EP1611516A2 - Unite commandee par programme - Google Patents

Unite commandee par programme

Info

Publication number
EP1611516A2
EP1611516A2 EP04724981A EP04724981A EP1611516A2 EP 1611516 A2 EP1611516 A2 EP 1611516A2 EP 04724981 A EP04724981 A EP 04724981A EP 04724981 A EP04724981 A EP 04724981A EP 1611516 A2 EP1611516 A2 EP 1611516A2
Authority
EP
European Patent Office
Prior art keywords
program
controlled unit
memory
read
protection
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP04724981A
Other languages
German (de)
English (en)
Inventor
Werner BÖNING
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Infineon Technologies AG
Original Assignee
Infineon Technologies AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Infineon Technologies AG filed Critical Infineon Technologies AG
Publication of EP1611516A2 publication Critical patent/EP1611516A2/fr
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F12/00—Accessing, addressing or allocating within memory systems or architectures
    • G06F12/14—Protection against unauthorised use of memory or access to memory
    • G06F12/1458—Protection against unauthorised use of memory or access to memory by checking the subject access rights
    • G06F12/1483—Protection against unauthorised use of memory or access to memory by checking the subject access rights using an access-table, e.g. matrix or list

Definitions

  • the present invention relates to a device according to the preamble of claim 1, i.e. a program-controlled unit with a memory for storing data, and with a memory protection device for protecting the memory from read access by persons not authorized for this purpose.
  • Such a program-controlled unit is, for example, a microcontroller, a microprocessor, or a signal processor.
  • FIG. 6 The basic structure of such a program-controlled unit is shown in FIG. 6.
  • the program-controlled unit shown in FIG. 6 is designated by the reference symbol PG. It contains a CPU CPU, a memory device M connected to the CPU, and peripheral units Pl to Pn connected to the CPU via a bus BUS.
  • the CPU executes a program which is stored in the memory device M or in another memory device not shown in FIG. 6, which other memory device can be a further internal memory device or an external memory device provided outside the program-controlled unit PG.
  • the memory device M is used to store a program and / or the associated operands and / or other data.
  • the peripheral units P1 to Pn include, for example, a DMA controller, an A / D converter, a D / A converter, a timer, interfaces and controllers for input and / or
  • the data to be protected are stored in an internal memory of the program-controlled unit, such as the memory device M, and to equip the program-controlled unit with a memory protection device that prevents read access to the data by unauthorized persons internal memory blocked.
  • the known program-controlled units in which read access to the internal memory by unauthorized persons is blocked, either do not offer perfect read protection, and / or are complicated to use, and / or have a complicated structure and / or have only limited Possible uses.
  • the present invention is therefore based on the object of developing the program-controlled unit in accordance with the preamble of patent claim 1 in such a way that it offers reliable reading protection, has a simple structure, is easy to handle, and can be used universally.
  • the memory to be protected can be reliably and easily protected against read access by persons not authorized for this purpose.
  • FIG. 1 shows the structure of a storage device of the program-controlled unit described below that can be protected against access by persons not authorized to do so
  • FIG. 2 shows the arrangement of protection configuration bits in a first user configuration block of the memory device shown in FIG. 1
  • Figure 3 shows the arrangement of protection configuration bits in a second user configuration block in the
  • FIG. 1 shows the storage device
  • FIG. 4 shows the arrangement of protection configuration bits in a third user configuration block of the memory device shown in FIG. 1,
  • FIG. 5 shows the structure of a configuration register of the memory device shown in FIG. 1, and
  • Figure 6 shows the structure of a program-controlled unit.
  • the program-controlled unit described below is a microcontroller. However, it should already be pointed out at this point that it could also be any other program-controlled unit such as a microprocessor or a signal processor.
  • the microcontroller described has the same basic structure as the program-controlled unit shown in FIG. 6. However, it contains protective mechanisms by means of which it can be prevented in a particularly simple, flexible and reliable manner that data stored in the storage device M can be read out and / or changed by persons not authorized to do so. Data is understood to mean both data representing commands (command code) and "normal" data such as operands, parameters, constants etc. which do not represent a command code.
  • these protective mechanisms are part of the memory device.
  • the structure of the memory device M of the microcontroller presented here is shown in FIG.
  • the memory device contains a memory module MM and an interface MI.
  • the memory module MM is the memory, the content of which is to be protected from being read out and / or changed by a person who is not authorized for this purpose.
  • the memory module MM contains a part MMP used as program memory, a part MMD used as data memory, and further components, not shown in FIG. 1, such as, in particular, sense amplifiers, buffer memories, control devices, etc.
  • the memory module MM could also be a memory used exclusively as program memory, or a memory used exclusively as data memory.
  • data opernds, constants, etc.
  • programs can also be stored in the data memory.
