AES 128-bit ecb cbc 模式 C语言加密算法

源码查看：

https://github.com/kokke/tiny-AES128-C

aes.h

#ifndef _AES_H_#define _AES_H_#include <stdint.h>// #define the macros below to 1/0 to enable/disable the mode of operation.//// CBC enables AES128 encryption in CBC-mode of operation and handles 0-padding.// ECB enables the basic ECB 16-byte block algorithm. Both can be enabled simultaneously.// The #ifndef-guard allows it to be configured before #include'ing or at compile time.#ifndef CBC  #define CBC 1#endif#ifndef ECB  #define ECB 1#endif#if defined(ECB) && ECBvoid AES128_ECB_encrypt(const uint8_t* input, const uint8_t* key, uint8_t *output);void AES128_ECB_decrypt(const uint8_t* input, const uint8_t* key, uint8_t *output);#endif // #if defined(ECB) && ECB#if defined(CBC) && CBCvoid AES128_CBC_encrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv);void AES128_CBC_decrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv);#endif // #if defined(CBC) && CBC#endif //_AES_H_

aes.c

/*This is an implementation of the AES128 algorithm, specifically ECB and CBC mode.The implementation is verified against the test vectors in:  National Institute of Standards and Technology Special Publication 800-38A 2001 EDECB-AES128----------  plain-text:    6bc1bee22e409f96e93d7e117393172a    ae2d8a571e03ac9c9eb76fac45af8e51    30c81c46a35ce411e5fbc1191a0a52ef    f69f2445df4f9b17ad2b417be66c3710  key:    2b7e151628aed2a6abf7158809cf4f3c  resulting cipher    3ad77bb40d7a3660a89ecaf32466ef97     f5d3d58503b9699de785895a96fdbaaf     43b1cd7f598ece23881b00e3ed030688     7b0c785e27e8ad3f8223207104725dd4 NOTE:   String length must be evenly divisible by 16byte (str_len % 16 == 0)        You should pad the end of the string with zeros if this is not the case.*//*****************************************************************************//* Includes:                                                                 *//*****************************************************************************/#include <stdint.h>#include <string.h> // CBC mode, for memset#include "aes.h"/*****************************************************************************//* Defines:                                                                  *//*****************************************************************************/// The number of columns comprising a state in AES. This is a constant in AES. Value=4#define Nb 4// The number of 32 bit words in a key.#define Nk 4// Key length in bytes [128 bit]#define KEYLEN 16// The number of rounds in AES Cipher.#define Nr 10// jcallan@github points out that declaring Multiply as a function // reduces code size considerably with the Keil ARM compiler.// See this link for more information: https://github.com/kokke/tiny-AES128-C/pull/3#ifndef MULTIPLY_AS_A_FUNCTION  #define MULTIPLY_AS_A_FUNCTION 0#endif/*****************************************************************************//* Private variables:                                                        *//*****************************************************************************/// state - array holding the intermediate results during decryption.typedef uint8_t state_t[4][4];static state_t* state;// The array that stores the round keys.static uint8_t RoundKey[176];// The Key input to the AES Programstatic const uint8_t* Key;#if defined(CBC) && CBC  // Initial Vector used only for CBC mode  static uint8_t* Iv;#endif// The lookup-tables are marked const so they can be placed in read-only storage instead of RAM// The numbers below can be computed dynamically trading ROM for RAM - // This can be useful in (embedded) bootloader applications, where ROM is often limited.static const uint8_t sbox[256] =   {  //0     1    2      3     4    5     6     7      8    9     