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@@ -0,0 +1,572 @@
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+/*
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+
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+This is an implementation of the AES algorithm, specifically ECB, CTR and CBC mode.
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+Block size can be chosen in aes.h - available choices are AES128, AES192, AES256.
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+
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+The implementation is verified against the test vectors in:
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+ National Institute of Standards and Technology Special Publication 800-38A 2001 ED
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+
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+ECB-AES128
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+----------
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+
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+ plain-text:
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+ 6bc1bee22e409f96e93d7e117393172a
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+ ae2d8a571e03ac9c9eb76fac45af8e51
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+ 30c81c46a35ce411e5fbc1191a0a52ef
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+ f69f2445df4f9b17ad2b417be66c3710
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+
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+ key:
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+ 2b7e151628aed2a6abf7158809cf4f3c
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+
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+ resulting cipher
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+ 3ad77bb40d7a3660a89ecaf32466ef97
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+ f5d3d58503b9699de785895a96fdbaaf
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+ 43b1cd7f598ece23881b00e3ed030688
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+ 7b0c785e27e8ad3f8223207104725dd4
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+
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+
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+NOTE: String length must be evenly divisible by 16byte (str_len % 16 == 0)
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+ You should pad the end of the string with zeros if this is not the case.
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+ For AES192/256 the key size is proportionally larger.
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+
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+*/
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+
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+
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+/*****************************************************************************/
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+/* Includes: */
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+/*****************************************************************************/
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+#include <string.h> // CBC mode, for memset
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+#include "dtuaes.h"
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+
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+/*****************************************************************************/
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+/* Defines: */
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+/*****************************************************************************/
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+// The number of columns comprising a state in AES. This is a constant in AES. Value=4
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+#define Nb 4
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+
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+#if defined(AES256) && (AES256 == 1)
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+ #define Nk 8
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+ #define Nr 14
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+#elif defined(AES192) && (AES192 == 1)
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+ #define Nk 6
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+ #define Nr 12
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+#else
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+ #define Nk 4 // The number of 32 bit words in a key.
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+ #define Nr 10 // The number of rounds in AES Cipher.
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+#endif
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+
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+// jcallan@github points out that declaring Multiply as a function
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+// reduces code size considerably with the Keil ARM compiler.
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+// See this link for more information: https://github.com/kokke/tiny-AES-C/pull/3
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+#ifndef MULTIPLY_AS_A_FUNCTION
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+ #define MULTIPLY_AS_A_FUNCTION 0
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+#endif
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+
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+
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+
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+
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+/*****************************************************************************/
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+/* Private variables: */
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+/*****************************************************************************/
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+// state - array holding the intermediate results during decryption.
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+typedef uint8_t state_t[4][4];
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+
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+
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+
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+// The lookup-tables are marked const so they can be placed in read-only storage instead of RAM
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+// The numbers below can be computed dynamically trading ROM for RAM -
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+// This can be useful in (embedded) bootloader applications, where ROM is often limited.
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+static const uint8_t sbox[256] = {
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+ //0 1 2 3 4 5 6 7 8 9 A B C D E F
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+ 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
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+ 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
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+ 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
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+ 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
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+ 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
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+ 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
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+ 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
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+ 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
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+ 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
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+ 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
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+ 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
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+ 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
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+ 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
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+ 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
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+ 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
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+ 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 };
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+
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+#if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
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+static const uint8_t rsbox[256] = {
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+ 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
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+ 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
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+ 0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
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+ 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
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+ 0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
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+ 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
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+ 0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
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+ 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
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+ 0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
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+ 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
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+ 0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
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+ 0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
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+ 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
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+ 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
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+ 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
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+ 0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d };
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+#endif
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+
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+// The round constant word array, Rcon[i], contains the values given by
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+// x to the power (i-1) being powers of x (x is denoted as {02}) in the field GF(2^8)
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+static const uint8_t Rcon[11] = {
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+ 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36 };
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+
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+/*
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+ * Jordan Goulder points out in PR #12 (https://github.com/kokke/tiny-AES-C/pull/12),
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+ * that you can remove most of the elements in the Rcon array, because they are unused.
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+ *
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+ * From Wikipedia's article on the Rijndael key schedule @ https://en.wikipedia.org/wiki/Rijndael_key_schedule#Rcon
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+ *
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+ * "Only the first some of these constants are actually used ¨C up to rcon[10] for AES-128 (as 11 round keys are needed),
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+ * up to rcon[8] for AES-192, up to rcon[7] for AES-256. rcon[0] is not used in AES algorithm."
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+ */
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+
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+
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+/*****************************************************************************/
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+/* Private functions: */
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+/*****************************************************************************/
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+/*
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+static uint8_t getSBoxValue(uint8_t num)
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+{
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+ return sbox[num];
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+}
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+*/
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+#define getSBoxValue(num) (sbox[(num)])
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+
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+// This function produces Nb(Nr+1) round keys. The round keys are used in each round to decrypt the states.
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+static void KeyExpansion(uint8_t* RoundKey, const uint8_t* Key)
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+{
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+ unsigned i, j, k;
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+ uint8_t tempa[4]; // Used for the column/row operations
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+
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+ // The first round key is the key itself.
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+ for (i = 0; i < Nk; ++i)
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+ {
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+ RoundKey[(i * 4) + 0] = Key[(i * 4) + 0];
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+ RoundKey[(i * 4) + 1] = Key[(i * 4) + 1];
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+ RoundKey[(i * 4) + 2] = Key[(i * 4) + 2];
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+ RoundKey[(i * 4) + 3] = Key[(i * 4) + 3];
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+ }
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+
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+ // All other round keys are found from the previous round keys.
