Package com.dalsemi.onewire.application.sha

Class SHAiButtonCoprVM

java.lang.Object
com.dalsemi.onewire.application.sha.SHAiButtonCopr
com.dalsemi.onewire.application.sha.SHAiButtonCoprVM
public class SHAiButtonCoprVM extends SHAiButtonCopr

Class for simulating an instance of a SHA iButton Coprocessor involved in SHA Transactions. The Coprocessor is used for digitally signing transaction data as well as generating random challenges for users and verifying their response.

With this class, no DS1963S SHA iButton is necessary for the coprocessor in SHA Transactions. The simulated Coprocessor iButton verifies signatures and signs data for User iButtons.

This class makes use of several performance enhancements for TINI. For instance, most methods are synchronized to access instance variable byte arrays rather than creating new byte arrays every time a transaction is performed. This could hurt performance in multi-threaded applications, but the usefulness of having several threads contending to talk to a single iButton is questionable since the methods in com.dalsemi.onewire.adapter.DSPortAdapter beginExclusive(boolean) and endExclusive() should be used.

See Also:

  • Field Details

    • secretPage

      protected byte[][] secretPage
      8 8-byte Secrets for this simulated SHAiButton

    • address

      protected byte[] address
      1-Wire Address for this simulated device

  • Constructor Details

  • Method Details

    • save

      public boolean save(String filename, boolean saveSecretData) throws OneWireException, OneWireIOException

      Saves simulated coprocessor configuration info to an (almost) standard-format to a hard drive file.

      Parameters:
      filename - The filename of the simulated coprocessor's data file ("shaCopr.dat")
      saveSecretData - If true, the raw secret information is also written to the file @throws OneWireIOException on a 1-Wire communication error such as reading an incorrect CRC from a 1-Wire device. This could be caused by a physical interruption in the 1-Wire Network due to shorts or a newly arriving 1-Wire device issuing a 'presence pulse'. @throws OneWireException on a communication or setup error with the 1-Wire adapter @return true if the info was successfully saved
      Throws:
      OneWireException
      OneWireIOException

    • save

      public boolean save(OneWireContainer owc, String filename, boolean saveSecretData) throws OneWireException, OneWireIOException

      Saves simulated coprocessor configuration info to an (almost) standard-format to a 1-Wire Memory Device's TMEX file.

      Parameters:
      owc - 1-Wire Memory Device with valid TMEX file structure.
      filename - The TMEX filename of the simulated coprocessor's data file ("COPR.2")
      saveSecretData - If true, the raw secret information is also written to the file. @throws OneWireIOException on a 1-Wire communication error such as reading an incorrect CRC from a 1-Wire device. This could be caused by a physical interruption in the 1-Wire Network due to shorts or a newly arriving 1-Wire device issuing a 'presence pulse'. @throws OneWireException on a communication or setup error with the 1-Wire adapter @return true if the info was successfully saved
      Throws:
      OneWireException
      OneWireIOException

    • load

      public boolean load(String filename)

      Loads coprocessor configuration information from an (almost) standard service file on hard drive. If secret information was saved, this routine automatically loads it.

      Parameters:
      filename - The filename of the simulated coprocessor's data file ("shaCopr.dat")
      Returns:
      true if the info was successfully loaded

    • load

      public boolean load(OneWireContainer owc, String filename)

      Loads coprocessor configuration information from an (almost) standard service TMEX file on 1-Wire memory device. If secret information was saved, this routine automatically loads it.

      Parameters:
      owc - 1-Wire memory device with valid TMEX file structure
      filename - The TMEX filename of the simulated coprocessor's data file ("COPR.2")
      Returns:
      true if the info was successfully loaded

    • load

      public boolean load(OneWireContainer18 owc, String filename)

      Loads coprocessor configuration information from a standard TMEX service file on a DS1963S.

      Parameters:
      owc - DS1963S set up as a valid coprocessor
      filename - The TMEX filename of the coprocessor's data file ("COPR.0")
      Returns:
      true if the info was successfully loaded

    • createDataSignature

      public boolean createDataSignature(byte[] accountData, byte[] signScratchpad, byte[] mac_buffer, int macStart) throws OneWireException, OneWireIOException

      Given a 32-byte array for page data and a 32-byte array for scratchpad content, this function will create a 20-byte signature for the data based on SHA-1. The format of the calculation of the data signature is as follows: First 4-bytes of signing secret, 32-bytes of accountData, 12 bytes of scratchpad data starting at index 8, last 4-bytes of signing secret, 3 bytes of scratchpad data starting at index 20, and the rest is padding as specified for standard SHA-1. This is all laid out, in detail, in the DS1963S data sheet.

      The resulting 20-byte signature is copied into mac_buffer starting at macStart. If you're updating a signature that already exists in the accountData array, it is acceptable to call the method like so: 

         copr.createDataSignature(accountData, spad, accountData, 8);
      assuming that the signature starts at index 8 of the accountData array.

