I hate doing captchas and would rather pay a small amount of grin in place of having to complete the captcha

Captchas are a pet peeve of mine. The worst is when it says find all the motorcycles, and one of them is a scooter and you don’t know if that counts as a motorcycle, because it’s a scooter.

I just want to skip them with money, sorta like a toll road, but for captcha free internet surfing.


But Grin on layer one is probably not a good fit for that. It takes ten minutes to get to ten confirmations. Even waiting for one confirmation is too long, just to be able to open a website.

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This could be done as a small app with an embedded grin web wallet — you send a small quantity of grin to the app’s wallet, and the app provides human or AI-powered captcha completion services by instantly deducting grin from that web wallet.

Over time, this could be evolved to direct instant payments to the site, either via instant third-party web wallet transfer or via a lightning-style network.


But Grin on layer one is probably not a good fit for that. It takes ten minutes to get to ten confirmations. Even waiting for one confirmation is too long, just to be able to open a website.

I was kinda hoping finalizing the slatepack transaction would be enough work to let me in the website.

Even if it’s not enough work, i still think it’s cool how grin’s interactive transactions can open the door to new kinds of cryptocurrency applications.

Side thought: Thinking in reverse here,l if there was a finalize/humanize option instead of just finalize, it could be used as proof of human payment. In that, if you add some sort of optional captcha (fuck) to the finalization step, one could prove the transaction was coming from a person.

solve captcha to BTC (2010)

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It would prove that finalization was done manually, you can’t know who did the captcha though since that can be outsourced. What would you gain if you knew that human finalized it?

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I can’t think of an application that would use proof of human spending right now, I also couldn’t conceptualize Uber, or facebook 20 years ago.

Actually maybe I just did think of an application. If a payment is sent and it’s proven to be from a human, then there would be no need for me to complete a 3rd party captcha, since the whole point of a captcha is to prove you’re not a robot.

The interactivity opens up new uses of the If/then statement. What that could be used for, I don’t really know.

If the transaction was manually sent then: ?
If the transaction was sent by a human then: ?

I can’t give you a specific answer, but it’s kinda fun to think about.

The thing with PoW (captcha) is that it’s supposed to be hard to muster up an attack even if you have more resources than anyone can dream of. If captcha requires human labor (which isn’t really true anymore), it’s far more resistant to attacks than your idea. Accepting money instead of PoW will let anyone DoS you by paying you. You may be happy with that, of course, but it’s entirely different from being resistant to DoS.

I imagine that Satoshi thought it would be difficult for a single entity (even a large government) to control 50% of the mining power. If it weren’t for centralized hardware manufacturing and huge mining pools, it would probably be true. Right now I don’t really see how PoW is any better than PoS in practice.


Very interesting thoughts, thank you.

I’d love to talk more about PoW vs PoS. Do we have any examples of PoS without a centralized checkpoint actually working yet?

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PoWork = Clock-cycles
PoMemory = Clock-cycles + bits
PoSpacetime = bits + time
PoHumanwork = time and biometrics

So Beam or Grin = PoMemory

Am I Right?


  1. Article. A Taxonomy of Blockchain Consensus Methods. Jeff Nijsse and Alan Litchfield.

Scarce Resource
A resource that is difficult to replace, access, or create and thus scarce, accrues value as it is consumed or exploited. The potential for the growth of value is a motivation that encourages acceptable behaviour in the emergence of consensus. Six types of resource are identified.

  1. Clock-cycles have non-zero cost, meaning the computational work done to find a hash value that is subject to a target requirement. The computational work cannot be recovered or undone. A cryptographic requirement is that the hash function is one-way, so the originating data cannot be inferred, but is easily verifiable.
  1. Tokens held by a user may be committed to maintaining a protocol. PoS allocates users a stake in the system proportionate to their number of tokens. In general, tokens that are held as stake cannot be used in transactions. Honesty is encouraged by both advantaging nodes that validate transactions and create blocks at the risk of forfeiting their stake (slashing) for dishonest behaviour. A variation, DPoS, hands block production responsibility to a set of validators, or delegates, which are a subset of the network. Often the validators must be known to the network and thus subject to ridicule if they behave maliciously as in proof-of-authority.
  1. Votes are used to determine a majority and is a common method for gaining consensus with nearly half of the methods in Table 3 employing votes as the scarce resource. A BFT system must determine consensus by the replicas voting on the state. Votes have no tradable value and generally a node is permitted one vote per round, although an additional vote may be permitted in each subsequent round. Classical consensus methods that maintain state in a non-blockchain system, such as PBFT, use voting or a round-robin style to elect leaders.
  1. Bits represent the state of a transistor and occupy a finite amount of space in storage. PoCapacity methods allocate a user some stake in the system by requiring that a proportion of storage is kept aside. If the computer is a blockchain node, the allocation cannot be used for other purposes. PoMemory requires access to volatile storage; Ethash (Ethereum) commits a pseudorandom dataset to a DAG which grows linearly resulting in access that is limited by the memory bandwidth [18]. Storage volumes tend to scale more slowly than computer processor clock-cycles and can reduce the domination of performance-enhanced processor architectures, such as Application Specific Integrated Circuits (ASICs).
  1. Time is independent of computing advances. As clock-cycles and read/write times reduce, blockchains secured by these resources may be exposed to unforeseen factors. Thus, PoET processors provide additional execution environments or enclaves, that cannot be accessed by the system. These modules can return a random delay to a process that can then be used to assign block proposers.
  1. Biometrics are a range of indicators that can verify identity or life. Similar to a PoW hash function requiring a known average number of clock-cycles, a blockchain based on proof-of-biometrics can require a unique biological solution. While biometrics are typically understood to be consistent parameters, such as facial, iris, voice, and fingerprint recognition systems, other systems may include affordances available only to humans or to specific humans. To be successful, such a system must be easy to use, require minimal input, and validate or authenticate rapidly. For example, the Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA) system is easy for humans to solve but difficult for a compute.