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+ for (i = Nk; i < Nb * (Nr + 1); ++i)
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+ {
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+ {
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+ k = (i - 1) * 4;
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+ tempa[0]=RoundKey[k + 0];
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+ tempa[1]=RoundKey[k + 1];
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+ tempa[2]=RoundKey[k + 2];
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+ tempa[3]=RoundKey[k + 3];
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+
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+ }
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+
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+ if (i % Nk == 0)
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+ {
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+ // This function shifts the 4 bytes in a word to the left once.
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+ // [a0,a1,a2,a3] becomes [a1,a2,a3,a0]
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+
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+ // Function RotWord()
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+ {
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+ const uint8_t u8tmp = tempa[0];
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+ tempa[0] = tempa[1];
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+ tempa[1] = tempa[2];
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+ tempa[2] = tempa[3];
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+ tempa[3] = u8tmp;
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+ }
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+
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+ // SubWord() is a function that takes a four-byte input word and
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+ // applies the S-box to each of the four bytes to produce an output word.
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+
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+ // Function Subword()
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+ {
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+ tempa[0] = getSBoxValue(tempa[0]);
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+ tempa[1] = getSBoxValue(tempa[1]);
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+ tempa[2] = getSBoxValue(tempa[2]);
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+ tempa[3] = getSBoxValue(tempa[3]);
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+ }
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+
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+ tempa[0] = tempa[0] ^ Rcon[i/Nk];
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+ }
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+#if defined(AES256) && (AES256 == 1)
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+ if (i % Nk == 4)
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+ {
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+ // Function Subword()
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+ {
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+ tempa[0] = getSBoxValue(tempa[0]);
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+ tempa[1] = getSBoxValue(tempa[1]);
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+ tempa[2] = getSBoxValue(tempa[2]);
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+ tempa[3] = getSBoxValue(tempa[3]);
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+ }
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+ }
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+#endif
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+ j = i * 4; k=(i - Nk) * 4;
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+ RoundKey[j + 0] = RoundKey[k + 0] ^ tempa[0];
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+ RoundKey[j + 1] = RoundKey[k + 1] ^ tempa[1];
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+ RoundKey[j + 2] = RoundKey[k + 2] ^ tempa[2];
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+ RoundKey[j + 3] = RoundKey[k + 3] ^ tempa[3];
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+ }
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+}
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+
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+void AES_init_ctx(struct AES_ctx* ctx, const uint8_t* key)
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+{
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+ KeyExpansion(ctx->RoundKey, key);
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+}
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+#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1))
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+void AES_init_ctx_iv(struct AES_ctx* ctx, const uint8_t* key, const uint8_t* iv)
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+{
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+ KeyExpansion(ctx->RoundKey, key);
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+ memcpy (ctx->Iv, iv, AES_BLOCKLEN);
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+}
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+void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv)
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+{
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+ memcpy (ctx->Iv, iv, AES_BLOCKLEN);
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+}
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+#endif
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+
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+// This function adds the round key to state.
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+// The round key is added to the state by an XOR function.
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+static void AddRoundKey(uint8_t round, state_t* state, const uint8_t* RoundKey)
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+{
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+ uint8_t i,j;
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+ for (i = 0; i < 4; ++i)
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+ {
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+ for (j = 0; j < 4; ++j)
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+ {
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+ (*state)[i][j] ^= RoundKey[(round * Nb * 4) + (i * Nb) + j];
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+ }
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+ }
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+}
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+
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+// The SubBytes Function Substitutes the values in the
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+// state matrix with values in an S-box.
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+static void SubBytes(state_t* state)
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+{
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+ uint8_t i, j;
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+ for (i = 0; i < 4; ++i)
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+ {
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+ for (j = 0; j < 4; ++j)
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+ {
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+ (*state)[j][i] = getSBoxValue((*state)[j][i]);
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+ }
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+ }
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+}
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+
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+// The ShiftRows() function shifts the rows in the state to the left.
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+// Each row is shifted with different offset.
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+// Offset = Row number. So the first row is not shifted.
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+static void ShiftRows(state_t* state)
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+{
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+ uint8_t temp;
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+
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+ // Rotate first row 1 columns to left
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+ temp = (*state)[0][1];
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+ (*state)[0][1] = (*state)[1][1];
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+ (*state)[1][1] = (*state)[2][1];
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+ (*state)[2][1] = (*state)[3][1];
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+ (*state)[3][1] = temp;
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+
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+ // Rotate second row 2 columns to left
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+ temp = (*state)[0][2];
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+ (*state)[0][2] = (*state)[2][2];
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+ (*state)[2][2] = temp;
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+
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+ temp = (*state)[1][2];
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+ (*state)[1][2] = (*state)[3][2];
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+ (*state)[3][2] = temp;
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+
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+ // Rotate third row 3 columns to left
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+ temp = (*state)[0][3];
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+ (*state)[0][3] = (*state)[3][3];
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+ (*state)[3][3] = (*state)[2][3];
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+ (*state)[2][3] = (*state)[1][3];
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+ (*state)[1][3] = temp;
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+}
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+
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+static uint8_t xtime(uint8_t x)
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+{
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+ return ((x<<1) ^ (((x>>7) & 1) * 0x1b));
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+}
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+
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+// 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)
|
|
|
+
|
zack