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- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // CryptLib_Aes
- //
- // Implementation of AES block cipher. Originally written by Kokke (https://github.com/kokke). Modified by WaterJuice
- // retaining Public Domain license.
- //
- // AES is a block cipher that operates on 128 bit blocks. Encryption an Decryption routines use an AesContext which
- // must be initialised with the key. An AesContext can be initialised with a 128, 192, or 256 bit key. Use the
- // AesInitialise[n] functions to initialise the context with the key. Once an AES context is initialised its contents
- // are not changed by the encrypting and decrypting functions. A context only needs to be initialised once for any
- // given key and the context may be used by the encrypt/decrypt functions in simultaneous threads.
- // All operations are performed byte wise and this implementation works in both little and endian processors.
- // There are no alignment requirements with the keys and data blocks.
- //
- // This is free and unencumbered software released into the public domain - November 2017 waterjuice.org
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // IMPORTS
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- #include "CryptLib_Aes.h"
- #include <stdint.h>
- #include <memory.h>
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // DEFINES
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // Array holding the intermediate results during decryption.
- typedef struct
- {
- uint8_t state[4][4];
- } AesState;
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // CONSTANTS
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // AES lookup values
- static const uint8_t SBOX[256] =
- {
- 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
- 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
- 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
- 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
- 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
- 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
- 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
- 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
- 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
- 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
- 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
- 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
- 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
- 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
- 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
- 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
- };
- 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 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 };
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // INTERNAL FUNCTIONS
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // KeyExpansion
- //
- // 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 const* Key, // [in]
- AesContext* Context // [in out]
- )
- {
- uint32_t i;
- uint8_t k;
- uint8_t temp [4]; // Used for the column/row operations
- // The first round key is the key itself.
- for( i=0; i<Context->KeySizeInWords; i++ )
- {
- Context->RoundKey[(i * 4) + 0] = Key[(i * 4) + 0];
- Context->RoundKey[(i * 4) + 1] = Key[(i * 4) + 1];
- Context->RoundKey[(i * 4) + 2] = Key[(i * 4) + 2];
- Context->RoundKey[(i * 4) + 3] = Key[(i * 4) + 3];
- }
- // All other round keys are found from the previous round keys.
- for( i=Context->KeySizeInWords; i<4*(Context->NumberOfRounds+1); i++ )
- {
- #ifdef _MSC_VER
- // Visual Studio code analysis complains about the following code that the index into Context->RoundKey
- // may be -4. This is because it is concerned that 'i' may be zero. However we know that 'i' will not
- // be zero as it starts at Context->KeySizeInWords which is never going to be zero when this function
- // is called (It will have one of 3 values assigned to it by the initialise functions). So we need to
- // just suppress the warning here to stop Visual Studio complaining.
- #pragma warning( suppress : 6385 )
- #endif
- temp[0] = Context->RoundKey[(i-1) * 4 + 0];
- temp[1] = Context->RoundKey[(i-1) * 4 + 1];
- temp[2] = Context->RoundKey[(i-1) * 4 + 2];
- temp[3] = Context->RoundKey[(i-1) * 4 + 3];
- if( 0 == i % Context->KeySizeInWords )
- {
- // This function shifts the 4 bytes in a word to the left once.
- // [a0,a1,a2,a3] becomes [a1,a2,a3,a0]
- k = temp[0];
- temp[0] = temp[1];
- temp[1] = temp[2];
- temp[2] = temp[3];
- temp[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.
- temp[0] = SBOX[temp[0]];
- temp[1] = SBOX[temp[1]];
- temp[2] = SBOX[temp[2]];
- temp[3] = SBOX[temp[3]];
- temp[0] = temp[0] ^ RCON[i/Context->KeySizeInWords];
- }
- if( AES_KEY_SIZE_256/4 == Context->KeySizeInWords )
- {
- // Only performed with 256 bit sized keys
- if( 4 == i % Context->KeySizeInWords )
- {
- // Function Subword()
- temp[0] = SBOX[temp[0]];
- temp[1] = SBOX[temp[1]];
- temp[2] = SBOX[temp[2]];
- temp[3] = SBOX[temp[3]];
- }
- }
- Context->RoundKey[i*4 + 0] = Context->RoundKey[(i-Context->KeySizeInWords)*4 + 0] ^ temp[0];
- Context->RoundKey[i*4 + 1] = Context->RoundKey[(i-Context->KeySizeInWords)*4 + 1] ^ temp[1];
- Context->RoundKey[i*4 + 2] = Context->RoundKey[(i-Context->KeySizeInWords)*4 + 2] ^ temp[2];
- Context->RoundKey[i*4 + 3] = Context->RoundKey[(i-Context->KeySizeInWords)*4 + 3] ^ temp[3];
- }
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // AddRoundKey
- //
- // This function adds the round key to state. The round key is added to the state by an XOR function.
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- static
- void
- AddRoundKey
- (
- uint32_t Round, // [in]
- AesContext const* Context, // [in]
- AesState* State // [in out]
- )
- {
- uint32_t i;
- uint32_t j;
- for( i=0; i<4; i++ )
- {
- for( j=0; j<4; j++ )
- {
- State->state[i][j] ^= Context->RoundKey[(Round*4*4) + (i*4) + j];
- }
- }
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // SubBytes
- //
- // The SubBytes Function Substitutes the values in the state matrix with values in an S-box.
