System and method for writing secure data to disk
AssigneeHitachi Global Storage Technologies Netherlands B.V.
InventorsZvonimir Bandic, Martin Chen, Fu-Ying Huang, Bruce Wilson
Life of this patent
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Abstract
Secure data is written to a disk during manufacture in such a way that it can be read but not copied. Methods include writing triangular transitions or very slow transitions from positive magnetic to negative magnetic and then erasing the negative parts to yield a code that consists of positive read back amplitudes only. Or, high frequency transitions can be written during servo writing.
Claims21
A method for writing secure data onto a magnetic recording disk, comprising writing the secure data in a way that renders infeasible at least one of:
- copying, and altering, the secure data, the secure data being at least one of:
- a serial number associated with hardware or software, a hash result, an encryption key.
At least one disk pre-formatted with at least one pattern representing a code, the pattern being written by at least one method selected from the group consisting of:
- a magnetic printing process, a servo writing process, and use of a write head not used in a drive subsequently provided with the disk, wherein
- the pattern is established at least in part by substantially erasing a number of feature periods in a sequence of features, the code representing a serial number associated with hardware or software and/or a hash result and/or an encryption key.
At least one disk pre-formatted with at least one pattern representing a code, wherein the pattern is established by writing high frequency transitions during servo writing when the disk rotates at a speed less than the speed at which die disk rotates during normal read and write operations, such that when the disk rotates during normal read and write operations, the pattern cannot be altered using a write head associated with the disk, the code representing a serial number associated with hardware or software, or a hash result, or an encryption key.
A read channel chip configured to read secure data, comprising:
- at least one variable gain amplifier (VGA);
- at least one matched filter receiving input from the VGA, the filler being trained for each head and each track zone of a secure data region of a hard disk drive being read;
- and
- at least one threshold detector receiving input from the matched filter, the detector outputting only positive pulses in response to signal peaks above a threshold.
A method for writing a message on a recording disk, comprising:
- prior to vending the disk, writing a pattern on the disk, wherein the pattern has at least one of:
- a shape that is different from the shape of magnetic transitions written to the disk during normal operating data writes, and a frequency that is higher than the normal operating write frequency of the disk, such that the pattern has at least one of:
- strong positive peaks and low-amplitude negative peaks, and a higher than usual frequency that, while being readable, is not writable using normal operating write circuitry of the disk;
- and
- in accordance with at least one code representing a serial number, erasing parts of the pattern to establish the message.
Dependencies are inferred from the claim text.