Comment by voxic11

They are encrypted to prevent others from training on the reasoning trace. But before anthropic started encrypting the reasoning traces they were signed. The signature was to prevent the user from being able to manipulate the reasoning part of the context because this reasoning part is considered "more trustworthy" by the model. So it would be bad if the user could manipulate the reasoning to convince the model to do something dangerous/against policy. Encryption keeps this property while also preventing the reasoning from being used for training.