The present invention belongs to the technical field of digital messaging, whatever the content transported (encrypted or not) or the sender(s)/recipient(s) scheme retained (anonymous, 1:1 or 1:N, or even N:1), and for messages having a limited or unlimited time availability (ephemeral or sustainable). By digital messaging, it is meant a technical system (computer, application, network, . . . ) for routing a message and its digital content from a sender to a recipient.

BACKGROUND OF THE INVENTION

The current digital messaging systems allow a sender to send a digital content to one or more recipients. This content travels digitally from the sender to the recipient(s) by remaining in digital form. The content may sometimes have a limited lifetime, i.e. be associated with an integrated or external erasing system. The content may also be encrypted, generally previously requiring the exchange of encryption keys between the sender and the recipient. The content, even encrypted, is routed without particular condition from the sender to the recipient, which may access the content from the moment that the latter has travelled from a server to another one and has reached its saving or archiving destination. All the current systems are based on a unique identifier to define a sender or a recipient. Hence, a content leaving a sender is always recovered by the recipient, or at least the owner of the destination identifier. Initiatives have been taken in the field to refine the conditions of delivery of a message, for example on the condition of being in a certain geographical location (generally defined by GPS, Wi-H, radio or acoustic triangulation, or other) or near another user belonging to a group of users; these applications are called “location-based messaging”.

Hence, the systems proposed do not allow the sharing of a digital content between a sender and a recipient strictly conditioned by the implementation of one or more material subjects. The existing methods do not allow attaching a digital content to a material subject. The invention hence aims at remedying this lack by proposing to condition the delivery of a message to the condition that the recipient has been at one moment or another in relation with a material subject or an image of the latter. This way to proceed allows simply improving the confidentiality of the messages without necessarily using cryptography. Moreover, it is known in psychology that human has always used his particular relation with material object to remember particular moments, to signify or ritualize certain events or to share emotions. The word “souvenir” that characterizes the object brought back from a journey or offered to close friends, or also linked to a monument, is a testimony of this connivance between personal or collective memory and the material subjects that surround us. This is hence a secure messaging method that, according to the material subjects chosen, also provides an additional dimension of evocation.

SUMMARY OF THE INVENTION

Hence, the present invention has first for object to transmit a content from one or more sender(s) to one or more recipient(s) by conditioning the delivery thereof to at least one dual authentication i.e., on the one hand, the authentication of the recipient, and on the other hand, the authentication of a material subject that serves as a key to the delivery of the message and that has been used for the preparation thereof. This is hence a method of digital messaging associated with this material subject.

The matter is, figuratively, to place digital Post-it™ on any type of material (physical) object and to create a very interesting experience for the recipient(s), or even also for the sender(s). This virtualization of the attached content has also for advantage to avoid a real or virtual visual pollution, because it is settable and between two worlds.

In order to achieve this object, the invention relates to an electronic message transmission method comprising the following steps:initially, choice by a sender of at least one material subject having at least one authentication area showing a microstructure at a given observation magnification, then acquisition or implementation of at least one first image of the authentication area,recording, by the sender, of the electronic message to be transmitted on a server system,recording on the server system of at least one identifier of at least one recipient of the message, each identifier being associated with the message to be transmitted,notification to each recipient of the existence of a message,acquisition of at least one second image of the authentication area of the material subject, the second image being acquired with a quality substantially equivalent to that of the first image so that the first and the second images contain a substantially equivalent level of information relating to the authentication area,alignment of the first and second images with respect to each other or with respect to a same reference and, jointly or not with the alignment, determination from the first image of a first unitary authenticator of the material subject, and determination from the second image of a second unitary authenticator of the material subject,comparison of the unitary authenticators,transmission to the server system of an identifier of at least one recipient associated with the second unitary authenticator,in case of similarity between the first and second unitary authenticators and matching between the recipient identifier recorded in the server system and the transmitted recipient identifier, transmission to the recipient of the message associated with its identifier and with the unitary authenticator.

The invention has hence for advantage to guarantee that the recipient(s) has(have) been in possession or in presence of the material subject before the delivery of the message, and hence to simply secure the exchange.

In the sense of the invention, the notion of message transmission means equivalently a transmission in “push” mode or a recovery in “pull” mode. Likewise, in the sense of the invention, the phrase “determining a unitary authenticator” is synonymous of the phrase “extracting a unitary authenticator”.

It is to be noted that each authenticator may in particular be consisted of the corresponding image without this is however necessarily the case.

