Diff: Devices/DS28C36_DS2476.hpp

Revision:

5:a8c83a2e6fa4

Parent:

3:f818ea5172ed

Child:

6:471901a04573

--- a/Devices/DS28C36_DS2476.hpp	Fri Jan 19 10:25:02 2018 -0600
+++ b/Devices/DS28C36_DS2476.hpp	Wed Jan 23 13:11:04 2019 -0600
@@ -1,411 +1,775 @@
-/*******************************************************************************
-* Copyright (C) 2017 Maxim Integrated Products, Inc., All Rights Reserved.
-*
-* Permission is hereby granted, free of charge, to any person obtaining a
-* copy of this software and associated documentation files (the "Software"),
-* to deal in the Software without restriction, including without limitation
-* the rights to use, copy, modify, merge, publish, distribute, sublicense,
-* and/or sell copies of the Software, and to permit persons to whom the
-* Software is furnished to do so, subject to the following conditions:
-*
-* The above copyright notice and this permission notice shall be included
-* in all copies or substantial portions of the Software.
-*
-* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
-* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
-* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
-* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
-* OTHER DEALINGS IN THE SOFTWARE.
-*
-* Except as contained in this notice, the name of Maxim Integrated
-* Products, Inc. shall not be used except as stated in the Maxim Integrated
-* Products, Inc. Branding Policy.
-*
-* The mere transfer of this software does not imply any licenses
-* of trade secrets, proprietary technology, copyrights, patents,
-* trademarks, maskwork rights, or any other form of intellectual
-* property whatsoever. Maxim Integrated Products, Inc. retains all
-* ownership rights.
-*******************************************************************************/
-
-#ifndef MaximInterface_DS28C36_DS2476
-#define MaximInterface_DS28C36_DS2476
-
-#include <stddef.h>
-#include <stdint.h>
-#include <vector>
-#include <MaximInterface/Links/I2CMaster.hpp>
-#include <MaximInterface/Links/Sleep.hpp>
-#include <MaximInterface/Utilities/array.hpp>
-#include <MaximInterface/Utilities/Ecc256.hpp>
-#include <MaximInterface/Utilities/Export.h>
-#include <MaximInterface/Utilities/RomId.hpp>
-#include <MaximInterface/Utilities/ManId.hpp>
-#include <MaximInterface/Utilities/Sha256.hpp>
-#include <MaximInterface/Utilities/system_error.hpp>
-#include <MaximInterface/Utilities/FlagSet.hpp>
-
-namespace MaximInterface {
-
-/// Interface to the DS28C36 authenticator.
-class DS28C36 {
-public:
-  /// Device command results.
-  enum ErrorValue {
-    ProtectionError = 0x55,
-    InvalidParameterError = 0x77,
-    InvalidSequenceError = 0x33,
-    InvalidEcdsaInputOrResultError = 0x22,
-    AuthenticationError = 0x100,
-    InvalidResponseError = 0x101 ///< Response does not match expected format.
-  };
-
-  /// Device memory pages.
-  enum PageNum {
-    UserData0 = 0,
-    UserData1,
-    UserData2,
-    UserData3,
-    UserData4,
-    UserData5,
-    UserData6,
-    UserData7,
-    UserData8,
-    UserData9,
-    UserData10,
-    UserData11,
-    UserData12,
-    UserData13,
-    UserData14,
-    UserData15,
-    PublicKeyAX,
-    PublicKeyAY,
-    PublicKeyBX,
-    PublicKeyBY,
-    PublicKeyCX,
-    PublicKeyCY,
-    PrivateKeyA,
-    PrivateKeyB,
-    PrivateKeyC,
-    SecretA,
-    SecretB,
-    DecrementCounter,
-    RomOptions,
-    GpioControl,
-    PublicKeySX,
-    PublicKeySY
-  };
-
-  /// Available keys for ECDSA operations.
-  enum KeyNum { KeyNumA = 0, KeyNumB = 1, KeyNumC = 2, KeyNumS = 3 };
-
-  /// Available secrets for HMAC operations.
-  enum SecretNum { SecretNumA = 0, SecretNumB = 1, SecretNumS = 2 };
-
-  /// Data hash type when verifying an ECDSA signature.
-  enum HashType {
-    HashInBuffer = 0, ///< Hash is loaded in the buffer.
-    DataInBuffer = 1, ///< Compute hash from data loaded in the buffer.
-    THASH = 2         ///< Use THASH from Compute Multiblock Hash command.
-  };
-
-  /// Available PIO states when verifying an ECDSA signature.
-  enum PioState { Unchanged, Conducting, HighImpedance };
-
-  /// Holds a device memory page.
-  typedef array<uint_least8_t, 32> Page;
-
-  /// Holds page authentication input data.
-  typedef array<uint_least8_t, 75> PageAuthenticationData;
-
-  /// Page protection types.
-  enum PageProtectionType {
-    RP = 0x01,   ///< Read protection.
-    WP = 0x02,   ///< Write protection.
-    EM = 0x04,   ///< EPROM emulation mode.
-    APH = 0x08,  ///< Authentication write protection HMAC.
-    EPH = 0x10,  ///< Encryption and authenticated write protection HMAC.
-    AUTH = 0x20, ///< Public Key C is set to authority public key.
-    ECH = 0x40,  ///< Encrypted read and write using shared key from ECDH.
-    ECW = 0x80   ///< Authentication write protection ECDSA.
-  };
-  typedef FlagSet<PageProtectionType, 8> PageProtection;
-
-  /// Holds an encrypted device memory page.
-  struct EncryptedPage {
-    typedef array<uint_least8_t, 8> Challenge;
-
-    /// Total size of all elements in bytes.
