Transactions

Types

Type	From	To	Who creates it
Coinbase	COINBASE	Validator	Automatic (block reward)
Transfer	User	Recipient	User (signed)
Token op	User	Contract	User (via SRC-20)

Structure

Transaction {
    txid,           // SHA-256 of signing payload
    from_address,   // 0x + 40 hex
    to_address,
    amount,         // sentri (u64)
    fee,            // sentri (min 10,000 = 0.0001 SRX)
    nonce,          // sequential per sender
    timestamp,
    signature,      // ECDSA hex
    public_key,     // secp256k1 hex
    chain_id,       // 7119
    data,           // optional — token ops (JSON)
}

Signing

ECDSA on secp256k1 (same as Bitcoin/Ethereum).

Payload built from BTreeMap (sorted keys → deterministic JSON). The txid is SHA-256 of that payload.

On verify: recover pubkey from signature, derive address via Keccak-256, check it matches from_address. Can't forge txs from someone else's address.

Chain ID (7119) in the signing payload = replay protection across networks.

Mempool

Where txs wait before getting into a block.

Rules to get in

• Valid signature, pubkey derives to from_address
• Nonce = on_chain_nonce + pending_count
• Balance ≥ amount + fee + pending spends
• Fee ≥ 10,000 sentri (0.0001 SRX)
• Valid address format, not zero address
• Amount > 0 (except token ops)
• Timestamp not >5min future, not >1hr old
• No duplicate txid
• Chain ID = 7119

Limits

Total	10,000 txs
Per sender	100 txs
Max age	1 hour (auto-pruned)
Per block	100 txs

Higher-fee txs get picked first.

Fees

Min fee: 0.0001 SRX (10,000 sentri).

Fee → ceil(fee/2) burned + floor(fee/2) to validator

50% burn creates deflationary pressure. Eventually burns > rewards = net deflation.

Nonce

Sequential counter per address, starting at 0. Must be exact — gaps rejected. Prevents replay within the same chain.

Coinbase

One per block, always first tx:

• From: "COINBASE"
• Amount: block reward (1 SRX in Era 0)
• Fee: 0, nonce: 0, no signature

Token Operations

Encoded in the data field as JSON:

{"op": "deploy",   "name": "...", "symbol": "...", "supply": N, "decimals": N}
{"op": "transfer", "contract": "SRC20_...", "to": "0x...", "amount": N}
{"op": "burn",     "contract": "SRC20_...", "amount": N}
{"op": "approve",  "contract": "SRC20_...", "spender": "0x...", "amount": N}

Still need SRX for gas. See Token Standards.

Overflow Protection

All monetary math uses checked_add/checked_sub. Returns error on overflow/underflow. No wrapping, no unchecked arithmetic on balances.