A      B    C     D     E     F  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 };static const uint8_t rsbox[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 };// The round constant word array, Rcon[i], contains the values given by // x to th e power (i-1) being powers of x (x is denoted as {02}) in the field GF(2^8)// Note that i starts at 1, not 0).static const uint8_t Rcon[255] = {  0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a,   0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39,   0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a,   0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8,   0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef,   0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc,   0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b,   0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3,   0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94,   0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20,   0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35,   0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f,   0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04,   0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63,   0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd,   0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb  };/*****************************************************************************//* Private functions:                                                        *//*****************************************************************************/static uint8_t getSBoxValue(uint8_t num){  return sbox[num];}static uint8_t getSBoxInvert(uint8_t num){  return rsbox[num];}// This function produces Nb(Nr+1) round keys. The round keys are used in each round to decrypt the states. static void KeyExpansion(void){  uint32_t i, j, k;  uint8_t tempa[4]; // Used for the column/row operations    // The first round key is the key itself.  for(i = 0; i < Nk; ++i)  {    RoundKey[(i * 4) + 0] = Key[(i * 4) + 0];    RoundKey[(i * 4) + 1] = Key[(i * 4) + 1];    RoundKey[(i * 4) + 2] = Key[(i * 4) + 2];    RoundKey[(i * 4) + 3] = Key[(i * 4) + 3];  }  // All other round keys are found from the previous round keys.  for(; (i < (Nb * (Nr + 1))); ++i)  {    for(j = 0; j < 4; ++j)    {      tempa[j]=RoundKey[(i-1) * 4 + j];    }    if (i % Nk == 0)    {      // This function rotates the 4 bytes in a word to the left once.      // [a0,a1,a2,a3] becomes [a1,a2,a3,a0]      // Function RotWord()      {        k = tempa[0];        tempa[0] = tempa[1];        tempa[1] = tempa[2];        tempa[2] = tempa[3];        tempa[3] = k;      }      // SubWord() is a function that takes a four-byte input word and       // applies the S-box to each of the four bytes to produce an output word.      // Function Subword()      {        tempa[0] = getSBoxValue(tempa[0]);        tempa[1] = getSBoxValue(tempa[1]);        tempa[2] = getSBoxValue(tempa[2]);        tempa[3] = getSBoxValue(tempa[3]);      }      tempa[0] =  tempa[0] ^ Rcon[i/Nk];    }    else if (Nk > 6 && i % Nk == 4)    {      // Function Subword()      {        tempa[0] = getSBoxValue(tempa[0]);        tempa[1] = getSBoxValue(tempa[1]);        tempa[2] = getSBoxValue(tempa[2]);        tempa[3] = getSBoxValue(tempa[3]);      }    }    RoundKey[i * 4 + 0] = RoundKey[(i - Nk) * 4 + 0] ^ tempa[0];    RoundKey[i * 4 + 1] = RoundKey[(i - Nk) * 4 + 1] ^ tempa[1];    RoundKey[i * 4 + 2] = RoundKey[(i - Nk) * 4 + 2] ^ tempa[2];    RoundKey[i * 4 + 3] = RoundKey[(i - Nk) * 4 + 3] ^ tempa[3];  }}// This function adds the round key to state.