  • the memory module MM is formed by a flash memory.
  • the memory module MM can also be another reprogrammable non-volatile memory, for example an EEPROM, or a permanent memory such as a ROM, or a volatile memory such as a RAM.
  • the program memory MMP is divided into 14 sectors MMPSO to MMPS13, the sectors
  • MMPS1 to MMPS13 are provided for storing programs, and the sector MMPSO is provided for storing configuration data.
  • the sectors MMPS1 to MMPS13 intended for the storage of programs each have a storage capacity of 16 kByte, the sector MMPS9 a storage capacity of 128 kByte, the sector MMPS10 a storage capacity of 256 kByte, and the sectors MMPS11 to MMPS13 each a storage capacity of 512 kbytes.
  • the configuration data stored in the MMPSO sector are used to configure the write protection and the read protection, by means of which unauthorized persons are prevented from reading and / or changing the data stored in the sectors MMPS1 to MMPS13 and in the data memory MMD.
  • the data memory MMD has a memory capacity of 128 kbytes and is divided into two sectors MMDS1 and MMDS2, each of which comprises 64 kbytes.
  • both the number of sectors and the size of the sectors can be arbitrarily much larger or smaller.
  • the memory module MM is addressed via the MI interface. This means that all access to the memory module MM takes place via the interface MI.
  • the interface MI contains a control device CTRL, an error correction device ECU, and further components, not shown in FIG. 1, such as buffers, latches, registers, etc.
  • the interface MI and the memory module MM are connected to one another via a control bus CTRLBUS1, an address bus ADDRBUS1, a write data bus WD ⁇ TABUS1, a read data bus RDATABUS1, and error correction data buses ECCBUS1 and ECCBUS2.
  • the interface MI is connected to the CPU and other components of the microcontroller, which can access the memory device M, via a control bus CTRLBUS2, an address bus ADDRBUS2, a write data bus WDATABUS2, and a read data bus RDATABUS2.
  • CMOS complementary metal-oxide-semiconductor
  • PCP peripheral control processor
  • the control device CTRL of the interface MI first checks whether the access is permissible. An inadmissible access exists in particular if a read protection is effective, by which the reading of the data requested by the read access from the memory device M is to be prevented. If the control device CTRL determines that it is an illegal access to the memory device M, it does not carry out this access and also signals to the CPU and / or other microcontroller components that an illegal access to the memory device M has taken place. Otherwise, ie if the access is permissible, causes the control device CTRL to transmit appropriate control signals and addresses to the memory module
  • control signals and addresses transmitted from the control device CTRL to the memory module MM are transmitted via the control bus CTRLBUS1 and the address bus ADDRBUS1; the data output by the memory module MM are transmitted via the read data bus RDATABUS1.
  • the memory module MM In addition to the data transmitted via the read data bus RDATABUS1, the memory module MM also outputs error correction or ECC data associated with this data. This data is transferred via the ECCBUS2.
  • the error correction device ECU then checks, by evaluating the data received via the buses RDATABUS1 and ECCBUS2, whether the data transmitted via the read data bus RDATABUS1 is error-free. If the data is not error-free and it is a correctable error, it corrects it. How errors are recognized and corrected using an ECC (error correction code) is known and requires no further explanation.
  • the interface MI then outputs the data, which may have been corrected by the memory module MM, via the read data bus RDATABUS2 to the device from which the read access originated.
  • All other accesses to the storage device M in particular also the accesses by which the deletion of data stored in the storage device M is initiated, and the accesses by which the writing of data into the storage device M is initiated by the transfer of, for example based on the JEDEC standard
  • the command sequences to the memory device M are initiated or initiated.
  • the transmission of a command sequence to the memory device M is ultimately nothing more than write access to the memory device MDh, the memory device M receives a write signal via the control bus CTRLBUS2, an address via the address bus ADDRBUS2, and data via the write data bus WDATABUS2.
  • a command sequence can comprise one or more successive write accesses to the memory device M.
  • the interface MI does not interpret write accesses to the memory device M as an access by means of which the data transmitted via the write data bus WDATABUS2 are to be written into the memory module MM. Instead, it interprets write access as commands. To be more precise, it determines which action is to be carried out on the basis of the addresses transmitted via the address bus ADDRBUS2 and the data transmitted via the write data bus WDATABUS2.
  • a command sequence is transmitted to the memory device M, which represents a command "Erase Sector".
  • this command sequence consists of 6 write cycles, of which 5 cycles are pure fail-safe cycles, i.e. Cycles with fixed addresses and data are, and only in one cycle (in the example considered the sixth cycle) a variable address and / or variable data are transmitted.
  • Such a command sequence can consist, for example, in that
  • the address of the sector to be deleted and the data 30 are transmitted to the memory device M.
