for both hashing and network serialization. The encoding order is:

RLP([
    chain_id,
    nonce,
    gas_price,
    gas_limit,
    to,
    value,
    input,
    encryption_pubkey,
    encryption_nonce,
    message_version,
    recent_block_hash,
    expires_at_block,
    signed_read,
])

The type prefix 0x4A is prepended for EIP-2718 envelope encoding.

EIP-712 Signing

When message_version >= 2, the transaction uses EIP-712 typed data signing instead of raw RLP hash signing. This provides:

• Structured data -- Wallets can display human-readable transaction details

• Domain separation -- Signatures are bound to a specific chain and contract

• Better UX -- Hardware wallets and browser extensions can show meaningful information

Notes

• Type 0x4A is the Seismic-specific transaction type, distinct from all standard Ethereum types

• input contains encrypted data after the filler pipeline processes the transaction

• Cannot be used for Create transactions -- to must be TxKind::Call(address) for seismic transactions

• to_legacy_tx() is used internally for gas estimation, since the RPC expects legacy format

• Validation methods are primarily used by the node/TEE, not by client code

See Also

• TxSeismicElements -- Encryption metadata struct

• TxSeismicMetadata -- AAD construction from transaction fields

• SeismicTxEnvelope -- Signed wrapper containing Signed<TxSeismic>

• Shielded Calls -- How to use TxSeismic in practice

• Encryption -- Detailed encryption pipeline