Crypto may offer ‘key blinding’. I did some research and it was obscure, but there may be something there. ‘Group signatures’ may be related.
Satoshi Nakamoto, 2010
Source: https://bitcointalk.org/index.php?topic=770.msg9074#msg9074
Group signatures were introduced by David Chaum and Eugene van Heyst in 1991. This cryptographic signing technique is the predecessor of ring signatures as applied in Monero.
