Watermarking in an encrypted domain

Abstract

Methods, apparatus and systems for embedding auxiliary information in encrypted host signals are provided. The present invention enables secure application of digital watermarks at any point in the transmission and/or distribution of digital content by enabling the insertion of a plurality of digital watermarks, without the knowledge of the encryption/decryption keys, into a digital host content that has been encrypted with an encryption key. The embedded watermarks persist throughout the content subsequent to the decryption of the content. The disclosed techniques are applicable to content that has been encrypted using a variety of different encryption techniques and algorithms, including stream ciphers, block ciphers, symmetric and asymmetric encryption algorithms. These methods are further adapted to enable the insertion of watermarks into a content that is compressed prior to encryption.

1 - 4 . (canceled) 
     
     
         5 . A method for facilitating watermarking of an encrypted host content, the method comprising:
 producing the encrypted host content at least in-part by:
 (a1) obtaining an unencrypted version of the host content, 
 (b1) embedding a first watermark symbol value into a first set of segments of the unencrypted version of the host content to produce a first embedded host content, and 
 (c1) encrypting the first embedded host content to produce the encrypted host content; 
   producing an unencrypted auxiliary information at least in-part by:
 (a2) embedding a second watermark symbol value into the first set of segments of the unencrypted version of the host content to produce a second embedded host content, and 
 (b2) modifying the second embedded host content using the first embedded host content to produce the unencrypted auxiliary information; and 
   transmitting the encrypted host content and the unencrypted auxiliary information to a remote device to allow insertion of a particular watermark that comprises both the first and the second symbol values in the encrypted host content, the insertion comprising processing a subset of the first set of segments of the encrypted content using corresponding segments from the unencrypted auxiliary information to convert the first embedded watermark symbol value to the second watermark symbol value in each of the subset of the first set of segments without decrypting the subset of the first set of segments.   
     
     
         6 . The method of  claim 5 , wherein modifying the second embedded host content using the first embedded host content comprises conducting an exclusive OR operation between the first embedded host content and the second embedded host content. 
     
     
         7 . The method of  claim 5 , wherein processing a subset of the first set of segments of the encrypted content comprises conducting an exclusive OR operation between the he first set of segments of the encrypted content and the corresponding segments from the unencrypted auxiliary information. 
     
     
         8 . The method of  claim 5 , wherein:
 producing the encrypted host content and the unencrypted auxiliary information is carried out at a pre-processing center; and   transmitting the encrypted host content and the unencrypted auxiliary information is triggered by a request for the host content.   
     
     
         9 . The method of  claim 5 , further comprising, prior to the transmitting, encrypting the unencrypted auxiliary information to produce an encrypted auxiliary content, wherein the encrypted auxiliary content is decrypted prior to processing of the subset of the first set segments of the encrypted content. 
     
     
         10 . The method of  claim 5 , further comprising:
 prior to encrypting the first embedded host content, compressing the first embedded host content;   prior to modifying the second embedded host content, compressing the second embedded host content; and   modifying the second embedded host content using the first embedded host content comprises modifying compressed blocks of the second embedded host content using compressed blocks of the first embedded host content; wherein   processing the subset of the first set of segments of the encrypted host content comprises processing the subset of the first set of segments of the encrypted host content on a compressed-block by compressed-block basis.   
     
     
         11 . The method of  claim 10 , wherein processing the subset of the first set of segments is carried out on a compressed-block by compressed-block basis without decompressing of the compressed blocks. 
     
     
         12 . The method of  claim 10 , further comprising embedding a common watermark value into a second set of segments of the unencrypted version of the host content such that the first embedded host content and the second embedded host content include the common watermark value in the second set of segments of the first embedded host content that are aligned with the second set of segments in the second embedded host content. 
     
     
         13 . The method for watermarking an encrypted host content, the method comprising:
 obtaining the encrypted host content that includes a first watermark value embedded therein, the encrypted host content having been produced at least in-part by:
 embedding the first watermark symbol value into a first set of segments of an unencrypted version of the host content to produce a first embedded host content, and 
 encrypting the first embedded host content to produce the encrypted host content; 
   obtaining an unencrypted auxiliary information, the auxiliary unencrypted content having been produced at least in-part by:
 embedding a second watermark symbol value into the first set of segments of the unencrypted version of the host content to produce a second embedded host content, and 
 modifying the second embedded host content using the first embedded host content to produce the unencrypted auxiliary information; and 
   embedding a particular watermark that comprises both the first and the second symbol values in the encrypted host content by processing a subset of the first set of segments of the encrypted content using corresponding segments from the unencrypted auxiliary information to convert the first embedded watermark symbol value to the second watermark symbol value in each of the subset of the first set of segments without decrypting the subset of the first set of segments.   
     