  • the addresses and data are given above in hexadecimal format and that the data stored in the memory module MM are deleted in units of sectors, that is to say that only an entire sector can be deleted at any time.
  • the memory module MM is not a flash memory, but rather a RAM, a ROM, an EEPROM etc.
  • the deletion can also take place in other units, for example page by page, word by word, etc.
  • the control device CTRL decodes the command sequence supplied to the memory device M by write accesses. More precisely, it determines the action to be performed from the addresses and data supplied to it by the write accesses.
  • the control device CTRL checks whether this is permissible access to the memory device M. Inadmissible access exists in particular if write protection is effective for the sector to be deleted. If the control device CTRL determines that it is an illegal access to the memory device M, it does not carry out this access and also signals to the CPU and / or other microcontroller components that unauthorized access to the
  • Storage device M is done. Otherwise, i.e. if the access is permissible, the control device CTRL, by transmitting appropriate control signals and addresses to the memory module MM, causes the sector specified in the "Erase Sector" command to be deleted in the memory module MM.
  • a command sequence is first transmitted to the memory device M, which represents a command "Enter Page Mode".
  • This command sequence can consist, for example, of the address 5554 and the data 50 being transferred to the memory device M in a write access to the memory device M.
  • a page comprises 256 bytes when accessing the MMP program memory and 128 bytes when accessing the MMD data memory.
  • the sizes of the pages can be of any size independently of one another.
  • the "enter page mode" command and also the further page commands described in more detail below need only be provided if the memory module MM is described page by page.
  • the memory module can also be written in larger or smaller units, for example word by word. The change to page mode does not yet result in data being written into the memory module MM. This only happens with a "Write Page” command that will be described in more detail later.
  • the data to be written into the memory module MM must first be transferred to the memory device M. This is done by one or more "load page" commands.
  • a command sequence representing a "load page” command can, for example, consist in the fact that in a write access to the memory device M the address 5550 and, as data, 32 or 64 bits of the data which are to be written into the memory module MM are transmitted to the memory device M. become.
  • the control device CTRL writes the data contained in the command sequence into a buffer of the interface MI, for example formed by a register.
  • the control device CTRL more precisely the error correction device ECU thereof, generates error correction or ECC data for this data, using which errors contained in the read-out data can be recognized and / or corrected when this data is subsequently read out from the memory module MM , and also stores this data in a buffer, for example formed by a register.
  • command sequences representing "load page” are fed to the memory device M in succession until as much data is stored in the buffer as is comprised by a page.
  • the memory device M is then supplied with a command sequence representing a "write page” command.
  • This command sequence can consist, for example, in that
  • the address of the page to be written within the memory module and the data AA are transmitted to the memory device as the address.
  • the control device CTRL checks whether it is the access in question is a permissible access to the memory device M. Inadmissible access exists in particular if write protection is effective, by means of which changes to the content of the memory area to be written on are to be prevented. If the control device CTRL determines that it is an illegal access to the memory device M, it does not carry out this access and also signals to the CPU and / or other microcontroller components that an illegal access to the memory device M has taken place.
  • control device CTRL by transmitting the corresponding control signals, addresses and data to the memory module MM, causes the data stored in the buffer memory to match the data in the "write page". Command-specified location within the memory module.
  • ECC data is transmitted from the control device CTRL to the memory module MM via the error correction data bus ECCBUS1 and also stored in the memory module MM.
  • the read protection and write protection already mentioned several times above should and can prevent data stored in the memory device M from being read out and / or changed by persons not authorized to do so.
  • the settings that can be made by the user are made.
  • UCBs user configuration blocks
  • the UCBs mentioned are part of the MMPSO sector of the program memory MMP and can only be written by the user of the program-controlled unit, but cannot be read out.
  • the sector MMPSO of the program memory MMP contains three UCBs in the example considered, which are referred to below as UCB0, UCB1, and UCB2.
  • Each UCB consists of four pages (Page 0 to Page 3), each of which has 256 bytes.
  • the UCB0 can be written and deleted by a first user of the program-controlled unit and contains in the example considered
  • a password which can be selected by the first user, using which the first user can temporarily cancel the read protection defined by his read protection settings and / or the write protection defined by his write protection settings, and
  • a predetermined confirmation code by writing it into the UCB0, the first user confirms the validity of the data stored in the UCB0.
  • the read protection settings and the write protection settings comprise two bytes in the example considered. These bytes are referred to below as protection setting bytes and are shown in FIG. 2.
  • Bits 0 to 12 of the protection setting bytes are write protection setting bits, by means of which it is specified for which of the sectors MMPS1 to MMPS13 of the program memory write protection is to be effective; the write protection setting bits are identified in FIG. 2 by the reference symbols SOL to S12L.
  • the write protection setting bits are identified in FIG. 2 by the reference symbols SOL to S12L.
