A lightweight AES implementation with Cipher Block Chaining and Ciphertext Stealing.
Dependents: AES_HelloWorld AES_ExtendedTests AESslave_modified_test AESslave_modified_test_27-9-2017 ... more
Revision 0:6132f54fa9e9, committed 2015-09-04
- Comitter:
- neilt6
- Date:
- Fri Sep 04 02:03:00 2015 +0000
- Child:
- 1:09347d4bc827
- Commit message:
- Initial commit
Changed in this revision
AES.cpp | Show annotated file Show diff for this revision Revisions of this file |
AES.h | Show annotated file Show diff for this revision Revisions of this file |
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/AES.cpp Fri Sep 04 02:03:00 2015 +0000 @@ -0,0 +1,503 @@ +/* AES Cipher Library + * Copyright (c) 2015 Neil Thiessen + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include "AES.h" + +const char AES::m_Sbox[256] = { + 0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, + 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76, + 0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, + 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0, + 0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, + 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15, + 0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, + 0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75, + 0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, + 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84, + 0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, + 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF, + 0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, + 0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8, + 0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, + 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2, + 0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, + 0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73, + 0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, + 0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB, + 0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, + 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79, + 0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, + 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08, + 0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, + 0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A, + 0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, + 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E, + 0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, + 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF, + 0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, + 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16 +}; + +const char AES::m_InvSbox[256] = { + 0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, + 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB, + 0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, + 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB, + 0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, + 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E, + 0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, + 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25, + 0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, + 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92, + 0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, + 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84, + 0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, + 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06, + 0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, + 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B, + 0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, + 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73, + 0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, + 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E, + 