Several companies offer customized cryptographic algorithms, for example Crypto AG (www.crypto.ch/en/company):
The individually created customer algorithms are unknown to anyone else and are not used by anyone else. A cryptographic attack is not possible, even from an identical unit.
Only the customers know the algorithms:
Autonomous profiling of algorithms: you are the only one who knows the algorithm. Not even Crypto AG has access to it. Moreover, you can use a second additional algorithm when collaborating with other organisations.
These algorithms are hardware-based:
Hardware-based encryption is the foundation for maximum cryptographic diversity – for speed reasons on the one hand and for its immunity to tampering on the other (no readout of data). This approach also ensures that the encryption processes remain cryptographically separated from the network. No common operating system is needed (viral resistance).
Thales offers something similar and calls it Programmable Cryptography (www.thales-esecurity.com/solutions/by-technology-focus/programmable-cryptography)
A company called Mils offers customized algorithms as well (www.mils.com/en/technology/customized-algorithms/)
How does this work? How can they offer a cryptographic algorithm that can be customized by non-specialist customers without support and not run the risk of creating an insecure algorithm? (Ignoring the assumption that this might be the goal)
Note that Crypto AG states that the algorithms runs on hardware. Depending on what they mean by hardware (I understand it as a non-programmable logic circuit with fixed gate connectivity), this severely narrows the available algorithms.