Secure Data Shredding in Non-Volatile Memory Using Secret Sharing
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Solution Overview
Problem
Existing data storage devices face challenges in securely erasing data due to residual signatures, erasure mechanism failures, and block failures, which allow unauthorized access to previously stored data despite multiple overwrite attempts.
Innovation Solution
A data shredding method involving a hash function and combinatorial logic to securely store a multi-bit secret in non-volatile memory, where a random string is processed into secret shares and stored separately from the output value, allowing for secure shredding by erasing the secret shares without affecting the output value, utilizing universal hash functions and secret sharing techniques to distribute the random string across memory blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple overwrite attempts are performed to erase data, then data recovery becomes more difficult, but residual signatures and erasure mechanism failures still allow unauthorized access
Solution Approach 1:
The patent segments the data erasure process into multiple independent operations: generating secret shares from the original data, storing shares in different memory locations, and performing targeted erasure operations on specific shares. This segmentation ensures that residual signatures in one location do not compromise the entire dataset, as unauthorized access requires multiple shares which remain protected even when some are erased.
Solution Approach 2:
The patent performs preliminary actions by transforming the original secret data into secret shares using secret sharing schemes before storage. This preliminary transformation ensures that even if residual signatures remain in memory locations, the original secret cannot be recovered without collecting sufficient shares, thereby addressing the residual signature problem proactively rather than reactively.
2Reliability
If secret shares are stored in separate memory locations, then secure shredding becomes possible by erasing only shares, but device complexity increases
Solution Approach 1:
The patent introduces intermediary components including a data manager module that coordinates between the host system and memory operations, and uses intermediary data structures such as mapping tables that track secret share locations. These intermediaries abstract the complexity of managing distributed shares, enabling secure shredding functionality without requiring complex changes to the underlying memory device architecture.
3Loss of information
If erasure operation is applied to secret shares, then the original secret is shredded, but the output value remains intact in memory
Solution Approach 1:
The patent extracts and isolates the secret share data from the complete secret reconstruction set by storing shares in separate memory locations that can be independently targeted. When shredding is required, only the necessary secret shares are erased while leaving other data such as output values in different locations intact, thereby achieving selective information loss without affecting unrelated data.
Data Source
AI summary
Apparatus and method for secure data shredding in an imperfect data storage device. In some embodiments, a hash function is applied to multi-bit random sequence to generate an output hash. A combinatorial logic function logically combines the output hash with a secret to provide an output value. The random string is processed into a plurality of secret shares which are stored in a first location in a non-volatile memory and the output value is stored in a different, second location of the memory. The secret is subsequently shredded by applying an erasure operation upon the secret shares in the first location of the memory.