Patent ID: 11909877
Assignee: KONINKLIJKE PHILIPS N.V.
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 17:
18. A computer program stored on a non-transitory medium, wherein the computer program when executed on a processor:
establishes communication with a public-key encryption device;
generates a first private-key matrix;
computes a first public-key matrix from the first private-key matrix, and allow transfer of the first public-key matrix to the public-key encryption device;
receives from the public-key encryption device an indication of a key size and/or matrix size;
receives a second public-key matrix and a masked transmission key, wherein the second public-key matrix has fewer matrix elements than the first public-key matrix;
computes a first raw shared key from the second public-key matrix and the first private-key matrix;
computes the first raw shared key comprising a matrix multiplication between the second public-key matrix and the first private-key matrix; and
unmasks the masked transmission key in dependence on the received size using at least part of the first raw shared key to obtain a transmission key; and
performing a handshake with the private-key decryption device, wherein the handshaking comprises:
receiving at least two indications of at least two first public-key matrices of the private-key decryption device from the private-key decryption device,
wherein the two first public-key matrices have different sizes;
selecting the larger of the first public-key matrix and the second public-key matrix;
sending an indication of the selected first public-key matrix to the private-key decrypting device; and

requesting the first public-key matrix when the first public-key matrix is not available in a key-cache, wherein the transmission key is encapsulated with the selected first-public key.