-    static const size_t size = Challenge::csize + Page::csize;
-
-    Challenge challenge;
-    Page data;
-  };
-
-  /// Number of memory pages on the device.
-  static const int memoryPages = 32;
-
-  DS28C36(const Sleep & sleep, I2CMaster & master, uint_least8_t address = 0x36)
-      : sleep_(&sleep), master(&master), address_(address & 0xFE) {}
-
-  void setSleep(const Sleep & sleep) { this->sleep_ = &sleep; }
-  void setMaster(I2CMaster & master) { this->master = &master; }
-  uint_least8_t address() const { return address_; }
-  void setAddress(uint_least8_t address) { this->address_ = (address & 0xFE); }
-
-  /// Write memory with no protection.
-  /// @param pageNum Number of page to write.
-  /// @param page Data to write.
-  MaximInterface_EXPORT error_code writeMemory(int pageNum, const Page & page);
-
-  /// Read memory with no protection.
-  /// @param pageNum Number of page to read.
-  /// @param[out] page Data that was read.
-  MaximInterface_EXPORT error_code readMemory(int pageNum, Page & page);
-
-  /// Write the temporary buffer.
-  /// @param data Data to write.
-  /// @param dataSize Size of data to write.
-  MaximInterface_EXPORT error_code writeBuffer(const uint_least8_t * data,
-                                               size_t dataSize);
-
-  /// Read the temporary buffer.
-  /// @param[out] data Data that was read.
-  MaximInterface_EXPORT error_code
-  readBuffer(std::vector<uint_least8_t> & data);
-
-  /// Read the protection settings of a page.
-  /// @param pageNum Number of page to read.
-  /// @param[out] protection Protection that was read.
-  MaximInterface_EXPORT error_code
-  readPageProtection(int pageNum, PageProtection & protection);
-
-  /// Set the protection settings of a page.
-  /// @param pageNum Number of page to write.
-  /// @param protection Protection to write.
-  MaximInterface_EXPORT error_code
-  setPageProtection(int pageNum, const PageProtection & protection);
-
-  /// Decrement the decrement-only counter.
-  MaximInterface_EXPORT error_code decrementCounter();
-
-  /// Read a block of random data from the RNG.
-  /// @param[out] data Buffer to hold random data from RNG.
-  /// @param dataSize Number of bytes to read from 1 to 64 and length of data.
-  MaximInterface_EXPORT error_code readRng(uint_least8_t * data,
-                                           size_t dataSize);
-
-  /// Read memory with encryption.
-  /// @param pageNum Number of page to read from.
-  /// @param secretNum Secret to use for encryption.
-  /// @param[out] page Data that was read.
-  MaximInterface_EXPORT error_code encryptedReadMemory(int pageNum,
-                                                       SecretNum secretNum,
-                                                       EncryptedPage & page);
-
-  /// Compute and read page authentication with ECDSA.
-  /// @param pageNum Number of page to authenticate.
-  /// @param keyNum Private key to use for authentication.
-  /// Key S cannot be used with this command.
-  /// @param[out] signature Computed page signature.
-  MaximInterface_EXPORT error_code computeAndReadEcdsaPageAuthentication(
-      int pageNum, KeyNum keyNum, Ecc256::Signature & signature);
-
-  /// Compute and read page authentication with HMAC.
-  /// @param pageNum Number of page to authenticate.
-  /// @param secretNum Secret to use for authentication.
-  /// @param[out] hmac Computed page HMAC.
-  MaximInterface_EXPORT error_code computeAndReadHmacPageAuthentication(
-      int pageNum, SecretNum secretNum, Sha256::Hash & hmac);
-
-  /// Write with SHA2 authentication.
-  /// @param pageNum Number of page to write.
-  /// @param secretNum Secret to use for authentication.
-  /// @param page Data to write.
-  MaximInterface_EXPORT error_code authenticatedSha2WriteMemory(
-      int pageNum, SecretNum secretNum, const Page & page);
-
-  /// Compute SHA2 secret and optionally lock.
-  /// @param pageNum Number of page to use in computation.
-  /// @param msecretNum Master secret to use in computation.
-  /// @param dsecretNum Destination secret to receive the computation result.
-  /// @param writeProtectEnable
-  /// True to lock the destination secret against further writes.
-  MaximInterface_EXPORT error_code
-  computeAndLockSha2Secret(int pageNum, SecretNum msecretNum,
-                           SecretNum dsecretNum, bool writeProtectEnable);
-
-  /// Generate a new ECDSA key pair.
-  /// @param keyNum Key to generate. Key S cannot be used with this command.
-  /// @param writeProtectEnable True to lock the key against further writes.
-  MaximInterface_EXPORT error_code
-  generateEcc256KeyPair(KeyNum keyNum, bool writeProtectEnable);
-
-  /// Compute a hash over multiple blocks.
-  /// @param firstBlock True if this is the first block being hashed.
-  /// @param lastBlock True if this is the last block being hashed.
-  /// @param data Data block to hash.
-  /// @param dataSize Size of data to hash.
-  /// Should be 64 bytes unless this is the last block.
-  MaximInterface_EXPORT error_code
-  computeMultiblockHash(bool firstBlock, bool lastBlock,
-                        const uint_least8_t * data, size_t dataSize);
-
-  /// Verify ECDSA signature.
-  /// @param keyNum Public key to use for verification.
-  /// @param hashType Source of the data hash input.
-  /// @param signature Signature to verify.
-  /// @param pioa New state of PIOA if verification successful.
-  /// @param piob New state of PIOB if verification successful.