0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, + 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B, + 0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, + 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4, + 0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, + 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F, + 0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, + 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF, + 0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, + 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61, + 0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, + 0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D +}; + +const unsigned int AES::m_Rcon[10] = { + 0x01000000, 0x02000000, 0x04000000, 0x08000000, + 0x10000000, 0x20000000, 0x40000000, 0x80000000, + 0x1B000000, 0x36000000 +}; + +AES::AES() +{ + //Initialize the member variables to default values + m_CipherMode = MODE_ECB; + m_Rounds = 0; + clear(); +} + +AES::AES(const char* key, KeySize keySize, CipherMode mode, const char* iv) +{ + //Set up the cipher with the specified parameters + setup(key, keySize, mode, iv); +} + +AES::~AES() +{ + //Erase any sensitive information + clear(); +} + +void AES::setup(const char* key, KeySize keySize, CipherMode mode, const char* iv) +{ + //Set the cipher mode + m_CipherMode = mode; + + //Determine the number of rounds from the key size + m_Rounds = (int)keySize + 6; + + //Check if the key pointer is NULL + if (key == NULL) { + //Set a blank key + memset(m_Key, 0, sizeof(m_Key)); + } else { + //Expand the key + expandKey(key, keySize); + } + + //Check if the initialization vector pointer is NULL + if (iv == NULL) { + //Set a blank initialization vector + memset(m_CarryVector, 0, 16); + } else { + //Copy the initialization vector to the carry vector + memcpy(m_CarryVector, iv, 16); + } +} + +void AES::encrypt(void* data, size_t length) +{ + //Encrypt the specified data in-place + encrypt(data, (char*)data, length); +} + +void AES::encrypt(const void* src, char* dest, size_t length) +{ + //Convert the source pointer for byte access + const char* srcBytes = (const char*)src; + + //Check if the length is less than 1 block + if (length > 0 && length < 16) { + //Copy the partial source block to the state array + memcpy(m_State, srcBytes, length); + + //Pad the state array with zeroes + memset(m_State + length, 0, 16 - length); + + //Perform CBC pre-processing if necessary + if (m_CipherMode == MODE_CBC) { + //XOR the state array with the carry vector + for (int i = 0; i < 16; i++) + m_State[i] = m_State[i] ^ m_CarryVector[i]; + } + + //Encrypt the state array + aesEncrypt(); + + //Perform CBC post-processing if necessary + if (m_CipherMode == MODE_CBC) { + //Save the state array as the next carry vector + memcpy(m_CarryVector, m_State, 16); + } + + //Copy the state array to the destination block + memcpy(dest, m_State, 16); + return; + } + + //Encrypt all of the data + while (length > 0) { + //Copy the next source block to the state array + memcpy(m_State, srcBytes, 16); + srcBytes += 16; + length -= 16; + + //Perform CBC pre-processing if necessary + if (m_CipherMode == MODE_CBC) { + //XOR the state array with the carry vector + for (int i = 0; i < 16; i++) + m_State[i] = m_State[i] ^ m_CarryVector[i]; + } + + //Encrypt the state array + aesEncrypt(); + + //Perform CBC post-processing if necessary + if (m_CipherMode == MODE_CBC) { + //Save the state array as the next carry vector + memcpy(m_CarryVector, m_State, 16); + } + + //Perform ciphertext stealing if the next block is a partial block + if (length > 0 && length < 16) { + //Copy the last partial source block to a temporary buffer (in case of in-place encryption) + char temp[length]; + memcpy(temp, srcBytes, length); + + //Copy the leading bytes of the state array to the last partial destination block + memcpy(dest + 16, m_State, length); + + //Copy the temporary