Secure digital content distribution system and secure hard drive

A secure hard drive comprises a storage medium that stores encrypted digital content and corresponding encrypted content keys. A public key decryption module receives one of the encrypted content keys from the storage medium and decrypts the encrypted content key using a private key to generate a content key. A block decryption module receives the encrypted digital content corresponding to the one of the encrypted content keys from the storage medium and the content key from the public key decryption module and decrypts the encrypted content using the content key. The storage medium is a magnetic storage medium. The public key decryption module and the block decryption module are implemented by a system on chip (SOC). A content player receives the decrypted digital content from the block decryption module and generates at least one of an analog output signal and a digital output signal.

FIELD OF THE INVENTION

The present invention relates to the distribution of digital content such as audio, video, music, still pictures and the like, and more particularly to secure content distribution systems and secure hard drives.

BACKGROUND OF THE INVENTION

Digital content such as but not limited to computer software, still pictures, audio, music, and video is typically distributed using digital video (or versatile) discs (DVDs), compact discs (CDs), floppy disks, and/or via the Internet. Content providers have had a difficult time preventing piracy of their content. Typically, users store the digital content using hard drives, CDs, DVDs, floppy disks or other electronic storage media. The losses that can be attributed to piracy are well in excess of billions of dollars annually and growing at an alarming pace. Because the medium and the drive are separable, it is very difficult to defeat bit-by-bit copies of the digital content. For example, pirates of DVDs used bit-by-bit copying before the DVD encryption scheme was cracked.

SUMMARY OF THE INVENTION

A secure hard drive according to the present invention comprises a storage medium that stores encrypted digital content and corresponding encrypted content keys. A public key decryption module receives one of the encrypted content keys from the storage medium and decrypts the encrypted content key using a private key to generate a content key. A block decryption module receives the encrypted digital content corresponding to the one of the encrypted content keys from the storage medium and the content key from the public key decryption module and decrypts the encrypted content using the content key.

In other features, the storage medium is a magnetic storage medium. The public key decryption module and the block decryption module are implemented by a system on chip (SOC). A content player receives the decrypted digital content from the block decryption module and generates at least one of an analog output signal and a digital output signal. An identification (ID) module provides an ID. The private key and a public key are based on the ID. A controller performs buffer management and timing of read/write operations.

A system comprises the secure hard drive and further comprises an external host and a control interface that provides an interface between the controller and the external host. The external host is one of a computer and a portable media player.

In yet other features, a watermark detector communicates with an output of the content player and determines whether the analog signal that is output by the content player contains a watermark. The storage medium stores a content directory having content directory entries for the content. The public key decryption module performs digital signature verification of the content directory entry corresponding to the content that is selected for play.

In other features, at least one of the content directory entries contains a clear content counter that specifies a portion of the corresponding content that is not encrypted. A content distributor identification (ID) field that identifies a content distributor supplying the corresponding content. A content status field that has one of an active status and a passive status. The active status enables playback and the inactive status disables playback. A signature field for the content distributor supplying the corresponding content. A content key location field that contains a first offset value points to a content key for the selected content in a content key block stored on the storage medium. A content location field that contains a second offset value that points to the selected content in an encrypted content block stored on the storage medium.

In still other features, the content includes at least one of audio, video, and still pictures. The system comprises a distributed communications network and at least one content distributor that transmits encrypted content, an encrypted content key, and a content directory entry for a content selection to the secure hard drive via the external host and the distributed communications network. The storage medium contains encrypted content that is pre-stored thereon.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The secure content distribution system according to the present invention integrates the content storage medium with the drive. Since the manufacture of hard drives is a highly specialized industry, a high level of security is provided through this integration. The present invention allows distribution of a secure personal content library with a low risk of loss of the digital content to piracy.

Referring now toFIG. 1, a secure content distribution system10according to the present invention is shown. The secure content distribution system10includes a distributed communications system14such as the Internet, a Bluetooth network, a local area network (LAN), a wide area network (WAN), a cellular network, a satellite network or other suitable network. One or more content distributors18-1,18-2, . . . , and18-N (collectively content distributors18) distribute secure digital content such as a software, video, audio, still pictures, music and the like over the distributed communications system14.

A network device22such as a personal computer, portable media players such as personal digital assistants (PDA), cellular phones, MP3 players, and/or other any other device communicates either wirelessly and/or directly with the content distributors18over the distributed communications system14. The network device facilitates a connection to the content distributors18. The network device22is removably connected to a portable media player28that includes a secure hard drive32. The network device22includes a software agent26such as a browser that negotiates a link with the content distributor18and manages the transfer of data to the secure hard drive32. The portable media players can also directly connect to the distributed communications system14. A trusted third party (TTP) distributes and authenticates public keys for the secure hard drives32and the content distributors18. The content distributor18-3may also pre-store digital content on the secure hard drive32with either an active status (can be played) or inactive status (cannot be played), as will be described further below.

