[jere]

>1. electrum's signature verification dialog takes a message, address, and signature and doesn't the hashing for you; there's no option to provide a pre-hashed input so the hashing couldn't have only happened on CSW's machine

>2. the electrum download includes the code used to do the hashing, so if the hashing code was corrupted, it implies the electrum download itself was compromised

The part I didn't explain thoroughly (because I thought it would be confusing) is that there are two hashes involved. The signature/verification only does one hashing internally. BUT Wright performs (or claims to perform) an additional one beforehand.

Why 2 hashes? Because it matches the transaction signing process of bitcoin, where he is copying his inputs/outputs from.

It's described in more (technical) detail here: http://blog.erratasec.com/2016/05/satoshi-how-craig-wrights-...