buffer to the state array + memcpy(m_State, temp, length); + + //Perform CBC processing if necessary + if (m_CipherMode == MODE_CBC) { + //Pad the state array with zeroes + memset(m_State + length, 0, 16 - length); + + //XOR the state array with the carry vector + for (int i = 0; i < 16; i++) + m_State[i] = m_State[i] ^ m_CarryVector[i]; + } + + //Encrypt the state array + aesEncrypt(); + length = 0; + } + + //Copy the state array to the destination block + memcpy(dest, m_State, 16); + dest += 16; + } +} + +void AES::decrypt(void* data, size_t length) +{ + //Decrypt the specified data in-place + decrypt((const char*)data, data, length); +} + +void AES::decrypt(const char* src, void* dest, size_t length) +{ + //Convert the destination pointer for byte access + char* destBytes = (char*)dest; + + //Check if the length is less than 1 block + if (length > 0 && length < 16) { + //Copy the complete source block to the state array + memcpy(m_State, src, 16); + + //Decrypt the state array + aesDecrypt(); + + //Perform CBC processing if necessary + if (m_CipherMode == MODE_CBC) { + //XOR the state array with the carry vector + for (int i = 0; i < 16; i++) + m_State[i] = m_State[i] ^ m_CarryVector[i]; + + //Save the source block as the next carry vector + memcpy(m_CarryVector, src, 16); + } + + //Copy the leading bytes of the state array to the destination block + memcpy(destBytes, m_State, length); + return; + } + + //Encrypt all of the data + while (length > 0) { + //Copy the next source block to the state array + memcpy(m_State, src, 16); + src += 16; + length -= 16; + + //Decrypt the state array + aesDecrypt(); + + //Reverse ciphertext stealing if the next block is a partial block + if (length > 0 && length < 16) { + //Perform CBC processing if necessary + if (m_CipherMode == MODE_CBC) { + //XOR the state array with the last partial source block + for (int i = 0; i < length; i++) + m_State[i] = m_State[i] ^ src[i]; + } + + //Copy the last partial source block to a temporary buffer (in case of in-place decryption) + char temp[length]; + memcpy(temp, src, length); + + //Copy the leading bytes of the state array to the last partial destination block + memcpy(destBytes + 16, m_State, length); + + //Copy the temporary buffer to the state array + memcpy(m_State, temp, length); + + //Decrypt the state array + aesDecrypt(); + length = 0; + } + + //Perform CBC processing if necessary + if (m_CipherMode == MODE_CBC) { + //XOR the state array with the carry vector + for (int i = 0; i < 16; i++) + m_State[i] = m_State[i] ^ m_CarryVector[i]; + + //Save the source block as the next carry vector + memcpy(m_CarryVector, src - 16, 16); + } + + //Copy the state array to the destination block + memcpy(destBytes, m_State, 16); + destBytes += 16; + } +} + +void AES::clear() +{ + //Erase the key, state array, and carry vector + memset(m_Key, 0, sizeof(m_Key)); + memset(m_State, 0, sizeof(m_State)); + memset(m_CarryVector, 0, sizeof(m_CarryVector)); +} + +void AES::aesEncrypt() +{ + addRoundKey(0); + for (int r = 1; r < m_Rounds; r++) { + subBytes(); + shiftRows(); + mixColumns(); + addRoundKey(r); + } + subBytes(); + shiftRows(); + addRoundKey(m_Rounds); +} + +void AES::aesDecrypt() +{ + addRoundKey(m_Rounds); + for (int r = m_Rounds - 1; r > 0; r--) { + invShiftRows(); + invSubBytes(); + addRoundKey(r); + invMixColumns(); + } + invShiftRows(); + invSubBytes(); + addRoundKey(0); +} + +void AES::expandKey(const char* key, int nk) +{ + unsigned int temp; + int i = 0; + + while(i < nk) { + m_Key[i] = (key[4*i] << 24) + (key[4*i+1] << 16) + (key[4*i+2] << 8) + key[4*i+3]; + i++; + } + i = nk; + while(i < 4*(m_Rounds+1)) { + temp = m_Key[i-1]; + if(i % nk == 0) + temp = subWord(rotWord(temp)) ^ m_Rcon[i/nk-1]; + else if(nk > 6 && i % nk == 4) + temp = subWord(temp); + m_Key[i] = m_Key[i-nk] ^ temp; + i++; + } +} + +unsigned int AES::rotWord(unsigned int w) +{ + return (w << 8) + (w >> 