DGX GoldTokenLedger - Source Reconstruction

Contract: 0x55b9a11c2e8351b4ffc7b11561148bfac9977855 Compiler: solc 0.3.6 native, --optimize --optimize-runs=1 Runtime bytecode: 6,770 bytes Verification status: Source reconstructed. All 44 function names known. Compiler identified by matching dispatcher prefix (60606040523615...), v0.3.x gas stipend (PUSH2 0x61da GAS SUB CALL), and constant-optimizer multiplication trick (PUSH1 X PUSH1 0x02 EXP PUSH<n> Y MUL). Reconstructed source compiles to 6,483 bytes (287 short of target); the remaining gap is in shared subroutines that the optimizer creates from cross-function CSE patterns we have not been able to reproduce without the original source structure.

About

The DGX GoldTokenLedger is the core token contract of Digix Global's gold-backed token system, deployed on Ethereum mainnet in early 2016. Digix was one of the first projects to tokenize a real-world asset on Ethereum, representing physical gold bars stored in vaults in Singapore.

The contract implements an ERC20-like token with:

• Demurrage fees - storage costs that accrue over time based on token balance and holding period
• Transaction fees - percentage-based fees on transfers, capped at a maximum
• Custodian/vendor/auditor roles - verified through linked registry contracts
• Minting - controlled through a separate gold registry contract
• Recasting - converting tokens back to physical gold through a recast contract

All configuration (fee rates, wallet addresses, role registries) is read from an on-chain config contract, making the system modular.

Source reconstruction

All 44 public function dispatch entries were identified by reverse-engineering the on-chain bytecode. The source in GoldTokenLedger.sol reproduces the full contract logic.

Selector 0x65afd0ed = regFeePayment

The selector 0x65afd0ed was the last unknown name on the contract — not present in 4byte.directory and over 17,000 brute-force name guesses returned no match. Anthony Eufemio (Digix CTO) provided the original function name and the exact payStorageFee implementation, confirming:

• Selector 0x65afd0ed = regFeePayment(address) on the GoldRegistry
• The token-side payStorageFee implementation, including variable names (_gold, _sfee) and the use of addUser, deductFees, and balanceOf helpers

The reconstructed source now reflects these exact names and structure.

All 44 function selectors

Selector	Function
0x012beac9	vendorRegistry()
0x0627f5a9	getFeeDays(address)
0x095ea7b3	approve(address,uint256)
0x0e666e49	userExists(address)
0x13af4035	setOwner(address)
0x17a950ac	actualBalanceOf(address)
0x18160ddd	totalSupply()
0x23b872dd	transferFrom(address,address,uint256)
0x24d7806c	isAdmin(address)
0x28b2362f	custodianRegistry()
0x35c80c8c	isCustodian(address)
0x377141d9	calculateDemurrage(address)
0x3ec27341	getConfigAddress()
0x458f5815	redemptionFee()
0x46396e18	goldTokenLedger()
0x49b90557	isAuditor(address)
0x4a619fa6	txFeeWallet()
0x4e03ab49	accountingWallet()
0x4e0fb2a4	auditRelease()
0x64e1721c	ledgerMint(address,address,uint256,uint256)
0x65448a76	storageRate()
0x694d98e5	recastContract()
0x6d786740	billingPeriod()
0x70a08231	balanceOf(address)
0x79502c55	config()
0x7d92f6be	goldRegistry()
0x82e717f7	requiredConfirmations()
0x893d20e8	getOwner()
0x8da5cb5b	owner()
0x8facfa01	deductFees(address)
0x92f00233	minterContract()
0x9dec628b	demurrageCalc(uint256,uint256)
0xa9059cbb	transfer(address,uint256)
0xc1a27089	recastFee()
0xc8028bee	auditorRegistry()
0xcf820461	txFee()
0xd104a136	getBase()
0xd3dd22da	txFeeMax()
0xd60f66de	recastCall(address,address,uint256,uint256)
0xdd62ed3e	allowance(address,address)
0xec1d9bf4	isGoldRegistry(address)
0xee54d54f	isVendor(address)
0xfae9d06d	calculateTxFee(uint256,address)
0xfd6e248e	payStorageFee(address)

Linked contracts

Contract	Address	Role
Config	0x8568f930a560e4b84147d291342655a75d4f69a9	Configuration registry
Config helper	0x9988ffccd8620f49e355915fdbcc28d54b68cc98	Config accessor
Gold Registry	0x782059ecf4d5dc7fc2079c191917de44638c4d38	Fee management, role verification
Recast contract	0xb1d9062c1ebb025b62018b40af2f563599acf602	Token recasting
Minter contract	0xf58b008970f45b9de73a65c9f80307c20527a0f5	Token minting
Payment history	0x55dbd10c0e2ca1e86b2c5045d0c0a53059f3a816	Stores fee payment timestamps

payStorageFee flow

payStorageFee(_gold)
  -> GoldRegistry.getFee(_gold)           // get fee amount (_sfee)
  -> addUser(tx.origin) if new            // create account if first interaction
  -> deductFees(tx.origin)                // settle accrued demurrage
  -> check balanceOf(tx.origin) >= _sfee  // revert if insufficient
  -> GoldRegistry.regFeePayment(_gold)    // 0x65afd0ed - record timestamp
  -> deduct _sfee from tx.origin
  -> credit _sfee to accounting wallet
  -> emit Transfer event

Compiler identification

Three signatures in the on-chain bytecode pin down the compiler:

1. Dispatcher prefix 60606040523615 6101f8 57 60e060020a 600035 04 63... — pre-v0.4.8 (no 63ffffffff AND-mask) and pre-v0.4.0 (no payable value-checks before each function entry).
2. Gas stipend every external call uses PUSH2 0x61da GAS SUB CALL (gas - 25050). v0.4.x changed this to PUSH1 0x32 GAS SUB CALL (gas - 50). The 0x61da value is the v0.3.x signature.
3. Constant optimizer every 14-22 byte string literal is encoded as PUSH1 X PUSH1 0x02 EXP PUSH<n> Y MUL instead of PUSH32 LITERAL, saving 11 bytes per literal. This pass only fires under --optimize-runs=1 (size-optimized). With default --optimize-runs=200, the same compiler emits PUSH32 directly.

Recompiling our reconstructed source with solc-0.3.6 --optimize --optimize-runs=1 reproduces all three signatures. Other versions miss at least one: v0.3.0–v0.3.5 don't apply the constant optimizer here even with --optimize-runs=1; v0.4.0–v0.4.7 add value-checks unless every function is payable; v0.4.8+ insert the 63ffffffff mask.

Attribution

Source reconstructed by EthereumHistory via bytecode reverse engineering. The function name regFeePayment for selector 0x65afd0ed and the exact payStorageFee implementation were provided by Anthony Eufemio (Digix CTO). Compiler identification (solc 0.3.6 --optimize-runs=1) was bracketed by sweeping prefix/gas-stipend/constant-optimizer signatures across solc 0.1.1 through 0.4.21.