      Overrides:
      createDataSignature in class SHAiButtonCopr
      Parameters:
      accountData - the 32-byte data page for which the signature is generated.
      signScratchpad - the 32-byte scratchpad contents for which the signature is generated. This will contain parameters such as the user's write cycle counter for the page, the user's 1-wire address, and the page number where account data is stored.
      mac_buffer - used to return the 20-byte signature generated by signing the page using the coprocessor's system signing secret.
      macStart - the offset into mac_buffer where copying should start.
      Returns:
      true if successful, false if an error occurred (use getLastError() for more information on the type of error)
      Throws:
      OneWireIOException - on a 1-Wire communication error such as reading an incorrect CRC from a 1-Wire device. This could be caused by a physical interruption in the 1-Wire Network due to shorts or a newly arriving 1-Wire device issuing a 'presence pulse'.
      OneWireException - on a communication or setup error with the 1-Wire adapter
      See Also:

    • generateChallenge

      public boolean generateChallenge(int offset, byte[] ch, int start) throws OneWireIOException, OneWireException

      Generates a 3 byte random challenge in the iButton, sufficient to be used as a challenge to be answered by a User iButton. The user answers the challenge with an authenticated read of it's account data.

      The DS1963S will generate 20 bytes of pseudo random data, though only 3 bytes are needed for the challenge. Programs can add more 'randomness' by selecting different bytes from the 20 bytes of random data using the offset parameter.

      The random number generator is actually the DS1963S's SHA engine, which requires page data to compute a hash. Select a page number with the page_number parameter.

      Overrides:
      generateChallenge in class SHAiButtonCopr
      Parameters:
      offset - offset into the 20 random bytes to draw random data from (must be in range 0-16)
      ch - buffer for the challenge to be returned (must be of length 3 or more)
      start - the starting index into array ch to begin copying the challenge bytes.
      Returns:
      true if successful, false if an error occurred (use getLastError() for more information on the type of error)
      Throws:
      OneWireIOException - on a 1-Wire communication error such as reading an incorrect CRC from a 1-Wire device. This could be caused by a physical interruption in the 1-Wire Network due to shorts or a newly arriving 1-Wire device issuing a 'presence pulse'.
      OneWireException - on a communication or setup error with the 1-Wire adapter
      See Also:

    • verifyAuthentication

      public boolean verifyAuthentication(byte[] fullBindCode, byte[] pageData, byte[] scratchpad, byte[] verify_mac, byte authCmd) throws OneWireIOException, OneWireException

      Determines if a SHAiButtonUser belongs to the system defined by this Coprocessor iButton.See the usage example in this class for initializing a Coprocessor iButton.

      The first step in user authentication is to recreate the user's unique secret on the coprocessor button using bindSecretToiButton(int,byte[],byte[],int). Then the coprocessor signs the pageData to produce a MAC. If the MAC matches that produced by the user, the user belongs to the system.

      The TMEX formatted page with the user's account data is in the 32-byte parameter pageData. If the verification is successful, the data data signature must still be verified with the verifySignature() method.

      Failure of this method does not necessarily mean that the User iButton does not belong to the system. It is possible that a communication disruption here could cause a CRC error that would be indistinguishable from a failed authentication. However, repeated attempts should reveal whether it was truly a communication problem or a User iButton that does not belong to the system.

      Overrides:
      verifyAuthentication in class SHAiButtonCopr
      Parameters:
      fullBindCode - 15-byte binding code used to recreate user iButtons unique secret in the coprocessor.
      pageData - 32-byte buffer containing the data page holding the user's account data.
      scratchpad - the 32-byte scratchpad contents for which the signature is generated. This will contain parameters such as the user's write cycle counter for the page, the user's 1-wire address, and the page number where account data is stored.
      verify_mac - the 20-byte buffer containing the user's authentication response to the coprocessor's challenge.
      Returns:
      true if the operation was successful and the user's MAC matches that generated by the coprocessor.
      Throws:
      OneWireIOException - on a 1-Wire communication error such as reading an incorrect CRC from a 1-Wire device. This could be caused by a physical interruption in the 1-Wire Network due to shorts or a newly arriving 1-Wire device issuing a 'presence pulse'.
      OneWireException - on a communication or setup error with the 1-Wire adapter
      See Also:

    • createDataSignatureAuth

      public boolean createDataSignatureAuth(byte[] accountData, byte[] signScratchpad, byte[] mac_buffer, int macStart, byte[] fullBindCode) throws OneWireException, OneWireIOException

      Creates a data signature, but instead of using the signing secret, it uses the authentication secret, bound for a particular button.

      fullBindCode is ignored by the Coprocessor VM. Instead of binding the secret to the signing page, the coprocessor VM "cheats" and lets you sign the workspace page, where (presumably) the secret is already bound.