-  MaximInterface_EXPORT error_code verifyEcdsaSignature(
-      KeyNum keyNum, HashType hashType, const Ecc256::Signature & signature,
-      PioState pioa = Unchanged, PioState piob = Unchanged);
-
-  /// Authenticate a public key for authenticated writes or encrypted reads with ECDH.
-  /// @param authWrites True to select authentication for writes.
-  /// @param ecdh True to select ECDH key exchange.
-  /// @param keyNum Private key to use for ECDH key exchange.
-  /// Key A or B can be selected.
-  /// @param csOffset Certificate customization field ending offset in buffer.
-  /// @param signature Signature to use for authentication of public key S.
-  MaximInterface_EXPORT error_code
-  authenticateEcdsaPublicKey(bool authWrites, bool ecdh, KeyNum keyNum,
-                             int csOffset, const Ecc256::Signature & signature);
-
-  /// Write with ECDSA authentication.
-  /// @param pageNum Number of page to write.
-  /// @param page Data to write.
-  MaximInterface_EXPORT error_code
-  authenticatedEcdsaWriteMemory(int pageNum, const Page & page);
-
-  /// Create data used by the Compute and Read Page Authentication command to
-  /// generate a signature.
-  MaximInterface_EXPORT static PageAuthenticationData
-  createPageAuthenticationData(const RomId & romId, const Page & page,
-                               const Page & challenge, int pageNum,
-                               const ManId & manId);
-
-  MaximInterface_EXPORT static const error_category & errorCategory();
-
-protected:
-  // Timing constants.
-  static const int generateEcdsaSignatureTimeMs = 50;
-  static const int generateEccKeyPairTimeMs = 100;
-  static const int verifyEsdsaSignatureOrComputeEcdhTimeMs = 150;
-  static const int sha256ComputationTimeMs = 3;
-  static const int readMemoryTimeMs = /*1*/ 2;
-  static const int writeMemoryTimeMs = 15;
-
-  error_code writeCommand(uint_least8_t command,
-                          const uint_least8_t * parameters,
-                          size_t parametersSize);
-
-  error_code writeCommand(uint_least8_t command) {
-    return writeCommand(command, NULL, 0);
-  }
-
-  error_code readVariableLengthResponse(uint_least8_t * response,
-                                        size_t & responseSize);
-
-  error_code readFixedLengthResponse(uint_least8_t * response,
-                                     size_t responseSize);
-
-  void sleep(int ms) const { (*sleep_)(ms); }
-
-private:
-  enum AuthType {
-    HmacWithSecretA = 0,
-    HmacWithSecretB = 1,
-    HmacWithSecretS = 2,
-    EcdsaWithKeyA = 3,
-    EcdsaWithKeyB = 4,
-    EcdsaWithKeyC = 5
-  };
-
-  const Sleep * sleep_;
-  I2CMaster * master;
-  uint_least8_t address_;
-
-  error_code computeAndReadPageAuthentication(int pageNum, AuthType authType);
-};
-
-/// Read the device ROM ID and MAN ID using the Read Memory command on the
-/// ROM Options page.
-/// @param[out] romId
-/// Read ROM ID valid when operation is successful. May be set to NULL.
-/// @param[out] manId
-/// Read MAN ID valid when operation is successful. May be set to NULL.
-MaximInterface_EXPORT error_code readRomIdAndManId(DS28C36 & ds28c36,
-                                                   RomId * romId,
-                                                   ManId * manId);
-
-/// Hash arbitrary length data with successive Compute Multiblock Hash commands.
-/// @param data Data to hash.
-/// @param dataSize Size of data to hash.
-MaximInterface_EXPORT error_code computeMultiblockHash(
-    DS28C36 & ds28c36, const uint_least8_t * data, const size_t dataSize);
-
-/// Verify ECDSA signature.
-/// @param publicKey Public key to use for verification.
-/// @param data Data to verify.
-/// @param dataSize Size of data to verify.
-/// @param signature Signature to verify.
-/// @param pioa New state of PIOA if verification successful.
-/// @param piob New state of PIOB if verification successful.
-MaximInterface_EXPORT error_code verifyEcdsaSignature(
-    DS28C36 & ds28c36, DS28C36::KeyNum publicKey, const uint_least8_t * data,
-    size_t dataSize, const Ecc256::Signature & signature,
-    DS28C36::PioState pioa = DS28C36::Unchanged,
-    DS28C36::PioState piob = DS28C36::Unchanged);
-
-/// Verify ECDSA signature.
-/// @param publicKey
-/// Public key to use for verification which is loaded into Public Key S.
-/// @param data Data to verify.
-/// @param dataSize Size of data to verify.
-/// @param signature Signature to verify.
-/// @param pioa New state of PIOA if verification successful.
-/// @param piob New state of PIOB if verification successful.
-MaximInterface_EXPORT error_code
-verifyEcdsaSignature(DS28C36 & ds28c36, const Ecc256::PublicKey & publicKey,
-                     const uint_least8_t * data, size_t dataSize,
-                     const Ecc256::Signature & signature,
-                     DS28C36::PioState pioa = DS28C36::Unchanged,
-                     DS28C36::PioState piob = DS28C36::Unchanged);
-
-inline error_code make_error_code(DS28C36::ErrorValue e) {
-  return error_code(e, DS28C36::errorCategory());
-}
-
-/// Interface to the DS2476 coprocessor.
-class DS2476 : public DS28C36 {
-public:
-  DS2476(const Sleep & sleep, I2CMaster & master, uint_least8_t address = 0x76)
-      : DS28C36(sleep, master, address) {}
-
-  /// Generate ECDSA signature.
-  /// @param keyNum Private key to use to create signature.
