Cascade encryption is pretty common. I remember using 3 ciphers with TrueCrypt in the 2000s. There are some theoretical issues that prevent you from using ciphe

Cascade encryption is pretty common. I remember using 3 ciphers with TrueCrypt in the 2000s. There are some theoretical issues that prevent you from using cipher1(cipher2(x)) though. See https://en.wikipedia.org/wiki/Multiple_encryption#Importance_of_the_first_layer https://en.wikipedia.org/wiki/Multiple_encryption#Importance... In practice post-quantum encryption is always combined with normal encryption so this sorta thing should become even more common in the future.