Time-Bound Tokens: How Tokenized Time, Ownership, and Yields Could Unlock New Possibilities for Crypto Assets
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Time-Bound Tokens: How Tokenized Time, Ownership, and Yields Could Unlock New Possibilities for Crypto Assets
How exactly are time-locked tokens implemented, and what are some feasible application scenarios?
Navigating Web3 tides with focused insightsAuthor: Ricsson Ngo, Shatabarto Bhattacharya
Compiled by: TechFlow
Introduction
What new possibilities might emerge in the crypto world when time itself becomes tokenizable?
Recently, a concept known as "Time-Bound Tokens" (TBT) has been proposed, with growing interest in its technical design and potential use cases. In both traditional finance and cryptocurrency assets, “time” often governs certain rights—such as loan repayments, time-limited rentals, options, and futures. Within a specific timeframe (condition), you hold certain rights over an asset, which then yield economic benefits upon expiration (outcome).
This real-world logic of “condition → outcome” can clearly be encoded via smart contracts, suggesting that time-based conditions are indeed ripe for tokenization.
So how exactly can Time-Bound Tokens be implemented? And what practical applications might they enable? This article explores these questions and reveals promising new narratives on the horizon.
Summary
A Time-Bound Token (TBT) is a token that enables the transfer and management of ownership across an asset’s timeline. At its core, it represents a pure form of optionality. It can represent time-constrained assets such as rentable NFTs, escrowed positions, time-limited governance rights, generalized options, real estate leases, and more. The mechanism behind TBTs involves dividing a token (whether an FT or NFT) into periodic time segments, each of which can be owned by different addresses.
Introduction
The design of TBT prioritizes utility. The owner of a TBT has the right to invoke functions that allow them to derive economic or financial benefit from the underlying asset. Ownership is determined by checking whether the current time falls within the time segment claimed by the user. Examples of such benefits include:
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Using a wrapped Crypto Kitty to hatch new Crypto Kitty eggs.
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Earning fees from a wrapped Uniswap liquidity position.
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Invoking governance-related functions.
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Swapping between USDC and ETH according to a constant sum formula (options).
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Representing rental rights for real estate.
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Receiving recurring payments.
Let’s consider a thought experiment based on the above example. Suppose Alice owns 100 TBTs from month 0 to month 1, while Bob owns 100 TBTs from month 1 to month 2. Now assume that 0.5 months have passed since month 0. Alice can call the utility function as many times as needed, but Bob cannot, because the current time falls within Alice's declared time segment. After month 1, Alice will lose access to the utility function, while Bob must wait until month 1 to begin benefiting from it. Once a TBT’s full duration expires, the token ceases to exist.
TBTs can be transferred just like regular tokens. Importantly, this transfer represents both a transfer of claim rights and token quantity. For instance, Alice could transfer 50 TBTs covering months 0 to 1 to Bob, leaving her with 50 TBTs for the same period, while Bob now holds 50 TBTs (months 0–1) plus his original 100 TBTs (months 1–2). Similarly, Charlie could transfer 100 TBTs from month 6 onward to Oscar, so Charlie retains 100 TBTs from month 2 to month 6, while Oscar gains 100 TBTs starting at month 6 and continuing indefinitely.
Implementation Details
Below is a draft of an early interface implementation for TBT (TechFlow note: code snippets included; readers uninterested in technical details may skip directly to the conclusion).
We follow a multi-token standard similar to ERC-1155, where IDs represent different tokens. A supply of 1 indicates an NFT, while a supply greater than 1 indicates a fungible token.
Code Example:
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function period(uint256 id) external view returns (uint256 seconds)
This function returns the number of seconds per period for the TBT with the given ID. The timestamp between two periods is referred to as a time tick. Periods should not be too short, as this would lead to high gas costs for TBT operations. Nor should they be too long, as this would reduce flexibility. Common social conventions include weekly, monthly, quarterly, semiannual, and annual cycles.
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function shift(uint256 id) external view returns (uint256 seconds)
This function returns the initial offset in seconds from which we start counting periods. The offset must be less than the period length.
