The present invention relates to a marking device, a system, a method and a decryption device according to the preambles of the independent patent claims.

Marking devices, such as stamps, label printers, and the like are well known in the art and are popularly applied in many fields of daily life. In particular stamps are often used to add a certain layer of security to files, signed documents, such as business contracts, or the like. For example a stamp combining a company logo and a date may lead to the perception that a document is genuine. Each document bears source values which describe the origin or the context of a document, such as a date, a name, initials of a name, or the like.

However, the tools needed for forgery of stamps, such as high-quality scanners, printers, and image editing software, have become widely available and affordable. This has significantly reduced the security of conventional stamps. For example, a stamp could be scanned from one document bearing source values referring to it, and scanned and printed as part of a forged document bearing different source values, e.g. for forging the date when a contract was signed.

The present invention therefore aims at alleviating these shortcomings by adding an additional layer of security to a document which has been marked with a marking device, such as a stamp. Particularly, the invention aims at providing a means verifying the validity of the stamp as relating to the context of the document.

The object of the present invention is solved by a marking device with the characterizing features of the independent patent claim. Preferred features of the invention are encompassed by the dependent claims.

The invention concerns a marking device for generating a marking on a carrier medium or earner surface, the marking device comprising an input means adapted to input a first value and a printing device which is

- optionally adapted to print a first marking element comprising a first value onto the carrier medium or carrier surface,

- and adapted to print a second marking element comprising a second value onto the carrier medium or carrier surface.

It is provided, that an encryption device is provided, which encryption device comprises an encryption means equipped with an encryption function to encrypt the first value in order to generate the second value.

Optionally it can be provided, that the printing device is adapted to at least partially allow manipulation of the first value, wherein said manipulation of the first value may in particular be affected by input means.

Optionally it can be provided, that the printing device comprises or is a stamp device, a relief printing device, or a cutting device.

Optionally it can be provided, that the printing device comprises a first printing means and a second printing means.

Optionally it can be provided, that the encryption device comprises or is a mechanical encryption device, in which the encryption means comprises mechanical means, such as rotors, wheels, spokes, cogs, or the like, in order to encrypt the first value. Optionally it can be provided, that the encryption device comprises or is a digital encryption device, in which the encryption means is provided by a microcontroller, a processor, or a computer, which is adapted to encrypt the first value.

Optionally it can be provided, that the encryption means provides a bijective relation between the first value and the second value and/or in that the encryption means provides a non-bijective relation between the first value and the second value.

Optionally it can be provided, that the encryption function is a mathematical function or algorithm.

Optionally it can be provided, that the first value and/or the first marking element is preferably derived from the document to be marked and comprises or is one or more of the following: a date; a combination of letters, such as a personal name, the initials of a personal name, a company name; a logo; a derivate of the above, such as the number of strokes in a Chinese character or properties relating to the type of strokes used in a Chinese character, or any similar characterization in any non-latin alphabet; or the like.

Optionally it can be provided, that the second value and/or the second marking element comprises or is one or more of the following: an URL; a hash value; a machine readable code, such as a bar code, a OR code; a series of alphanumeric or non-alphanumeric characters, including characters from non-latin alphabets; or the like.

Optionally it can be provided, that a marking device identifier is provided, which marking device identifier preferably allows linking of the marking device to the encryption function.

Optionally it can be provided, that that the first printing means and the second means are a stamp device.

Optionally it can be provided, that the first value and/or the first marking element is a date, an initial of a name, or a derivate an initial of a name, such as the number of strokes in a Chinese character or properties relating to the type of strokes used in a Chinese character, or any similar characterization in any non-latin alphabet, and/or a company logo, Optionally it can be provided, that the second value and/or the second marking element is an URL containing a hash value as an alphanumeric chain of characters, and

Optionally it can be provided, that the encryption device is a mechanical encryption device.

Optionally it can be provided, that the printing device comprises or is an electronically driven printer.

