Symmetric encryption device, and method used

SYMMETRIC ENCRYPTION DEVICE AND PROCEDURE USED

DESCRIPTION OBJECT OF THE INVENTION

The object of the present invention is a symmetric encryption device that allows information to be protected, either between two extremes, unicast mode, or where appropriate, between a limited group of users, multicast mode. Said device is connected to a computer through the RJ45 connector, the encryption device emitting the information already protected through a second RJ45 connector. The device uses a key exchange algorithm based on the calculation of inverse modulo one integer and contains a radio frequency module that communicates with another device consisting of a keyboard that can optionally include an LCD screen that allows users to enter sensitive data independently from the computer. In turn, the encryption device, through radio frequency, can interact with the sensitive data input device by sending information to the display for the user. Finally, the encryption device can use the radio frequency system to communicate with other mobile devices, generally telephones.

BACKGROUND OF THE INVENTION Different types of information encryption devices are known in the current state of the art, almost all of them based on communications between a sender and a receiver exclusively. Thus, document ES 2245305 is known which describes a public key encryption system employing a public key / private key pair as well as a method and apparatus for increasing authentication security using a stronger biometric authentication system. to manipulation and characterized by generating a public key / private key pair from a biometric record, using the private key after prior biometric authentication. In this encryption system, there is no claim regarding the encryption process in any of the contemplated modalities, Unicast or Multicast, but it does mention the reliability of the private key, after biometric authentication.

ES 2094135 focuses on a communication network with key distribution over an analog architecture of subscriber networks, although it also mentions digital communications. The system is made up of several devices, an encryption unit that obtains the encryption codes from a code distribution authority and an element for managing the allocation of said encryption codes, also mentioning that the code allocation management module You can connect to an authentication server to manage a list of certificates. In this case, the document does not contemplate a single security element either for an entire local network, or for local networks joined virtually or, if necessary, to Multicast networks.

Document ES 2130570 mentions a system and apparatus for encrypting / decrypting data blocks. The system uses the so-called cipher blockchain method (CBC) and whose device is linked to a block-based algorithm, XOR operations and the use of shift registers. In this case, again, no mention is made of encryption in Multicast environments or a device specially designed to encrypt simultaneously in both scenarios, Unicast and Multicast and that distributes a symmetric key to a whole group of users through an inverse calculation. modulo an integer. Nor does it make any reference to special protection mechanisms for the device such as anti-opening, anti-displacement mechanisms, etc.

Document ES 2158081 refers to a cryptographic system and method with a key deposit feature and more specifically to the generation, certification, storage and secure distribution of cryptographic keys used in cryptographic communication systems and more particularly, the document refers to a cryptographic key deposit and public key certificate management system executed by a self-certification chip device. The non-relation with the invention described in this document is evident.

Document ES 2221932 describes a cryptographic apparatus with double direct feed function, that is, it refers to cryptographic apparatuses, and more particularly to a cryptographic processor that uses a double direct feed arrangement to implement an encryption algorithm having a complementary property, in such a way that the investments at the input of the cryptographic processor can be detected at the output of the same. It is evident that the invention reflected in document ES 2221932 is not related to the device and method described in this invention.

Document ES 2262210 contemplates a system for secure transmission of data signals, more specifically, a system comprising means for encrypting data signals using a first key, means for transmitting encrypted data signals to subscribers, means for decrypting the encrypted data signals on each of the subscribers using the first key, means for encrypting the first key using a second key, said second key being different for each group of subscribers who have a common interest in a type of program, means for transmitting the first encrypted key to all subscribers, means for decrypting the first encrypted key for each of the subscribers using the second key . In this case we can see that a Multicast scenario is contemplated where there is a second key for each group of subscribers. Obviously, the bandwidth efficiency of this system is better than a Unicast-oriented system but the security is very low because the key cannot be recalculated immediately after adding or removing members from each group. Furthermore, it does not use authentication mechanisms such as those used in the central device of the present patent.

Document ES 2274557, system for providing encrypted data, system for decrypting encrypted data and method for providing a communication interface in said decrypting system, refers to a system for protecting information for content players that in turn contain a decryption system. also contemplated in the patent. In our case, the device is a generic and symmetric encryption / decryption device with symmetric key calculation and distribution used to encrypt any content coming from a computer and broadcast it in a Unicast or Multicast scenario and where there are secure authentication mechanisms for the different group members, Unicast or Multicast. Thus, none of the documents located in the current state of the art describe a system like that of the invention, consisting of a symmetric key encryption, calculation and distribution device, simultaneously oriented to Unicast and Multicast environments, consisting of an element anti-tamper protection that includes various sensors for opening detection and unauthorized transfer, It contains a method of analysis of the information coming from the computer and has several standard and proprietary encryption methods.