-  /// Key S cannot be used with this command.
-  /// @param[out] signature Computed signature.
-  MaximInterface_EXPORT error_code
-  generateEcdsaSignature(KeyNum keyNum, Ecc256::Signature & signature);
-
-  /// Compute unique SHA2 secret.
-  /// @param msecretNum Master secret to use in computation.
-  MaximInterface_EXPORT error_code
-  computeSha2UniqueSecret(SecretNum msecretNum);
-
-  /// Compute SHA2 HMAC.
-  /// @param[out] hmac Computed HMAC.
-  MaximInterface_EXPORT error_code computeSha2Hmac(Sha256::Hash & hmac);
-};
-
-/// Enable coprocessor functionality on the DS2476 by writing to the
-/// ROM Options page.
-MaximInterface_EXPORT error_code enableCoprocessor(DS2476 & ds2476);
-
-} // namespace MaximInterface
-
-#endif
+/*******************************************************************************
+* Copyright (C) 2017 Maxim Integrated Products, Inc., All Rights Reserved.
+*
+* Permission is hereby granted, free of charge, to any person obtaining a
+* copy of this software and associated documentation files (the "Software"),
+* to deal in the Software without restriction, including without limitation
+* the rights to use, copy, modify, merge, publish, distribute, sublicense,
+* and/or sell copies of the Software, and to permit persons to whom the
+* Software is furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included
+* in all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
+* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+* OTHER DEALINGS IN THE SOFTWARE.
+*
+* Except as contained in this notice, the name of Maxim Integrated
+* Products, Inc. shall not be used except as stated in the Maxim Integrated
+* Products, Inc. Branding Policy.
+*
+* The mere transfer of this software does not imply any licenses
+* of trade secrets, proprietary technology, copyrights, patents,
+* trademarks, maskwork rights, or any other form of intellectual
+* property whatsoever. Maxim Integrated Products, Inc. retains all
+* ownership rights.
+*******************************************************************************/
+
+#ifndef MaximInterface_DS28C36_DS2476
+#define MaximInterface_DS28C36_DS2476
+
+#include <stdint.h>
+#include <vector>
+#include <MaximInterface/Links/I2CMaster.hpp>
+#include <MaximInterface/Links/Sleep.hpp>
+#include <MaximInterface/Utilities/array_span.hpp>
+#include <MaximInterface/Utilities/Ecc256.hpp>
+#include <MaximInterface/Utilities/Export.h>
+#include <MaximInterface/Utilities/RomId.hpp>
+#include <MaximInterface/Utilities/ManId.hpp>
+#include <MaximInterface/Utilities/Sha256.hpp>
+#include <MaximInterface/Utilities/system_error.hpp>
+#include <MaximInterface/Utilities/FlagSet.hpp>
+
+namespace MaximInterface {
+
+/// Interface to the DS28C36 authenticator.
+class DS28C36 {
+public:
+  /// Device command results.
+  enum ErrorValue {
+    ProtectionError = 0x55,
+    InvalidParameterError = 0x77,
+    InvalidSequenceError = 0x33,
+    InvalidEcdsaInputOrResultError = 0x22,
+    AuthenticationError = 0x100,
+    InvalidResponseError = 0x101 ///< Response does not match expected format.
+  };
+
+  // Device memory pages.
+  static const int publicKeyAxPage = 16;
+  static const int publicKeyAyPage = 17;
+  static const int publicKeyBxPage = 18;
+  static const int publicKeyByPage = 19;
+  static const int publicKeyCxPage = 20;
+  static const int publicKeyCyPage = 21;
+  static const int privateKeyAPage = 22;
+  static const int privateKeyBPage = 23;
+  static const int privateKeyCPage = 24;
+  static const int secretAPage = 25;
+  static const int secretBPage = 26;
+  static const int decrementCounterPage = 27;
+  static const int romOptionsPage = 28;
+  static const int gpioControlPage = 29;
+  static const int publicKeySxPage = 30;
+  static const int publicKeySyPage = 31;
+
+  /// Number of memory pages on the device.
+  static const int memoryPages = 32;
+
+  /// Available keys for ECDSA operations.
+  enum KeyNum { KeyNumA = 0, KeyNumB = 1, KeyNumC = 2, KeyNumS = 3 };
+
+  /// Available secrets for HMAC operations.
+  enum SecretNum { SecretNumA = 0, SecretNumB = 1, SecretNumS = 2 };
+
+  /// Data hash type when verifying an ECDSA signature.
+  enum HashType {
+    HashInBuffer = 0, ///< Hash is loaded in the buffer.
+    DataInBuffer = 1, ///< Compute hash from data loaded in the buffer.
+    THASH = 2         ///< Use THASH from Compute Multiblock Hash command.
+  };
+
+  /// Available PIO states when verifying an ECDSA signature.
+  enum PioState { Unchanged, Conducting, HighImpedance };
+
+  /// Holds a device memory page.
+  typedef array_span<uint_least8_t, 32> Page;
+
+  /// Format page authentication input data.
+  class PageAuthenticationData;
+
+  /// Format authenticated write input data.
+  class WriteAuthenticationData;
+
+  /// Format compute secret input data.
+  class ComputeSecretData;
+
+  /// Format encryption or decryption HMAC input data.
+  class EncryptionHmacData;
+
+  /// Access fields in the ROM Options page. Can be used with writeMemory and
+  /// readMemory functions.
+  class RomOptions;
+
+  /// Access fields in the GPIO Control page. Can be used with writeMemory and
+  /// readMemory functions.
+  class GpioControl;
+
+  /// Page protection types.
