[willthames]

128 bits isn't twice as strong as 64 bits. 65 bits is twice as strong as 64 bits. 2^64 ~= 10^19 - or 10 million million million times stronger.

[mSparks]

technically its around ln(n)ln(ln(n)) stronger "best case"

thats a lot closer to 2 than 10 million million million

whoever taught you integer factorisation and the dlp are order c^n was either lying to you or had been lied to.