Quote from: Pieter Wuille on June 29, 2017, 08:33:06 PM

Quote from: aliashraf on June 29, 2017, 08:28:30 PM

Yes @Pietre, I do agree, several problems will be fixed but one problem will be created: the signatures that you think 'in particular are only required to validate the blockchain state ' will loose their immutability for this simple fact that they are not been hashed. right?

The statement above is false. The signatures are still hashed and committed to by blocks. No immutability is lost. If you don't believe me, please read BIP 141 carefully:

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A new wtxid is defined: the double SHA256 of the new serialization with witness data:

...

A new block rule is added which requires a commitment to the wtxid.

...

A witness root hash is calculated with all those wtxid as leaves, in a way similar to the hashMerkleRoot in the block header.

Quote from: aliashraf on June 29, 2017, 08:28:30 PM

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By removing this data from the transaction structure committed to the transaction merkle tree, several problems are fixed:

The data is removed from the transaction merkle tree, and instead committed to in the witness merkle tree. That witness merkle tree is committed to in the coinbase.

Fair! I now understand, I overlooked the fact that wtxids have to be committed to the transaction merkle tree indirectly, and this way, they can provide immutability for the signature data which have been excluded from the primary hash procedure. Thanks for the patience and the reply.

I'm not done yet with the whole problem though as I think this 'detaching process' (detaching data from its signature), has possible consequences like 'weakening' the incentives for nodes to keep track of the signatures.

It is what I have to analyse a bit more and will share it with you asap.