Tron, Cardano, Verge and Ripple – Four Cryptocurrencies That Actually Meet the Definition of Vaporware (news.bitcoin.com)

‘Vaporware’ is a term that’s tossed about loosely, often against cryptocurrency projects that have no clear use case. It’s an easy accusation to make given that many crypto projects are still at the development stage, and haven’t had a chance to prove themselves. This year’s vaporware could be next year’s ethereum – or at least so the investors hope. While a vast number of cryptocurrencies are derided as vaporware, the following four attract this jibe more than most.

Bitcoin

What is the precise definition of “witness program”?

BIP 141 uses the term “witness program” extensively without, apparently, adhering to a consistent definition.

From the heading “Witness Program”:

A scriptPubKey (or redeemScript as defined in BIP16/P2SH) that consists of a 1-byte push opcode (for 0 to 16) followed by a data push between 2 and 40 bytes gets a new special meaning. The value of the first push is called the “version byte”. The following byte vector pushed is called the “witness program”. [my emphasis]

https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki#witness-program

In other words, a “witness program” is a byte sequence 2 to 40 bytes in length. In P2WPKH authentication, the witness program is the 20-byte hash value of a public key. In P2WSH authentication, the witness program is the 32-byte hash value of the serialize “witness script” (last element of witness data).

At least, this is what I gather from reading the definition under the heading.

However, BIP 141 makes other references to “witness program” that seem to suggest something else. For example:

  • “In addition, opcodes within the witness program are counted identical to as previously within the P2SH check script.”
  • “The P2WPKH witness program is then executed as described in the previous example.”

Also, headings seem to suggest that “witness program” means something else:

What is a precise definition for the term “witness program?”

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