2 files changed, 55 insertions, 46 deletions

diff --git a/aes.c b/aes.c
index d44d281..bb026fd 100644
--- a/aes.c
+++ b/aes.c
@@ -37,18 +37,28 @@ NOTE:   String length must be evenly divisible by 16byte (str_len % 16 == 0)
 #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
+
+#ifdef AES256
+    #define Nk 8
+    #define KEYLEN 32
+    #define Nr 14
+    #define keyExpSize 240
+#elif defined(AES192)
+    #define Nk 6
+    #define KEYLEN 24
+    #define Nr 12
+    #define keyExpSize 208
+#else
+    #define Nk 4        // The number of 32 bit words in a key.
+    #define KEYLEN 16   // Key length in bytes
+    #define Nr 10       // The number of rounds in AES Cipher.
+    #define keyExpSize 176
+#endif
 
 // jcallan@github points out that declaring Multiply as a function 
 // reduces code size considerably with the Keil ARM compiler.
@@ -66,7 +76,7 @@ typedef uint8_t state_t[4][4];
 static state_t* state;
 
 // The array that stores the round keys.
-static uint8_t RoundKey[176];
+static uint8_t RoundKey[keyExpSize];
 
 // The Key input to the AES Program
 static const uint8_t* Key;
@@ -116,27 +126,25 @@ static const uint8_t rsbox[256] =
   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  };
+static const uint8_t Rcon[256] = {
+    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, 0x8d };
 
 
 /*****************************************************************************/
@@ -155,7 +163,7 @@ static uint8_t getSBoxInvert(uint8_t 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;
+  uint32_t i, k;
   uint8_t tempa[4]; // Used for the column/row operations
   
   // The first round key is the key itself.
@@ -168,15 +176,19 @@ static void KeyExpansion(void)
   }
 
   // All other round keys are found from the previous round keys.
-  for(; (i < (Nb * (Nr + 1))); ++i)
+  //i == Nk
+  for(i = Nk; i < Nb * (Nr + 1); ++i)
   {
-    for(j = 0; j < 4; ++j)
     {
-      tempa[j]=RoundKey[(i-1) * 4 + j];
+      tempa[0]=RoundKey[(i-1) * 4 + 0];
+      tempa[1]=RoundKey[(i-1) * 4 + 1];
+      tempa[2]=RoundKey[(i-1) * 4 + 2];
+      tempa[3]=RoundKey[(i-1) * 4 + 3];
     }
+
     if (i % Nk == 0)
     {
-      // This function rotates the 4 bytes in a word to the left once.
+      // This function shifts the 4 bytes in a word to the left once.
       // [a0,a1,a2,a3] becomes [a1,a2,a3,a0]
 
       // Function RotWord()
@@ -201,7 +213,8 @@ static void KeyExpansion(void)
 
       tempa[0] =  tempa[0] ^ Rcon[i/Nk];
     }
-    else if (Nk > 6 && i % Nk == 4)
+#ifdef AES256
+    if (i % Nk == 4)
     {
       // Function Subword()
       {
@@ -211,6 +224,7 @@ static void KeyExpansion(void)
         tempa[3] = getSBoxValue(tempa[3]);
       }
     }
+#endif
     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];
@@ -451,7 +465,7 @@ static void BlockCopy(uint8_t* output, const uint8_t* input)
 #if defined(ECB) && ECB
 
 
-void AES128_ECB_encrypt(const uint8_t* input, const uint8_t* key, uint8_t* output)
+void AES_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);
@@ -464,7 +478,7 @@ void AES128_ECB_encrypt(const uint8_t* input, const uint8_t* key, uint8_t* outpu
   Cipher();
 }
 
-void AES128_ECB_decrypt(const uint8_t* input, const uint8_t* key, uint8_t *output)
+void AES_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);
@@ -496,7 +510,7 @@ static void XorWithIv(uint8_t* buf)
   }
 }
 
-void AES128_CBC_encrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv)
+void AES_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 */
@@ -536,7 +550,7 @@ void AES128_CBC_encrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length,
   }
 }
 
-void AES128_CBC_decrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv)
+void AES_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 */
@@ -577,7 +591,4 @@ void AES128_CBC_decrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length,
   }
 }
 
-
 #endif // #if defined(CBC) && CBC
-
-
diff --git a/aes.h b/aes.h
index e86ab7f..b5be559 100644
--- a/aes.h
+++ b/aes.h
@@ -19,22 +19,20 @@
 #endif
 
 
-
 #if defined(ECB) && ECB
 
-void 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);
+void AES_ECB_encrypt(const uint8_t* input, const uint8_t* key, uint8_t *output);
+void AES_ECB_decrypt(const uint8_t* input, const uint8_t* key, uint8_t *output);
 
 #endif // #if defined(ECB) && ECB
 
 
 #if defined(CBC) && CBC
 
-void 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);
+void AES_CBC_encrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv);
+void AES_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_