The invention concerns a decryption device for encrypting a first value or for decrypting a second value encrypted by a marking device, in particular by a marking device according to the invention.

The invention concerns a system comprising a marking device according to the invention and a decryption device, wherein the decryption device is adapted to read or receive the second value, and wherein the decryption device is adapted to decrypt the second value in order to generate a decrypted value, and/or wherein the decryption device is adapted to read or receive the first value, and wherein the decryption device is adapted to encrypt the first value in order to generate an encrypted value.

Optionally it can be provided, that the decryption device is a computer connected to a network, optionally comprising a biockchain.

The invention concerns a system comprising at least a first marking device and a second marking device, wherein the first marking device and the second marking device each are a marking device according to the invention, wherein the first marking device and the second marking device are equipped with different encryption functions.

The invention concerns a system comprising a plurality of marking devices, preferably more than 10, more preferably more than 100, according to the invention, wherein each marking device is equipped with a unique encryption function.

The invention concerns method to verify the validity of a document comprising the steps in the following order

- input a first value, - optionally marking the document using a marking device by printing a first marking element comprising a first value

- marking the document using a marking device, in particular a second marking device, by printing a second marking element comprising a second value, wherein the second value is encrypted from the first value by an encryption means, preferably marking the document using a marking device according to the invention,

and

- reading the second value by or forwarding the second value to a decryption device,

- decrypting the second value using the reversed encryption function to form a decrypted value, and

- comparing the first value, which is derived from the document, with the decrypted value,

or

- deriving the first value from the document and sending the first value to a decryption device,

- encrypting the first value using the encryption function to form an encrypted value, and

- comparing the second value on the document with the encrypted value.

Optionally it can be provided, that the first value is a document identifier value, which is derived from the document and which allows identifying the marked document.

Optionally the method further comprises the step of comparing the first value and/or the second value with the document identifier value on the document.

A preferred embodiment of the invention contains the following steps:

- Input a first value, wherein this first value may be or is derived from the

document to be marked. The first value may be derived from a document identifier value or may be a document identifier value. The first value may be entered via input means of the marking device. - Marking the document using a marking device by printing a marking element comprising a second value, wherein the second value is encrypted from the first value by an encryption means.

- Reading the second value by or forwarding the second value to a decryption device,

- decrypting the second value using the reversed encryption function to form a decrypted value, and

- comparing the first value, which is derived from the document with the

decrypted value,

or as an alternative;

- Deriving the first value from the document and sending the first value to the decryption device,

- encrypting the first value using the encryption function to form an encrypted value, and

- comparing the second value on the document with the encrypted value.

According to this embodiment the first value may or may not be printed on the document.

A marking device of the present invention may comprise a printing device which is adjusted to print at least a first marking element and a second marking element onto a surface or a medium. The marking element(s) may comprise textual, numeric, or graphic information.

The first marking element may contain a first value, while the second marking element may contain a second value. According to the invention, an encryption device may be provided which may use an encryption means for encrypting the first value in order to generate the second value. The second value may be an encrypted version of the first value. The encryption device may be adapted to encrypt the first value, and to output the second value. The encryption means may be equipped with an encryption function which can be applied to the first value. Thus, the first value and the second value will be in a direct relation which is imparted by the encryption function. For example the first value may be or may be derived from a date, a name, such as the name of the user of the stamp or the name of the addressee of the document, initials of a name, or the like, or a derivate of all those, such as the number of strokes in a

Chinese character or properties relating to the type of strokes used in a Chinese character, or any similar characterization in any non-latin alphabet, which may be individually adjusted on the marking device. In particular the first value is or is derived from a document identifier value, like a document number or one of the above mentioned values, which allow identifying the document marked with the first and second value. The first value may also comprise or be a non-unique or unique identifier of the stamp. Therefore, an input means may be provided which may serve the purpose to manipulate or alter the first value. Such manipulation may for example comprise setting the correct date or setting the name of the current user of the marking device, or setting the name of the addressee of a document. The input means may for example comprise wheels, buttons, or the like, in order to mechanically manipulate the first value. Alternatively, the input means may also comprise electronical input means, for example a touchscreen, a keypad, or the like. A first value which is derived from the document may be information or an abbreviation of information of the document, like a name or the initials or the first three letters of a name and/or an additional information like the date of the document, a document number or an abbreviation of the date of the document or the document number.