+  enum PageProtectionType {
+    RP = 0x01,   ///< Read protection.
+    WP = 0x02,   ///< Write protection.
+    EM = 0x04,   ///< EPROM emulation mode.
+    APH = 0x08,  ///< Authentication write protection HMAC.
+    EPH = 0x10,  ///< Encryption and authenticated write protection HMAC.
+    AUTH = 0x20, ///< Public Key C is set to authority public key.
+    ECH = 0x40,  ///< Encrypted read and write using shared key from ECDH.
+    ECW = 0x80   ///< Authentication write protection ECDSA.
+  };
+  typedef FlagSet<PageProtectionType, 8> PageProtection;
+
+  /// Challenge for an encrypted device memory page.
+  typedef array_span<uint_least8_t, 8> EncryptionChallenge;
+
+  DS28C36(Sleep & sleep, I2CMaster & master, uint_least8_t address = 0x36)
+      : sleep_(&sleep), master(&master), address_(address & 0xFE) {}
+
+  void setSleep(Sleep & sleep) { sleep_ = &sleep; }
+
+  void setMaster(I2CMaster & master) { this->master = &master; }
+
+  uint_least8_t address() const { return address_; }
+
+  void setAddress(uint_least8_t address) { address_ = address & 0xFE; }
+
+  /// Write memory with no protection.
+  /// @param pageNum Number of page to write.
+  /// @param page Data to write.
+  MaximInterface_EXPORT error_code writeMemory(int pageNum,
+                                               Page::const_span page);
+
+  /// Read memory with no protection.
+  /// @param pageNum Number of page to read.
+  /// @param[out] page Data that was read.
+  MaximInterface_EXPORT error_code readMemory(int pageNum, Page::span page);
+
+  /// Write the temporary buffer.
+  /// @param data Data to write.
+  MaximInterface_EXPORT error_code writeBuffer(span<const uint_least8_t> data);
+
+  /// Read the temporary buffer.
+  /// @param[out] data Data that was read.
+  MaximInterface_EXPORT error_code
+  readBuffer(std::vector<uint_least8_t> & data);
+
+  /// Read the protection settings of a page.
+  /// @param pageNum Number of page to read.
+  /// @param[out] protection Protection that was read.
+  MaximInterface_EXPORT error_code
+  readPageProtection(int pageNum, PageProtection & protection);
+
+  /// Set the protection settings of a page.
+  /// @param pageNum Number of page to write.
+  /// @param protection Protection to write.
+  MaximInterface_EXPORT error_code
+  setPageProtection(int pageNum, const PageProtection & protection);
+
+  /// Decrement the decrement-only counter.
+  MaximInterface_EXPORT error_code decrementCounter();
+
+  /// Read a block of random data from the RNG.
+  /// @param[out] data Random data from RNG with length from 1 to 64.
+  MaximInterface_EXPORT error_code readRng(span<uint_least8_t> data);
+
+  /// Read memory with encryption.
+  /// @param pageNum Number of page to read from.
+  /// @param secretNum Secret to use for encryption.
+  /// @param[out] challenge Encryption challenge that was read.
+  /// @param[out] data Encrypted page data that was read.
+  MaximInterface_EXPORT error_code
+  encryptedReadMemory(int pageNum, SecretNum secretNum,
+                      EncryptionChallenge::span challenge, Page::span data);
+
+  /// Compute and read page authentication with ECDSA.
+  /// @param pageNum Number of page to authenticate.
+  /// @param keyNum Private key to use for authentication.
+  /// Key S cannot be used with this command.
+  /// @param[out] signature Computed page signature.
+  MaximInterface_EXPORT error_code computeAndReadPageAuthentication(
+      int pageNum, KeyNum keyNum, Ecc256::Signature::span signature);
+
+  /// Compute and read page authentication with HMAC.
+  /// @param pageNum Number of page to authenticate.
+  /// @param secretNum Secret to use for authentication.
+  /// @param[out] hmac Computed page HMAC.
+  MaximInterface_EXPORT error_code computeAndReadPageAuthentication(
+      int pageNum, SecretNum secretNum, Sha256::Hash::span hmac);
+
+  /// Write with SHA2 authentication.
+  /// @param pageNum Number of page to write.
+  /// @param secretNum Secret to use for authentication.
+  /// @param page Data to write.
+  MaximInterface_EXPORT error_code authenticatedSha2WriteMemory(
+      int pageNum, SecretNum secretNum, Page::const_span page);
+
+  /// Compute SHA2 secret and optionally lock.
+  /// @param pageNum Number of page to use in computation.
+  /// @param msecretNum Master secret to use in computation.
+  /// @param dsecretNum Destination secret to receive the computation result.
+  /// @param writeProtectEnable
+  /// True to lock the destination secret against further writes.
+  MaximInterface_EXPORT error_code
+  computeAndLockSha2Secret(int pageNum, SecretNum msecretNum,
+                           SecretNum dsecretNum, bool writeProtectEnable);
+
+  /// Generate a new ECDSA key pair.
+  /// @param keyNum Key to generate. Key S cannot be used with this command.
+  /// @param writeProtectEnable True to lock the key against further writes.
+  MaximInterface_EXPORT error_code
+  generateEcc256KeyPair(KeyNum keyNum, bool writeProtectEnable);
+
+  /// Compute a hash over multiple blocks.
+  /// @param firstBlock True if this is the first block being hashed.
+  /// @param lastBlock True if this is the last block being hashed.
+  /// @param data
+  /// Data block to hash. Should be 64 bytes unless this is the last block.
+  MaximInterface_EXPORT error_code computeMultiblockHash(
+      bool firstBlock, bool lastBlock, span<const uint_least8_t> data);
+
+  /// Verify ECDSA signature.
