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Implement decryption

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This commit is contained in:
Manuel Vögele
2019-05-15 09:26:42 +02:00
parent 702c37656f
commit d03fe358e7
3 changed files with 122 additions and 10 deletions
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104
aes.cpp
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@@ -25,7 +25,7 @@ const uint8_t AES::sbox[256] = {
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 };
const uint8_t AES::rsbox[256] = {
const uint8_t AES::r_sbox[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,
@@ -84,6 +84,24 @@ void AES::encrypt_ecb(uint8_t data[16], const uint8_t key[16])
add_round_key(data, round_keys[10]);
}
void AES::decrypt_ecb(uint8_t data[16], const uint8_t key[16])
{
PROFILER_RECORD;
uint8_t round_keys[11][16];
construct_round_keys(key, round_keys);
add_round_key(data, round_keys[10]);
r_shift_rows(data);
r_sub_bytes(data);
for (int r = 9;r > 0;r--)
{
add_round_key(data, round_keys[r]);
r_mix_columns(data);
r_shift_rows(data);
r_sub_bytes(data);
}
add_round_key(data, round_keys[0]);
}
void AES::add_round_key(uint8_t data_[16], const uint8_t key_[16])
{
PROFILER_RECORD;
@@ -104,6 +122,15 @@ void AES::sub_bytes(uint8_t data[16])
}
}
void AES::r_sub_bytes(uint8_t data[16])
{
PROFILER_RECORD;
for (int i = 0;i < 16;i++)
{
data[i] = r_sbox[data[i]];
}
}
#define SWAP(x, y, tmp) tmp = x; x = y; y = tmp
void AES::shift_rows(uint8_t data[16])
@@ -125,6 +152,25 @@ void AES::shift_rows(uint8_t data[16])
data[3] = tmp;
}
void AES::r_shift_rows(uint8_t data[16])
{
PROFILER_RECORD;
uint8_t tmp = data[13];
data[13] = data[9];
data[9] = data[5];
data[5] = data[1];
data[1] = tmp;
SWAP(data[2], data[10], tmp);
SWAP(data[6], data[14], tmp);
tmp = data[3];
data[3] = data[7];
data[7] = data[11];
data[11] = data[15];
data[15] = tmp;
}
#undef SWAP
void AES::mix_columns(uint8_t data[16])
@@ -141,6 +187,20 @@ void AES::mix_columns(uint8_t data[16])
memcpy(data, data_new, 16);
}
void AES::r_mix_columns(uint8_t data[16])
{
PROFILER_RECORD;
uint8_t data_new[16];
for (int i = 0;i < 4;i++)
{
data_new[i * 4 + 0] = gf_multE(data[i * 4 + 0]) ^ gf_multB(data[i * 4 + 1]) ^ gf_multD(data[i * 4 + 2]) ^ gf_mult9(data[i * 4 + 3]);
data_new[i * 4 + 1] = gf_mult9(data[i * 4 + 0]) ^ gf_multE(data[i * 4 + 1]) ^ gf_multB(data[i * 4 + 2]) ^ gf_multD(data[i * 4 + 3]);
data_new[i * 4 + 2] = gf_multD(data[i * 4 + 0]) ^ gf_mult9(data[i * 4 + 1]) ^ gf_multE(data[i * 4 + 2]) ^ gf_multB(data[i * 4 + 3]);
data_new[i * 4 + 3] = gf_multB(data[i * 4 + 0]) ^ gf_multD(data[i * 4 + 1]) ^ gf_mult9(data[i * 4 + 2]) ^ gf_multE(data[i * 4 + 3]);
}
mempcpy(data, data_new, 16);
}
void AES::construct_round_keys(const uint8_t initial_key_[16], uint8_t round_keys_[11][16])
{
PROFILER_RECORD;
@@ -195,6 +255,44 @@ uint8_t AES::gf_mult2(uint8_t value)
uint8_t AES::gf_mult3(uint8_t value)
{
PROFILER_RECORD;
uint8_t result = gf_mult2(value);
return result ^ value;
return gf_mult2(value) ^ value;
}
uint8_t AES::gf_mult4(uint8_t value)
{
PROFILER_RECORD;
return gf_mult2(gf_mult2(value));
}
uint8_t AES::gf_mult8(uint8_t value)
{
PROFILER_RECORD;
return gf_mult2(gf_mult4(value));
}
uint8_t AES::gf_mult9(uint8_t value)
{
PROFILER_RECORD;
return gf_mult8(value) ^ value;
}
uint8_t AES::gf_multB(uint8_t value)
{
PROFILER_RECORD;
return gf_mult8(value) ^ gf_mult3(value);
}
uint8_t AES::gf_multD(uint8_t value)
{
PROFILER_RECORD;
uint8_t gf4 = gf_mult4(value);
return gf_mult2(gf4) ^ gf4 ^ value;
}
uint8_t AES::gf_multE(uint8_t value)
{
PROFILER_RECORD;
uint8_t gf2 = gf_mult2(value);
uint8_t gf4 = gf_mult2(gf2);
return gf_mult2(gf4) ^ gf4 ^ gf2;
}