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authorAndreas Bogk <andreas@oxytocin.(none)>2009-01-19 01:37:53 +0100
committerAndreas Bogk <andreas@oxytocin.(none)>2009-01-19 01:37:53 +0100
commitbe6e464fcafecdf695d82fdf07e7e8d75b12418a (patch)
tree549e7723b68b0abfc5e088b2c849d462c211c341
parentde8840a20db148df2cdae4a6ab3f1273ea448f23 (diff)
performance optimization.
-rw-r--r--A5.1/C/calculate_chain.c167
1 files changed, 8 insertions, 159 deletions
diff --git a/A5.1/C/calculate_chain.c b/A5.1/C/calculate_chain.c
index 23361a3..a7d3266 100644
--- a/A5.1/C/calculate_chain.c
+++ b/A5.1/C/calculate_chain.c
@@ -127,6 +127,7 @@ typedef word bit;
/* Calculate the parity of a 32-bit word, i.e. the sum of its bits modulo 2 */
bit parity(word x) {
+ // x ^= x>>32;
x ^= x>>16;
x ^= x>>8;
x ^= x>>4;
@@ -152,7 +153,7 @@ word R1, R2, R3;
* return the majority value of those 3 bits. */
bit majority() {
int sum;
- sum = parity(R1&R1MID) + parity(R2&R2MID) + parity(R3&R3MID);
+ sum = ((R1&R1MID) >> 8) + ((R2&R2MID) >> 10) + ((R3&R3MID) >> 10);
if (sum >= 2)
return 1;
else
@@ -173,169 +174,16 @@ inline void clock() {
R3 = clockone(R3, R3MASK, R3TAPS);
}
-/* Clock all three of R1,R2,R3, ignoring their middle bits.
- * This is only used for key setup. */
-void clockallthree() {
- R1 = clockone(R1, R1MASK, R1TAPS);
- R2 = clockone(R2, R2MASK, R2TAPS);
- R3 = clockone(R3, R3MASK, R3TAPS);
-}
-
/* Generate an output bit from the current state.
* You grab a bit from each register via the output generation taps;
* then you XOR the resulting three bits. */
bit getbit() {
- return parity(R1&R1OUT)^parity(R2&R2OUT)^parity(R3&R3OUT);
-}
-
-/* Do the A5/1 key setup. This routine accepts a 64-bit key and
- * a 22-bit frame number. */
-void keysetup(byte key[8], word frame) {
- int i;
- bit keybit, framebit;
-
- /* Zero out the shift registers. */
- R1 = R2 = R3 = 0;
-
- /* Load the key into the shift registers,
- * LSB of first byte of key array first,
- * clocking each register once for every
- * key bit loaded. (The usual clock
- * control rule is temporarily disabled.) */
- for (i=0; i<64; i++) {
- clockallthree(); /* always clock */
- keybit = (key[i/8] >> (i&7)) & 1; /* The i-th bit of the key */
- R1 ^= keybit; R2 ^= keybit; R3 ^= keybit;
- }
-
- /* Load the frame number into the shift
- * registers, LSB first,
- * clocking each register once for every
- * key bit loaded. (The usual clock
- * control rule is still disabled.) */
- for (i=0; i<22; i++) {
- clockallthree(); /* always clock */
- framebit = (frame >> i) & 1; /* The i-th bit of the frame # */
- R1 ^= framebit; R2 ^= framebit; R3 ^= framebit;
- }
-
- /* Run the shift registers for 100 clocks
- * to mix the keying material and frame number
- * together with output generation disabled,
- * so that there is sufficient avalanche.