Referring now toFIG. 2, when a consumer visits a web site of the content distributor18, the consumer may wish to purchase content. The content distributor18uses an encryption module50that encrypts content54using a content key56. The content key56is preferably a randomly selected key, although other methods for determining content keys may be used. The content key56is then encrypted using a public key58of the secure hard drive32that requests the content54. The consumer downloads encrypted content60and an encrypted content key64over the distributed communications system14onto the secure hard drive32.

Referring now toFIG. 3A, the secure hard drive32is shown in further detail and includes a SOC70and a magnetic medium72, which stores the encrypted content60and the encrypted content keys64. While the SOC70is shown, components of the SOC70can be implemented as discrete components. As will be described below, only the SOC on the secure hard drive32can recover the content key56. The SOC70includes a control interface74that provides an external interface to a host and/or network device. The control interface74communicates with a controller76, which performs buffer management, times read/write events and performs other hard drive operations. The controller76may include one or more of the following components: a central processing unit (CPU), memory, a hard drive controller (HDC), a buffer manager, firmware, a universal serial bus (USB), and/or other components.

The controller76communicates with a read channel circuit80and a preamplifier82, which recover the data from the read signal that is generated by the read/write head as it passes over the magnetic medium72. The read signal is processed by the read channel80and the controller76to generate digital data signals. Some of the digital data signals include the encrypted content key64, which is output to a public key decryption module84. A chip ID module86outputs a chip ID to the public key decryption module84. The SOC70has a unique chip ID, which is used to generate a private key for the SOC70. The private key, in turn, is used to generate a public key for the SOC70. For example, the public key decryption module80may contains a sub-module that converts the Chip-ID to the private key. Various algorithms may be used to generate the private key.

The public key decryption module84uses the private key of the SOC70to decrypt the encrypted content key64and outputs the content key56to a block decryption module90. The controller76outputs the encrypted content60to the block decryption module90, which uses the content key56to decrypt the encrypted content60. The block decryption module90outputs the content to a content player88, which generates an analog and/or digital output signal that includes at least one of audio, video, still pictures, and the like.

The SOC70may optionally include a watermark detector92that determines whether the analog signal that is output by the content player88includes a watermark. The watermark includes copy control information embedded in the analog signal. In other words, the watermark detector92is used to defeat analog attacks such as capture and re-coding.

Referring now toFIG. 3B, one implementation of the controller76is shown to include a serial and/or parallel interface94such as but not limited to serial ATA and/or Integrated Device Electronics (IDE), a hard disk controller (HDC)96, a buffer98, a spindle voice coil module (VCM)100, and a processor102. The spindle VCM100, which interfaces with the HDC96and a spindle motor104, controllably rotates the magnetic medium72. The spindle VCM100also interfaces with a read/write arm106that is used to position a magneto-resistive (MR) head108. A resistance of the MR head108varies as it passes in proximity to stored positive and negative magnetic fields on the magnetic medium72, which represent digital ones and zeros. The buffer98stores data that is associated with read/write operations and other control functions of the controller76. The processor102performs processing that is associated with the read/write operations and other functions of the controller76. While a specific implementation is shown for the controller76, skilled artisans will appreciate that there are other suitable controller configurations that are contemplated.

Referring now toFIG. 4, processing of the content directory is shown in further detail. The content distributor18creates a content directory and/or a content directory entry for the selected content. The content directory entry may include data such as but not limited to the title, artist, and status (active (can be played) and inactive (cannot be played)). The content directory is preferably protected by a digital signature of the content distributor18so that others cannot modify the fields that are stored in the content directory.

The content distributor18may use an encryption module120and a private key122to sign the content directory and/or the content directory entry. A signed content directory126is transmitted over the distributed communications system14or otherwise input to the secure hard drive32. For example, one implementation where the distributed communications system14is not used includes a secure hard drive32with pre-recorded content. The pre-recorded content may be inactive (cannot be played) or active (can be played).

The secure hard drive32includes a decryption module130, which uses the public key132of the content distributor18to generate a verified content directory134from the signed content directory126. While others may view the signed content directory126, they are unable to modify it. While this is an effective method for securing the content directory124, the signed content directory126is typically at least twice the size of the content directory124.

An alternate implementation for signing the content directory124is shown inFIG. 5. A one-way hash module140uses a hash function to generate a digest141from the content directory124. The digest is then signed with a private key of the content distributor18in an encryption module142. The plaintext content directory124is also transmitted or otherwise loaded on the secure hard drive32. The secure hard drive32includes a decryption module150that uses the public key of the content distributor18to recover the digest141. The secure hard drive32also includes a one-way hash module140that generates a calculated digest. The two digests (the recovered digest and the hash-generated digest) are compared by a comparing module154, which generates a valid digest signal if they match and an invalid digest signal if they do not. Both the secure hard drive32and the content distributor18preferably maintain a copy of the content directory. If the secure hard drive32fails, all of the digital content that is owned by the consumer can be replaced after proper verification.