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- static
- void
- SubBytes
- (
- AesState* State // [in out]
- )
- {
- uint32_t i;
- uint32_t j;
- for( i=0; i<4; i++ )
- {
- for( j=0; j<4; j++ )
- {
- State->state[j][i] = SBOX[ State->state[j][i] ];
- }
- }
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // ShiftRows
- //
- // 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
- (
- AesState* State // [in out]
- )
- {
- uint8_t temp;
- // Rotate first row 1 columns to left
- temp = State->state[0][1];
- State->state[0][1] = State->state[1][1];
- State->state[1][1] = State->state[2][1];
- State->state[2][1] = State->state[3][1];
- State->state[3][1] = temp;
- // Rotate second row 2 columns to left
- temp = State->state[0][2];
- State->state[0][2] = State->state[2][2];
- State->state[2][2] = temp;
- temp = State->state[1][2];
- State->state[1][2] = State->state[3][2];
- State->state[3][2] = temp;
- // Rotate third row 3 columns to left
- temp = State->state[0][3];
- State->state[0][3] = State->state[3][3];
- State->state[3][3] = State->state[2][3];
- State->state[2][3] = State->state[1][3];
- State->state[1][3] = temp;
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // xtime
- //
- // Performs a calculation
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- static
- uint8_t
- xtime
- (
- uint8_t x // [in]
- )
- {
- return (x<<1) ^ ( ((x>>7) & 1) * 0x1b );
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // MixColumns
- //
- // MixColumns function mixes the columns of the state matrix
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- static
- void
- MixColumns
- (
- AesState* State // [in out]
- )
- {
- uint32_t i;
- uint8_t Tmp;
- uint8_t Tm;
- uint8_t t;
- for( i=0; i<4; i++ )
- {
- t = State->state[i][0];
- Tmp = State->state[i][0] ^ State->state[i][1] ^ State->state[i][2] ^ State->state[i][3] ;
- Tm = State->state[i][0] ^ State->state[i][1] ; Tm = xtime(Tm); State->state[i][0] ^= Tm ^ Tmp ;
- Tm = State->state[i][1] ^ State->state[i][2] ; Tm = xtime(Tm); State->state[i][1] ^= Tm ^ Tmp ;
- Tm = State->state[i][2] ^ State->state[i][3] ; Tm = xtime(Tm); State->state[i][2] ^= Tm ^ Tmp ;
- Tm = State->state[i][3] ^ t ; Tm = xtime(Tm); State->state[i][3] ^= Tm ^ Tmp ;
- }
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // Multiply
- //
- // Multiply is used to multiply numbers in the field GF(2^8). This is defined as a macro.
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- #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)))))) \
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // InvMixColumns
- //
- // InvMixColumns function mixes the columns of the state matrix.
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- static
- void
- InvMixColumns
- (
- AesState* State // [in out]
- )
- {
- uint32_t i;
- uint8_t a;
- uint8_t b;
- uint8_t c;
- uint8_t d;
- for( i=0; i<4; i++ )
- {
- a = State->state[i][0];
- b = State->state[i][1];
- c = State->state[i][2];
- d = State->state[i][3];
- State->state[i][0] = Multiply(a, 0x0e) ^ Multiply(b, 0x0b) ^ Multiply(c, 0x0d) ^ Multiply(d, 0x09);
- State->state[i][1] = Multiply(a, 0x09) ^ Multiply(b, 0x0e) ^ Multiply(c, 0x0b) ^ Multiply(d, 0x0d);
- State->state[i][2] = Multiply(a, 0x0d) ^ Multiply(b, 0x09) ^ Multiply(c, 0x0e) ^ Multiply(d, 0x0b);
- State->state[i][3] = Multiply(a, 0x0b) ^ Multiply(b, 0x0d) ^ Multiply(c, 0x09) ^ Multiply(d, 0x0e);
- }
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // InvSubBytes
- //
- // The InvSubBytes Function Substitutes the values in the state matrix with values in an S-box.
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- static
- void
- InvSubBytes
- (
- AesState* State // [in out]
- )
- {
- uint32_t i;
- uint32_t j;
- for( i=0; i<4; i++ )
- {
- for( j=0; j<4; j++ )
- {
- State->state[j][i] = RSBOX[ State->state[j][i] ];
- }
- }
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // InvShiftRows
- //
- // Inverse of ShiftRows
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- static
- void
- InvShiftRows
- (
- AesState* State // [in out]
- )
- {
- uint8_t temp;
- // Rotate first row 1 columns to right
- temp = State->state[3][1];
- State->state[3][1] = State->state[2][1];
- State->state[2][1] = State->state[1][1];
- State->state[1][1] = State->state[0][1];
- State->state[0][1] = temp;
- // Rotate second row 2 columns to right
- temp = State->state[0][2];
- State->state[0][2] = State->state[2][2];
- State->state[2][2] = temp;
- temp = State->state[1][2];
- State->state[1][2] = State->state[3][2];
- State->state[3][2] = temp;
- // Rotate third row 3 columns to right
- temp = State->state[0][3];
- State->state[0][3] = State->state[1][3];
- State->state[1][3] = State->state[2][3];
- State->state[2][3] = State->state[3][3];
- State->state[3][3] = temp;
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // EXPORTED FUNCTIONS
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // AesInitialise128
- //
- // Initialises an AesContext with a 128 bit key.