  • bit SOL to S12L one bit is assigned to one of the sectors MMPS1 to MMPS13. More specifically, bit SOL is assigned to sector MMPS1, bit S1L is assigned to sector MMPS2, bit S2L is assigned to sector MMPS3, ..., and bit S12L is assigned to sector MMPS13.
  • the value of the individual bits SOL to S12L determines whether write protection should be effective for the assigned sector or not. For example, if the bit S5L has the value 1, this means that write protection should be effective for the assigned sector MMPS6; if this bit has the value 0, this means that no write protection should
  • Bit 15 of the protection setting bytes is a read protection setting bit, by means of which it is specified whether read protection should be effective for the memory module MM; the read protection setting bit is identified in FIG. 2 by the reference symbol RPRO. If the RPRO bit has the value 1, this means that read protection should be effective; if the RPRO bit has the value 0, this means that no read protection should be effective.
  • the password comprises 64 bits, but can also be any length or shorter.
  • the protection setting bytes and the password are part of the first page (Page 0) of UCBO
  • the confirmation code is part of the third page (Page 2) of UCBO
  • the remaining pages (Pages 1 and 3) of UCBO are reserved for future use.
  • the UCBl can be written and deleted by a second user of the program-controlled unit and, in the example under consideration, contains
  • the write protection settings are contained in two protection setting bytes. These protection setting bytes are illustrated in Figure 3.
  • the protection setting bytes of the UCBl largely correspond to the protection setting bytes of the UCBO. The only difference is that there is no read protection setting bit RPRO in the protection setting bytes of the UCBl. This has the effect that the second user cannot determine whether read protection should be effective or not; only the first user can do this.
  • the protection setting bytes of the UCBl contain setting bits SOL to S12L, via which the second user can set for which of the sectors MMPSl to MMPS13 write protection should be effective.
  • the password comprises 64 bits, but can also be any length or shorter.
  • the protection setting bytes and the password are part of the first page
  • the UCB2 has some special features compared to the UCBO and the UCBl and will be described in more detail later.
  • the user or the users of the microcontroller can set whether or to what extent read protection and / or write protection should be effective.
  • the first user of the microcontroller must set the read protection setting bit RPRO of the protection setting bytes of the UCBO.
  • both the UCBO and the UCBl could contain one or more read protection setting bits. Then both the first user and the second user could set whether and if so for which areas of the memory module read protection should be effective. Of course, it would also be possible that only the second user can use appropriate settings in UCBl to specify whether and if so to what extent read protection should be effective.
  • the first user of the microcontroller and / or the second user of the microcontroller must set one or more of the write protection setting bits SOL to S12L of the protection setting bytes of the UCBO or UCBl.
  • write protection settings bits SOL to S12L of UCBO and UCB1 are used to set for which areas of the memory module MM, more precisely for which sectors of the memory module, write protection should be effective. Write protection is only effective for those sectors to which the set bits under the write protection setting bits SOL to S12L are assigned. If, for example, only the write protection setting bit S3L of the UCBO and the write protection setting bit S5L of the UCBl are set from the write protection setting bits SOL to S12L of the UCBO and the UCBl, this means that write protection is only effective for the sectors MMPS4 and MMPS6 should be.
  • the UCB2 already mentioned above can be replaced by a third
  • the write protection settings are contained in two protection setting bytes. This
  • Bits 0 to 12 of the protection setting bytes are write protection setting bits, by means of which it is specified for which of the sectors MMPS1 to MMPS13 of the program memory write protection is to be effective; the write protection setting bits are identified in FIG. 4 by the reference symbols SOROM to S12ROM.
  • One bit of the bits SOROM to S12ROM is assigned to one of the sectors MMPS1 to MMPS13. More specifically, the bit SOROM is assigned to the sector MMPS1, the bit S1ROM is assigned to the sector MMPS2, the bit S2ROM is assigned to the sector MMPS3, ... and the bit S12ROM is assigned to the sector MMPS13.
  • the value of the individual bits SOROM to S12ROM determines whether write protection should be effective for the assigned sector or not. For example, if the bit S5ROM has the value 1, this means that write protection should be effective for the assigned sector MMPS6; if this bit has the value 0, this means that no write protection should be effective for the assigned sector MMPS6.
  • the protection setting bytes of the UCB2 essentially correspond to the protection setting bytes of the UCB1.
  • the UCB2 can no longer be deleted and cannot be rewritten after the confirmation code has been written.
  • the write protection defined by UCB2 cannot be temporarily deactivated. This has the effect that the write protection setting bits of the UCB2 specify whether and, if so, which areas of the memory module MM are like a memory that can never be reprogrammed, that is, how a ROM behave. After the confirmation code has been written into it, the UCB2 behaves like a ROM that is at least unreadable by the user.
