A circuit arrangement comprising: an encryption circuit; a decryption circuit; and a cryptographic shell circuit having a transmit channel and a receive channel in parallel with the transmit channel, wherein: the transmit channel includes an encryption interface circuit coupled to the encryption circuit and the encryption interface circuit is configured to determine first cryptographic parameters based on data in a plaintext input packet and input the first cryptographic parameters and plaintext data of the plaintext input packet to the encryption circuit; the receive channel includes a decryption interface circuit coupled to the decryption circuit, and the decryption interface circuit is configured to determine second cryptographic parameters based on data in a ciphertext input packet and input the second cryptographic parameters and ciphertext data of the ciphertext input packet to the decryption circuit; the encryption circuit is configured to encrypt the plaintext data of the plaintext input packet based on the first cryptographic parameters; and the decryption circuit is configured to decrypt the ciphertext data of the ciphertext input packet based on the second cryptographic parameters. an encryption circuit; a decryption circuit; and a cryptographic shell circuit having a transmit channel and a receive channel in parallel with the transmit channel, wherein: the transmit channel includes an encryption interface circuit coupled to the encryption circuit and the encryption interface circuit is configured to determine first cryptographic parameters based on data in a plaintext input packet and input the first cryptographic parameters and plaintext data of the plaintext input packet to the encryption circuit; the receive channel includes a decryption interface circuit coupled to the decryption circuit, and the decryption interface circuit is configured to determine second cryptographic parameters based on data in a ciphertext input packet and input the second cryptographic parameters and ciphertext data of the ciphertext input packet to the decryption circuit; the encryption circuit is configured to encrypt the plaintext data of the plaintext input packet based on the first cryptographic parameters; and the decryption circuit is configured to decrypt the ciphertext data of the ciphertext input packet based on the second cryptographic parameters. the transmit channel includes an encryption interface circuit coupled to the encryption circuit and the encryption interface circuit is configured to determine first cryptographic parameters based on data in a plaintext input packet and input the first cryptographic parameters and plaintext data of the plaintext input packet to the encryption circuit; the receive channel includes a decryption interface circuit coupled to the decryption circuit, and the decryption interface circuit is configured to determine second cryptographic parameters based on data in a ciphertext input packet and input the second cryptographic parameters and ciphertext data of the ciphertext input packet to the decryption circuit; the encryption circuit is configured to encrypt the plaintext data of the plaintext input packet based on the first cryptographic parameters; and the decryption circuit is configured to decrypt the ciphertext data of the ciphertext input packet based on the second cryptographic parameters.