// The round key is added to the state by an XOR function.static void AddRoundKey(uint8_t round){  uint8_t i,j;  for(i=0;i<4;++i)  {    for(j = 0; j < 4; ++j)    {      (*state)[i][j] ^= RoundKey[round * Nb * 4 + i * Nb + j];    }  }}// The SubBytes Function Substitutes the values in the// state matrix with values in an S-box.static void SubBytes(void){  uint8_t i, j;  for(i = 0; i < 4; ++i)  {    for(j = 0; j < 4; ++j)    {      (*state)[j][i] = getSBoxValue((*state)[j][i]);    }  }}// The ShiftRows() function shifts the rows in the state to the left.// Each row is shifted with different offset.// Offset = Row number. So the first row is not shifted.static void ShiftRows(void){  uint8_t temp;  // Rotate first row 1 columns to left    temp           = (*state)[0][1];  (*state)[0][1] = (*state)[1][1];  (*state)[1][1] = (*state)[2][1];  (*state)[2][1] = (*state)[3][1];  (*state)[3][1] = temp;  // Rotate second row 2 columns to left    temp           = (*state)[0][2];  (*state)[0][2] = (*state)[2][2];  (*state)[2][2] = temp;  temp       = (*state)[1][2];  (*state)[1][2] = (*state)[3][2];  (*state)[3][2] = temp;  // Rotate third row 3 columns to left  temp       = (*state)[0][3];  (*state)[0][3] = (*state)[3][3];  (*state)[3][3] = (*state)[2][3];  (*state)[2][3] = (*state)[1][3];  (*state)[1][3] = temp;}static uint8_t xtime(uint8_t x){  return ((x<<1) ^ (((x>>7) & 1) * 0x1b));}// MixColumns function mixes the columns of the state matrixstatic void MixColumns(void){  uint8_t i;  uint8_t Tmp,Tm,t;  for(i = 0; i < 4; ++i)  {      t   = (*state)[i][0];    Tmp = (*state)[i][0] ^ (*state)[i][1] ^ (*state)[i][2] ^ (*state)[i][3] ;    Tm  = (*state)[i][0] ^ (*state)[i][1] ; Tm = xtime(Tm);  (*state)[i][0] ^= Tm ^ Tmp ;    Tm  = (*state)[i][1] ^ (*state)[i][2] ; Tm = xtime(Tm);  (*state)[i][1] ^= Tm ^ Tmp ;    Tm  = (*state)[i][2] ^ (*state)[i][3] ; Tm = xtime(Tm);  (*state)[i][2] ^= Tm ^ Tmp ;    Tm  = (*state)[i][3] ^ t ;        Tm = xtime(Tm);  (*state)[i][3] ^= Tm ^ Tmp ;  }}// Multiply is used to multiply numbers in the field GF(2^8)#if MULTIPLY_AS_A_FUNCTIONstatic uint8_t Multiply(uint8_t x, uint8_t y){  return (((y & 1) * x) ^       ((y>>1 & 1) * xtime(x)) ^       ((y>>2 & 1) * xtime(xtime(x))) ^       ((y>>3 & 1) * xtime(xtime(xtime(x)))) ^       ((y>>4 & 1) * xtime(xtime(xtime(xtime(x))))));  }#else#define Multiply(x, y)                                \      (  ((y & 1) * x) ^                              \      ((y>>1 & 1) * xtime(x)) ^                       \      ((y>>2 & 1) * xtime(xtime(x))) ^                \      ((y>>3 & 1) * xtime(xtime(xtime(x)))) ^         \      ((y>>4 & 1) * xtime(xtime(xtime(xtime(x))))))   \#endif// MixColumns function mixes the columns of the state matrix.// The method used to multiply may be difficult to understand for the inexperienced.// Please use the references to gain more information.static void InvMixColumns(void){  int i;  uint8_t a,b,c,d;  for(i=0;i<4;++i)  {     a = (*state)[i][0];    b = (*state)[i][1];    c = (*state)[i][2];    d = (*state)[i][3];    (*state)[i][0] = Multiply(a, 0x0e) ^ Multiply(b, 0x0b) ^ Multiply(c, 0x0d) ^ Multiply(d, 0x09);    (*state)[i][1] = Multiply(a, 0x09) ^ Multiply(b, 0x0e) ^ Multiply(c, 0x0b) ^ Multiply(d, 0x0d);    (*state)[i][2] = Multiply(a, 0x0d) ^ Multiply(b, 0x09) ^ Multiply(c, 0x0e) ^ Multiply(d, 0x0b);    (*state)[i][3] = Multiply(a, 0x0b) ^ Multiply(b, 0x0d) ^ Multiply(c, 0x09) ^ Multiply(d, 0x0e);  }}// The SubBytes Function Substitutes the values in the// state matrix with values in an S-box.static void InvSubBytes(void){  uint8_t i,j;  for(i=0;i<4;++i)  {    for(j=0;j<4;++j)    {      (*state)[j][i] = getSBoxInvert((*state)[j][i]);    }  }}static void InvShiftRows(void){  uint8_t temp;  // Rotate first row 1 columns to right    temp=(*state)[3][1];  (*state)[3][1]=(*state)[2][1];  (*state)[2][1]=(*state)[1][1];  (*state)[1][1]=(*state)[0][1];  (*state)[0][1]=temp;  // Rotate second row 2 columns to right   temp=(*state)[0][2];  (*state)[0][2]=(*state)[2][2];  (*state)[2][2]=temp;  temp=(*state)[1][2];  (*state)[1][2]=(*state)[3][2];  (*state)[3][2]=temp;  // Rotate third row 3 columns to right  temp=(*state)[0][3];  (*state)[0][3]=(*state)[1][3];  (*state)[1][3]=(*state)[2][3];  (*state)[2][3]=(*state)[3][3];  (*state)[3][3]=temp;}// Cipher is the main function that encrypts the PlainText.static void Cipher(void){  uint8_t round = 0;  // Add the First round key to the state before starting the rounds.  