AES Class Reference

Class providing functionality for 128-bit AES decryption. More...

#include <aes.h>

Collaboration diagram for AES:

Public Member Functions
	AES (const aes_key_t masterKey)
	Construct a new AES object. More...
void	decrypt (uint8_t *cipher)
	Decrypt a cipher using the 128-bit AES algorithm. More...

Private Member Functions
void	createKeySchedule (const aes_key_t masterKey, sub_keys_t subKeys) const
	Create the AES key-schedule & store all subkeys in mSubkeys. More...
void	addRoundKey (const aes_key_t roundKey, state_t state)
	Add the key for the current round to state. More...
void	invMixCols (state_t state)
	Inverse MixColumn sublayer. More...
void	invShiftRows (state_t state)
	Inverse ShiftRows sublayer. More...
void	invByteSub (state_t state)
	Inverse Byte Substituion layer. More...

Private Attributes
sub_keys_t	mSubkeys = {}
	Array that contains all subkeys.
Logger	mLog
	Logger.
Masking	mMasking
	Masking object.
sub_keys_t	mOriginalSubKeys
	Array that contains all original subkeys, if masking is enabled.
Hiding	mHiding
	Hiding object.
uint8_t	mShuffledSBoxIndices [STATE_BYTES] = {}
	Array of indices of the S-Box, if shuffling is enabled.

Static Private Attributes
static uint8_t	mRCs [ROUNDS]
	Array of round coefficients that are used in the key schedule.

Detailed Description

Class providing functionality for 128-bit AES decryption.

If MASKING is defined, the class also provides functionality for masking and unmasking AES-decryption.

Authors

Philipp Karg (phili.nosp@m.pp.k.nosp@m.arg@t.nosp@m.um.d.nosp@m.e)

Date

23.05.2022

Copyright

Philipp Karg 2022

Constructor & Destructor Documentation

AES()

AES::AES

(

const aes_key_t

masterKey

)

Construct a new AES object.

Parameters

[in]

masterKey

(const aes_key_t): The master key.

Member Function Documentation

addRoundKey()

void AES::addRoundKey ( const aes_key_t  roundKey, state_t  state  )

private

Add the key for the current round to state.

X-OR each byte of state with the corresponding byte in roundKey.

Parameters

[in]	roundKey	(const aes_key_t): Key for the current round.
[in,out]	state	( state_t): Current state matrix.

createKeySchedule()

void AES::createKeySchedule ( const aes_key_t  masterKey, sub_keys_t  subKeys  ) const

private

Create the AES key-schedule & store all subkeys in mSubkeys.

• The first subkey is masterKey.
• The remaining subkeys are calculated as defined in the AES standard. See p. 106-108 for reference.

Parameters

[in]	masterKey	(const aes_key_t): The master key, which is used to create the key schedule.
[out]	subKeys	( sub_keys_t): Array that contains all subkeys.

decrypt()

void AES::decrypt

(

uint8_t *

cipher

)

Decrypt a cipher using the 128-bit AES algorithm.

See also

p. 110-112

Parameters

[in,out]

cipher

(uint8_t *): Cipher to decrypt.

invByteSub()

void AES::invByteSub ( state_t  state )

private

Inverse Byte Substituion layer.

Substitute each byte in state with the corresponding value in #INV_S_BOX.

Parameters

[in,out]

state

( state_t): Current state matrix.

invMixCols()

void AES::invMixCols ( state_t  state )

private

Inverse MixColumn sublayer.

Do a matrix-matrix multiplication of state & #INV_MIX_COL_MATRIX.

Parameters

[in,out]

state

( state_t): Current state matrix.

invShiftRows()

void AES::invShiftRows ( state_t  state )

private

Inverse ShiftRows sublayer.

Rotate each row of the state matrix by the row-number to the right.

Parameters

[in,out]

state

( state_t): Current state matrix.

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The documentation for this class was generated from the following file:

• aes.h