aes128.h-Dateireferenz

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Funktionen
void	aes128_expandkey (void *expanded_key, const void *aes_key)
void	aes128_encrypt_block (void *out_buffer, const void *inp_buffer, const unsigned char *expkey)
void	aes128_decrypt_block (void *out_buffer, const void *inp_buffer, const unsigned char *expkey)
void	aes128_cbc_encrypt (void *buffer, const unsigned char *expkey, const void *iv, int len)
void	aes128_cbc_decrypt (void *buffer, const unsigned char *expkey, const void *iv, int len)

Dokumentation der Funktionen

void aes128_cbc_decrypt	(	void *	buffer,
		const unsigned char *	expkey,
		const void *	iv,
		int	len
	)

Definiert in Zeile 425 der Datei aes128.c.

{
    int i;
    uint32_t xorl[4];
    uint32_t tmpl[4];
    uint32_t *bufl = (uint32_t *)buffer;

    memcpy( xorl, iv, 16 );
    while( len > 0 ){
        memcpy( tmpl, bufl, 16 );
        aes128_decrypt_block(bufl, bufl, expkey );  // decrypt current block
        for( i = 0; i < 4; i++ ) bufl[i] ^= xorl[i];
        memcpy( xorl, tmpl, 16 );
        bufl += 4;
        len -= 16;
    }
}

void aes128_cbc_encrypt	(	void *	buffer,
		const unsigned char *	expkey,
		const void *	iv,
		int	len
	)

Definiert in Zeile 409 der Datei aes128.c.

{
    int i;
    uint32_t xorl[4];
    uint32_t *bufl = (uint32_t *)buffer;

    memcpy( xorl, iv, 16 );
    while( len > 0 ){
        for( i = 0; i < 4; i++ ) bufl[i] ^= xorl[i];
        aes128_encrypt_block(bufl, bufl, expkey );  // encrypt current block
        memcpy( xorl, bufl, 16 );
        bufl += 4;
        len -= 16;
    }
}

void aes128_decrypt_block	(	void *	out_buffer,
		const void *	inp_buffer,
		const unsigned char *	expkey
	)

Definiert in Zeile 387 der Datei aes128.c.

{
    unsigned char *out = (unsigned char *)out_buffer;
    unsigned char *in  = (unsigned char *)inp_buffer;
    unsigned char state[Nb * 4];
    unsigned round;

    memcpy (state, in, sizeof(state));

    AddRoundKey ((uint32_t *)state, (uint32_t *)expkey + Nr * Nb);
    InvShiftRows(state);

    for( round = Nr; round--; )
    {
        AddRoundKey ((uint32_t *)state, (uint32_t *)expkey + round * Nb);
        if( round )
            InvMixSubColumns (state);
    } 

    memcpy (out, state, sizeof(state));
}

void aes128_encrypt_block	(	void *	out_buffer,
		const void *	inp_buffer,
		const unsigned char *	expkey
	)

Definiert in Zeile 365 der Datei aes128.c.

{
    unsigned char *out = (unsigned char *)out_buffer;
    unsigned char *in  = (unsigned char *)inp_buffer;
    unsigned char state[Nb * 4];
    unsigned round;

    memcpy (state, in, Nb * 4);
    AddRoundKey ((uint32_t *)state, (uint32_t *)expkey);

    for( round = 1; round < Nr + 1; round++ ) {
        if( round < Nr )
            MixSubColumns (state);
        else
            ShiftRows (state);

        AddRoundKey ((uint32_t *)state, (uint32_t *)expkey + round * Nb);
    }

    memcpy (out, state, sizeof(state));
}

void aes128_expandkey	(	void *	expanded_key,
		const void *	aes_key
	)

Definiert in Zeile 330 der Datei aes128.c.

{
    unsigned char *expkey = (unsigned char *)expanded_key;
    unsigned char *key = (unsigned char *)aes_key;
    unsigned char tmp0, tmp1, tmp2, tmp3, tmp4;
    unsigned idx;

    memcpy (expkey, key, Nk * 4);

    for( idx = Nk; idx < Nb * (Nr + 1); idx++ ) {
        tmp0 = expkey[4*idx - 4];
        tmp1 = expkey[4*idx - 3];
        tmp2 = expkey[4*idx - 2];
        tmp3 = expkey[4*idx - 1];
        if( !(idx % Nk) ) {
            tmp4 = tmp3;
            tmp3 = Sbox[tmp0];
            tmp0 = Sbox[tmp1] ^ Rcon[idx/Nk];
            tmp1 = Sbox[tmp2];
            tmp2 = Sbox[tmp4];
        } else if( Nk > 6 && idx % Nk == 4 ) {
            tmp0 = Sbox[tmp0];
            tmp1 = Sbox[tmp1];
            tmp2 = Sbox[tmp2];
            tmp3 = Sbox[tmp3];
        }

        expkey[4*idx+0] = expkey[4*idx - 4*Nk + 0] ^ tmp0;
        expkey[4*idx+1] = expkey[4*idx - 4*Nk + 1] ^ tmp1;
        expkey[4*idx+2] = expkey[4*idx - 4*Nk + 2] ^ tmp2;
        expkey[4*idx+3] = expkey[4*idx - 4*Nk + 3] ^ tmp3;
    }
}