Systems and methods for managing cryptographic keys in an avionic data transfer system are provided. A host device associated with the avionic data transfer system can receive one or cryptographic keys via a key fill interface. For instance, in one embodiment, the host device can receive one or more cryptographic keys from a removable data cartridge. The host device can act as a key server for other cryptographic units associated with the avionic data transfer system via a data bus. For instance, the host device can distribute one or more cryptographic keys to other cryptographic units associated with aircraft via an aircraft bus. The other cryptographic units can use the one or more cryptographic keys for cryptographic processing of data.