+  /// @param keyNum Public key to use for verification.
+  /// @param hashType Source of the data hash input.
+  /// @param signature Signature to verify.
+  /// @param pioa New state of PIOA if verification successful.
+  /// @param piob New state of PIOB if verification successful.
+  MaximInterface_EXPORT error_code verifyEcdsaSignature(
+      KeyNum keyNum, HashType hashType, Ecc256::Signature::const_span signature,
+      PioState pioa = Unchanged, PioState piob = Unchanged);
+
+  /// Authenticate a public key for authenticated writes or encrypted reads with ECDH.
+  /// @param authWrites True to select authentication for writes.
+  /// @param ecdh True to select ECDH key exchange.
+  /// @param keyNum Private key to use for ECDH key exchange.
+  /// Key A or B can be selected.
+  /// @param csOffset Certificate customization field ending offset in buffer.
+  /// @param signature Signature to use for authentication of public key S.
+  MaximInterface_EXPORT error_code authenticateEcdsaPublicKey(
+      bool authWrites, bool ecdh, KeyNum keyNum, int csOffset,
+      Ecc256::Signature::const_span signature);
+
+  /// Write with ECDSA authentication.
+  /// @param pageNum Number of page to write.
+  /// @param page Data to write.
+  MaximInterface_EXPORT error_code
+  authenticatedEcdsaWriteMemory(int pageNum, Page::const_span page);
+
+  MaximInterface_EXPORT static const error_category & errorCategory();
+
+protected:
+  // Timing constants.
+  static const int generateEcdsaSignatureTimeMs = 50;
+  static const int generateEccKeyPairTimeMs = 100;
+  static const int verifyEsdsaSignatureOrComputeEcdhTimeMs = 150;
+  static const int sha256ComputationTimeMs = 3;
+  static const int readMemoryTimeMs = /*1*/ 2;
+  static const int writeMemoryTimeMs = 15;
+
+  error_code writeCommand(uint_least8_t command,
+                          span<const uint_least8_t> parameters);
+
+  error_code writeCommand(uint_least8_t command) {
+    return writeCommand(command, span<const uint_least8_t>());
+  }
+
+  error_code readVariableLengthResponse(span<uint_least8_t> & response);
+
+  error_code readFixedLengthResponse(span<uint_least8_t> response);
+
+  void sleep(int ms) const { sleep_->invoke(ms); }
+
+private:
+  enum AuthType {
+    HmacWithSecretA = 0,
+    HmacWithSecretB = 1,
+    HmacWithSecretS = 2,
+    EcdsaWithKeyA = 3,
+    EcdsaWithKeyB = 4,
+    EcdsaWithKeyC = 5
+  };
+
+  const Sleep * sleep_;
+  I2CMaster * master;
+  uint_least8_t address_;
+
+  error_code computeAndReadPageAuthentication(int pageNum, AuthType authType);
+};
+
+/// Interface to the DS2476 coprocessor.
+class DS2476 : public DS28C36 {
+public:
+  DS2476(Sleep & sleep, I2CMaster & master, uint_least8_t address = 0x76)
+      : DS28C36(sleep, master, address) {}
+
+  /// Generate ECDSA signature.
+  /// @param keyNum Private key to use to create signature.
+  /// Key S cannot be used with this command.
+  /// @param[out] signature Computed signature.
+  MaximInterface_EXPORT error_code
+  generateEcdsaSignature(KeyNum keyNum, Ecc256::Signature::span signature);
+
+  /// Compute unique SHA2 secret.
+  /// @param msecretNum Master secret to use in computation.
+  MaximInterface_EXPORT error_code
+  computeSha2UniqueSecret(SecretNum msecretNum);
+
+  /// Compute SHA2 HMAC.
+  /// @param[out] hmac Computed HMAC.
+  MaximInterface_EXPORT error_code computeSha2Hmac(Sha256::Hash::span hmac);
+};
+
+inline error_code make_error_code(DS28C36::ErrorValue e) {
+  return error_code(e, DS28C36::errorCategory());
+}
+
+/// Hash arbitrary length data with successive Compute Multiblock Hash commands.
+/// @param data Data to hash.
+MaximInterface_EXPORT error_code
+computeMultiblockHash(DS28C36 & ds28c36, span<const uint_least8_t> data);
+
+/// Verify ECDSA signature.
+/// @param publicKey Public key to use for verification.
+/// @param data Data to verify.
+/// @param signature Signature to verify.
+/// @param pioa New state of PIOA if verification successful.
+/// @param piob New state of PIOB if verification successful.
+MaximInterface_EXPORT error_code verifyEcdsaSignature(
+    DS28C36 & ds28c36, DS28C36::KeyNum publicKey,
+    span<const uint_least8_t> data, Ecc256::Signature::const_span signature,
+    DS28C36::PioState pioa = DS28C36::Unchanged,
+    DS28C36::PioState piob = DS28C36::Unchanged);
+
+/// Verify ECDSA signature.
+/// @param publicKey
+/// Public key to use for verification which is loaded into Public Key S.
+/// @param data Data to verify.
+/// @param signature Signature to verify.
+/// @param pioa New state of PIOA if verification successful.
+/// @param piob New state of PIOB if verification successful.
+MaximInterface_EXPORT error_code verifyEcdsaSignature(
+    DS28C36 & ds28c36, Ecc256::PublicKey::const_span publicKey,
+    span<const uint_least8_t> data, Ecc256::Signature::const_span signature,
+    DS28C36::PioState pioa = DS28C36::Unchanged,
+    DS28C36::PioState piob = DS28C36::Unchanged);
+
+/// Read the device ROM ID and MAN ID using the Read Memory command on the
+/// ROM Options page.
