diff options
Diffstat (limited to 'aes.c')
| -rw-r--r-- | aes.c | 145 |
1 files changed, 70 insertions, 75 deletions
@@ -37,18 +37,29 @@ 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 +#define BLOCKLEN 16 //Block length in bytes AES is 128b block only + +#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 +77,7 @@ 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 +127,25 @@ 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 +164,7 @@ 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 +177,19 @@ 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 < 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 +214,8 @@ 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 +225,7 @@ 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]; @@ -434,16 +449,6 @@ static void InvCipher(void) AddRoundKey(0); } -static void BlockCopy(uint8_t* output, const uint8_t* input) -{ - uint8_t i; - for (i=0;i<KEYLEN;++i) - { - output[i] = input[i]; - } -} - - /*****************************************************************************/ /* Public functions: */ @@ -451,10 +456,10 @@ 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, const uint32_t length) { // Copy input to output, and work in-memory on output - BlockCopy(output, input); + memcpy(output, input, length); state = (state_t*)output; Key = key; @@ -464,10 +469,10 @@ 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, const uint32_t length) { // Copy input to output, and work in-memory on output - BlockCopy(output, input); + memcpy(output, input, length); state = (state_t*)output; // The KeyExpansion routine must be called before encryption. @@ -490,19 +495,16 @@ void AES128_ECB_decrypt(const uint8_t* input, const uint8_t* key, uint8_t *outpu static void XorWithIv(uint8_t* buf) { uint8_t i; - for(i = 0; i < KEYLEN; ++i) + for(i = 0; i < BLOCKLEN; ++i) //WAS for(i = 0; i < KEYLEN; ++i) but the block in AES is always 128bit so 16 bytes! { buf[i] ^= Iv[i]; } } -void AES128_CBC_encrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv) +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 */ - - BlockCopy(output, input); - state = (state_t*)output; + uint8_t extra = length % BLOCKLEN; /* Remaining bytes in the last non-full block */ // Skip the key expansion if key is passed as 0 if(0 != key) @@ -516,33 +518,30 @@ void AES128_CBC_encrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, Iv = (uint8_t*)iv; } - for(i = 0; i < length; i += KEYLEN) + for(i = 0; i < length; i += BLOCKLEN) { XorWithIv(input); - BlockCopy(output, input); + memcpy(output, input, BLOCKLEN); state = (state_t*)output; Cipher(); Iv = output; - input += KEYLEN; - output += KEYLEN; + input += BLOCKLEN; + output += BLOCKLEN; + //printf("Step %d - %d", i/16, i); } - if(remainders) + if(extra) { - BlockCopy(output, input); - memset(output + remainders, 0, KEYLEN - remainders); /* add 0-padding */ + memcpy(output, input, extra); state = (state_t*)output; Cipher(); } } -void AES128_CBC_decrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv) +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 */ - - BlockCopy(output, input); - state = (state_t*)output; + uint8_t extra = length % BLOCKLEN; /* Remaining bytes in the last non-full block */ // Skip the key expansion if key is passed as 0 if(0 != key) @@ -557,27 +556,23 @@ void AES128_CBC_decrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, Iv = (uint8_t*)iv; } - for(i = 0; i < length; i += KEYLEN) + for(i = 0; i < length; i += BLOCKLEN) { - BlockCopy(output, input); + memcpy(output, input, BLOCKLEN); state = (state_t*)output; InvCipher(); XorWithIv(output); Iv = input; - input += KEYLEN; - output += KEYLEN; + input += BLOCKLEN; + output += BLOCKLEN; } - if(remainders) + if(extra) { - BlockCopy(output, input); - memset(output+remainders, 0, KEYLEN - remainders); /* add 0-padding */ + memcpy(output, input, extra); state = (state_t*)output; InvCipher(); } } - #endif // #if defined(CBC) && CBC - - |