A method for watermarking documents comprising: identifying and locating spaces in a received original document (10) by a location analysis (110) module which distinguishes between intra-word spaces and inter-word spaces; minimizing an error probability of interference between intra-word spaces and inter-word spaces in the watermarked document (20) by an optimization module (111); encoding (113) the message (30) into codewords and encoding (114) the codewords into the watermark;
embedding the watermark to generate (115) the watermarked document (20) by modifying the intra-word spaces and inter-word spaces of the original document (10).

Some implementations may provide a computer-implemented method for validating a digital document, the method including: receiving, at a computing device, the digital document comprising at least two digital watermarks, the digital document issued by a central entity; retrieving a first digital watermark from the digital document, the first digital watermark visually presented at a first time point; retrieving a second digital watermark from the digital document, the second digital watermark visually presented at a second time point, the second digital watermark being different from the first digital watermark and the second time point being different from the first time point; and reading the digital document based on the retrieved first and second digital watermarks.

One aspect of the present invention discloses a device for content security. The device includes: an application execution unit configured to generate and control content in response to a content control command requested by a user; and a DRM agent configured to communicate with the application execution unit, to detect the content control command generated by the application execution unit, and to perform control on the content, and the DRM agent comprises a tracing module configured to insert security information into the content in order to prevent and trace content leakage.

The specification discloses a method of generating and recognizing voice based playback information, and a recording medium for storing instructions for performing the method. That is, a voice playback file for outputting voice is converted to playback information, and the voice is outputted by playing back the voice playback file, when the playback information is recognized. Thus, a recording function, which can be utilized in various fields, can be provided without using a separate storage for storing the voice playback file.

Disclosed are methods, systems, devices, apparatus, media, and other implementations, including a method that includes obtaining input visual data comprising a sequence of symbols, selected from a symbol set, with each of the symbols associated with a glyph representation. The method also includes obtaining a code message comprising code message symbols, and modifying at least one of the symbols of the input visual data to a different glyph representation associated with a respective at least one of the code message symbols to generate, at a first time instance, a resultant coded visual data.

The system is disclosed for visual marking sensitive documents for leak prevention. Each time an action is taken with regard to a document (e.g., creation, viewing, downloading), that action is added to a distributed ledger, essentially creating a unique hash for a new instance of the document. This new hash is visually embedded in the document as a code comprising a plurality of differently shaded pixels, wherein some of the pixels directly encode information regarding the document (e.g., an account that generated the new instance of the document, a date, a time, a unique ID for the document, etc.) and some of the pixels do not encode information. The code is capable of being scanned either digitally or physically on a printed version of the document, such that the immediate source of the document, corresponding to who leaked the document, is able to be discerned.

In some embodiments, an authentication system may be configured to process one or more tokens that incorporates one or more tailored-wavelength-range coded patterns, codes represented within a steganographic image, or overlapping codes. As an example, such a token may include (i) one or more invisible-ink-printed patterns printed using infrared ink corresponding to different tailored wavelength ranges within the infrared light spectrum, (ii) one or more steganographic images in which invisible-ink-printed patterns are interweaved within the steganographic images, (iii) visible-ink-printed patterns and invisible-ink-printed patterns printed substantially within the visible ink portions of the visible-ink-printed patterns, or (iv) other features, where the invisible-ink-printed patterns correspond to one or more authentication codes or other data for token authentication.

A method for watermarking a document containing at least one text portion comprising the following steps: determining a specific character font comprising, for at least one character, an original graphic and at least one variation, each of the variations being associated with a different value, said character being termed encodable characters; using the specific character font to encode an item of information in the text portion of the document, by replacing at least one original graphic with a variation, the original graphic and the variation or variations being identified as a single character by a first optical character recognition process referred to as standard OCR and identified as a plurality of characters by a second optical character recognition process referred to as specific OCR that is capable of determining if the represented character is the original graphic or one of the variations of same and, if so, making it possible to determine the variation that is represented, a strict order relationship being defined on the encodable characters in order to establish the order in which the encodable characters are to be processed during the decoding phase.

The system is disclosed for visual marking sensitive documents for leak prevention. Each time an action is taken with regard to a document (e.g., creation, viewing, downloading), that action is added to a distributed ledger, essentially creating a unique hash for a new instance of the document. This new hash is visually embedded in the document as a code comprising a plurality of differently shaded pixels, wherein some of the pixels directly encode information regarding the document (e.g., an account that generated the new instance of the document, a date, a time, a unique ID for the document, etc.) and some of the pixels do not encode information. The code is capable of being scanned either digitally or physically on a printed version of the document, such that the immediate source of the document, corresponding to who leaked the document, is able to be discerned.

One aspect of the present invention discloses a device for content security. The device includes: an application execution unit configured to generate and control content in response to a content control command requested by a user; and a DRM agent configured to communicate with the application execution unit, to detect the content control command generated by the application execution unit, and to perform control on the content, and the DRM agent comprises a tracing module configured to insert security information into the content in order to prevent and trace content leakage.