By “message”, it is meant a digital set comprising at least content as well as information about a sender and a recipient, or even metadata of other natures (timestamp, geolocation, . . . ).

In the sense of the invention, it is to be understood by “server system” a computer system that comprises one or more servers not necessarily located at a same place and that is adapted to implement the invention. Hence, within the framework of this server system, the machine that perform the transmission of the messages is not necessarily that which performs the authentication operations, nor that which operates the saving of the data, it being understood that the server system can also comprise a single machine that performs all the operations allocated within the framework of the invention. In the case of a distributed-architecture server system, the servers implemented are commonly called “nodes”.

The invention also relates to an electronic message transmission method comprising the following steps:recording of the electronic message to be transmitted on a server system,implementation of at least two material subjects each having at least one authentication area showing a microstructure at a given observation magnification,implementation of an alignment reference,acquisition of at least one first image of the authentication area of each material subject, and alignment of each first image with respect to the alignment reference and, jointly or not with the alignment, determination from each first image of a first unitary authenticator of each material subject,recording on the server system of the first authenticator of each material subject, said authenticator comprising an image of the authentication area and/or an authenticator derived from this image,acquisition of at least one second image of the authentication area of at least one candidate material subject, the second image being acquired with a quality substantially equivalent to that of the first image so that the first and the second image contain a substantially equivalent level of information relating to the authentication area,alignment of the second image with respect to the alignment reference and, jointly or not with the alignment, determination from the second image of a candidate unitary authenticator of the candidate materiel subject,transmission to the server of a recipient identifier associated with the candidate authenticator,comparison of the candidate unitary authenticator with the first unitary authenticators recorded in the server system and, in case of similarity between the candidate unitary authenticator and a first unitary authenticator, transmission of the message to the recipient whose identifier is associated with the candidate unitary authenticator.

In the sense of the invention, by “alignment reference”, it is to be understood a reference image that may be of any nature, such as, for example: an image of a reference subject of the same family, type or category as the material subjects implemented, an image of remarkable points near the authentication area, an image of a pattern or sign present in or near each authentication area, without this list is limitative.

According to a feature of the invention, the message transmission method comprises a step of recording at least one identifier of a recipient associated with at least one unitary authenticator of a material subject.

According to a feature of the invention, it is proceeded to the determination, in each authentication area image of a material subject, of singular points and descriptors of a singular area associated with each singular point, the descriptors being associated with each corresponding singular point, and to the determination, from said image, of a unitary authenticator of said material subject.

Moreover, according to the invention, the different steps are not necessarily performed in the sequential order in which they are enumerated.

Hence, for example and according to a variant embodiment, in a phase of message recording, it is proceeded at least to the following steps:recording of the content of the electronic message to be transmitted on the server system, the content being associated with the message to be transmitted,recording on the server system of at least one identifier of at least one recipient of the message, each identifier being associated with the message to be transmitted,recording on the server system of at least one identifier of at least one sender of the message, each identifier being associated with the message to be transmitted,implementation of at least one material subject having at least one authentication area showing a microstructure at a given observation magnification,acquisition by a device accessible to the sender of at least one first image of an authentication area,determination, from the first image, of at at least one first unitary authenticator of a material subject,recording of a unitary authenticator of the material subject on the server system in association with the message to be transmitted.

In a phase of message recovery by each recipient, it is proceeded to at least the following steps:acquisition by a device accessible to the recipient of at least one second image of an authentication area of a material subject,determination, in the second image, of singular points and descriptors of a singular area associated with each singular point, the descriptors being associated with each corresponding singular point,extraction, from the second image, of a second candidate unitary authenticator of the material subject,implementation of an alignment by means of the singular points and their associated descriptors, then comparison of the first and second images and/or of their respective unitary authenticators,implementation of a phase of authentication of the recipient identifier on the one hand and of the candidate unitary authenticator of the material subject with those associated with the message to be delivered and stored in the server system,in case of sufficient similarity between the first and second images or their respective unitary authenticators and matching between the recipient identifier recorded in the server system and the identifier of the candidate recipient, transmission to the recipient of the message associated with its identifier and with the generator material subject.

The step of determination in the first image of singular points and descriptors may then occur either in the recording phase or in the recovery phase or out of these phases.

