After you receive your physical HASHMARK, you can claim your digital token by carefully following the instructions here: Instructions and tool for claiming digital token via secure commit/reveal. If you require assistance, join our Discord


Hashmarks are a grid of 100 unique hand forged iron sculptures, a cryptographically linked set of digital tokens, and a site specific happening in Patagonia. Hashmarks are about information through time. Mark making as the residue of a one-way process (geological, handcrafted, cryptographic). What is revealed from the traces that are left behind? What remains unknown?

The site specific event is presented in partnership with Bright Moments taking place Nov 6th-8th, 2023. Event and itinerary can be found on the Bright Moments website.

What follows is a compilation of supporting images, writings, sound and video that have grown to be part of the work and help to describe it in a circuitous way. If you'd like to see immediately what you get before making a decision to purchase, skip to the FAQ.




"hash(v. ): from Old French "hache" (ax) to "hack, chop into small pieces" cfr cryptographic hash that scrambles/chops up information in a special way, leaving a mark/imprint that is connected to the original, but does not reveal it in its entirety."

"Cryptographic hash functions, like time based processes (geo/ecological, societal) are one-way. Move forward, but not back. Imprints/traces are clues to what previously existed but may now be faded or lost. physical vs digital is less important - it's about the information carried."

"hashmarks: delineate measurements of space or time, geographic coordinates; to indicate congruence in geometry; produce tonal shading; unary number systems(tally marks, roman numerals). Earliest forms of writing were to record transactions."


"hashchain: similar to a blockchain, successive use of a hash keccak256(keccak256(..)) produces a series of one-time auth keys. Without revealing the root of the hash chain inscribed on the back, one-time keys will interact with the associated digital token over time."

The videos and images above showing sculptures are representative examples only. The actual 100 sculptures will only be revealed at the event; it's central to the work that this will be the only time and place the 10x10 grid will be viewed together, and the only time this group of people will all be together, before breaking apart and spreading across the globe. A one-way entropic process, leaving behind only a trace.

At the same time it's important to me that collectors generally know what they're getting in advance of purchasing. All objects are made from steel and measure approx 1.25" square. They range in complexity and style. In my view there are no clear "grails". All are hand forged and unique.


The information on the back of the sculpture will allow you to claim the digital token. The smart contract is self authored and deployed from my ETH address. There are no external dependencies. The artwork is a static image stored as an on-chain SVG that resembles a rubbing of the physical token.

The sculptures will each have a unique 32 byte a key ( referred to as k) laser engraved on the reverse. This is NOT a secret key for an ETH wallet. It is the root of a hashchain - hashing k repeatedly using keccak256 (SHA-3) produces a chain of hashes.

H^1(k) = H(k)
H^2(k) = H(H(k))
H^3(k) = H(H(H(k))) etc.

Hash chains can be used as one-time passwords. For example, the 10th hash of secret key H^10(k) for each token is stored as a challenge in the smart contract; users must produce the data that hashes to that value, which is the 9th hash of the secret key since H(H^9(k)) = H^10(k). Users can submit the 9th hash of the secret key without revealing the secret key, allowing a sequence of 10 one-time-passwords.

A commit-reveal scheme will be used to prevent front running. Users submit H^9(k) to claim the token.

SVG data for all tokens will be pre-stored on chain, but will encrypted via a hash based stream cipher using H^9(k) as the secret key. User submits H^9(k) to claim their token, revealing it (unencrypting it on the fly). Some users may choose never to claim their token: the on-chain data is there, but is unrevealed (encrypted)

Time based token mechanism:(work in progress): The digital token will fade over time, requiring periodic refreshing using successive elements of the hash chain. For example, after a period of time (tenatively 1 year) a claimed digital token will begin to fade. The colors of the dynamic SVG will gradually reduce in contrast until they reach a uniform grey.

That is, unless the token is "refreshed". Users can refresh the token after 1 year by submitting H^8(k), and the next year by submitting H^7(k) and so on. If the secret key (physical object) is ever lost, or NFT sold to a buyer without knowledge of the secret key, the token will not be able to be refreshed and will eventually fade. Fading is not permanent; if the key is retrieved the token can once again be refreshed.

After a period of 10 years of refreshing once per year, users submit H^1(k) and the token becomes immortal, never fading.

This mechanism is intended to incentivize keeping the physical object(or at least the secret key) and the digital token together for 10 year period. Secondary buyers of digital tokens will also need the physical/secret key.

A separate smart contract function could return a giant SVG of a 10x10 grid of all objects in their current states. either missing(unrevealed), revealed, faded, or immortal.

If secret key gets leaked after claiming, best an attacker can do is pay gas to refresh the token. Can't steal it.

POTENTIALLY, when token becomes immortal, and if I'm still alive, the owner of the physical object becomes eligible to have a similar forged object from pure gold (must pay an agreed amount for cost of material). Collector must be able to prove they own the physical, either in person, or I could issue a challenge to send me photographs of the physical object in certain lighting conditions that would be difficult to fake.


While this question is not always important for an artwork, craft and toolmaking are central to my practice. I talk about craft in this conversation with Alex Estorick and Tyler Hobbs. WHEN TYLER HOBBS MET 0XDEAFBEEF: The artists discuss the physical craft of generative art with Elisabeth Sweet and Alex Estorick

"Tool making. The ability and agency to make/modify one's tools is an important part of my art practice. Whether working with code or metal, I often find myself in a flow state feedback loop where it's tough to know where the tool ends and the workpiece begins."

"Tool sets built up over time (whether code libraries or steel hand tools) can define a personal style. I use caution in choosing 3rd party tools(who made it and why?) lest it leave its imprint on my work."

"Do digital computers leave a mark? Yes, but I think it's much more the design choice of software developers rather than any inherent machine aesthetic. cf. Mills make things square, but lathes make things round."

"Days are for forging, (Friday) nights are for sewing. One stitch at a time. this is the preferred rhythm of my life."

Each object will be protective pouch made of oil-tanned leather. Saddle stiched with linen thread with the help of my 10yo son.


What do you I get?

Can the digital token be bought/sold?

The digital token is an ERC721 and can be bought and sold on any standard marketplace (Opensea, etc). That being said... WARNING: do not buy a Hashmarks NFT on the secondary market unless you have also made arrangement to buy the physical sculpture from the owner. As explained above, the image of the digital token will fade over time, requiring it to be refreshed using the secret key engraved on the back of the physical sculpture.

After claiming the digital token, if the physical sculpture is stolen, can the thief use the secret key to steal the digital token?

No. Claiming the token is a one time event using the 10th hash of the secret key. After that, the 9th,8th,7th etc hashes are used for refreshing the token yearly, but they don't affect the ownership in any way.

If I'm hacked or lose access to the ETH wallet, can I still refresh it?

Yes. Refreshing is independent of ownership. Even if a digital token is stolen, or accidently transferred to an unowned ETH address, if you still have the sculpture and engraved secret key, you can submit 9th,8th,7th etc hashes to continue to refresh the token. Or to spite the thief, you can let it fade.

What if I lose the physical token?

If you lose the secret key before the token has been refreshed 10 times, then it will eventually fade.


I'd like to acknowledge several inspirational artists working with blockchain as a subject and medium.

Additionally, there have been many works that explore mechanisms for linking physical items and digital tokens.