[srgseg]

The "Confidential Transactions" scheme for cryptocurrencies uses homomorphic encryption.

The idea is that you can prove that the encrypted input and output amounts in a transaction balance to zero, without having to actually reveal what any of those amounts are.

See https://people.xiph.org/~greg/confidential_values.txt

[tuxxy]

CTs don't use homomorphic encryption. They use "additively homomorphic commitments" which are, essentially, cryptographic proofs.