I was using the SecTransforms created by SecEncryptTransformCreate and SecDecryptTransformCreate, just for encryption and decryption of certain binary data with a symmetric cipher. Judging from the documentation I found CryptoKit should be powerful enough to do the same. Thanks, Jakob

With the latest runtime libraries on macOS 15.3.1 it seems to work, the crash cannot be reproduced anymore, using the same test code as about one year ago.