Referring now toFIG. 6, an exemplary content directory entry160is shown. Skilled artisans will appreciate that the content directory will contain an entry for each content selection. The content directory entry160includes a content distributor identification (ID) field162that identifies the content distributor18. Content title and artist fields164and166describe the title of the content and name of the artist, respectively. A content status field168identifies whether the content is active or inactive. A clear content counter172specifies a predetermined portion (bits, bytes, segments and/or any other measure) at the beginning of the digital content that is not encrypted. The clear content counter172is specified by the content distributor18.

A key hash value field174contains a hash value. The encrypted content key can be hashed and the hash value can be protected by the content distributor's signature. The key hash value is used to defeat a possible hacker. For example, without this field, a hacker can purchase one content selection (active) and have other inactive content selections. The hacker could play the inactive content selections by replacing the content location and the content key location fields in the inactive content directory entries with the content location and content key location of the active content selection. A secure hard drive without the hash field may allow this to occur. If the key hash value field is used, this approach will be prevented.

A content distributor's signature field176contains the signature of the content distributor, which can be verified using the content distributor's public key. The content key location field178contains an offset value that points to a selected content key180in a content key data block182. A content location field184contains an offset value that points to encrypted content186in an encrypted data block190. The fields178and184will typically be determined by the secure hard drive32rather than the content distributor18.

Referring now toFIG. 7, typical steps that are implemented by the content distributor18for secure content distribution according to the present invention are shown. A consumer visits a website of the content distributor18in step200. In step202, the content distributor18determines whether the consumer purchases content. If step202is true, the content distributor18encrypts the selected digital content with the random content key and sends the encrypted content to the secure hard drive32in step204.

In step208, the content distributor18encrypts the content key with the public key of the secure hard drive32and sends the encrypted content key to the secure hard drive32. As can be appreciated, the encrypted content and the encrypted content key can be sent to the purchasing consumer at the same time. The content directory may be signed and sent at this time using the methods described above. In step210, the content distributor18determines whether the consumer exits the website of the content distributor. If yes, control ends. Otherwise, control returns to step202.

Referring now toFIG. 8, operation of the clear content counter in the secure hard drive32is illustrated. In step220, the secure hard drive32determines whether the user selects content for play. If not, control loops back to step220. Otherwise when the user selects content to be played, the secure hard drive32determines whether the content has a content status that is equal to active in step222. If true, the secure hard drive32plays the content in step223. Otherwise, control determines whether the clear content counter is greater than zero in step224. If not, control sends a message to the user that the content is not active and that a sample is not available in step225. If step224is true, a counter is set to zero in step226. In step228, the content is played and the counter is incremented. In step230, the secure hard drive32determines whether the counter is greater than the clear content counter. If false, control continues with step228. Otherwise the sample time is over when the counter exceeds the clear content counter. A message is sent to the user that the sample is over in step234. Additional steps and/or dialogue may be initiated with the user to solicit purchase of the sampled digital content. Steps225and234may be omitted if desired.

Referring now toFIG. 9, steps for playing back content are shown. In step250, control determines whether the consumer selects content for playback. If not, control loops back to step250. In step252, control retrieves the encrypted content key, the content directory entry and the encrypted content that are associated with the selected content. In step254, the digital signature is verified. In step256, control determines whether the digital signal is valid. If not, control ends in step257. Otherwise control continues with step258and the content key is decrypted with the private key of the secure hard drive32. In step260, the content is decrypted using the decrypted content key. In step264, an analog signal is generated from the decrypted content and is output to an audio and/video playback device. In step266, control determines whether a watermark is detected (when the optional watermark detector is used). If not, control ends in step257. Otherwise, control determines whether the selected content is over. If not, control ends in step257. Otherwise control loops back to step260.

There are many advantages when content is distributed using the secure hard drive32and the secure content distribution system10according to the present invention. The content distributors18have end-to-end control of the encryption of their digital content. The content key is not revealed to anyone else on the network other than the content distributor18. On the consumer side, the content key is never revealed outside of the SOC70. Security is not compromised even if a hacker hacks into the firmware of the secure hard drive32. The chip-ID is part of a very complicated chip (the SoC). Therefore, it would take a significant amount of effort to determine the chip-ID. Even if the hacker can determine the chip-ID, it is still very difficult to determine the private key from the chip-ID. For example, a keyed-hash function and/or other coding techniques can be used to generate the private key from the chip-ID. Therefore, the system cannot be compromised without breaking the encryption/decryption scheme, which is unlikely.

Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. For example, while the present invention is described in conjunction with magnetic storage systems, other electronic storage may be used such as memory and/or optical storage. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.