DESCRIPTION OF THE INVENTION

An object of the present invention is an information encryption / decryption system that allows operating in two modes: Unicast or Multicast.

This encryption system consists of a symmetric encryption device valid for Unicast and Multicast environments and which has two RJ45 connectors, at least two USB connectors, at least one bluetooth device and at least one WiFi device. The device also has a radio frequency module that includes the 433MHz, 860MHz, 2.4GHz and 5GHz ISM bands, depending on configuration. The encryption device is covered by a metal casing that has strategically placed bolts that press switches placed on the electronic circuit of the device. These switches detect an unauthorized opening attempt. It also contains infrared diodes to detect the opening of the device cover.

The encryption device connects to the computer through one of the RJ45 connectors. The device's other RJ45 connector connects to the data network, either an intranet or directly to a router for Internet access.

Once the device is connected, the data that comes from the computer through the Ethernet connector is interpreted by the encryption device and, if necessary, said data is encrypted and forwarded through the device's Ethernet output port to the local network or to the Internet.

As it is a symmetric encryption device, it is evident that the information sent must be decrypted by an identical unit at the destination and connected in the same way to the destination computer.

It is also possible to connect this encryption device as an independent element of a local network and that is capable of encrypting and decrypting all the outgoing and incoming information on the local network.

The device has two RJ45 connectors that can correspond to two different IPv4 addresses or, where appropriate, that device can have a single IPv4 address. In the first case, the device obtains the information to be encrypted from the computer, acting as its "gateway", the figure and then forwards it through the second IPv4 address. In the second case, the device obtains the information from the computer, the number and forwards it through the second connector, being able to use the same IPv4 address as the computer in that case since it acts as a bridge between the computer and the network Exterior.

In Unicast environments, the device can encrypt in a standard way using a standard symmetric algorithm, for example AES, and using a signature integer modulo-based inverse algorithm. In the case of Multicast environments, the device can act both as a key server and / or service or as a receiving node for encrypted Multicast information using the algorithm based on the calculation of inverses that is explained in subsequent paragraphs.

In a more detailed description, the device contains an electronic board formed by a microprocessor as a central computing element. The anti-opening mechanism blocks the device, invalidating its use. For this, it consists of a 9-volt battery that feeds the anti-opening system at all times and that allows you to delete information contained in the microprocessor, additional memories or even the destruction of these elements, as appropriate, as well as encryption keys. The anti-opening mechanism is formed by a series of strategically arranged infrared diodes, capable of detecting a light variation compatible with the opening process, the signal being saturated in the event of such opening. There is also an additional module with a motion and acceleration sensor to avoid moving the device without prior permission. This module, after the aforementioned, can be deactivated for a certain time through software. Not so the light detection mechanism. The electronic board of the device has four buttons that are activated by the metal casing. When it tries to be removed by unauthorized personnel, as soon as one of the buttons is in the open state, the central microprocessor will detect the event and invalidate the device.

In Multicast mode, with the device acting as a key and information server, clients / users of the Multicast group can also share information among themselves and authenticate either against the server or among themselves. All this without consuming a high bandwidth, with which, the system is suitable for any computing environment, from those microcontrollers with low computing resources to the most powerful existing computers.

Thus, the device is capable of encrypting information from a computer or even from an undetermined group of computers and returning said information to each of said computers so that it can be sent by email or stored where required.

A single device like the one mentioned above allows encryption / decryption of messages within an intranet. If you want certain information to circulate between different intranets or corporations even in a different geographical area, the other end must have a device with the same characteristics. The secret information will be adapted so that that external device can decrypt the source information. The encryption device can also obtain sensitive data from a remote computer, located anywhere in the world and connected to the Internet. This can be used, for example, for banking operations or those in which it is necessary to enter certain information and ensure that such information will not be obtained through any virus within the remote computer or other type of attack that seeks to obtain sensitive information related to the bank transaction or any other type of transaction entered into the remote computer. Thus, the device consisting of a keyboard plus an LCD display as user interfaces, can be connected through a USB or bluetooth port. This keyboard + LCD device allows the information to be encrypted by means of the symmetric encryption algorithm, previously calculating the symmetric key sent by the key server device through a private integer x¡, which the keyboard + LCD device previously distributed also has by the key server. This information is sent through the user's computer to the encryption device, which also acts as a key server, located in a data center, for example. The sensitive information that the user needs to enter in her computer will be typed through the keyboard arranged for it and shown in real time on the LCD display. The keyboard + LCD device sends this sensitive information plus the rest of the necessary information to the encryption device located elsewhere on the Internet. In this way, any operation that requires the entry of data such as bank accounts, etc. it will be protected and sent to the encryption device.

