Shingled Data Confidentiality via Sector Encryption and Zone MACs
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Solution Overview
Problem
Existing data storage devices with shingled writing face challenges in maintaining data confidentiality and integrity, particularly due to the need for extensive overhead in integrity checks and the inability to overwrite tracks without erasing overlapping data, leading to inefficiencies in track density and data management.
Innovation Solution
Implementing a method that uses a unique write counter and encryption key with logical block addresses to encrypt and decrypt sectors, along with a message authentication code (MAC) for each zone, allowing sector-by-sector encryption and decoupling integrity checks from read operations, thereby enhancing data confidentiality and integrity while minimizing storage overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional integrity check methods are used for shingled data tracks, then data integrity can be verified, but extensive overhead is required and read operations must read entire zones
Solution Approach 1:
The patent divides the data storage into zones with unique write counters for each zone, and uses sector-specific message authentication codes (MACs) instead of requiring entire zone reads. This segmentation allows integrity verification to be performed on individual sectors or smaller units rather than requiring complete zone reads, reducing the quantity of data that must be processed during integrity checks.
Solution Approach 2:
The patent pre-calculates and stores message authentication codes (MACs) with the data during the write operation. These MACs are computed in advance using the unique write counter and encryption key, so that during read operations, integrity verification can be performed quickly by comparing the stored MAC with a newly computed MAC, without requiring extensive processing or reading of entire zones.
2Reliability
If encryption is implemented for data confidentiality, then data security is improved, but processing overhead increases
Solution Approach 1:
The patent applies encryption at the sector level rather than requiring complete zone decryption, allowing selective encryption and decryption of only the specific sectors being accessed. This local approach reduces processing overhead by avoiding the need to decrypt entire zones when only individual sectors or small portions are being read.
Solution Approach 2:
The patent pre-computes encryption keys and message authentication codes during the write operation, storing them with the encrypted data. This preliminary action ensures that decryption and verification can be performed efficiently during read operations without requiring complex real-time key derivation or extensive processing overhead.
3Quantity of substance
If shingled writing is used to increase track density, then storage capacity is improved, but the ability to overwrite tracks is limited due to overlapping data
Solution Approach 1:
The patent assigns unique write counters to each zone before writing data, and incorporates these counters into the encryption key and message authentication code calculations. This preliminary assignment creates a versioning system where each write operation is uniquely identified, allowing the system to track and manage overlapping data from different write operations, thereby enabling safe overwriting in shingled magnetic recording.
Solution Approach 2:
The patent uses message authentication codes that incorporate unique write counters to provide feedback about the validity and version of stored data. During read operations, the system verifies the MAC to ensure data integrity and can determine whether the retrieved data is from the most recent write operation or an earlier overlapping write, enabling intelligent handling of track overwriting in shingled writing.
Data Source
AI summary
A method, apparatus and a data storage device are provided for implementing data confidentiality and integrity of data stored in overlapping, shingled data tracks on a recordable surface of a storage device. A unique write counter is stored for each zone written to the recordable surface of the storage device. An encryption key is used together with the write counter information and a logical block address to encrypt each sector being written, and to decrypt all sectors being read. An individual sector is decrypted, obtaining the write counter information and reading the data sector. A message authentication code is stored for each zone. All sectors of the zone are read to perform integrity check on a sector.