verilog/dv/user_aes/aes.c - third_party/shuttle/sky130/mpw-006/slot-005 - Git at Google

 /*

 This is an implementation of the AES algorithm, specifically ECB, CTR and CBC mode.
 Block size can be chosen in aes.h - available choices are AES128, AES192, AES256.

 The implementation is verified against the test vectors in:
   National Institute of Standards and Technology Special Publication 800-38A 2001 ED

 ECB-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.
         For AES192/256 the key size is proportionally larger.

 */


 /*****************************************************************************/
 /* Includes:                                                                 */
 /*****************************************************************************/
 #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

 #if defined(AES256) && (AES256 == 1)
     #define Nk 8
     #define Nr 14
 #elif defined(AES192) && (AES192 == 1)
     #define Nk 6
     #define Nr 12
 #else
     #define Nk 4        // The number of 32 bit words in a key.
     #define Nr 10       // The number of rounds in AES Cipher.
 #endif

 // 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-AES-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];


 // 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 };

 #if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
 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 };
 #endif

 // The round constant word array, Rcon[i], contains the values given by
 // x to the power (i-1) being powers of x (x is denoted as {02}) in the field GF(2^8)
 static const uint8_t Rcon[11] = {
   0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36 };

 /*
  * Jordan Goulder points out in PR #12 (https://github.com/kokke/tiny-AES-C/pull/12),
  * that you can remove most of the elements in the Rcon array, because they are unused.
  *
  * From Wikipedia's article on the Rijndael key schedule @ https://en.wikipedia.org/wiki/Rijndael_key_schedule#Rcon
  *
  * "Only the first some of these constants are actually used – up to rcon[10] for AES-128 (as 11 round keys are needed),
  *  up to rcon[8] for AES-192, up to rcon[7] for AES-256. rcon[0] is not used in AES algorithm."
  */


 /*****************************************************************************/
 /* Private functions:                                                        */
 /*****************************************************************************/
 /*
 static uint8_t getSBoxValue(uint8_t num)
 {
   return sbox[num];
 }
 */
 #define getSBoxValue(num) (sbox[(num)])

 // This function produces Nb(Nr+1) round keys. The round keys are used in each round to decrypt the states.
 static void KeyExpansion(uint8_t* RoundKey, const uint8_t* Key)
 {
   unsigned 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 = Nk; i < Nb * (Nr + 1); ++i)
   {
     {
       k = (i - 1) * 4;
       tempa[0]=RoundKey[k + 0];
       tempa[1]=RoundKey[k + 1];
       tempa[2]=RoundKey[k + 2];
       tempa[3]=RoundKey[k + 3];

     }

     if (i % Nk == 0)
     {
       // This function shifts the 4 bytes in a word to the left once.
       // [a0,a1,a2,a3] becomes [a1,a2,a3,a0]

       // Function RotWord()
       {
         const uint8_t u8tmp = tempa[0];
         tempa[0] = tempa[1];
         tempa[1] = tempa[2];
         tempa[2] = tempa[3];
         tempa[3] = u8tmp;
       }

       // 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];
     }
 #if defined(AES256) && (AES256 == 1)
     if (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]);
       }
     }
 #endif
     j = i * 4; k=(i - Nk) * 4;
     RoundKey[j + 0] = RoundKey[k + 0] ^ tempa[0];
     RoundKey[j + 1] = RoundKey[k + 1] ^ tempa[1];
     RoundKey[j + 2] = RoundKey[k + 2] ^ tempa[2];
     RoundKey[j + 3] = RoundKey[k + 3] ^ tempa[3];
   }
 }

 void AES_init_ctx(struct AES_ctx* ctx, const uint8_t* key)
 {
   KeyExpansion(ctx->RoundKey, key);
 }
 #if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1))
 void AES_init_ctx_iv(struct AES_ctx* ctx, const uint8_t* key, const uint8_t* iv)
 {
   KeyExpansion(ctx->RoundKey, key);
   memcpy (ctx->Iv, iv, AES_BLOCKLEN);
 }
 void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv)
 {
   memcpy (ctx->Iv, iv, AES_BLOCKLEN);
 }
 #endif