Subsequently, the first value may be encrypted by the encryption means by applying the encryption function to the first value. According to the invention, multiple alternatives for the embodiment of the encryption means are possible. In particular, the encryption means may be a mechanical encryption means, an electromechanical means, a digital encryption means, or a combination of these.

According to the invention an encryption device is provided. In particular the marking device comprises the encryption device. The encryption device may be connected to the printing device. The encryption device may be a part of the marking device. The encryption device may also be an external computer, or the like, at least detachably connected to the printing device. In case the encryption means is or comprises a mechanical encryption means, it may comprise mechanical means, such as rotors, wheels, spokes, cogs, or the like, in order to encrypt the first value. The mechanical encryption means may move parts of the stamping device in order to apply the encryption function. Such mechanical encryption means are known in the art. Examples include but are not limited to: a rotating axis with perpendicular extruded pins (for example, the pins touch bars that move parts of the printing device); a rotating axis with holes (for example, feathered bans move in the holes which in turn moves parts of the printing device); a non-moving flat surface with perpendicular extruded pins (for example, bars move past the surface, and some of the bars interact with the pins, which in turn move parts of the printing device); a non- moving flat surface with holes (for example, some bars move inside the holes, while some other cannot which in turn moves parts of the printing device).

In case the encryption means is or comprises a digital encryption means, the marking device will possibly comprise a microcontroller adapted to encode the first value. The microcontroller may be a part of the marking device, or the microcontroller may be an external device connected to the marking device. The encryption process may be initiated by a signal received by a sensor, such as a mechanical signal or an optical or a digital signal. Subsequently, the microcontroller may read or detect the first value, preferably by detecting the positioning of the respective parts of the printing device. Such detection can be achieved by potentiometers, which is particularly preferable if the marking device is a stamp with mechanical input means. Detection of the first value and transformation into an electrical signal may be achieved using transformation means. After having received the first value, the encryption means may apply the encryption function to the first value in order to generate the second value.

In a specific embodiment of the invention, the printing device may comprise a first printing means and a second printing means. The printing means may be of the same or of different nature, For example, the first printing means may be a stamp device, while the second printing means may be an electronically controlled or driven printer. However, in another example, the first printing means and the second printing means may both be a stamp device. The first printing means and the second printing means may also both be an electronically controlled or driven printer. The second value may be an encrypted or encrypted form of the first value. The second value may be printed using the printing device in a plurality of embodiments. The second value may be in an intelligible form for a human, for example an URL containing a specific value or hash. The second value may also be a chain of alphanumeric characters, non-alphanumeric characters, and characters from non-latin alphabets. Alternately, the second value may also be in a typically non-intelligibie form for a human, for example in a machine-readable form as a QR code, a barcode, or the like. The second value may additionally be linked to specific information about the used encryption function. Thus, the second value may additionally comprise a marking device identifier. The marking device identifier may allow identifying the encryption function that has been used for encrypting the first value. While the marking device identifier may be a part of the second value, the marking device identifier may also be provided as a separate value, for example as a third value. The marking device identifier may also be a part of the first value.

According to the invention, a marking device identifier may be provided. Thus, the marking device identifier may be a part of the marking device, in particular a part of a printing device. The marking device identifier may be adapted to output a marking device identifier. In particular, the printing device may be adapted to print a marking device identifier.

The encryption function may in particular be a mathematical function, a series of mathematical function, an algorithm, or the like. Encryption functions to be used in combination with the marking device of the present invention are well known to one skilled in the art and may particularly depend on the specific embodiment of the used printing device and encryption device.