AddRoundKey(0);     // There will be Nr rounds.  // The first Nr-1 rounds are identical.  // These Nr-1 rounds are executed in the loop below.  for(round = 1; round < Nr; ++round)  {    SubBytes();    ShiftRows();    MixColumns();    AddRoundKey(round);  }    // The last round is given below.  // The MixColumns function is not here in the last round.  SubBytes();  ShiftRows();  AddRoundKey(Nr);}static void InvCipher(void){  uint8_t round=0;  // Add the First round key to the state before starting the rounds.  AddRoundKey(Nr);   // There will be Nr rounds.  // The first Nr-1 rounds are identical.  // These Nr-1 rounds are executed in the loop below.  for(round=Nr-1;round>0;round--)  {    InvShiftRows();    InvSubBytes();    AddRoundKey(round);    InvMixColumns();  }    // The last round is given below.  // The MixColumns function is not here in the last round.  InvShiftRows();  InvSubBytes();  AddRoundKey(0);}static void BlockCopy(uint8_t* output, const uint8_t* input){  uint8_t i;  for (i=0;i<KEYLEN;++i)  {    output[i] = input[i];  }}/*****************************************************************************//* Public functions:                                                         *//*****************************************************************************/#if defined(ECB) && ECBvoid AES128_ECB_encrypt(const uint8_t* input, const uint8_t* key, uint8_t* output){  // Copy input to output, and work in-memory on output  BlockCopy(output, input);  state = (state_t*)output;  Key = key;  KeyExpansion();  // The next function call encrypts the PlainText with the Key using AES algorithm.  Cipher();}void AES128_ECB_decrypt(const uint8_t* input, const uint8_t* key, uint8_t *output){  // Copy input to output, and work in-memory on output  BlockCopy(output, input);  state = (state_t*)output;  // The KeyExpansion routine must be called before encryption.  Key = key;  KeyExpansion();  InvCipher();}#endif // #if defined(ECB) && ECB#if defined(CBC) && CBCstatic void XorWithIv(uint8_t* buf){  uint8_t i;  for(i = 0; i < KEYLEN; ++i)  {    buf[i] ^= Iv[i];  }}void AES128_CBC_encrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv){  uintptr_t i;  uint8_t remainders = length % KEYLEN; /* Remaining bytes in the last non-full block */  BlockCopy(output, input);  state = (state_t*)output;  // Skip the key expansion if key is passed as 0  if(0 != key)  {    Key = key;    KeyExpansion();  }  if(iv != 0)  {    Iv = (uint8_t*)iv;  }  for(i = 0; i < length; i += KEYLEN)  {    XorWithIv(input);    BlockCopy(output, input);    state = (state_t*)output;    Cipher();    Iv = output;    input += KEYLEN;    output += KEYLEN;  }  if(remainders)  {    BlockCopy(output, input);    memset(output + remainders, 0, KEYLEN - remainders); /* add 0-padding */    state = (state_t*)output;    Cipher();  }}void AES128_CBC_decrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv){  uintptr_t i;  uint8_t remainders = length % KEYLEN; /* Remaining bytes in the last non-full block */    BlockCopy(output, input);  state = (state_t*)output;  // Skip the key expansion if key is passed as 0  if(0 != key)  {    Key = key;    KeyExpansion();  }  // If iv is passed as 0, we continue to encrypt without re-setting the Iv  if(iv != 0)  {    Iv = (uint8_t*)iv;  }  for(i = 0; i < length; i += KEYLEN)  {    BlockCopy(output, input);    state = (state_t*)output;    InvCipher();    XorWithIv(output);    Iv = input;    input += KEYLEN;    output += KEYLEN;  }  if(remainders)  {    BlockCopy(output, input);    memset(output+remainders, 0, KEYLEN - remainders); /* add 0-padding */    state = (state_t*)output;    InvCipher();  }}#endif // #if defined(CBC) && CBC