+/// @param[out] romId Read ROM ID valid when operation is successful.
+/// @param[out] manId Read MAN ID valid when operation is successful.
+MaximInterface_EXPORT error_code readRomIdAndManId(DS28C36 & ds28c36,
+                                                   RomId::span romId,
+                                                   ManId::span manId);
+
+/// Enable coprocessor functionality on the DS2476 by writing to the
+/// ROM Options page.
+MaximInterface_EXPORT error_code enableCoprocessor(DS2476 & ds2476);
+
+class DS28C36::PageAuthenticationData {
+public:
+  typedef array_span<uint_least8_t,
+                     RomId::size + 2 * Page::size + 1 + ManId::size>
+      Result;
+
+  PageAuthenticationData() : result_() {}
+
+  /// Formatted data result.
+  Result::const_span result() const { return result_; }
+
+  /// @{
+  /// 1-Wire ROM ID of the device.
+  RomId::span romId() {
+    return make_span(result_).subspan<romIdIdx, RomId::size>();
+  }
+
+  RomId::const_span romId() const {
+    return const_cast<PageAuthenticationData &>(*this).romId();
+  }
+
+  PageAuthenticationData & setRomId(RomId::const_span romId) {
+    copy(romId, this->romId());
+    return *this;
+  }
+
+  MaximInterface_EXPORT PageAuthenticationData & setAnonymousRomId();
+  /// @}
+
+  /// @{
+  /// Data from a device memory page.
+  Page::span page() {
+    return make_span(result_).subspan<pageIdx, Page::size>();
+  }
+
+  Page::const_span page() const {
+    return const_cast<PageAuthenticationData &>(*this).page();
+  }
+
+  PageAuthenticationData & setPage(Page::const_span page) {
+    copy(page, this->page());
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// Random challenge used to prevent replay attacks.
+  Page::span challenge() {
+    return make_span(result_).subspan<challengeIdx, Page::size>();
+  }
+
+  Page::const_span challenge() const {
+    return const_cast<PageAuthenticationData &>(*this).challenge();
+  }
+
+  PageAuthenticationData & setChallenge(Page::const_span challenge) {
+    copy(challenge, this->challenge());
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// Number of the page to use data from.
+  int pageNum() const { return result_[pageNumIdx]; }
+
+  PageAuthenticationData & setPageNum(int pageNum) {
+    result_[pageNumIdx] = pageNum;
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// Manufacturer ID of the device.
+  ManId::span manId() {
+    return make_span(result_).subspan<manIdIdx, ManId::size>();
+  }
+
+  ManId::const_span manId() const {
+    return const_cast<PageAuthenticationData &>(*this).manId();
+  }
+
+  PageAuthenticationData & setManId(ManId::const_span manId) {
+    copy(manId, this->manId());
+    return *this;
+  }
+  /// @}
+
+private:
+  typedef Result::span::index_type index;
+
+  static const index romIdIdx = 0;
+  static const index pageIdx = romIdIdx + RomId::size;
+  static const index challengeIdx = pageIdx + Page::size;
+  static const index pageNumIdx = challengeIdx + Page::size;
+  static const index manIdIdx = pageNumIdx + 1;
+
+  Result::array result_;
+};
+
+class DS28C36::WriteAuthenticationData {
+public:
+  typedef PageAuthenticationData::Result Result;
+
+  WriteAuthenticationData() : data() {}
+
+  /// Formatted data result.
+  Result::const_span result() const { return data.result(); }
+
+  /// @{
+  /// 1-Wire ROM ID of the device.
+  RomId::span romId() { return data.romId(); }
+
+  RomId::const_span romId() const { return data.romId(); }
+
+  WriteAuthenticationData & setRomId(RomId::const_span romId) {
+    data.setRomId(romId);
+    return *this;
+  }
+
+  WriteAuthenticationData & setAnonymousRomId() {
+    data.setAnonymousRomId();
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// Existing data contained in the page.
+  Page::span oldPage() { return data.page(); }
+
+  Page::const_span oldPage() const { return data.page(); }
+
+  WriteAuthenticationData & setOldPage(Page::const_span oldPage) {
+    data.setPage(oldPage);
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// New data to write to the page.
+  Page::span newPage() { return data.challenge(); }
+
+  Page::const_span newPage() const { return data.challenge(); }
+
+  WriteAuthenticationData & setNewPage(Page::const_span newPage) {
+    data.setChallenge(newPage);
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// Page number for write operation.
+  int pageNum() const { return data.pageNum(); }
+
+  WriteAuthenticationData & setPageNum(int pageNum) {
+    data.setPageNum(pageNum);
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// Manufacturer ID of the device.
+  ManId::span manId() { return data.manId(); }
+
+  ManId::const_span manId() const { return data.manId(); }
+
+  WriteAuthenticationData & setManId(ManId::const_span manId) {
+    data.setManId(manId);
+    return *this;
+  }
+  /// @}
+
+private:
+  PageAuthenticationData data;
+};
+
+class DS28C36::ComputeSecretData {
+public:
+  typedef PageAuthenticationData::Result Result;
+
+  ComputeSecretData() : data() {}
+
+  /// Formatted data result.
+  Result::const_span result() const { return data.result(); }
+
+  /// @{
+  /// 1-Wire ROM ID of the device.
+  RomId::span romId() { return data.romId(); }
+
+  RomId::const_span romId() const { return data.romId(); }
+
+  ComputeSecretData & setRomId(RomId::const_span romId) {
+    data.setRomId(romId);
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// Binding Data contained in the selected page.