The encryption function may be a bijective function. This means that by using the encryption function the first value can be encrypted to form the second value. A reversed form of the encryption function, i.e., the decryption function, may be used to decrypt the second value to form the first value again. In case the encryption function is a bijective function, the decryption function results in one single solution for the first value.

In an alternative embodiment, the encryption function may be a non-bijective function. This means that by using the encryption function the first value can be encrypted to form tiie second value. A reversed form of the encryption function may in this case not be used to decrypt the second value to output the first value again. In case the encryption function is a non-bijective function, the decryption function does not result in one single solution for the first value. In case of a non-bijective function, it is also possible that the encryption function cannot be reversed, or that application of the reversed encryption function does not deliver any solution. In another alternative embodiment, an electromechanical rotor cipher device, such as the well-known Enigma machine, may be used as encryption means. In such an encryption means, first values are inputted on a keyboard, second values are printed by the device.

The invention may further relate to a system comprising a marking device according to the invention with a decryption device. The decryption device may be an external device which may be adapted to read or to receive a value which optionally might be printed by the marking device. This value may preferably be the first value and/or the second value, optionally along with a further value, such as the value of the marking device identifier. The first value is preferably a value derived from information of the marked document and in particular a document identifier value. The decryption device may also be part of the encryption device, wherein the encryption mode and the decryption mode may be switched using a switching means.

The decryption device may further be adapted to encrypt the genuine first value to form the second value using the encryption function or it may be adapted to decrypt the second value to form the first value using a reverse encryption function, or a decryption function. Thus, the decryption device needs to apply the correct encryption function. Alternately, the decryption device may also apply a decryption function, depending on if the encryption function is bijective or non-bijective. Correct selection of the encryption function may be achieved by using the marking device identifier, which may be part of the first value or the second value, or which may be a separate value, for example a third value.

Optionally, one or a plurality of values, in particular the first value, the second value, and/or the third value may be stored in a centralized or a decentralized database. Such decentralized database or storage may particularly be a blockchain, for example the bitcoin blockchain.

The invention may further relate to a method to verify the validity of a document. As used herein, the expressions“first value" and“second value" may relate to values that have been printed onto a surface using the marking device. The first value may be the same value that has been input by the user. The first value may also be a derivative from the value that has been input by the user

In a method for verifying the validity of a document, the values on the document, i.e, in particular first and second value may be decrypted or encrypted in order to form a decrypted or encrypted value.

The genuine first value may be encrypted to form an encrypted value. The encrypted value may be compared to the second value on the document. If the encrypted value and the second value match, the document may be considered genuine.

The second value may be decrypted in order to form a decrypted value. The decrypted value may be compared to the first value, which is derived from the document. If the decrypted value and the genuine first value match, the document may be considered genuine.

Further features of the invention will become apparent from the specific embodiments of the invention which will be described hereinafter. The following description is solely used to describe the invention in more detail by way of example. The features of the following examples are not meant to limit the scope of protection which is solely conferred by the patent claims. Figures are used to illustrate the invention, in which;

Fig, 1 shows an illustration of a marking generated by a marking device according to a first embodiment of the invention;

Fig. 2 shows an illustration of a marking generated by a marking device according to a second embodiment of the invention.

If not otherwise indicated, the reference numerals in the figure refer to the elements marking 1 , first value 2, second value 3, additional value 4, URL 5, marking device identifier 6.

In a first embodiment of the invention, the marking device is a stamp, in which the printing device is a stamp device adapted to print a sequence of three letters (e.g., the first three letters of the user's name or the name of the author of the stamped document or the addressee of the document) along with a date. Said sequence of three letters along with the date together forms the first value. The first value may be manipulated and set by an input means, which in this exemplary example is provided as turning wheels for mechanically setting the first value. Thus, the value may for example be set to represent the current date on which the marking has been generated and the first three letters of the user's surname.