main.c

#include <stdio.h>#include <string.h>#include <stdint.h>// Enable both ECB and CBC mode. Note this can be done before including aes.h or at compile-time.// E.g. with GCC by using the -D flag: gcc -c aes.c -DCBC=0 -DECB=1#define CBC 1#define ECB 1#include "aes.h"static void phex(uint8_t* str);static void test_encrypt_ecb(void);static void test_decrypt_ecb(void);static void test_encrypt_ecb_verbose(void);static void test_encrypt_cbc(void);static void test_decrypt_cbc(void);int main(void){    test_encrypt_cbc();    test_decrypt_cbc();    test_decrypt_ecb();    test_encrypt_ecb();    test_encrypt_ecb_verbose();        return 0;}// prints string as hexstatic void phex(uint8_t* str){    unsigned char i;    for(i = 0; i < 16; ++i)        printf("%.2x", str[i]);    printf("\n");}static void test_encrypt_ecb_verbose(void){    // Example of more verbose verification    uint8_t i, buf[64], buf2[64];    // 128bit key    uint8_t key[16] =        { (uint8_t) 0x2b, (uint8_t) 0x7e, (uint8_t) 0x15, (uint8_t) 0x16, (uint8_t) 0x28, (uint8_t) 0xae, (uint8_t) 0xd2, (uint8_t) 0xa6, (uint8_t) 0xab, (uint8_t) 0xf7, (uint8_t) 0x15, (uint8_t) 0x88, (uint8_t) 0x09, (uint8_t) 0xcf, (uint8_t) 0x4f, (uint8_t) 0x3c };    // 512bit text    uint8_t plain_text[64] = { (uint8_t) 0x6b, (uint8_t) 0xc1, (uint8_t) 0xbe, (uint8_t) 0xe2, (uint8_t) 0x2e, (uint8_t) 0x40, (uint8_t) 0x9f, (uint8_t) 0x96, (uint8_t) 0xe9, (uint8_t) 0x3d, (uint8_t) 0x7e, (uint8_t) 0x11, (uint8_t) 0x73, (uint8_t) 0x93, (uint8_t) 0x17, (uint8_t) 0x2a,                               (uint8_t) 0xae, (uint8_t) 0x2d, (uint8_t) 0x8a, (uint8_t) 0x57, (uint8_t) 0x1e, (uint8_t) 0x03, (uint8_t) 0xac, (uint8_t) 0x9c, (uint8_t) 0x9e, (uint8_t) 0xb7, (uint8_t) 0x6f, (uint8_t) 0xac, (uint8_t) 0x45, (uint8_t) 0xaf, (uint8_t) 0x8e, (uint8_t) 0x51,                               (uint8_t) 0x30, (uint8_t) 0xc8, (uint8_t) 0x1c, (uint8_t) 0x46, (uint8_t) 0xa3, (uint8_t) 0x5c, (uint8_t) 0xe4, (uint8_t) 0x11, (uint8_t) 0xe5, (uint8_t) 0xfb, (uint8_t) 0xc1, (uint8_t) 0x19, (uint8_t) 0x1a, (uint8_t) 0x0a, (uint8_t) 0x52, (uint8_t) 0xef,                               (uint8_t) 0xf6, (uint8_t) 0x9f, (uint8_t) 0x24, (uint8_t) 0x45, (uint8_t) 0xdf, (uint8_t) 0x4f, (uint8_t) 0x9b, (uint8_t) 0x17, (uint8_t) 0xad, (uint8_t) 0x2b, (uint8_t) 0x41, (uint8_t) 0x7b, (uint8_t) 0xe6, (uint8_t) 0x6c, (uint8_t) 0x37, (uint8_t) 0x10 };    memset(buf, 0, 64);    memset(buf2, 0, 64);    // print text to encrypt, key and IV    printf("ECB encrypt verbose:\n\n");    printf("plain text:\n");    for(i = (uint8_t) 0; i < (uint8_t) 4; ++i)    {        phex(plain_text + i * (uint8_t) 16);    }    printf("\n");    printf("key:\n");    phex(key);    printf("\n");    // print the resulting cipher as 4 x 16 byte strings    printf("ciphertext:\n");    for(i = 0; i < 4; ++i)    {        AES128_ECB_encrypt(plain_text + (i*16), key, buf+(i*16));        phex(buf + (i*16));    }    printf("\n");}static void test_encrypt_ecb(void){  uint8_t key[] = {0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6, 0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c};  uint8_t in[]  = {0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a};  uint8_t out[] = {0x3a, 0xd7, 0x7b, 0xb4, 0x0d, 0x7a, 0x36, 0x60, 0xa8, 0x9e, 0xca, 0xf3, 0x24, 0x66, 0xef, 0x97};  uint8_t buffer[16];  AES128_ECB_encrypt(in, key, buffer);  printf("ECB decrypt: ");  if(0 == memcmp((char*) out, (char*) buffer, 16))  {    printf("SUCCESS!