Key encapsulation mechanisms

A computing system comprising:

• a data processing apparatus;
• and
• a non-transitory computer-readable medium storing instructions that are operable when executed by the data processing apparatus to perform operations comprising:
• applying an error vector derivation function to a random value to produce an error vector, wherein applying the error vector derivation function to the random value comprises:
• applying a pseudorandom function to the random value to produce a pseudorandom function output;
• applying a filter to the pseudorandom function output to produce a filtered pseudorandom function output, the filtered pseudorandom function output comprising t integers;
• and
• generating the error vector based on the filtered pseudorandom function output, the error vector having a Hamming weight equal to t;
• obtaining a plaintext value based on the random value;
• using the error vector and the plaintext value in an encryption function to produce a ciphertext;
• applying a key derivation function to the random value to produce a key derivation function output, the key derivation function output comprising a symmetric key and a confirmation value;
• using the symmetric key to generate an encrypted message based on an unencrypted message;
• and
• providing the ciphertext, the confirmation value, and the encrypted message for transmission in a communication network.

A key decapsulation method, comprising:

• obtaining a ciphertext and an encrypted message transmitted between nodes in a communication system;
• applying a decryption function to the ciphertext to produce a first decryption function output and a second decryption function output;
• obtaining a seed value based on the first decryption function output;
• applying a key derivation function to the seed value to produce a key derivation function output, the key derivation function output comprising a symmetric key;
• applying an error vector derivation function to the seed value to produce an error vector check value, wherein applying the error vector derivation function to the seed value comprises:
• applying a pseudorandom function to the seed value to produce a pseudorandom function output;
• applying a filter to the pseudorandom function output to produce a filtered pseudorandom function output, the filtered pseudorandom function output comprising t integers;
• and
• generating the error vector check value based on the filtered pseudorandom function output, the error vector check value having a Hamming weight equal to t;
• comparing the second decryption function output with the error vector check value;
• and
• by operation of one or more processors in a computer system, using the symmetric key to decrypt the encrypted message in response a determination that the second decryption function output is equal to the error vector check value.

A computing system comprising:

• a data processing apparatus;
• and
• a non-transitory computer-readable medium storing instructions that are operable when executed by the data processing apparatus to perform operations comprising:
• obtaining a ciphertext an encrypted message transmitted between nodes in a communication system;
• applying a decryption function to the ciphertext to produce a first decryption function output and a second decryption function output;
• obtaining a seed value based on the first decryption function output;
• applying a key derivation function to the seed value to produce a key derivation function output, the key derivation function output comprising a symmetric key;
• applying an error vector derivation function to the seed value to produce an error vector check value, wherein applying the error vector derivation function to the seed value comprises:
• applying a pseudorandom function to the seed value to produce a pseudorandom function output;
• applying a filter to the pseudorandom function output to produce a filtered pseudorandom function output, the filtered pseudorandom function output comprising t integers;
• and
• generating the error vector check value based on the filtered pseudorandom function output, the error vector check value having a Hamming weight equal to t;
• comparing the second decryption function output with the error vector check value;
• and
• using the symmetric key to decrypt the encrypted message in response a determination that the second decryption function output is equal to the error vector check value.