/* ---------------------------------------------------------------------------- */ /* Atmel Microcontroller Software Support */ /* SAM Software Package License */ /* ---------------------------------------------------------------------------- */ /* Copyright (c) 2015, Atmel Corporation */ /* */ /* All rights reserved. */ /* */ /* Redistribution and use in source and binary forms, with or without */ /* modification, are permitted provided that the following condition is met: */ /* */ /* - Redistributions of source code must retain the above copyright notice, */ /* this list of conditions and the disclaimer below. */ /* */ /* Atmel's name may not be used to endorse or promote products derived from */ /* this software without specific prior written permission. */ /* */ /* DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR */ /* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF */ /* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE */ /* DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT, */ /* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT */ /* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, */ /* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF */ /* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING */ /* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, */ /* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /* ---------------------------------------------------------------------------- */ /** \addtogroup aes_module Working with AES * \ingroup peripherals_module * The AES driver provides the interface to configure and use the AES peripheral. * \n * * The Advanced Encryption Standard (AES) specifies a FIPS-approved * cryptographic algorithm that can be used to protect electronic data. The AES * algorithm is a symmetric block cipher that can encrypt (encipher) and decrypt * (decipher) information. * Encryption converts data to an unintelligible form called ciphertext. * Decrypting the ciphertext converts the data back into its original form, * called plaintext. The CIPHER bit in the AES Mode Register (AES_MR) allows * selection between the encryption and the decryption processes. The AES is * capable of using cryptographic keys of 128/192/256 bits to encrypt and * decrypt data in blocks of 128 bits. * This 128-bit/192-bit/256-bit key is defined in the Key Registers (AES_KEYWRx) * and set by AES_WriteKey(). The input to the encryption processes of the CBC, * CFB, and OFB modes includes, in addition to the plaintext, a 128-bit data * block called the initialization vector (IV), * which must be set with AES_SetVector(). * The initialization vector is used in an initial step in the encryption of a * message and in the corresponding decryption of the message. * The Initialization Vector Registers are also used by the CTR mode to set the * counter value. * * To Enable a AES encryption and decryption,the user has to follow these few * steps: * * * * For more accurate information, please look at the AES section of the * Datasheet. * * Related files :\n * \ref aes.c\n * \ref aes.h\n */ /*@{*/ /*@}*/ /** * \file * * Implementation of Advanced Encryption Standard (AES) * */ /*---------------------------------------------------------------------------- * Headers *----------------------------------------------------------------------------*/ #include "chip.h" #include "aes.h" /*---------------------------------------------------------------------------- * Exported functions *----------------------------------------------------------------------------*/ /** * \brief Starts Manual encryption/decryption process. */ void AES_Start(void) { AES->AES_CR = AES_CR_START; } /** * \brief Resets the AES. A software triggered hardware reset of the AES * interface is performed. */ void AES_SoftReset(void) { AES->AES_CR = AES_CR_SWRST; } /** * \brief Configures an AES peripheral with the specified parameters. * \param mode Desired value for the AES mode register (see the datasheet). */ void AES_Configure(uint32_t mode) { AES->AES_MR = mode; } /** * \brief Enables the selected interrupts sources on a AES peripheral. * \param sources Bitwise OR of selected interrupt sources. */ void AES_EnableIt(uint32_t sources) { AES->AES_IER = sources; } /** * \brief Disables the selected interrupts sources on a AES peripheral. * \param sources Bitwise OR of selected interrupt sources. */ void AES_DisableIt(uint32_t sources) { AES->AES_IDR = sources; } /** * \brief Get the current status register of the given AES peripheral. * \return AES status register. */ uint32_t AES_GetStatus(void) { return AES->AES_ISR; } /** * \brief Set the 128-bit/192-bit/256-bit cryptographic key used for * encryption/decryption. * \param pKey Pointer to a 16/24/32 bytes cipher key. * \param keyLength length of key */ void AES_WriteKey(const uint32_t *pKey, uint32_t keyLength) { AES->AES_KEYWR[0] = pKey[0]; AES->AES_KEYWR[1] = pKey[1]; AES->AES_KEYWR[2] = pKey[2]; AES->AES_KEYWR[3] = pKey[3]; if (keyLength >= 24) { AES->AES_KEYWR[4] = pKey[4]; AES->AES_KEYWR[5] = pKey[5]; } if (keyLength == 32) { AES->AES_KEYWR[6] = pKey[6]; AES->AES_KEYWR[7] = pKey[7]; } } /** * \brief Set the for 32-bit input Data allow to set the 128-bit data block * used for encryption/decryption. * \param data Pointer to the 16-bytes data to cipher/decipher. */ void AES_SetInput(uint32_t *data) { uint8_t i; for (i = 0; i < 4; i++) AES->AES_IDATAR[i] = data[i]; } /** * \brief Get the four 32-bit data contain the 128-bit data block which * has been encrypted/decrypted. * \param data pointer to the word that has been encrypted/decrypted.. */ void AES_GetOutput(uint32_t *data) { uint8_t i; for (i = 0; i < 4; i++) data[i] = AES->AES_ODATAR[i]; } /** * \brief Set four 64-bit initialization vector data block, which is used by * some modes of operation as an additional initial input. * \param pVector point to the word of the initialization vector. */ void AES_SetVector(const uint32_t *pVector) { AES->AES_IVR[0] = pVector[0]; AES->AES_IVR[1] = pVector[1]; AES->AES_IVR[2] = pVector[2]; AES->AES_IVR[3] = pVector[3]; } /** * \brief Set Length in bytes of the AAD data that is to be processed. * \param len Length. */ void AES_SetAadLen(uint32_t len) { AES->AES_AADLENR = len; } /** * \brief Set Length in bytes of the Length in bytes of the * plaintext/ciphertext (C) data that is to be processed.. * \param len Length. */ void AES_SetDataLen(uint32_t len) { AES->AES_CLENR = len; } /** * \brief Set The four 32-bit Hash Word registers expose the intermediate GHASH * value. May be read to save the current GHASH value so processing can later be * resumed, presumably on a later message fragment. modes of operation as an * additional initial input. * \param hash point to the word of the hash. */ void AES_SetGcmHash(uint32_t *hash) { uint8_t i; for (i = 0; i < 4; i++) AES->AES_GHASHR[i] = hash[i]; } /** * \brief Get The four 32-bit Tag which contain the final 128-bit GCM * Authentication tag Ħ°TĦħ when GCM processing is complete. * \param tag point to the word of the tag. */ void AES_GetGcmTag(uint32_t *tag) { uint8_t i; for (i = 0; i < 4; i++) tag[i] = AES->AES_TAGR[i]; } /** * \brief Reports the current value of the 32-bit GCM counter * \param counter Point to value of GCM counter. */ void AES_GetGcmCounter(uint32_t *counter) { *counter = AES->AES_CTRR; } /** * \brief Get the four 32-bit data contain the 128-bit H value computed from * the KEYW value * \param data point to the word that has been encrypted/decrypted. */ void AES_GetGcmH(uint32_t *h) { uint8_t i; for (i = 0; i < 4; i++) h[i] = AES->AES_GCMHR[i]; }