Key-Specific Decryption Engine for Secure Symmetric Cryptography
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Solution Overview
Problem
Existing digital signature techniques using asymmetric cryptography result in large digital signatures that increase message size, while symmetric encryption techniques are vulnerable to key exposure, compromising message authentication and tampering detection.
Innovation Solution
A key-specific decryption engine is generated for each symmetric key, using boolean functions to perform decryption without exposing the symmetric key, thus preventing key exposure and reducing message size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If asymmetric cryptography is used for digital signatures, then message authentication and tampering detection are improved, but message size increases
Solution Approach 1:
The patent extracts the authentication function from the encryption process by using a separate hash algorithm to generate a fixed-size digest of the message. This digest is then encrypted with the private key to create the signature, separating the authentication mechanism from the original message data and preventing the message size from increasing proportionally with the signature size.
Solution Approach 2:
The patent changes the parameter of signature size by using hash functions that produce fixed-length outputs regardless of the original message length. This transforms the signature size from being proportional to message size (in symmetric encryption) to being a fixed small value (in asymmetric encryption with hashing), resolving the contradiction between authentication reliability and message size.
2Quantity of substance
If symmetric encryption is used, then message size is reduced, but key exposure vulnerability increases
Solution Approach 1:
The patent applies asymmetry by using different keys for encryption and decryption in the signature verification process. The sender uses the private key to encrypt the hash, while the receiver uses the public key to decrypt and verify. This asymmetric key pair mechanism allows the symmetric encryption advantage of small message size to be maintained while eliminating the key exposure vulnerability through the use of asymmetric cryptography for key management.
3Ease of operation
If the symmetric key is stored in readable form, then decryption ease is improved, but key security deteriorates
Solution Approach 1:
The patent introduces the hash function as an intermediary between the message and the symmetric key. Instead of directly encrypting the message with the symmetric key, the system first computes a hash of the message and then encrypts this hash. This intermediary step allows the symmetric key to remain secure while still enabling efficient decryption and verification through the deterministic nature of hash functions.
Data Source
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AI summary
Techniques are described for performing decryption using a key-specific decryption engine. A message including an encrypted data portion is received. The encrypted data portion is formed by performing a symmetric encryption operation using a symmetric key. The encrypted data portion is decrypted using a key-specific decryption engine which does not use the symmetric key as an input. Also described are techniques for generating the key-specific decryption engine which may be implemented using boolean functions determined for the symmetric key.