\n");  }  else  {    printf("FAILURE!\n");  }}static void test_decrypt_cbc(void){  // Example "simulating" a smaller buffer...  uint8_t key[] = { 0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6, 0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c };  uint8_t iv[]  = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };  uint8_t in[]  = { 0x76, 0x49, 0xab, 0xac, 0x81, 0x19, 0xb2, 0x46, 0xce, 0xe9, 0x8e, 0x9b, 0x12, 0xe9, 0x19, 0x7d,                    0x50, 0x86, 0xcb, 0x9b, 0x50, 0x72, 0x19, 0xee, 0x95, 0xdb, 0x11, 0x3a, 0x91, 0x76, 0x78, 0xb2,                    0x73, 0xbe, 0xd6, 0xb8, 0xe3, 0xc1, 0x74, 0x3b, 0x71, 0x16, 0xe6, 0x9e, 0x22, 0x22, 0x95, 0x16,                     0x3f, 0xf1, 0xca, 0xa1, 0x68, 0x1f, 0xac, 0x09, 0x12, 0x0e, 0xca, 0x30, 0x75, 0x86, 0xe1, 0xa7 };  uint8_t out[] = { 0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,                    0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c, 0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,                    0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11, 0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef,                    0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17, 0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10 };  uint8_t buffer[64];  AES128_CBC_decrypt_buffer(buffer+0, in+0,  16, key, iv);  AES128_CBC_decrypt_buffer(buffer+16, in+16, 16, 0, 0);  AES128_CBC_decrypt_buffer(buffer+32, in+32, 16, 0, 0);  AES128_CBC_decrypt_buffer(buffer+48, in+48, 16, 0, 0);  printf("CBC decrypt: ");  if(0 == memcmp((char*) out, (char*) buffer, 64))  {    printf("SUCCESS!\n");  }  else  {    printf("FAILURE!\n");  }}static void test_encrypt_cbc(void){  uint8_t key[] = { 0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6, 0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c };  uint8_t iv[]  = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };  uint8_t in[]  = { 0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,                    0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c, 0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,                    0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11, 0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef,                    0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17, 0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10 };  uint8_t out[] = { 0x76, 0x49, 0xab, 0xac, 0x81, 0x19, 0xb2, 0x46, 0xce, 0xe9, 0x8e, 0x9b, 0x12, 0xe9, 0x19, 0x7d,                    0x50, 0x86, 0xcb, 0x9b, 0x50, 0x72, 0x19, 0xee, 0x95, 0xdb, 0x11, 0x3a, 0x91, 0x76, 0x78, 0xb2,                    0x73, 0xbe, 0xd6, 0xb8, 0xe3, 0xc1, 0x74, 0x3b, 0x71, 0x16, 0xe6, 0x9e, 0x22, 0x22, 0x95, 0x16,                     0x3f, 0xf1, 0xca, 0xa1, 0x68, 0x1f, 0xac, 0x09, 0x12, 0x0e, 0xca, 0x30, 0x75, 0x86, 0xe1, 0xa7 };  uint8_t buffer[64];  AES128_CBC_encrypt_buffer(buffer, in, 64, key, iv);  printf("CBC encrypt: ");  if(0 == memcmp((char*) out, (char*) buffer, 64))  {    printf("SUCCESS!\n");  }  else  {    printf("FAILURE!\n");  }}static void test_decrypt_ecb(void){  uint8_t key[] = {0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6, 0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c};  uint8_t in[]  = {0x3a, 0xd7, 0x7b, 0xb4, 0x0d, 0x7a, 0x36, 0x60, 0xa8, 0x9e, 0xca, 0xf3, 0x24, 0x66, 0xef, 0x97};  uint8_t out[] = {0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a};  uint8_t buffer[16];  AES128_ECB_decrypt(in, key, buffer);  printf("ECB decrypt: ");  if(0 == memcmp((char*) out, (char*) buffer, 16))  {    printf("SUCCESS!\n");  }  else  {    printf("FAILURE!\n");  }}