It has to be mentioned that the marking device described in this first embodiment may be a very simplified version of the actually used device - in particular with regards to the encryption means described hereinafter. However, it is thought that this simplified version is sufficient to illustrate the significant technical features of the invention.

The letters and numbers to be set are arranged on a set of independently movable first bands, each containing either the numbers 0 to 9 or 26 letters of the alphabet, respectively. Thus, in this application example, eight first bands containing numbers in order to display the date in the manner DD-MM-YYYY, wherein“D" stands for a digit of the day,“M" stands for a digit of the month and "Y” stands for a digit of the year.

Furthermore, the printing device of the present embodiment comprises three first bands each carrying 26 letters of the alphabet for printing said three letter combination. On the in total eleven first bands, the numbers are arranged in ascending order from 0 to 9, and the letters are as well arranged in an ascending order, i.e., from A to Z. In this embodiment, the first value is equivalent to the source value input by the user of the device, provided that the document is genuine.

Said first bands are conveyed by first rollers which can be manually moved in order to set the required date and the letters. The first rollers carry pins or teeth which translate their movement to second rollers, on which second bands having numbers and/or tetters are provided. In contrast to the first bands, the letters and numbers on the second bands are arranged in an arbitrary manner, i.e., preferably not in an ordered manner. By this means, the encryption function is generated, assigning each character on the first bands to a defined character on the second bands. Such process is also known as mono-alphabetical substitution. Thus, setting the letter sequence "ABC” as part of the first value, may translate into“4YS ^" as part of the second value. In this example, the encryption mechanism is used to encrypt letter "A” into“4", letter“B" into “Y" and letter "C” into“S". Encryption of the date is performed analogously, it is to be noted that numbers may be encrypted into letters and vice versa, or numbers may be encrypted into numbers and letters may be encrypted into letters.

In relation to the present invention the term "letters" may include characters of non-latin alphabets and/or non-alphanumeric characters.

Thus, the in total eleven characters of the first value (eight numbers of the date and three letters) will be encrypted into eleven characters of the second value using the described encryption mechanism. The encryption mechanism, or encryption function is bijective, which means that decryption of the second value using a reversed encryption function will result in one single solution for the first value.

In this example, the second value is linked to an URL allowing direct access to the validation function stored or calculated on a network-based server. The second value consists of a value formed of eleven characters. The value may be an alphanumeric or a non-alphanumeric value. In other embodiments, the value may comprise more or less characters. Besides the encrypted first value, a marking device identifier may be added to the second value, which allows reconstruction of the used encryption function. In this particular example, the marking device identifier adds one character to the eleven character value. The marking device identifier is a fixed value for a specific marking device.

An exemplary marking 1 generated by the marking device of the first embodiment of the invention is shown in Fig. 1. As above described the marking comprises a date and a sequence of three letters, representing the first value 2. The first value 2 can be arbitrarily selected by the user of the marking device. The second marking additionally comprises an URL 5 and a meriting device identifier 6.

During the marking of a document, the encryption function is used to encrypt the first value 1 in order to form the second value 3, which is an eleven character alphanumeric code, printed along with an URL 5 to access a website for validation of the marking 1. Additionally, the marking 1 may contain further information, such as an additional value 4 which in this example is a company logo. The additional value 4 is solely used for display purposes and does not influence the encryption process of the first value 2. The second value 3 is combined with a one-character marking device identifier 6, which is arranged directly in front of the second value 3.

The encryption function of the present example conveyed by the interaction of the first rollers and second rollers as part of the encryption means is as shown in Table 1 below for the specific example displayed in Fig. 1.

For validating the marking, the second value 3 may be fed into a decryption device, which in this example may be provided as a computer connected to a network.

Scanning of the second value 3 may for example be performed using a camera or a smartphone. The combination of the URL 5 and the second value 3 can be used to access a website where a decrypted value will be displayed. For displaying the decrypted value, the decryption device may apply a reversed encryption function to the second value 3, which in this example is in the form of a eleven character alphanumeric code. For selection of the correct encryption function, the decryption device employs the marking device identifier 6, which in this example is the character directly in front of the second value 3, in the specific example of Fig. 1 , the letter "x".