  • the protection setting bytes are part of the first page (Page 0) of UCB2
  • the confirmation code is part of the third page (Page 2) of UCB2
  • the remaining pages (Pages 1 and 3) of UCB2 are reserved for future use.
  • the UCBs can be written to by the first or the second or the third user by the transmission of special command sequences to the memory device M.
  • the UCBs can also be deleted and rewritten - also by transmitting special command sequences. However, they cannot be read out by the user of the program-controlled unit.
  • the UCB2 can no longer be deleted and no longer written to.
  • the write protection for the UCB to be deleted must first be canceled by the "Disable Write Protection" command already mentioned and described in more detail later, because although the sector MMPSO containing the UCBs does not have a write protection setting bit in the Assigned to UCBs, every UCB described correctly, ie including the correct confirmation code, is automatically read and write protected. Only if the UCB to be deleted has not yet been written to or has not been written to properly, ie without a valid confirmation code, is write protection no longer required.
  • a command sequence is transmitted to the memory device M, which represents a command "Erase UCB". This command sequence can consist, for example, that
  • the address of the UCB to be deleted and the data 40 are transmitted to the memory device.
  • the memory device M When the memory device M is supplied with a command sequence representing the command "Erase UCB", it recognizes, more precisely the control device CTRL thereof, that the UCB specified in the sixth cycle of the command sequence is to be deleted. The control device CTRL then checks whether this is a permissible access. Inadmissible access exists in particular if the UCB to be deleted is write-protected. If the control device determines that there is an illegal access, it does not execute the command and also signals the CPU and / or other microcontroller components that an illegal access to the memory device has occurred.
  • the control device CTRL by transmitting corresponding control signals and addresses to the memory module MM, causes the UCB specified in the "Erase UCB" command to be deleted in the sector MMPSO of the memory module MM.
  • the "Erase UCB” command does not cause the deletion of a complete sector of the memory module MM, but only a specific UCB of the MMPSO sector.
  • Writing to a UCB is only permitted if it has never been written to or has previously been deleted. Whether this is the case is checked by the control device CTRL and can be recognized, for example, by the fact that there is no or no valid confirmation code in the UCB to be described.
  • the command sequence representing the "Write UC Page" command can consist, for example, of:
  • the control device CTRL checks whether the access in question is an allowable access to the memory device M. Inadmissible access exists in particular if the UCB to be written already contains a valid confirmation code, i.e. is write-protected. If the control device CTRL determines that it is an illegal access to the memory device M, it does not carry out this access and also signals to the CPU and / or other microcontroller components that an illegal access to the memory device M has taken place. Otherwise, i.e.
  • the control device CTRL by transmitting the corresponding control signals, addresses and data to the memory module MM, causes the data supplied to the memory device M by the "Load Page” command and temporarily stored to the data in the "Write UC Page "command specified page of the UCB to be written.
  • the entries in UCBO, UCBl, and UCB2 are only effective if the respective confirmation code has been written in the UCBs. However, by deleting or writing to the UCBs, changes to the content of the UCBs only take effect when the microcontroller is next reset.
  • the confirmation code should only be written in the respective UCB if it is certain that the information stored in it is correct. In particular, it should be ensured that the password stored in the respective UCB is also the password that the user writes in the UCB wanted to. This can be determined, for example, using the "Disable Write Protection" command, which will be described in more detail later.
  • the transmission of a "Disable Write Protection" command to the memory device M results in an error message if the password contained in the command does not match the passwords stored in the UCB.
  • the user describing the UCB transmits to the storage device M a "Disable Write Protection" command which contains the password just written in the UCB as a password, it can be recognized from the occurrence or absence of this error message whether the password stored in the UCB is the User set password is or not.
  • the UCBO and the UCBl can be written and deleted as often as required by the first user or the second user of the microcontroller. Provision could also be made to allow the deletion and rewriting of UCBO and UCBl only a certain number of times. For example, it could be provided that the UCBO and the UCBl can be written to a maximum of five times.
  • the first user and the second user of the microcontroller have the option of temporarily overriding the settings contained in UCBO or UCB1 by transmitting appropriate commands, more precisely by transmitting command sequences representing these commands to the memory device M.
  • the read and write protection set by him in UCBO can be temporarily canceled by the first user or the write protection set by him in UCB1 by the second user.
  • commands mentioned include a "Disable Write Protection” command, a “Disable Read Protection” command, and a “Resume Protection” command.
  • a command sequence representing a "Disable Write Protection” command can consist, for example, in that
  • the address 1111 in a third cycle or in a third write access to the memory device, the address 1111 and, as data, an identifier which is assigned to the user initiating the command,
  • the address 3333 and the data 01 are transmitted to the memory device.