In the case of Multicast environments and, optionally in Unicast mode that require real-time information protection, the following algorithmic processes are carried out.

The process of protecting the Multicast information used by the device (although it is also valid for a Unicast environment) for a group of users is as follows. The information that is sent corresponding to the session key, which the other members of the system have to retrieve, does not require the use of complex calculations, but instead uses the calculation of inverse modulus an integer, both to construct the information to be sent. , so that each user (with a device like the one of the present invention or through corresponding software) retrieves the original information that hides this information that is sent.

The algorithm used here allows a group of users to access secret information, in real time, with the sending of a single message by the server, said secret information being retrieved by users from certain private information predistributed through a secure channel (using a standard encryption algorithm for this private information predistribution process) using the same device of the present invention. The scenario for which this scheme is proposed is as follows. They are intended to establish secure communications within a restricted group. The relevant elements of this scenario are the following,

• A central server, which we will refer to as a key server, that controls the keys that allow secure communications.

• The users. That they can join the group or leave it at any time.

The device, acting as a key server in the Multicast environment, will perform a series of calculations and distribute the session key to the corresponding Multicast or Unicast group. Thus, the key server will perform the necessary process to compute three large prime numbers, named g, m, and p. To get myp, we use the formula p = q^* m + 1, also knowing that m divides p - 1. Subsequently, we find g₁ as the generator of an integer ring modulo p, knowing that g will be between 1 and p - 1. Therefore, we already have the necessary process calculated by the key server, in this case, the device of the present invention.

An additional problem regarding the maintenance of group privacy occurs when there is a new member, or one of the members withdraws under any circumstance. In the first case, for the addition of a new member, the Multicast system must take into account that that member must have a secret key and, therefore, the server will recalculate the group key again. This is done through an efficient process that does not impair communications performance.

In the case that a member is registered or unsubscribed, there is the problem that we must ensure that said member cannot access the old session key or, respectively, the new key using the secret key that it has.

We know that each user is assigned private predistributed information. This information will be called x¿, being a large prime number. We define δ = k + m such that δ <x¡ for all x¡.

The key server computes r = g^k mod pyu = δ^'1 mod L with L = Γ7χ, and sends the data to the group members.

Thus, each member of the group receives u and calculates u ¹ mod x¡ = 5 since u mod L = δ u δ = 1 mod L u δ = 1 mod x¡

So we can conclude that we have a system of congruences of the form: u δ 1 mod xi

u δ 1 mod x₂

u δ 1 mod x. n

And we obtain a unique solution since δ <x¡ for all x¡. Once δ is obtained, the user has to calculate g⁵ mod p (with public g and p).

Therefore, when a new user (consisting of an electronic device such as the one mentioned in the present invention) joins the group, the system is then refreshed with a new g^k mod p including the private information of that new user in the calculation of the module such that U = L ^* x_{i +}i where x_{i +}i denotes the private information of the new user. Instead, if a user leaves the group then L is recalculated as shown below,

where x¡ denotes the private information of the user leaving the group. And then it refreshes with a new calculation of g^k mod p for a new value k.

Both g and p are public values ​​that anyone can know. Similarly, u is a value that is sent to the medium. However, by constructing our protocol, retrieving the value δ that allows us to access the session key, g^k mod p needs to know one of the factors x¡ of the integer L.

The algorithm shown above also has authentication mechanisms for all devices participating in secure communication. It should be noted that the authentication process, both in Unicast and Multicast mode, does not use any digital signature mechanism, so we avoid the use of public key cryptosystems since they require important computational requirements both in time and resources, which It is not suitable for most microcontrollers such as PICs, Atmel, ARM architectures in general, etc. Thus, the method used by the device of this invention is especially interesting for microcontrollers or microprocessors with very limited resources where the use of said resources is important for other more priority tasks and where authentication is also necessary.

In any secure communication system, group members must trust each other. This trust is generated from the calculations necessary to verify that the member on the other side is really who he claims to be. Therefore, in this section we will see how any member of the group is certain that the member who sends the keys is the key server and, on the other hand, how one member can identify the other.

In order for the devices of the users of the multicast group to be certain that the device that is acting as the information and key server is really who it claims to be, the following procedure is followed. Let a random number be generated by the server device such that a <x, for all / from 1 to n. The server calculates s = (cf)^'1 mod L where g^fc is the distributed key and L = Γ7χ ,. Also compute h (a) where h is a secure hash function, for example, using SHA-2. The server device, when it sends the parameter u, which is the refresh message and from which g is obtained^k mod m, adds the information (s * a, h (a)) that will allow the target device to authenticate the origin of u.

Thus, when the destination device receives the message (u, (s * a, h (a)), it calculates r = g^fc mod m using x, as we have seen previously.