- * We re-enable the majority-based clock control
- * rule from now on. */
- for (i=0; i<100; i++) {
- clock();
- }
-
- /* Now the key is properly set up. */
-}
-
-/* Generate output. We generate 228 bits of
- * keystream output. The first 114 bits is for
- * the A->B frame; the next 114 bits is for the
- * B->A frame. You allocate a 15-byte buffer
- * for each direction, and this function fills
- * it in. */
-void run(byte AtoBkeystream[], byte BtoAkeystream[]) {
- int i;
-
- /* Zero out the output buffers. */
- for (i=0; i<=113/8; i++)
- AtoBkeystream[i] = BtoAkeystream[i] = 0;
-
- /* Generate 114 bits of keystream for the
- * A->B direction. Store it, MSB first. */
- for (i=0; i<114; i++) {
- clock();
- AtoBkeystream[i/8] |= getbit() << (7-(i&7));
- }
-
- /* Generate 114 bits of keystream for the
- * B->A direction. Store it, MSB first. */
- for (i=0; i<114; i++) {
- clock();
- BtoAkeystream[i/8] |= getbit() << (7-(i&7));
- }
-}
-
-/* Test the code by comparing it against
- * a known-good test vector. */
-void test() {
- byte key[8] = {0x12, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF};
- word frame = 0x134;
- byte goodAtoB[15] = { 0x53, 0x4E, 0xAA, 0x58, 0x2F, 0xE8, 0x15,
- 0x1A, 0xB6, 0xE1, 0x85, 0x5A, 0x72, 0x8C, 0x00 };
- byte goodBtoA[15] = { 0x24, 0xFD, 0x35, 0xA3, 0x5D, 0x5F, 0xB6,
- 0x52, 0x6D, 0x32, 0xF9, 0x06, 0xDF, 0x1A, 0xC0 };
- byte AtoB[15], BtoA[15];
- int i, failed=0;
-
- keysetup(key, frame);
- run(AtoB, BtoA);
-
- /* Compare against the test vector. */
- for (i=0; i<15; i++)
- if (AtoB[i] != goodAtoB[i])
- failed = 1;
- for (i=0; i<15; i++)
- if (BtoA[i] != goodBtoA[i])
- failed = 1;
-
- /* Print some debugging output. */
- printf("key: 0x");
- for (i=0; i<8; i++)
- printf("%02X", key[i]);
- printf("\n");
- printf("frame number: 0x%06X\n", (unsigned int)frame);
- printf("known good output:\n");
- printf(" A->B: 0x");
- for (i=0; i<15; i++)
- printf("%02X", goodAtoB[i]);
- printf(" B->A: 0x");
- for (i=0; i<15; i++)
- printf("%02X", goodBtoA[i]);
- printf("\n");
- printf("observed output:\n");
- printf(" A->B: 0x");
- for (i=0; i<15; i++)
- printf("%02X", AtoB[i]);
- printf(" B->A: 0x");
- for (i=0; i<15; i++)
- printf("%02X", BtoA[i]);
- printf("\n");
-
- if (!failed) {
- printf("Self-check succeeded: everything looks ok.\n");
- return;
- } else {
- /* Problems! The test vectors didn't compare*/
- printf("\nI don't know why this broke; contact the authors.\n");
- exit(1);
- }
-}
-
-word bin2hex (char *string)
-{
- int i;
- word res = 0;
- int length;
-
- length = strlen (string);
-
- for (i = 0; i < length; i++)
- {
- res = res << 1;
- if (string[0] == '1') res += 1;
- string++;
- }
- return res;
-
+ // return parity(R1&R1OUT)^parity(R2&R2OUT)^parity(R3&R3OUT);
+ return ((R1&R1OUT) >> 18) ^ ((R2&R2OUT) >> 21) ^ ((R3&R3OUT) >> 22);
}
inline word calculate_link (word input, word count) {
- word result=0;
+ word result;
int i;
input ^= count ^ (count << 23) ^ (count << (22 + 23));
@@ -344,9 +192,10 @@ inline word calculate_link (word input, word count) {
R2 = (input >> 23) & R2MASK;
R3 = input & R3MASK;
- for(i=0;i<64;i++) {
- result = (result << 1)| getbit();
+ result = getbit();
+ for(i=1;i<64;i++) {
clock();
+ result = (result << 1)| getbit();
}
return result;
}
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