  • the memory device M When the memory device M is supplied with a command sequence representing the command "Disable Write Protection", it checks, more precisely the control device CTRL thereof, first of all whether the identifier transmitted in the third cycle is the identifier assigned to the first user or the identifier assigned to the second user, and whether the password transmitted in the fourth cycle and in the fifth cycle is the password that is stored in the UCB assigned to the user in question.
  • the password must match the password stored in UCBO if the data transmitted in the third cycle Generic identifier is the identifier assigned to the first user, or must match the password stored in UCB1 if the identifier transmitted in the third cycle is the identifier assigned to the second user.
  • the control device CTRL assumes that the command supplied to it is an illegal access (access by an unauthorized person) to the storage device M. In this case, the control device CTRL does not execute the command and also signals the CPU and / or other microcontroller components that the storage device M has been accessed in an unauthorized manner. Otherwise, the control device CTRL ensures that the write protection becomes ineffective to the extent to which the user specified in the third cycle of the command sequence in the UCB assigned to it becomes ineffective.
  • the extent to which write protection becomes ineffective also depends on the user from whom the "Disable Write Protection" command comes. More precisely, in the example considered, the settings and commands of the first user have priority. This means that a "Disable Write Protection" command initiated by the second user can only release the write protection for those sectors for which the first user does not request write protection. That is, if, for example, the write protection setting bits SOL and S1L are set in UCBO and the write protection setting bits SOL and S2L are set in UCBl, only a write protection for the MMPS3 sector is released by a "Disable Write Protection" command initiated by the second user , but not also the write protection for the MMPSl sector, because the first user has also set write protection for this sector. Conversely, however, the first user can also remove write protection for sectors for which the second user has set write protection. Ie if for example write protection setting bits SOL and S1L are set in UCBO and write protection setting bits in UCBl
  • first user and the second user have equal rights and that no user can remove write protection for sectors for which the other user has set write protection.
  • a "Disable Write Protection" command does not under any circumstances result in the write protection being released for a sector which, according to the settings in UCB2, should behave like a ROM.
  • a command sequence representing a "Disable Read Protection" command can consist, for example, of:
  • the address 1112 as data is the first half of the password which is stored in UCBO,
  • the address 3333 and the data 02 are transmitted to the memory device.
  • the memory device M When the memory device M is supplied with a command sequence representing the command "Disable Read Protection", it checks, more precisely the control device CTRL thereof, first of all whether the password transmitted in the fourth and in the fifth cycle matches the password stored in UCBO. If the check reveals that these conditions are not met, the control device CTRL assumes that the command supplied to it is an illegal access (access by an unauthorized person) to the memory device M. In this case, the control device CTRL does not execute the command and also signals the CPU and / or other microcontroller components that the storage device M has been accessed in an unauthorized manner. Otherwise the control device CTRL ensures that read protection is no longer effective.
  • a command sequence representing a "resume protection" command can consist, for example, in a single cycle or in a single write access the address 5554 and the data BB are transferred to the memory device M on the memory device.
  • the read protection and the write protection become effective again to the extent that it is defined by the read and write protection setting bits of the UCBO and the UCBl.
  • this memory configuration register is part of the control device CTRL of the memory device M.
  • the structure of the memory configuration register is shown in FIG. 5.
  • the memory configuration register is a 32-bit register, of which only bits 0 to 5 are of interest in the present case.
  • Bit 0 is designated with the reference character RPA, bit 1 with the reference character DCF, bit 2 with the reference character DDF, bit 3 with the reference character DDFDBG, bit 4 with the reference character DDFDMA, and bit 5 with the reference character DDFPCP.
  • the bit RPA indicates whether read protection should be effective. Read protection is effective and the RPA bit is set if the RPRO bit is set in UCBO and the read protection is not temporarily canceled by the "Disable Read Protection" command.
  • the bits DCF and DDF determine which type of
  • Read access to the memory module MM should be permitted, and the bits DDFDBG, DDFDMA, and DDFPCP and / or further or other control bits determine which microcontroller components that can access the memory device M can carry out permitted read accesses to the memory device M. , However, the bits DCF and DDF are only evaluated if bit RPA is set. More specifically,
  • RPA ReadProtectionA ⁇ tive
  • DDF Disable Data Fet ⁇ h
  • DDFDBG Disable Data Fetch from Debug Controller
  • a debug controller contained in the microcontroller i.e. for example the OCDS module already mentioned at the beginning, read accesses to the memory module MM (the program memory MMP and the data memory MMD) may execute; if the bit DDFDBG has the value 0, read accesses by the debug controller to the memory module MM are permissible, otherwise not.
  • DDFDMA bit Disable Data Fetch from DMA Controller
  • a DMA controller contained in the microcontroller reads access to the memory module MM (the program memory MMP and the data memory MMD). may lead; if the DDFDBG bit has the value 0, read accesses by the DMA controller to the memory module MM are permissible, otherwise not.