 // 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, state_t* state, const uint8_t* RoundKey)
 {
   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(state_t* state)
 {
   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(state_t* state)
 {
   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 matrix
 static void MixColumns(state_t* state)
 {
   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)
 // Note: The last call to xtime() is unneeded, but often ends up generating a smaller binary
 //       The compiler seems to be able to vectorize the operation better this way.
 //       See https://github.com/kokke/tiny-AES-c/pull/34
 #if MULTIPLY_AS_A_FUNCTION
 static 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)))))); /* this last call to xtime() can be omitted */
   }
 #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

 #if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
 /*
 static uint8_t getSBoxInvert(uint8_t num)
 {
   return rsbox[num];
 }
 */
 #define getSBoxInvert(num) (rsbox[(num)])

 // 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(state_t* state)
 {
   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(state_t* state)
 {
   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(state_t* state)
 {
   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;
 }
 #endif // #if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)

 // Cipher is the main function that encrypts the PlainText.
 static void Cipher(state_t* state, const uint8_t* RoundKey)
 {
   uint8_t round = 0;

   // Add the First round key to the state before starting the rounds.
   AddRoundKey(0, state, RoundKey);

   // There will be Nr rounds.
   // The first Nr-1 rounds are identical.
   // These Nr rounds are executed in the loop below.
   // Last one without MixColumns()
   for (round = 1; ; ++round)
   {
     SubBytes(state);
     ShiftRows(state);
     if (round == Nr) {
       break;
     }
     MixColumns(state);
     AddRoundKey(round, state, RoundKey);
   }
   // Add round key to last round
   AddRoundKey(Nr, state, RoundKey);
 }

 #if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
 static void InvCipher(state_t* state, const uint8_t* RoundKey)
 {
   uint8_t round = 0;

   // Add the First round key to the state before starting the rounds.
   AddRoundKey(Nr, state, RoundKey);

   // There will be Nr rounds.
   // The first Nr-1 rounds are identical.
   // These Nr rounds are executed in the loop below.
   // Last one without InvMixColumn()
   for (round = (Nr - 1); ; --round)
   {
     InvShiftRows(state);
     InvSubBytes(state);
     AddRoundKey(round, state, RoundKey);
     if (round == 0) {
       break;
     }
     InvMixColumns(state);
   }

 }
 #endif // #if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)

 /*****************************************************************************/
 /* Public functions:                                                         */
 /*****************************************************************************/
 #if defined(ECB) && (ECB == 1)


 void AES_ECB_encrypt(const struct AES_ctx* ctx, uint8_t* buf)
 {
   // The next function call encrypts the PlainText with the Key using AES algorithm.
   Cipher((state_t*)buf, ctx->RoundKey);
 }

 void AES_ECB_decrypt(const struct AES_ctx* ctx, uint8_t* buf)
 {
   // The next function call decrypts the PlainText with the Key using AES algorithm.
   InvCipher((state_t*)buf, ctx->RoundKey);
 }


 #endif // #if defined(ECB) && (ECB == 1)


 #if defined(CBC) && (CBC == 1)


 static void XorWithIv(uint8_t* buf, const uint8_t* Iv)
 {
   uint8_t i;
   for (i = 0; i < AES_BLOCKLEN; ++i) // The block in AES is always 128bit no matter the key size
   {
     buf[i] ^= Iv[i];
   }
 }

 void AES_CBC_encrypt_buffer(struct AES_ctx *ctx, uint8_t* buf, size_t length)
 {
   size_t i;
   uint8_t *Iv = ctx->Iv;
   for (i = 0; i < length; i += AES_BLOCKLEN)
   {
     XorWithIv(buf, Iv);
     Cipher((state_t*)buf, ctx->RoundKey);
     Iv = buf;
     buf += AES_BLOCKLEN;
   }
   /* store Iv in ctx for next call */
   memcpy(ctx->Iv, Iv, AES_BLOCKLEN);
 }

 void AES_CBC_decrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, size_t length)
 {
   size_t i;
   uint8_t storeNextIv[AES_BLOCKLEN];
   for (i = 0; i < length; i += AES_BLOCKLEN)
   {
     memcpy(storeNextIv, buf, AES_BLOCKLEN);
     InvCipher((state_t*)buf, ctx->RoundKey);
     XorWithIv(buf, ctx->Iv);
     memcpy(ctx->Iv, storeNextIv, AES_BLOCKLEN);
     buf += AES_BLOCKLEN;
   }