     
         14 . The method of  claim 13 , wherein modifying the second embedded host content using the first embedded host content comprises conducting an exclusive OR operation between content symbols of the first embedded host content and content symbols of the second embedded host content. 
     
     
         15 . The method of  claim 13 , wherein processing a subset of the first set of segments of the encrypted content comprises conducting an exclusive OR operation between the he first set of segments of the encrypted content and the corresponding segments from the unencrypted auxiliary information. 
     
     
         16 . The method of  claim 13 , wherein obtaining the encrypted host content and the unencrypted auxiliary information comprises receiving the encrypted host content and the unencrypted auxiliary information in response to a request for the host content. 
     
     
         17 . The method of  claim 13 , wherein the encrypted host content and the unencrypted auxiliary information are both in compressed format;
 processing the subset of the first set of segments of the encrypted host content comprises processing the subset of the first set of segments of the encrypted content on a compressed-block by compressed-block basis; and   the encrypted host content and the unencrypted auxiliary information having been generated in compressed format at least in-part by:
 prior to encrypting the first embedded host content, compressing the first embedded host content, 
 prior to modifying the second embedded host content, compressing the second embedded host content, and 
 modifying the second embedded host content using the first embedded host content comprises modifying compressed blocks of the second embedded host content using compressed blocks of the first embedded host content. 
   
     
     
         18 . The method of  claim 17 , wherein processing the subset of the first set of segments is carried out on a compressed-block by compressed-block basis without decompressing of the compressed blocks. 
     
     
         19 . A device, comprising:
 a watermark embedder to obtain an unencrypted version of the host content and embed a first watermark symbol value into a first set of segments of the unencrypted version of the host content to produce a first embedded host content, and to embed a second watermark symbol value into the first set of segments of the unencrypted version of the host content to produce a second embedded host content;   a modification circuit coupled to the watermark embedder to modify the second embedded host content using the first embedded host content to produce the unencrypted auxiliary information;   an encryptor coupled to the watermark embedder and to the circuit to encrypt the first embedded host content to produce the encrypted host content; and   a transmitter coupled to the encryptor and to the modification circuit to transmit the encrypted host content and the unencrypted auxiliary information to another device, wherein insertion of a particular watermark that comprises both the first and the second symbol values in the encrypted host content is enabled at least in-part when a subset of the first set of segments of the encrypted content is processed using corresponding segments from the unencrypted auxiliary information to convert the first embedded watermark symbol value to the second watermark symbol value in each of the subset of the first set of segments without decrypting the subset of the first set of segments.   
     
     
         20 . The device of  claim 19 , wherein the modification circuit comprises an exclusive OR circuit, one input of the exclusive OR circuit coupled to digital samples of the first embedded host content and another input of the exclusive OR circuit coupled to digital samples of the second embedded host content. 
     
     
         21 . The device of  claim 19 , further comprising, a second encryptor coupled to the modification circuit and to the transmitter to encrypt the unencrypted auxiliary information to produce an encrypted auxiliary content for transmission to another device. 
     
     
         22 . The device of  claim 19 , further comprising a compression component coupled to the watermark embedder, to the encryptor and to the modification circuit to compress the first embedded host content and to provide the compressed first embedded host content to the encryptor, and to compress the second embedded host content and to provide the compressed second embedded host content to the modification circuit. 
     
     
         23 . The device of  claim 19 , wherein the watermark embedder further embeds a common watermark value into a second set of segments of the unencrypted version of the host content such that the first embedded host content and the second embedded host content include the common watermark value in the second set of segments of the first embedded host content that are aligned with the second set of segments in the second embedded host content. 
     
     
         24 . A device, comprising
 a receiver to receive an encrypted host content and an unencrypted auxiliary information,
 the encrypted host content including a first watermark symbol value embedded therein and having been produced at least in-part by embedding the first watermark symbol value into a first set of segments of an unencrypted version of the host content to produce a first embedded host content, and encrypting the first embedded host content to produce the encrypted host content, 
 the unencrypted auxiliary information having been produced by embedding a second watermark symbol value into the first set of segments of the unencrypted version of the host content to produce a second embedded host content, and modifying the second embedded host content using the first embedded host content to produce the unencrypted auxiliary information; and 
   a processing circuit coupled to the receiver to process a subset of the first set of segments of the encrypted content using corresponding segments from the unencrypted auxiliary information to convert the first embedded watermark symbol value to the second watermark symbol value in each of the subset of the first set of segments without decrypting the subset of the first set of segments, and to thereby embed a particular watermark that comprises both the first and the second symbol values in the encrypted host content.