24); +} + +unsigned int AES::invRotWord(unsigned int w) +{ + return (w >> 8) + (w << 24); +} + +unsigned int AES::subWord(unsigned int w) +{ + unsigned int out = 0; + for(int i = 0; i < 4; ++i) { + char temp = (w & 0xFF); + out |= (m_Sbox[temp] << (8*i)); + w = (w >> 8); + } + return out; +} + +void AES::subBytes() +{ + for(int i = 0; i < 16; ++i) + m_State[i] = m_Sbox[m_State[i]]; +} + +void AES::invSubBytes() +{ + for(int i = 0; i < 16; ++i) + m_State[i] = m_InvSbox[m_State[i]]; +} + +void AES::shiftRows() +{ + for(int r = 0; r < 4; ++r) { + unsigned int temp = (m_State[r] << 24) + (m_State[r+4] << 16) + (m_State[r+8] << 8) + m_State[r+12]; + int i = r; + while(i > 0) { + temp = rotWord(temp); + --i; + } + m_State[r] = temp >> 24; + m_State[r+4] = temp >> 16; + m_State[r+8] = temp >> 8; + m_State[r+12] = temp; + } +} + +void AES::invShiftRows() +{ + for(int r = 0; r < 4; ++r) { + unsigned int temp = (m_State[r] << 24) + (m_State[r+4] << 16) + (m_State[r+8] << 8) + m_State[r+12]; + int i = r; + while(i > 0) { + temp = invRotWord(temp); + --i; + } + m_State[r] = temp >> 24; + m_State[r+4] = temp >> 16; + m_State[r+8] = temp >> 8; + m_State[r+12] = temp; + } +} + +char AES::gmul(char a, char b) +{ + char p = 0; + char counter; + char carry; + for (counter = 0; counter < 8; counter++) { + if (b & 1) + p ^= a; + carry = (a & 0x80); + a <<= 1; + if (carry) + a ^= 0x001B; + b >>= 1; + } + return p; +} + +void AES::mul(char* r) +{ + char tmp[4] = {}; + memcpy(tmp, r, 4); + r[0] = gmul(tmp[0],2) ^ gmul(tmp[1],3) ^ tmp[2] ^ tmp[3]; + r[1] = tmp[0] ^ gmul(tmp[1],2) ^ gmul(tmp[2],3) ^ tmp[3]; + r[2] = tmp[0] ^ tmp[1] ^ gmul(tmp[2],2) ^ gmul(tmp[3],3); + r[3] = gmul(tmp[0],3) ^ tmp[1] ^ tmp[2] ^ gmul(tmp[3],2); +} + +void AES::invMul(char* r) +{ + char tmp[4] = {}; + memcpy(tmp, r, 4); + r[0] = gmul(tmp[0],0x0e) ^ gmul(tmp[1],0x0b) ^ gmul(tmp[2],0x0d) ^ gmul(tmp[3],9); + r[1] = gmul(tmp[0],9) ^ gmul(tmp[1],0x0e) ^ gmul(tmp[2],0x0b) ^ gmul(tmp[3],0x0d); + r[2] = gmul(tmp[0],0x0d) ^ gmul(tmp[1],9) ^ gmul(tmp[2],0x0e) ^ gmul(tmp[3],0x0b); + r[3] = gmul(tmp[0],0x0b) ^ gmul(tmp[1],0x0d) ^ gmul(tmp[2],9) ^ gmul(tmp[3],0x0e); +} + +void AES::mixColumns() +{ + for(int c = 0; c < 4; ++c) + mul(&m_State[4*c]); +} + +void AES::invMixColumns() +{ + for(int c = 0; c < 4; ++c) + invMul(&m_State[4*c]); +} + +void AES::addRoundKey(int round) +{ + for(int c = 0; c < 4; ++c) { + unsigned int temp = (m_State[4*c] << 24) + (m_State[4*c+1] << 16) + (m_State[4*c+2] << 8) + m_State[4*c+3]; + temp ^= m_Key[round*4+c]; + m_State[4*c] = temp >> 24; + m_State[4*c+1] = temp >> 16; + m_State[4*c+2] = temp >> 8; + m_State[4*c+3] = temp; + } +}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/AES.h Fri Sep 04 02:03:00 2015 +0000 @@ -0,0 +1,193 @@ +/* AES Cipher Library + * Copyright (c) 2015 Neil Thiessen + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#ifndef AES_H +#define AES_H + +#include "mbed.h" + +/** AES class. + * Used for encrypting/decrypting data using the AES block cipher. + * + * Example: + * @code + * #include "mbed.h" + * #include "AES.h" + * + * char message[] = { + * "Hello World!" + * }; + * + * const char key[32] = { + * 0x60, 0x3D, 0xEB, 0x10, 0x15, 0xCA, 0x71, 0xBE, + * 0x2B, 0x73, 0xAE, 0xF0, 0x85, 0x7D, 0x77, 0x81, + * 0x1F, 0x35, 0x2C, 0x07, 0x3B, 0x61, 0x08, 0xD7, + * 0x2D, 0x98, 0x10, 0xA3, 0x09, 0x14, 0xDF, 0xF4 + * }; + * + * const char iv[16] = { + * 0x74, 0x11, 0xF0, 0x45, 0xD6, 0xA4, 0x3F, 0x69, + * 0x18, 0xC6, 0x75, 0x42, 0xDF, 0x4C, 0xA7, 0x84 + * }; + * + * void printData(const void* data, size_t length) + * { + * const char* dataBytes = (const char*)data; + * for (size_t i = 0; i < length; i++) { + * if ((i % 8) == 0) + * printf("\n\t"); + * printf("0x%02X, ", dataBytes[i]); + * } + * printf("\n"); + * } + * + * int main() + * { + * AES aes; + * + * //Print the original message + * printf("Original message: \"%s\"", message); + * printData(message, sizeof(message)); + * + * //Encrypt