#Drivechain is a combination of two BIPs which allows for the creation of decentralized 2-way peg to move BTC between mainchain and a sidechains.
1) #BIP300 (Hashrate Escrows)
2) #BIP301 (Blind Merged Mining)
The #BIPs can be found here:
https://en.bitcoin.it/wiki/BIP_0300
https://en.bitcoin.it/wiki/BIP_0301
Checkout these resources as well to learn more:
Drivechain.xyz
Drivechain.info
layertwolabs.com