  Blockchains are turning into decentralized computing platforms and are
getting worldwide recognition for their unique advantages. There is an emerging
trend beyond payments that blockchains could enable a new breed of
decentralized applications, and serve as the foundation for Internet's security
infrastructure. The immutable nature of the blockchain makes it a winner on
security and transparency; it is nearly inconceivable for ledgers to be altered
in a way not instantly clear to every single user involved. However, most
blockchains fall short in privacy aspects, particularly in data protection.
Garlic Routing and Onion Routing are two of major Privacy Enhancing Techniques
(PETs) which are popular for anonymization and security. Garlic Routing is a
methodology using by I2P Anonymous Network to hide the identity of sender and
receiver of data packets by bundling multiple messages into a layered
encryption structure. The Onion Routing attempts to provide lowlatency
Internet-based connections that resist traffic analysis, deanonymization
attack, eavesdropping, and other attacks both by outsiders (e.g. Internet
routers) and insiders (Onion Routing servers themselves). As there are a few
controversies over the rate of resistance of these two techniques to privacy
attacks, we propose a PET-Enabled Sidechain (PETES) as a new privacy enhancing
technique by integrating Garlic Routing and Onion Routing into a Garlic Onion
Routing (GOR) framework suitable to the structure of blockchains. The
preliminary proposed GOR aims to improve the privacy of transactions in
blockchains via PETES structure.