the message in-place + * aes.setup(key, AES::KEY_256, AES::MODE_CBC, iv); + * aes.encrypt(message, sizeof(message)); + * aes.clear(); + * + * //Print the encrypted message + * printf("Encrypted message:"); + * printData(message, sizeof(message)); + * + * //Decrypt the message in-place + * aes.setup(key, AES::KEY_256, AES::MODE_CBC, iv); + * aes.decrypt(message, sizeof(message)); + * aes.clear(); + * + * //Print the decrypted message + * printf("Decrypted message: \"%s\"", message); + * printData(message, sizeof(message)); + * } + * @endcode + */ +class AES +{ +public: + /** Represents the different AES key sizes + */ + enum KeySize { + KEY_128 = 4, /**< 128-bit AES key */ + KEY_192 = 6, /**< 192-bit AES key */ + KEY_256 = 8 /**< 256-bit AES key */ + }; + + /** Represents the different cipher modes + */ + enum CipherMode { + MODE_ECB, /**< Electronic codebook */ + MODE_CBC /**< Cipher block chaining */ + }; + + /** Create a blank AES object + */ + AES(); + + /** Create an AES object with the specified parameters + * + * @param key Pointer to the AES key. + * @param keySize The AES key size as a KeySize enum. + * @param mode The cipher mode as a CipherMode enum (MODE_ECB by default). + * @param iv Pointer to the 16B initialization vector (NULL by default). + */ + AES(const char* key, KeySize keySize, CipherMode mode = MODE_ECB, const char* iv = NULL); + + /** Destructor + */ + ~AES(); + + /** Set up this AES object for encryption/decryption with the specified parameters + * + * @param key Pointer to the AES key. + * @param keySize The AES key size as a KeySize enum. + * @param mode The cipher mode as a CipherMode enum (MODE_ECB by default). + * @param iv Pointer to the 16B initialization vector (NULL by default). + */ + void setup(const char* key, KeySize keySize, CipherMode mode = MODE_ECB, const char* iv = NULL); + + /** Encrypt the specified data in-place, using CTS or zero-padding if necessary + * + * @param data Pointer to the data to encrypt (minimum 16B for output). + * @param length The length of the data to encrypt in bytes. + */ + void encrypt(void* data, size_t length); + + /** Encrypt the specified data, using CTS or zero-padding if necessary + * + * @param src Pointer to the data to encrypt. + * @param dest Pointer to an array in which to store the encrypted data (minimum 16B). + * @param length The length of the data to encrypt in bytes. + */ + void encrypt(const void* src, char* dest, size_t length); + + /** Decrypt the specified data in-place, and remove the padding if necessary + * + * @param data Pointer to the data to decrypt (minimum 16B). + * @param length The length of the decrypted data without padding in bytes. + */ + void decrypt(void* data, size_t length); + + /** Decrypt the specified data, and remove the padding if necessary + * + * @param src Pointer to the data to decrypt (minimum 16B). + * @param dest Pointer to an array in which to store the decrypted data. + * @param length The length of the decrypted data without padding in bytes. + */ + void decrypt(const char* src, void* dest, size_t length); + + /** Erase any sensitive information in this AES object + */ + void clear(); + +private: + //Member variables + static const char m_Sbox[256]; + static const char m_InvSbox[256]; + static const unsigned int m_Rcon[10]; + AES::CipherMode m_CipherMode; + int m_Rounds; + unsigned int m_Key[60]; + char m_State[16]; + char m_CarryVector[16]; + + //Internal methods + void aesEncrypt(); + void aesDecrypt(); + void expandKey(const char* key, int nk); + unsigned int rotWord(unsigned int w); + unsigned int invRotWord(unsigned int w); + unsigned int subWord(unsigned int w); + void subBytes(); + void invSubBytes(); + void shiftRows(); + void invShiftRows(); + char gmul(char a, char b); + void mul(char* r); + void invMul(char* r); + void mixColumns(); + void invMixColumns(); + void addRoundKey(int round); +}; + +#endif