 }

 #endif // #if defined(CBC) && (CBC == 1)


 #if defined(CTR) && (CTR == 1)

 /* Symmetrical operation: same function for encrypting as for decrypting. Note any IV/nonce should never be reused with the same key */
 void AES_CTR_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, size_t length)
 {
   uint8_t buffer[AES_BLOCKLEN];

   size_t i;
   int bi;
   for (i = 0, bi = AES_BLOCKLEN; i < length; ++i, ++bi)
   {
     if (bi == AES_BLOCKLEN) /* we need to regen xor compliment in buffer */
     {

       memcpy(buffer, ctx->Iv, AES_BLOCKLEN);
       Cipher((state_t*)buffer,ctx->RoundKey);

       /* Increment Iv and handle overflow */
       for (bi = (AES_BLOCKLEN - 1); bi >= 0; --bi)
       {
 	/* inc will overflow */
         if (ctx->Iv[bi] == 255)
 	{
           ctx->Iv[bi] = 0;
           continue;
         }
         ctx->Iv[bi] += 1;
         break;
       }
       bi = 0;
     }

     buf[i] = (buf[i] ^ buffer[bi]);
   }
 }

 #endif // #if defined(CTR) && (CTR == 1)
	/*

	This is an implementation of the AES algorithm, specifically ECB, CTR and CBC mode.
	Block size can be chosen in aes.h - available choices are AES128, AES192, AES256.

	The implementation is verified against the test vectors in:
	National Institute of Standards and Technology Special Publication 800-38A 2001 ED

	ECB-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.
	For AES192/256 the key size is proportionally larger.

	*/


	/*****************************************************************************/
	/* Includes: */
	/*****************************************************************************/
	#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

	#if defined(AES256) && (AES256 == 1)
	#define Nk 8
	#define Nr 14
	#elif defined(AES192) && (AES192 == 1)
	#define Nk 6
	#define Nr 12
	#else
	#define Nk 4 // The number of 32 bit words in a key.
	#define Nr 10 // The number of rounds in AES Cipher.
	#endif

	// 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-AES-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];



	// 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 };

	#if (defined(CBC) && CBC == 1) \|\| (defined(ECB) && ECB == 1)
	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 };
	#endif

	// The round constant word array, Rcon[i], contains the values given by
	// x to the power (i-1) being powers of x (x is denoted as {02}) in the field GF(2^8)
	static const uint8_t Rcon[11] = {
	0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36 };

	/*
	* Jordan Goulder points out in PR #12 (https://github.com/kokke/tiny-AES-C/pull/12),
	* that you can remove most of the elements in the Rcon array, because they are unused.
	*
	* From Wikipedia's article on the Rijndael key schedule @ https://en.wikipedia.org/wiki/Rijndael_key_schedule#Rcon
	*
	* "Only the first some of these constants are actually used – up to rcon[10] for AES-128 (as 11 round keys are needed),
	* up to rcon[8] for AES-192, up to rcon[7] for AES-256. rcon[0] is not used in AES algorithm."
	*/


	/*****************************************************************************/
	/* Private functions: */
	/*****************************************************************************/
	/*
	static uint8_t getSBoxValue(uint8_t num)
	{
	return sbox[num];
	}
	*/
	#define getSBoxValue(num) (sbox[(num)])