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- void
- AesInitialise128
- (
- uint8_t const Key [AES_KEY_SIZE_128], // [in]
- AesContext* Context // [out]
- )
- {
- memset( Context, 0, sizeof(*Context) );
- Context->KeySizeInWords = AES_KEY_SIZE_128 / sizeof(uint32_t);
- Context->NumberOfRounds = 10;
- KeyExpansion( Key, Context );
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // AesInitialise192
- //
- // Initialises an AesContext with a 192 bit key.
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- void
- AesInitialise192
- (
- uint8_t const Key [AES_KEY_SIZE_192], // [in]
- AesContext* Context // [out]
- )
- {
- memset( Context, 0, sizeof(*Context) );
- Context->KeySizeInWords = AES_KEY_SIZE_192 / sizeof(uint32_t);
- Context->NumberOfRounds = 12;
- KeyExpansion( Key, Context );
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // AesInitialise256
- //
- // Initialises an AesContext with a 256 bit key.
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- void
- AesInitialise256
- (
- uint8_t const Key [AES_KEY_SIZE_256], // [in]
- AesContext* Context // [out]
- )
- {
- memset( Context, 0, sizeof(*Context) );
- Context->KeySizeInWords = AES_KEY_SIZE_256 / sizeof(uint32_t);
- Context->NumberOfRounds = 14;
- KeyExpansion( Key, Context );
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // AesEncrypt
- //
- // Performs an AES encryption of one block (128 bits) with the AesContext initialised with one of the functions
- // AesInitialise[n]. Input and Output can point to same memory location, however it is more efficient to use
- // AesEncryptInPlace in this situation.
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- void
- AesEncrypt
- (
- AesContext const* Context, // [in]
- uint8_t const Input [AES_BLOCK_SIZE], // [in]
- uint8_t Output [AES_BLOCK_SIZE] // [out]
- )
- {
- memcpy( Output, Input, AES_BLOCK_SIZE );
- AesEncryptInPlace( Context, Output );
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // AesDecrypt
- //
- // Performs an AES decryption of one block (128 bits) with the AesContext initialised with one of the functions
- // AesInitialise[n]. Input and Output can point to same memory location, however it is more efficient to use
- // AesDecryptInPlace in this situation.
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- void
- AesDecrypt
- (
- AesContext const* Context, // [in]
- uint8_t const Input [AES_BLOCK_SIZE], // [in]
- uint8_t Output [AES_BLOCK_SIZE] // [out]
- )
- {
- memcpy( Output, Input, AES_BLOCK_SIZE);
- AesDecryptInPlace(Context, Output );
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // AesEncryptInPlace
- //
- // Performs an AES encryption of one block (128 bits) with the AesContext initialised with one of the functions
- // AesInitialise[n]. The encryption is performed in place.
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- void
- AesEncryptInPlace
- (
- AesContext const* Context, // [in]
- uint8_t Block [AES_BLOCK_SIZE] // [in out]
- )
- {
- uint32_t round = 0;
- // Add the First round key to the state before starting the rounds.
- AddRoundKey( 0, Context, (AesState*)Block );
- // 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<Context->NumberOfRounds; round++ )
- {
- SubBytes( (AesState*)Block );
- ShiftRows( (AesState*)Block );
- MixColumns( (AesState*)Block );
- AddRoundKey( round, Context, (AesState*)Block );
- }
- // The last round is given below.
- // The MixColumns function is not here in the last round.
- SubBytes( (AesState*)Block);
- ShiftRows( (AesState*)Block);
- AddRoundKey( Context->NumberOfRounds, Context, (AesState*)Block );
- }
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // AesDecryptInPlace
- //
- // Performs an AES decryption of one block (128 bits) with the AesContext initialised with one of the functions
- // AesInitialise[n]. The decryption is performed in place.
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- void
- AesDecryptInPlace
- (
- AesContext const* Context, // [in]
- uint8_t Block [AES_BLOCK_SIZE] // [in out]
- )
- {
- uint32_t round = 0;
- // Add the First round key to the state before starting the rounds.
- AddRoundKey( Context->NumberOfRounds, Context, (AesState*)Block );
- // The first NumberOfRounds-1 rounds are identical.
- for( round=(Context->NumberOfRounds-1); round>0; round-- )
- {
- InvShiftRows( (AesState*)Block );
- InvSubBytes( (AesState*)Block );
- AddRoundKey( round, Context, (AesState*)Block );
- InvMixColumns( (AesState*)Block );
- }
- // The MixColumns function is not here in the last round.
- InvShiftRows( (AesState*)Block );
- InvSubBytes( (AesState*)Block );
- AddRoundKey( 0, Context, (AesState*)Block );
- }
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