A short list of the evidence I was able to quickly put together:

• https://twitter.com/AaronvanW/status/850060132264407041 (Jihan indirectly confirms that they are using ASICBOOST on weibo)

• https://twitter.com/CollinCrypto/status/849802945294217217 (Jihan indirectly confirms that they are using it on twitter, then deletes tweets)

• Empty blocks indicate use of ASICBOOST (Antpool is mining lots of empty blocks)

• weird transaction shuffling is necessary for ASICBOOST. Bitmain engages in weird transaction shuffling: https://twitter.com/ElectrumWallet/status/849974808259559425 https://twitter.com/ElectrumWallet/status/850195695302696960

• someone actually found the stratum command used to activate ASICBOOST on antminers pointed to Antpool some 9 months ago: https://archive.fo/Ok3SJ

• segwit (unintentionally) breaks the covert form of ASCIBOOST. Bitmain oposes segwit.

• SegWit2MB, BU and Extension Blocks does not break covert ASICBOOST. Bitmain supports all of those proposals.

• Greg's fix blocks only covert ASICBOOST – it does literally nothing else. ANY miner not using covert ASICBOOST profits from such a fix since it prevents the competition from secretly using it. Bitmain opposes the fix.

I could go on all day, but I need to go. Feel free to provide more.

ah, one last pice of usefull information:

https://twitter.com/GigaBitcoin/status/849860111635853312 https://twitter.com/ElectrumWallet/status/849864151748968448

(explanations why ASICBOOST is an attack and NOT an optimization-)

paging u/seweso and u/CBergmann