Apparatus for limiting reproducible number of magnetic recording medium
First Claim
1. A reproducible number limiting apparatus for a magnetic recording medium using a reproducible number limiting algorithm comprising:
- scrambling means for scrambling an input bit stream using a scrambling key;
encryption means for encrypting said scrambling key used in said scrambling means'"'"' scrambling and additional information, and outputting a ciphertext;
decryption means for updating said additional information for every playback from the ciphertext using an encryption key, and destroying said scrambling key when said additional information satisfies a specific condition; and
descrambling means for descrambling a reproduced bit stream using said scrambling key from said decryption means;
wherein said encryption means comprises;
a key storage for storing an encryption key required in encryption;
an error correction code encoder for receiving data of predetermined bits and performing error-correcting encoding;
an adder for EXCLUSIVE-OR operating the output of said error correction code encoder and the additional information; and
a matrix multiplier for multiplying the output of said adder by a nonsingular matrix from said key storage, and outputting a ciphertext.
1 Assignment
0 Petitions
Accused Products
Abstract
A reproducible number limiting apparatus for a magnetic recording medium using a reproducible number limiting algorithm is disclosed including: scrambling means for scrambling an input bit stream using a scrambling key; encryption means for encrypting the scrambling key used in the scrambling means'"'"' scrambling and additional information, and outputting a ciphertext; a key storage for storing an encryption key required in encryption; recording/reproducing means for recording or reproducing the output of the scrambling means and encryption means; decryption means for updating the additional information for every playback from the ciphertext using an encryption key, and destroying the scrambling key when the additional information satisfies a specific condition; and descrambling means for descrambling a reproduced bit stream using the scrambling key from the decryption means.
34 Citations
19 Claims
-
1. A reproducible number limiting apparatus for a magnetic recording medium using a reproducible number limiting algorithm comprising:
-
scrambling means for scrambling an input bit stream using a scrambling key; encryption means for encrypting said scrambling key used in said scrambling means'"'"' scrambling and additional information, and outputting a ciphertext; decryption means for updating said additional information for every playback from the ciphertext using an encryption key, and destroying said scrambling key when said additional information satisfies a specific condition; and descrambling means for descrambling a reproduced bit stream using said scrambling key from said decryption means; wherein said encryption means comprises; a key storage for storing an encryption key required in encryption; an error correction code encoder for receiving data of predetermined bits and performing error-correcting encoding; an adder for EXCLUSIVE-OR operating the output of said error correction code encoder and the additional information; and a matrix multiplier for multiplying the output of said adder by a nonsingular matrix from said key storage, and outputting a ciphertext. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A reproducible number limiting apparatus for a magnetic recording medium using a reproducible number limiting algorithm comprising:
-
scrambling means for scrambling an input bit stream using a scrambling key; encryption means for encrypting said scrambling key used in said scrambling means'"'"' scrambling and additional information, and outputting a ciphertext; decryption means for updating said additional information for every playback from the ciphertext using an encryption key, and destroying said scrambling key when said additional information satisfies a specific condition; descrambling means for descrambling a reproduced bit stream using said scrambling key from said decryption means;
wherein said decryption means compromises;a matrix multiplier for obtaining a signal of predetermined bits from the ciphertext; an error correction code encoder for receiving the output of said matrix multiplier and performing error-correction decoding; and an additional information updating portion for updating the additional information of the ciphertext from the output of said error correction code decoder. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
-
-
17. A reproducible number limiting apparatus for a magnetic recording medium using a reproducible number limiting algorithm comprising:
-
scrambling means for scrambling an input bit stream using a scrambling key; encryption means for encrypting said scrambling key used in said scrambling means'"'"' scrambling and additional information, and outputting a ciphertext; decryption means for updating said additional information for every playback from the ciphertext using an encryption key, and destroying said scrambling key when said additional information satisfies a specific condition; descrambling means for descrambling a reproduced bit stream using said scrambling key from said decryption means; recording/reproducing means for recording or reproducing the output of said scrambling means and encryption means; a dummy region recording portion for recording the output of said encryption means on the magnetic recording medium; and a dummy region reproducing portion for reproducing the ciphertext recorded on the magnetic recoding medium by said dummy region recording portion; wherein said dummy region reproducing portion comprises a repetition code error correcting portion for performing error correction to prevent the SNR decrease of the output of said encryption means using a repetition code. - View Dependent Claims (18, 19)
-
Specification