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function transfer(address to, uint256 id, uint64 start, uint64 end, uint256 amount, bytes calldata data) external
This function allows the owner to transfer TBTs to a target address by specifying the start and end times for the given TBT. After subtracting the offset, both start and end times must be divisible by the period. If the start time is earlier than the current block timestamp, it defaults to the beginning of the current period. If the end time is zero, it is assumed to be infinite. The data structure should be implemented using chained mappings for optimal gas efficiency and minimal updates.
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function balanceOf(address owner, uint256 id) external view returns (bytes memory balance)
This function returns a byte array representing the owner’s entire timeline holdings. Callers must decode it using the following pure function:
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function decodeBalance(bytes memory balance) internal pure returns (TimeDelta[] memory timeDeltas)
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struct TimeDelta { uint64 time; int192 delta; }
The TimeDelta array is an efficient data structure for representing timeline positions. The 'time' field indicates the time tick at which a change occurs in the owner's holdings. The 'delta' field indicates the positive or negative change in TBT amount after that time tick. For example, suppose we have the following TimeDeltas:
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{ time: 1,700,000,000, delta: 100 }
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{ time: 1,700,010,000, delta: -50 }
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{ time: 1,700,030,000, delta: 150 }
This means the owner holds 100 TBTs from block timestamp 1,700,000,000 to 1,700,010,000. Then from 1,700,010,000 to 1,700,030,000, they hold 100 - 50 = 50 TBTs. Finally, from 1,700,030,000 onward, they hold 100 - 50 + 150 = 200 TBTs.
Note that this kind of implementation—using bytes and a decoder—only needs to return claims for arbitrary future times. We might modify the implementation to limit returns to a maximum range for better practicality.
Also note that the sum of deltas at any time tick must not be negative. Therefore, minting, burning, and transferring tokens must ensure this constraint. Additionally, over time, an owner’s balance should only display the most recent time ticks beyond the current period.
For example, using the same example above, suppose the block timestamp has advanced to 1,700,010,010. Then balanceOf should return the following time deltas:
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{ time: 1,700,010,000, delta: 50 }
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{ time: 1,700,030,000, delta: 150 }
Other functions not shown here—such as batch transfers, updates, paginated balanceOf, metadata, and onReceived—are also part of the full specification. The above functions represent key distinctions between TBT and existing token standards.
Another potential TBT implementation involves a single repository contract storing all TBTs, implementing core functionalities like updating timeline balances, minting, burning, and transferring. Anyone can initialize a TBT for a given ID. For scalability, callbacks (hooks) are set at multiple points throughout the TBT lifecycle. This approach offers potential advantages—for example, it may eliminate the need for approve and transferFrom, as contracts interfacing with TBTs can leverage multi-token transfer data directly.
Future Scope
With time-bound tokenization, we can now creatively financialize time-based assets. We can build AMMs for these assets—for example, markets that exchange TBTs from month 0 to month 1 against TBTs from month 1 to infinity. Existing protocols with similar functionality include:
Pendle Finance splits existing yield-bearing assets into two timelines:
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Yield Token: From now until maturity, where the utility function accumulates yield gains before expiry.
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Principal Token: Starting at maturity, users can unwrap and reclaim their principal after expiry.
The protocol enables exchanges between fixed yield and discounted pricing.
Timeswap enables time-based token swaps, also dividing assets into two timelines:
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Swap existing tokens for future tokens: The protocol exchanges pre-maturity tokens for post-maturity tokens, allowing users to buy discounted tokens.
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Swap future tokens for existing tokens: The protocol exchanges post-maturity tokens for pre-maturity ones, enabling leveraged exposure without liquidation.
TBTs will extend the capabilities of future iterations of these protocols and attract novel designs into the fixed maturity financial space. This token standard could spark DeFi’s expansion into fixed maturity products—an enormous, untapped market already dominant in traditional finance.
Renting NFTs for gaming is another popular use case. Gaming guilds often rent out their NFTs to players in exchange for in-game rewards. With TBTs, the flexibility and functionality of NFT leasing can be significantly enhanced.
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