Thus, when URL 5 including the second value 3 is entered into an internet-based computer or a similar device, the decryption device may apply the following process to decrypt the second value 3 to form the first value 2:

- Detecting the marking device identifier 6,

- Selecting the encryption function based on file detected marking device identifier

6,

- Applying the reversed encryption function to the second value 3, and

- tputting a decrypted value based on the second value 3 in combination with the reversed encryption function.

The generated decrypted value may now be compared with the first value 2 of the marking 1, wherein the first value 2 can be derived from the marked document.

Comparison with the initial values on the physical document is a manual process in this embodiment. The comparison may be performed by a human or by a comparison means, for example conferred by a computer. Matching of the decrypted value and the first value 2 will indicate that the marking is valid. If the output decrypted value and the first value 2 differ from each other it is likely that the marking 1 has been forged. In the intended use of the marking device 1 there may be a convention how the document itself is linked to the first value 2, e.g., always use the initials of the recipient name.

In a second embodiment of the invention, the printing device comprises a first printing means and a second printing means. The first printing means is adapted to print the first value while the second printing means is adapted to print the second value. The first printing means is a stamping device, such as the one described above with the first embodiment of the invention. Thus, a date and a sequence of three letters can be selected as the first value. Input means are provided as turning wheels, by which the first value can be modified by the user of the marking device. The input means are connected to potentiometers which are adapted to detect a selected first value by means of the positioning of the turning wheels. The potentiometers are adapted to transform first value into an electronic signal. In alternative embodiments, other transformation means may be used for this transformation. Suitable transforming means are known to one having ordinary skiil in the art.

The now electronic information of the first value is forwarded to the encryption device which comprises encryption means in the form of a microcontroller. In this embodiment, the encryption device is an integral part of the marking device. In other embodiments, the encryption device may also be an external device. The microcontroller applies the encryption function to the first value in order to generate the second value. The encryption function may be a complex mathematical encryption algorithm. Such algorithms are well known to those having ordinary skill in the art. In this embodiment, the second value is in the form of a QR code or another machine-readable code. The marking device identifier may be a part of the algorithm used to encode the first value.

The second printing device of this embodiment is an electronically controlled printer which is adjusted to print the QR code generated by the encryption device onto a surface or an element, such as a document or a sticker. The QR code can now be read using a suitable device, which may be connected or may be part of the decryption device. For example, the QR code may contain an URL as information, by using which the marking may be validated as described in the first exemplary embodiment.

An exemplary marking 1 generated by the marking device of the second embodiment of the invention is shown in Fig. 2. As described above, the marking 1 comprises a first value 2 consisting of a date and a three letter code. The marking 1 further comprises a second value 3 in the form of a QR code, a marking device identifier 6 in the form of a alphanumerical code and an additional value 4.

Apart from an encrypted version of the first value 2, the second value 3 contains information of the marking device identifier 6. The encryption function of this

embodiment is non-bijective, meaning that the second value 3 cannot be used to recalculate the first value 2.

A device scanning the first value 2 and the second value 3 may be directed to a website connected to a device applying the encryption function to the first value 2 in order to generate an encrypted value. The device may further compare the second value 3 to the encrypted value. Validity of the document is likely, if the second value 3 and the encrypted value match.

In a third exemplary embodiment of the present invention, at least two marking devices according to the first embodiment are provided, wherein the two marking devices employ two different encryption functions. The marking device identifier is used to indicate the used encryption function, allowing the decryption device to select the correct encryption function for re-calculating the first value. In this specific embodiment, the marking device identifier may as described be the first character of the second value. Specifically, the marking device indicator of the first marking device may be V whereas the marking device indicator for the second marking device may be“3”. If a plurality of marking devices is used two or more marking devices may carry the same marking device identifier.