Ciphertext Distribution Screening Before Lattice-Based Decryption

The patent applies preliminary action by performing a statistical distribution test on the encrypted bit sequence before decryption. The test device checks whether the bit sequence follows the expected uniform distribution characteristic of properly encrypted data. Only if the test passes does the system proceed with decryption using the secret key. This preliminary validation prevents chosen ciphertext attacks by rejecting maliciously crafted ciphertexts that would have abnormal bit distributions, thereby maintaining security without significantly impacting decryption speed for valid ciphertexts.

The patent replaces complex cryptographic verification mechanisms with a simpler statistical testing approach. Instead of using elaborate validation protocols or multiple cryptographic checks, the system uses a statistical test device that analyzes the bit distribution pattern. This substitution maintains high security by detecting non-uniform distributions indicative of attacks, while reducing system complexity through a more straightforward implementation that requires minimal additional hardware or computational resources.

The patent applies self-service by enabling the encrypted bit sequence to self-validate its own integrity through statistical distribution testing. The test device examines whether the ciphertext exhibits the expected uniform bit distribution properties. This self-verification mechanism allows the system to automatically detect and reject malformed or malicious ciphertexts without requiring external validation or complex operational procedures, thus maintaining ease of operation while significantly improving security against side channel and chosen ciphertext attacks.