      Overrides:
      createDataSignatureAuth in class SHAiButtonCopr
      Parameters:
      accountData - the 32-byte data page for which the signature is generated.
      signScratchpad - the 32-byte scratchpad contents for which the signature is generated. This will contain parameters such as the user's write cycle counter for the page, the user's 1-wire address, and the page number where account data is stored.
      mac_buffer - used to return the 20-byte signature generated by signing the page using the coprocessor's system signing secret.
      macStart - the offset into mac_buffer where copying should start.
      fullBindCode - ignored by simulated coprocessor
      Returns:
      true if successful, false if an error occurred (use getLastError() for more information on the type of error)
      Throws:
      OneWireIOException - on a 1-Wire communication error such as reading an incorrect CRC from a 1-Wire device. This could be caused by a physical interruption in the 1-Wire Network due to shorts or a newly arriving 1-Wire device issuing a 'presence pulse'.
      OneWireException - on a communication or setup error with the 1-Wire adapter
      See Also:

    • verifySignature

      public boolean verifySignature(byte[] pageData, byte[] scratchpad, byte[] verify_mac) throws OneWireIOException, OneWireException

      Verifies a User iButton's signed data on this Coprocessor iButton. The Coprocessor must recreate the signature based on the data in the file and the contents of the given scratchpad, and then match that with the signature passed in verify_mac.

      Overrides:
      verifySignature in class SHAiButtonCopr
      Parameters:
      pageData - the full 32 byte TMEX file from the User iButton (from verifyAuthentication) with the
      scratchpad - the 32-byte scratchpad contents for which the signature is generated. This will contain parameters such as the user's write cycle counter for the page, the user's 1-wire address, and the page number where account data is stored.
      verify_mac - the 20-byte buffer containing the signature the user had stored with the account data file.
      Returns:
      true if the data file is valid, false if an error occurred (use getLastError() for more information on the type of error)
      Throws:
      OneWireIOException - on a 1-Wire communication error such as reading an incorrect CRC from a 1-Wire device. This could be caused by a physical interruption in the 1-Wire Network due to shorts or a newly arriving 1-Wire device issuing a 'presence pulse'.
      OneWireException - on a communication or setup error with the 1-Wire adapter
      See Also:

    • bindSecretToiButton

      public boolean bindSecretToiButton(int pageNum, byte[] bindData, byte[] bindCode, int secretNum)

      Binds an installed secret to this virtual DS1963S by using well-known binding data and this DS1963S's (unique?) address. This makes the secret unique for this iButton. Coprocessor iButtons use this method to recreate the iButton's secret to verify authentication. Roving iButtons use this method to finalize their secret keys.

      Note that unlike in the installMasterSecret() method, the page number does not need to be equivalent to the secret_number modulo 8. The new secret (installed secret + binding code) is generated from this page but can be copied into another secret. User iButtons should bind to the same page the secret was installed on. Coprocessor iButtons must copy to a new secret to preserve the general system authentication secret.

      The binding should be either 7 bytes long or 15 bytes long. A 15-length byte array is unaltered and placed in the scratchpad for the binding. A 7-length byte array is combined with the page number and DS1963S unique address and then placed in the scratchpad. Coprocessors should use a pre-formatted 15-length byte array. User iButtons should let the method format for them (i.e. use the 7-length byte array option).

      Parameters:
      page - the page number that has the master secret already installed
      bind_data - 32 bytes of binding data used to bind the iButton to the system
      bind_code - the 7-byte or 15-byte binding code
      secret_number - secret number to copy the resulting secret to
      Returns:
      true if successful
      See Also:

    • installMasterSecret

      public boolean installMasterSecret(int pageNum, byte[] secret, int secretNum)

      Installs a secret on this virtual DS1963S. The secret is written in partial phrases of 47 bytes (32 bytes to a memory page, 15 bytes to the scratchpad) and is cumulative until the entire secret is processed. Secrets are associated with a page number. See the datasheet for more information on this association.

      In most cases, page should be equal to secret_number or secret_number+8, based on the association of secrets and page numbers. A secret is 8 bytes and there are 8 secrets. These 8 secrets are associated with the first 16 pages of memory.

      On TINI, this method will be slightly faster if the secret's length is divisible by 47. However, since secret key generation is a part of initialization, it is probably not necessary.

      Parameters:
      secret - the entire secret to be installed
      page - the page number used to write the partial secrets to
      secret_number - the secret 'page' to use (0 - 7)
      Returns:
      true if successful
      See Also:

    • toString

      public String toString()
      Returns a string representing the 1-Wire address of this SHAiButton.
      Overrides:
      toString in class SHAiButtonCopr
      Returns:
      a string containing the 8-byte address of this 1-Wire device.