/* Double function of the specification of OCB */
static void doubleB(unsigned char *l, const unsigned int len) {
/* If first bit of the byte is one, shifting and xor with 135 */
if ((l[0])&0x80) {
shiftB(l, len);
l[len - 1] = l[len - 1] ^ 0x87;
}
/* If it is zero, only shifting */
else shiftB(l, len);
}
void EditRatioWindow::react_Key(VKey vkey,KeyMod kmod,unsigned repeat)
{
switch( vkey )
{
case VKey_Up :
{
if( kmod&KeyMod_Shift )
shiftB(10*Coord(repeat));
else
shiftB(Coord(repeat));
}
break;
case VKey_Down :
{
if( kmod&KeyMod_Shift )
shiftB(-10*Coord(repeat));
else
shiftB(-Coord(repeat));
}
break;
case VKey_Right :
case VKey_NumPlus :
{
if( kmod&KeyMod_Shift )
shiftA(10*Coord(repeat));
else
shiftA(Coord(repeat));
}
break;
case VKey_Left :
case VKey_NumMinus :
{
if( kmod&KeyMod_Shift )
shiftA(-10*Coord(repeat));
else
shiftA(-Coord(repeat));
}
break;
}
}
void EditRatioWindow::react_Wheel(Point,MouseKey mkey,Coord delta)
{
if( mkey&MouseKey_Shift )
{
shiftB(delta);
}
else
{
shiftA(delta);
}
}
/* Under the 16-byte (128-bit) key at k and the 12-byte (96-bit) nonce at n, encrypt the plaintext at p and store it at c.
The length of the plaintext is a multiple of 16 bytes given at len (e.g., len = 2 for a 32-byte p). The length of the
ciphertext c is (len+1)*16 bytes. */
void aes128ocb(unsigned char *c, const unsigned char *k, const unsigned char *n, const unsigned char *p, const unsigned int len) {
/* Array of zeros for use with aes128e */
unsigned char zeros[16];
int i;
for (i = 0; i < 16; ++i) {
zeros[i] = 0x00;
}
unsigned char l[16];
unsigned char l_dollar[16];
aes128e(l, zeros, k);
/* Now l is l_star */
doubleB(l, 16);
/* Now l is l_dollar */
/* We keep l_dollar for using it for calculate the tag */
for (i = 0; i < 16; ++i) {
l_dollar[i] = l[i];
}
doubleB(l, 16);
/* Now l is l_0 */
/* m = bitlen(P)/128 */
unsigned int m = ((16*len)*8)/128;
/* numL is the maximum value of trailing zeros for the given size m */
unsigned int numL = msb(m) + 1;
/* ls is the array of all the l_i arrays */
unsigned char ls[numL][16];
int a;
for (a = 0; a < numL; ++a) {
for (i = 0; i < 16; ++i) {
ls[a][i] = l[i];
}
doubleB(l, 16);
}
/* Addition of 0x00000001 to the nonce */
unsigned char nonce[20];
nonce[0] = nonce[1] = nonce[2] = 0x00;
nonce[3] = 0x01;
a = 0;
for (i = 4; i < 20; ++i) {
nonce[i] = n[a];
++a;
}
/* Bottom is the integer value of the last 6 bits of nonce */
unsigned int bottom = nonce[15]&0x3F;
/* Temporal array for aes128e with last 6 bits of nonce to zero */
unsigned char top[16];
for (i = 0; i < 16; ++i) {
top[i] = nonce[i];
}
top[15] = nonce[15]&0xC0;
/* Calculation of ktop using the block cipher */
unsigned char ktop[16];
aes128e(ktop, top, k);
/* Stretch is ktop concatenated with the xor of the bits 1...64 and 9...72 of ktop */
unsigned char stretch[24];
for (i = 0; i < 16; ++i) {
stretch[i] = ktop[i];
}
a = 0;
for (i = 16; i < 24; ++i) {
stretch[i] = (ktop[a] ^ ktop[a + 1]);
++a;
}
/* Array of the m offset arrays */
unsigned char offset[m][16];
/* Array of the m checksum arrays */
unsigned char checksum[m][16];
/* Temporal array for get stretch[1 + bottom...128 + bottom] */
unsigned char tempS[24];
for (i = 0; i < 24; ++i) {
tempS[i] = stretch[i];
}
/* Shifting of stretch bottom times to the left */
for (i = 0; i < bottom; ++i) {
shiftB(tempS, 24);
}
/* Copy of temp array to offset and inicialization of checksum */
for (i = 0; i < 16; ++i) {
offset[0][i] = tempS[i];
checksum[0][i] = 0x00;
}
/* Temporal arrays for use them with aes128 as plaintext and ciphertext */
unsigned char temp1[16];
unsigned char temp2[16];
int ntzV;
/* Counters */
int countP1 = 0;
int countP2 = 0;
int countC = 0;
/* Loop over the m blocks */
for (i = 1; i <= m; ++i) {
/* Number of trailing zeros in i */
ntzV = ntz(i);
/* Calculation of the offset_i with xor betwen offset_{i-1} and l_{ntz(i)} */
for (a = 0; a < 16; ++a) {
offset[i][a] = offset[i - 1][a] ^ ls[ntzV][a];
}
/* Calculation of xor betwen p_i and offset_i for use it in aes128 */
for (a = 0; a < 16; ++a) {
temp1[a] = (p[countP1] ^ offset[i][a]);
++countP1;
}
aes128e(temp2, temp1, k);
/* Calculation of c_i with xor betwen offset_i and result of aes128 */
for (a = 0; a < 16; ++a) {
c[countC] = offset[i][a] ^ temp2[a];
++countC;
}
/* Calculation of checksum_i with the xor betwen checksum_{i-1} and p_i */
for (a = 0; a < 16; ++a) {
checksum[i][a] = checksum[i - 1][a] ^ p[countP2];
++countP2;
}
}
unsigned char tag[16];
unsigned char tempTag[16];
/* Calculation of the xor betwen checksum_m, offset_m and l_dollar for use it in aes128 to calculate the tag */
int w;
for (w = 0; w < 16; ++w) {
tempTag[w] = ((l_dollar[w] ^ offset[m][w]) ^ checksum[m][w]);
}
aes128e(tag, tempTag, k);
/* Concatenation of the tag at the end of the ciphertext. 16*m is the
current lenght of the cipher lenght and 16*m +16 is the total lenght */
int countTag = 0;
for (a = 16*m; a < (16*m + 16); ++a) {
c[a] = tag[countTag];
++countTag;
}
}