  • DDFPCP bit Disable Data Fetch from PCP
  • PCP Peripheral Control Processor
  • further configuration bits can also be provided, the value of which depends on whether a specific further component of the microcontroller or of the system containing the microcontroller is allowed to carry out read accesses to the memory module MM (the program memory MMP and the data memory MMD).
  • further configuration bits can be provided, the value of which depends on whether further processors of the microcontroller or processors provided outside the microcontroller are allowed to carry out read accesses to the memory module MM.
  • Which microcontroller component accesses the memory module MM and whether the access is a code fetch or a data fetch can be determined on the basis of an identifier that the microcontroller component accessing the memory module MM has on access transmitted to the memory module MM together with the read request or the write request to the memory module MM or the memory device M.
  • the memory configuration register can be read and written both by the hardware, in particular by the control device CTRL or another microcontroller component, and by the user of the microcontroller.
  • the memory configuration register is written by the user of the microcontroller by the transmission of a "write register" command to the memory device M, more precisely by the supply of a command sequence representing this command.
  • the writing of the memory configuration register could also take place in a different way, for example by a simple register access.
  • the user can only change certain bits of the memory configuration register, although even this is sometimes linked to certain conditions.
  • a command sequence representing a "write register” command can consist, for example, that - in a first cycle or in a first write access to the memory device, the address 5554 and the data
  • the address of the register to be written as the address, and as data the data to be written to this register are transferred to the memory device.
  • the memory device M When the memory device M is supplied with a command sequence representing the command "write register", it checks, more precisely the control device CTRL thereof, first of all whether this is an allowable access to the memory device M.
  • An illegal access exists, for example, if a reading protection is effective and the bit DCF and / or the bit DDF is to be changed. If the control device CTRL determines that it is an illegal access to the memory device M, it does not carry out this access and also signals to the CPU and / or other microcontroller components that an illegal access to the memory device M has taken place. Otherwise, i.e. if it is a permissible access, the control device CTRL causes the data transmitted in the second cycle of the command sequence to be written into the register specified in the second cycle of the command sequence.
  • the memory device M also contains a flash status register in addition to the memory configuration register, in which the current status of the memory module MM and any unauthorized access to the memory device M are displayed. This register cannot be overwritten by the user. The status and error displays contained therein can, however, be reset with the "Clear Status" command
  • a command sequence representing a "clear status" command can consist, for example, of the address 5554 in a write access to the memory device and the data DD are transmitted to the storage device.
  • Read Register exists, by means of which the contents of certain registers of the memory device M can be read out.
  • the registers that can be read out with the "Read Register” command also include the memory configuration register and the flash status register.
  • the user of the microcontroller has a whole range of options for configuring the read protection and the write protection according to his wishes.
  • the read protection and write protection are effective is also determined by the memory device M, more precisely by the control device CTRL thereof. This is explained in more detail below.
  • the control device CTRL or another microcontroller component checks whether a reading protection should be effective. This is the case if the read protection setting bit RPRO of the UCBO is set and a valid confirmation code has been written into the UCBO.
  • control device CTRL or another microcontroller component checks how the microcontroller should behave after being switched on or reset.
  • the microcontroller in question has three options for this, namely 1) that after start-up or reset, the microcontroller is to execute a program outside the memory device M, that is to say a program stored in an unprotected internal or external memory,
  • microcontroller should behave after commissioning or resetting is specified in the example under consideration by signals which are applied to certain input and / or output connections of the microcontroller while the microcontroller is being held or reset. By evaluating these signals, the microcontroller determines how it should behave after holding back or after resetting.
  • the control device CTRL or another microcontroller component ensures that the bits DCF and DDF of the memory configuration register are set Therefore, if read protection is requested at the same time, i.e. the bit RPA is set, neither read access to the program memory MMP nor read access to the data memory MMD are permitted. If the developer of the program stored outside the storage device M is not a person authorized to read out the storage device M, he cannot cancel the read protection, because for this he would have to know the password stored in UCBO, but this should not generally be the case. If the microcontroller after commissioning or
  • control device CTRL or another microcontroller component ensures that the
  • Bits DCF and DDF are set and thus a read protection is effective while the program is being executed.
  • microcontroller If the microcontroller is to execute a program stored within the memory device M after commissioning or resetting, this is permitted and, moreover, the control device CTRL or another microcontroller component ensures that the bits DCF and DDF of the memory device Configuration registers are reset, which allows both read access to the program memory MMP and read access to the data memory MMD.
  • the memory device M stored program contains instructions which ensure that the bits DCF and / or DDF of the memory configuration register are set before the execution of a jump into an unprotected memory or memory area.