	// This function produces Nb(Nr+1) round keys. The round keys are used in each round to decrypt the states.
	static void KeyExpansion(uint8_t* RoundKey, const uint8_t* Key)
	{
	unsigned 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 = Nk; i < Nb * (Nr + 1); ++i)
	{
	{
	k = (i - 1) * 4;
	tempa[0]=RoundKey[k + 0];
	tempa[1]=RoundKey[k + 1];
	tempa[2]=RoundKey[k + 2];
	tempa[3]=RoundKey[k + 3];

	}

	if (i % Nk == 0)
	{
	// This function shifts the 4 bytes in a word to the left once.
	// [a0,a1,a2,a3] becomes [a1,a2,a3,a0]

	// Function RotWord()
	{
	const uint8_t u8tmp = tempa[0];
	tempa[0] = tempa[1];
	tempa[1] = tempa[2];
	tempa[2] = tempa[3];
	tempa[3] = u8tmp;
	}

	// 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];
	}
	#if defined(AES256) && (AES256 == 1)
	if (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]);
	}
	}
	#endif
	j = i * 4; k=(i - Nk) * 4;
	RoundKey[j + 0] = RoundKey[k + 0] ^ tempa[0];
	RoundKey[j + 1] = RoundKey[k + 1] ^ tempa[1];
	RoundKey[j + 2] = RoundKey[k + 2] ^ tempa[2];
	RoundKey[j + 3] = RoundKey[k + 3] ^ tempa[3];
	}
	}

	void AES_init_ctx(struct AES_ctx* ctx, const uint8_t* key)
	{
	KeyExpansion(ctx->RoundKey, key);
	}
	#if (defined(CBC) && (CBC == 1)) \|\| (defined(CTR) && (CTR == 1))
	void AES_init_ctx_iv(struct AES_ctx* ctx, const uint8_t* key, const uint8_t* iv)
	{
	KeyExpansion(ctx->RoundKey, key);
	memcpy (ctx->Iv, iv, AES_BLOCKLEN);
	}
	void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv)
	{
	memcpy (ctx->Iv, iv, AES_BLOCKLEN);
	}
	#endif

	// 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, state_t* state, const uint8_t* RoundKey)
	{
	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(state_t* state)
	{
	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(state_t* state)
	{
	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 matrix
	static void MixColumns(state_t* state)
	{
	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)
	// Note: The last call to xtime() is unneeded, but often ends up generating a smaller binary
	// The compiler seems to be able to vectorize the operation better this way.
	// See https://github.com/kokke/tiny-AES-c/pull/34
	#if MULTIPLY_AS_A_FUNCTION
	static 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)))))); /* this last call to xtime() can be omitted */
	}
	#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

	#if (defined(CBC) && CBC == 1) \|\| (defined(ECB) && ECB == 1)
	/*
	static uint8_t getSBoxInvert(uint8_t num)
	{
	return rsbox[num];
	}
	*/
	#define getSBoxInvert(num) (rsbox[(num)])

	// 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(state_t* state)
	{
	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(state_t* state)
	{
	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(state_t* state)
	{
	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;
	}
	#endif // #if (defined(CBC) && CBC == 1) \|\| (defined(ECB) && ECB == 1)

	// Cipher is the main function that encrypts the PlainText.
	static void Cipher(state_t* state, const uint8_t* RoundKey)
	{
	uint8_t round = 0;

	// Add the First round key to the state before starting the rounds.
	AddRoundKey(0, state, RoundKey);

	// There will be Nr rounds.
	// The first Nr-1 rounds are identical.
	// These Nr rounds are executed in the loop below.
	// Last one without MixColumns()
	for (round = 1; ; ++round)
	{
	SubBytes(state);
	ShiftRows(state);
	if (round == Nr) {
	break;
	}
	MixColumns(state);
	AddRoundKey(round, state, RoundKey);
	}
	// Add round key to last round
	AddRoundKey(Nr, state, RoundKey);
	}

	#if (defined(CBC) && CBC == 1) \|\| (defined(ECB) && ECB == 1)
	static void InvCipher(state_t* state, const uint8_t* RoundKey)
	{
	uint8_t round = 0;