+  Page::span bindingData() { return data.page(); }
+
+  Page::const_span bindingData() const { return data.page(); }
+
+  ComputeSecretData & setBindingData(Page::const_span bindingData) {
+    data.setPage(bindingData);
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// Partial Secret used for customization.
+  Page::span partialSecret() { return data.challenge(); }
+
+  Page::const_span partialSecret() const { return data.challenge(); }
+
+  ComputeSecretData & setPartialSecret(Page::const_span partialSecret) {
+    data.setChallenge(partialSecret);
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// Page number for Binding Data.
+  int pageNum() const { return data.pageNum(); }
+
+  ComputeSecretData & setPageNum(int pageNum) {
+    data.setPageNum(pageNum);
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// Manufacturer ID of the device.
+  ManId::span manId() { return data.manId(); }
+
+  ManId::const_span manId() const { return data.manId(); }
+
+  ComputeSecretData & setManId(ManId::const_span manId) {
+    data.setManId(manId);
+    return *this;
+  }
+  /// @}
+
+private:
+  PageAuthenticationData data;
+};
+
+class DS28C36::EncryptionHmacData {
+public:
+  typedef array_span<uint_least8_t,
+                     EncryptionChallenge::size + RomId::size + 1 + ManId::size>
+      Result;
+
+  EncryptionHmacData() : result_() {}
+
+  /// Formatted data result.
+  Result::const_span result() const { return result_; }
+
+  /// @{
+  /// Random challenge used to prevent replay attacks.
+  EncryptionChallenge::span encryptionChallenge() {
+    return make_span(result_)
+        .subspan<encryptionChallengeIdx, EncryptionChallenge::size>();
+  }
+
+  EncryptionChallenge::const_span encryptionChallenge() const {
+    return const_cast<EncryptionHmacData &>(*this).encryptionChallenge();
+  }
+
+  EncryptionHmacData &
+  setEncryptionChallenge(EncryptionChallenge::const_span encryptionChallenge) {
+    copy(encryptionChallenge, this->encryptionChallenge());
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// 1-Wire ROM ID of the device.
+  RomId::span romId() {
+    return make_span(result_).subspan<romIdIdx, RomId::size>();
+  }
+
+  RomId::const_span romId() const {
+    return const_cast<EncryptionHmacData &>(*this).romId();
+  }
+
+  EncryptionHmacData & setRomId(RomId::const_span romId) {
+    copy(romId, this->romId());
+    return *this;
+  }
+
+  MaximInterface_EXPORT EncryptionHmacData & setAnonymousRomId();
+  /// @}
+
+  /// @{
+  /// Number of the page to use data from.
+  int pageNum() const { return result_[pageNumIdx]; }
+
+  EncryptionHmacData & setPageNum(int pageNum) {
+    result_[pageNumIdx] = pageNum;
+    return *this;
+  }
+  /// @}
+
+  /// @{
+  /// Manufacturer ID of the device.
+  ManId::span manId() {
+    return make_span(result_).subspan<manIdIdx, ManId::size>();
+  }
+
+  ManId::const_span manId() const {
+    return const_cast<EncryptionHmacData &>(*this).manId();
+  }
+
+  EncryptionHmacData & setManId(ManId::const_span manId) {
+    copy(manId, this->manId());
+    return *this;
+  }
+  /// @}
+
+private:
+  typedef Result::span::index_type index;
+
+  static const index encryptionChallengeIdx = 0;
+  static const index romIdIdx =
+      encryptionChallengeIdx + EncryptionChallenge::size;
+  static const index pageNumIdx = romIdIdx + RomId::size;
+  static const index manIdIdx = pageNumIdx + 1;
+
+  Result::array result_;
+};
+
+class DS28C36::RomOptions {
+public:
+  operator Page::const_span() const { return page; }
+  operator Page::span() { return page; }
+
+  bool anonymous() const { return page[anonymousIdx] == anonymousValue; }
+
+  void setAnonymous(bool anonymous) {
+    page[anonymousIdx] = (anonymous ? anonymousValue : 0);
+  }
+
+  ManId::const_span manId() const {
+    return make_span(page).subspan<22, ManId::size>();
+  }
+
+  RomId::const_span romId() const {
+    return make_span(page).subspan<24, RomId::size>();
+  }
+
+private:
+  static const Page::array::size_type anonymousIdx = 1;
+  static const Page::array::value_type anonymousValue = 0xAA;
+
+  Page::array page;
+};
+
+class DS28C36::GpioControl {
+public:
+  operator Page::const_span() const { return page; }
+  operator Page::span() { return page; }
+
+  bool pioaConducting() const {
+    return page[pioaConductingIdx] == pioConductingValue;
+  }
+
+  void setPioaConducting(bool pioaConducting) {
+    page[pioaConductingIdx] = (pioaConducting ? pioConductingValue : 0x55);
+  }
+
+  bool piobConducting() const {
+    return page[piobConductingIdx] == pioConductingValue;
+  }
+
+  void setPiobConducting(bool piobConducting) {
+    page[piobConductingIdx] = (piobConducting ? pioConductingValue : 0x55);
+  }
+
+  bool pioaLevel() const { return page[2] == pioLevelValue; }
+
+  bool piobLevel() const { return page[3] == pioLevelValue; }
+
+private:
+  static const Page::array::size_type pioaConductingIdx = 0;
+  static const Page::array::size_type piobConductingIdx = 1;
+  static const Page::array::value_type pioConductingValue = 0xAA;
+  static const Page::array::value_type pioLevelValue = 0x55;
+
+  Page::array page;
+};
+
+} // namespace MaximInterface
+
+#endif