  • the DCF bit is not set, it is possible to return to the memory device M, whereas if the DCF bit is set, this is not even possible. So that a return to the memory device M can take place, the command "Disable Read Protection" of the reading protection would have to be canceled.
  • the control device CTRL or another microcontroller component is preferably also immediately the bit DDFDBG of the memory configuration register, and possibly also the bits DDFDMA and / or DDFPCP of the memory configuration register set.
  • the bits mentioned can also be set and reset by corresponding commands in the executed program. This measure also prevents unauthorized persons from accessing the memory device M via the debug controller and / or the DMA controller and / or the peripheral control processor.
  • visual acuity protection is also automatically effective for the entire storage device M. This can prevent an unauthorized person from writing a reading routine (for example a Trojan horse) into the storage device M, which then writes the entire storage device Read memory content and output from the microcontroller.
  • the microcontroller also ensures that after commissioning or resetting the microcontroller to the extent defined in the UCBs, a selective, i.e. write protection independent of read protection is effective.
  • This selective write protection can be temporarily or completely canceled by the user by means of the commands "Disable Write Protection” and “Resume Protection”, more precisely by program commands by which the transmission of these commands to the memory device M is initiated.
  • the write protection coupled with the read protection can be temporarily canceled by means of the "Disable Read Protection" command.
  • the control device CTRL signals the CPU and / or another microcontroller component a memory protection violation if the memory device M is accessed in an impermissible manner. This can be done, for example, by means of a corresponding entry in a status register, for example in the aforementioned flash status register, and / or by an interrupt request. How the CPU responds to this depends primarily on the use of the microcontroller.
  • the reactions can, for example, but understandably not exclusively, consist of - That it is ensured that the program execution is ended and no further commands are executed until the next start-up or until the next reset of the microcontroller, or
  • the microcontroller can also react to an impermissible access to the memory device M in any other way.
  • the microcontroller's response can also depending on the type of unauthorized access. For example, it can be provided that the failed attempt to temporarily remove the read protection (Disable Read Protection) is sanctioned by harder or more extensive measures than an impermissible read access to the data memory MMD.
  • the UCBO can be described and deleted by a first user of the microcontroller, the UCBl can be described and deleted by a second user of the microcontroller, and the UCB2 can be described and deleted by a third user.
  • the microcontroller described is part of a motor vehicle control unit and the microcontroller executes a program, the commands and / or operands of which partly come from the manufacturer of the motor vehicle control unit and partly from the manufacturer of the motor vehicle, then both the manufacturer of the motor vehicle control unit and the manufacturer of the Protect your program parts and / or operands from being read out and / or from changes by authorized persons: the manufacturer of the motor vehicle control unit can be the first user of the microcontroller and configure the protection of his program parts and / or operands by corresponding description of the UCBO, and the manufacturer of the motor vehicle can be the second user of the microcontroller and configure the protection of its program parts and / or operands by correspondingly describing the UCBl; in addition, either the manufacturer of the motor vehicle control unit or the manufacturer of the motor vehicle can be the third user and the protection of its program parts and / or operands can also be done by correspondingly describing the UCB2 configure.
  • the third user can also be a third person or a third company that is involved in the development of the program stored in the memory device M.
  • a single person or a single company it is of course also possible for a single person or a single company to be both the first user and the second user.
  • the memory device M can be reliably protected in a very simple manner from access by persons not authorized to do so.
  • the scope of the reading protection and the scope of the writing protection can be optimally adapted to the respective conditions independently of one another.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Computer Security & Cryptography (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Storage Device Security (AREA)

Abstract

L'invention concerne une unité commandée par programme, qui comporte une mémoire, servant à mémoriser des données, et un dispositif de protection de mémoire, servant à protéger la mémoire contre des accès en lecture et/ou en écriture réalisés par des personnes non autorisées. Ladite unité commandée par programme est caractérisée en ce qu'elle est conçue de sorte qu'elle active automatiquement la protection de lecture si nécessaire et de sorte qu'une personne autorisée peut adapter la protection de lecture aux circonstances données.
EP04724981A 2003-04-04 2004-04-01 Unite commandee par programme Ceased EP1611516A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10315726A DE10315726A1 (de) 2003-04-04 2003-04-04 Programmgesteuerte Einheit
PCT/DE2004/000704 WO2004090730A2 (fr) 2003-04-04 2004-04-01 Unite commandee par programme

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EP1611516A2 true EP1611516A2 (fr) 2006-01-04

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US (1) US20060112246A1 (fr)
EP (1) EP1611516A2 (fr)
DE (1) DE10315726A1 (fr)
WO (1) WO2004090730A2 (fr)

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Also Published As

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US20060112246A1 (en) 2006-05-25
DE10315726A1 (de) 2004-11-04
WO2004090730A2 (fr) 2004-10-21
WO2004090730A3 (fr) 2005-04-21

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