	// Add the First round key to the state before starting the rounds.
	AddRoundKey(Nr, state, RoundKey);

	// There will be Nr rounds.
	// The first Nr-1 rounds are identical.
	// These Nr rounds are executed in the loop below.
	// Last one without InvMixColumn()
	for (round = (Nr - 1); ; --round)
	{
	InvShiftRows(state);
	InvSubBytes(state);
	AddRoundKey(round, state, RoundKey);
	if (round == 0) {
	break;
	}
	InvMixColumns(state);
	}

	}
	#endif // #if (defined(CBC) && CBC == 1) \|\| (defined(ECB) && ECB == 1)

	/*****************************************************************************/
	/* Public functions: */
	/*****************************************************************************/
	#if defined(ECB) && (ECB == 1)


	void AES_ECB_encrypt(const struct AES_ctx* ctx, uint8_t* buf)
	{
	// The next function call encrypts the PlainText with the Key using AES algorithm.
	Cipher((state_t*)buf, ctx->RoundKey);
	}

	void AES_ECB_decrypt(const struct AES_ctx* ctx, uint8_t* buf)
	{
	// The next function call decrypts the PlainText with the Key using AES algorithm.
	InvCipher((state_t*)buf, ctx->RoundKey);
	}


	#endif // #if defined(ECB) && (ECB == 1)





	#if defined(CBC) && (CBC == 1)


	static void XorWithIv(uint8_t* buf, const uint8_t* Iv)
	{
	uint8_t i;
	for (i = 0; i < AES_BLOCKLEN; ++i) // The block in AES is always 128bit no matter the key size
	{
	buf[i] ^= Iv[i];
	}
	}

	void AES_CBC_encrypt_buffer(struct AES_ctx ctx, uint8_t buf, size_t length)
	{
	size_t i;
	uint8_t *Iv = ctx->Iv;
	for (i = 0; i < length; i += AES_BLOCKLEN)
	{
	XorWithIv(buf, Iv);
	Cipher((state_t*)buf, ctx->RoundKey);
	Iv = buf;
	buf += AES_BLOCKLEN;
	}
	/* store Iv in ctx for next call */
	memcpy(ctx->Iv, Iv, AES_BLOCKLEN);
	}

	void AES_CBC_decrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, size_t length)
	{
	size_t i;
	uint8_t storeNextIv[AES_BLOCKLEN];
	for (i = 0; i < length; i += AES_BLOCKLEN)
	{
	memcpy(storeNextIv, buf, AES_BLOCKLEN);
	InvCipher((state_t*)buf, ctx->RoundKey);
	XorWithIv(buf, ctx->Iv);
	memcpy(ctx->Iv, storeNextIv, AES_BLOCKLEN);
	buf += AES_BLOCKLEN;
	}

	}

	#endif // #if defined(CBC) && (CBC == 1)



	#if defined(CTR) && (CTR == 1)

	/* Symmetrical operation: same function for encrypting as for decrypting. Note any IV/nonce should never be reused with the same key */
	void AES_CTR_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, size_t length)
	{
	uint8_t buffer[AES_BLOCKLEN];

	size_t i;
	int bi;
	for (i = 0, bi = AES_BLOCKLEN; i < length; ++i, ++bi)
	{
	if (bi == AES_BLOCKLEN) /* we need to regen xor compliment in buffer */
	{

	memcpy(buffer, ctx->Iv, AES_BLOCKLEN);
	Cipher((state_t*)buffer,ctx->RoundKey);

	/* Increment Iv and handle overflow */
	for (bi = (AES_BLOCKLEN - 1); bi >= 0; --bi)
	{
	/* inc will overflow */
	if (ctx->Iv[bi] == 255)
	{
	ctx->Iv[bi] = 0;
	continue;
	}
	ctx->Iv[bi] += 1;
	break;
	}
	bi = 0;
	}

	buf[i] = (buf[i] ^ buffer[bi]);
	}
	}

	#endif // #if defined(CTR) && (CTR == 1)