It also calculates s using its private number x, and finally gets h (a) comparing that h (a) with the one sent by the key server. If both are the same, authentication succeeds. If a user with the device /^', wants to authenticate the user with device j of the group, the device uses the protocol indicated below. The user /^', holder of χ ,, wants to authenticate user j, holder of ticket x¡. To do this, we proceed with the following algorithm:

one . The user / randomly chooses t such that 1 <t <m and sends it to the server.

2. The server calculates inv = f¹ mod L and return it to the user /^'.

3. User i sends user j, (inv, g mod m).

4. User and calculate <img file="WO2014167161A2_D0001.tif" /> sending the user /^', the pair (ft, g&gt; q).

5. User / calculate

P¡ = t {g^x mod m = t^*g^xjxi mod m so that user i positively authenticates aj as long as it is true that, βί = βί

In this way, we have a secure, real-time, plug-in system with server and user authentication mechanisms.

EXPLANATION OF THE FIGURES

Figure 1 shows the different components of the device. Figure 2 shows a schematic of the global system in Unicast communication on the Internet. Figure 3 shows a schematic of the global system in a local network environment.

Figure 4 shows a schematic of the global system in a multicast communication.

Figure 5 shows a system configuration using two RJ45 connectors, an IPv4 address and bridge mode configuration.

Figure 6 shows a system configuration using two different IPv4 addresses for each RJ45 connector in a local area (LAN) environment.

Figure 7 shows the interaction between the device and external elements.

Figure 8 shows the use of the keyboard + LCD device to remotely enter sensitive data that will reach the encryption device.

PREFERRED EMBODIMENT OF THE INVENTION

In view of the figures, a preferred embodiment of the proposed invention is described below.

Figure 1 shows the different components that are part of the symmetric encryption device (1) valid for Unicast and Multicast environments, comprising:

- A central microprocessor (1).

- Two RJ 45 connectors (2) and (3).

- An anti-opening protection module (4).

- Some external communication ports (5), (Bluetooth, USB, RF). - A 9V battery (6) that supplies the system to the anti-opening system and the microprocessor. The anti-opening mechanism (4) blocks the device (1) invalidating its use. To do this, it consists of a 9-volt battery (6) that feeds the anti-opening system (4) at all times and that allows you to delete information contained in the microprocessor or destroy it, as appropriate, as well as encryption keys. The anti-opening mechanism is formed by a series of strategically arranged infrared diodes capable of detecting a light variation compatible with the opening process, the signal being saturated in the event of such opening. There is also an additional module with a motion and acceleration sensor to avoid moving the device without prior permission. This module, after the aforementioned, can be deactivated for a certain time through software. Not so the light detection mechanism. The electronic board of the device has four buttons that are activated by the metal casing. When it tries to be removed by unauthorized personnel, as soon as one of the buttons is in the open state, the central microprocessor will detect the event and invalidate the device.

Figure 2 shows a schematic of the global system in a Unicast communication on the Internet that consists of using the encryption device (1) in which one of its RJ45 connectors is used to connect to a computer (9), while the other RJ45 connector is used to connect to the data network, either an intranet or directly to an Internet access router (8). Figure 3 shows a schematic of the global system in a local network environment, in which an encryption device (1) and a series of devices, such as mobile devices (1), are connected to an Ethernet hub (10) or similar. 1) and various computers (9), making the connection to the data network, either the Intranet or the Internet (8) through the Ethernet hub (10).

Figure 4 shows a diagram of the global system in a Multicast communication, where several Multicast groups (1 1), (12) and (13), and an encryption device are connected on the data network or the Internet (8). (1), which acts as a key server for each Multicast environment, and optionally as an information server in Multicast environments.

Figure 5 shows a system configuration using two RJ45 connectors, an IPv4 address and bridge mode configuration, where a first RJ45 connector (1 .1) of the encryption device (1 .1) connects to a computer (9 ), while the second RJ45 connector (1 .2) of the encryption device (1.2) connects to the Internet (8).

In figure 6, a system configuration is shown using two different IPv4 addresses (a) and (b) for two RJ45 connectors in a local area (LAN) environment, where an Ethernet hub (10) or similar is connected to the encryption device (1) with two connections through the two RJ45 connectors (1.1) and (1.2), a series of mobile devices (1 1) and a series of computers (9).

In figure 7 the interaction between the device and the external elements is shown, where a set (14) formed by a keyboard and a screen can be connected to an encryption device (1), also a mobile device (15) and / or or a generic radio frequency communication device.

Finally, figure 8 shows the use of the keyboard + LCD device (14) to remotely enter sensitive data that will reach the encryption device (1) through an Internet environment (8).