In the sense of the invention, the micro-texture of the authentication area is intrinsic and random in that it results from the nature itself of the authentication area of the material subject. In a preferred embodiment of the invention, each material subject used belong to the subject families comprising at least one authentication area having an essentially random intrinsic structure that is not easily reproducible, i.e. whose reproduction is difficult or even impossible in that it results notably from a non-predictable process at the observation scale. Such an authentication area with an essentially random and non-easily reproducible continuous medium structure corresponds to the “Physical Unclonable Functions” (PUFs) as defined in particular by the English-language publication Encyclopedia of Cryptography and Security, Edition January 2011, pages 929 to 934, in the article of Jorge Guajardo. Preferably, the authentication area of a material subject according to the invention corresponds to an intrinsic physical unclonable function, called “Intrinsic PUF” in the above-mentioned article. The inventors take advantage of the fact that the random nature of the microstructure of the authentication area is inherent or intrinsic to the nature itself of the subject because resulting from its mode of elaboration, development or growth so that it is not necessary to add to the authentication area a particular structure, in particular a printing, or an engraving.

However, if the microstructure itself of a material subject may be used to determine a unitary authenticator, it may also be used, but also for example the marks leaved by the interaction of an engraving, a printing, an embossing, a stamping with the material subject in its random character (for example: paper with inkjet printing, wherein the shape of the drops deposited on the paper may be sufficient).

According to a feature of the invention, in the message recording phase, at least one identifier of each recipient in the message to be transmitted is recorded on the server system and, in the recovery phase, an identifier of the recipient is implemented jointly with the authenticator of the candidate material subject and the message is then transmitted to the recipient only in case of positive authentication of these latter by the server system or any other device. In the sense of the invention, an identifier is a data or a set of data that allow identifying a recipient or a sender while offering a relatively high degree of certainty that the identity of the latter has not been usurped. Hence, an identifier may be, for example, a biometric data or the combination of a username with a password known by the only person that holds the identifier.

The unitary authenticator may be the acquired image(s) itself (themselves), an image extracted or derived from it (them), or any set of digital data deduced from the acquired image(s) and characterizing this (these) latter. For example, local invariant descriptors of the local features computed from the acquired image(s) that contains (contain) the structural or micro-structural spatial information of the authentication area.

According to another feature of the invention, previously to the message recovery phase, information relating to the material subject whose image of the authentication zone will have to be used for the recovery of the message is transmitted to each recipient. In the sense of the invention, the information relating to the material subject may be location information, position information, or information such as instructions allowing the recipient to know what it has to do to be in presence of the material subject.

According to a variant of this feature, the information relating to the material subject comprises at least one piece of information for geolocating the material subject.

According to another feature of the invention, previously to the message recovery phase, the material subject is delivered to each recipient.

According to another feature of the invention, the recipient is notified by a device of the availability of a message for it, or by any other means. Such a device may then either receive, in so-called “push” mode, a message informing it of the availability of a message to be recovered, or regularly check, in a so-called “pull” mode, the potential availability of a message to be recovered. The notification may also be a contextual display within a framework of an augmented reality visualization.

According to still another feature of the invention, in the message recovery phase, the message is visualized by each recipient in association with an image of the material subject and/or the environment thereof. It is then possible to use for that purpose any type of augmented reality techniques.

According to a feature of the invention, in the recording phase, the determination of a unitary authenticator of a material subject is performed by means of a given algorithm and, during the recovery phase, a mobile communication device is implemented, which comprises image acquisition means and computation means and which is adapted to implement the same algorithm for determining the second unitary authenticator, the candidate unitary authenticator of a material subject.

According to a feature of the invention, in the recording phase, the unitary authenticator of a material subject is an authentication image and, during the recovery phase, a mobile communication device is implemented, which comprises image acquisition means and computation means and which is adapted to implement a given algorithm for the alignment or even for the comparison of the authentication image and of the verification image.

According to a feature of the invention, in the recording phase, the unitary authenticator of a material subject is an authentication image and, during the recovery phase, a mobile communication device is implemented, which comprises image acquisition means and computation means and which is adapted to transmit to a server system the verification image, in a secure manner or not, without making locally the alignment or comparison computations.

According to a feature of the invention, the phases of alignment, determination of a unitary authenticator and comparison are performed partly in a mobile communication device that comprises image acquisition means and computation means and partly in at least one server system.

Of course, the various features and variants of the invention may be associated with each other according to various combinations, in so far as they are not exclusive from each other.

It appears that the invention proposes in particular a messaging system that allows a sender (designated by an identifier) to send a digital content to one or more recipients (designated by one or more identifiers), the content being associated with at least one material subject (each designated by at least one unitary authenticator).

