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micropython-curve25519
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small improvement for inversion

master
pmvr 2020-06-14 15:53:49 +02:00
parent 4b31304c08
commit 36be90765d
1 changed files with 24 additions and 31 deletions
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55
mpy-modules/curve25519/arithmetic.c
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@ -23,63 +23,55 @@ void shift_right(uint32_t *x) {
}
uint32_t add9_zxy(uint32_t *z, uint32_t *x, uint32_t *y) {
void add9_zxy(uint32_t *z, uint32_t *x, uint32_t *y) {
// for mod_inverse, operates on 9 words
uint32_t carry;
__asm__ volatile (
"LDMIA %1!, {r3-r6}\n"
"LDMIA %2!, {r7-r10}\n"
"LDMIA %0!, {r3-r6}\n"
"LDMIA %1!, {r7-r10}\n"
"ADDS r3, r3, r7\n"
"ADCS r4, r4, r8\n"
"ADCS r5, r5, r9\n"
"ADCS r6, r6, r10\n"
"STMIA %3!, {r3-r6}\n"
"LDMIA %1!, {r3-r6}\n"
"LDMIA %2!, {r7-r10}\n"
"STMIA %2!, {r3-r6}\n"
"LDMIA %0!, {r3-r6}\n"
"LDMIA %1!, {r7-r10}\n"
"ADCS r3, r3, r7\n"
"ADCS r4, r4, r8\n"
"ADCS r5, r5, r9\n"
"ADCS r6, r6, r10\n"
"STMIA %3!, {r3-r6}\n"
"LDMIA %1, {r3}\n"
"LDMIA %2, {r7}\n"
"STMIA %2!, {r3-r6}\n"
"LDMIA %0, {r3}\n"
"LDMIA %1, {r7}\n"
"ADCS r3, r3, r7\n"
"STMIA %3, {r3}\n"
"MOV %0, 0\n"
"ADCS %0, %0, 0\n"
: "=r" (carry) : "r" (x), "r" (y), "r" (z) : "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10"
"STMIA %2, {r3}\n"
: : "r" (x), "r" (y), "r" (z) : "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10"
);
return carry;
}
uint32_t sub9_zxy(uint32_t *z, uint32_t *x, uint32_t *y) {
void sub9_zxy(uint32_t *z, uint32_t *x, uint32_t *y) {
// for mod_inverse, operates on 9 words
uint32_t carry;
__asm__ volatile (
"LDMIA %1!, {r3-r6}\n"
"LDMIA %2!, {r7-r10}\n"
"LDMIA %0!, {r3-r6}\n"
"LDMIA %1!, {r7-r10}\n"
"SUBS r3, r3, r7\n"
"SBCS r4, r4, r8\n"
"SBCS r5, r5, r9\n"
"SBCS r6, r6, r10\n"
"STMIA %3!, {r3-r6}\n"
"LDMIA %1!, {r3-r6}\n"
"LDMIA %2!, {r7-r10}\n"
"STMIA %2!, {r3-r6}\n"
"LDMIA %0!, {r3-r6}\n"
"LDMIA %1!, {r7-r10}\n"
"SBCS r3, r3, r7\n"
"SBCS r4, r4, r8\n"
"SBCS r5, r5, r9\n"
"SBCS r6, r6, r10\n"
"STMIA %3!, {r3-r6}\n"
"LDMIA %1, {r3}\n"
"LDMIA %2, {r7}\n"
"STMIA %2!, {r3-r6}\n"
"LDMIA %0, {r3}\n"
"LDMIA %1, {r7}\n"
"SBCS r3, r3, r7\n"
"STMIA %3, {r3}\n"
"MOV %0, 0\n"
"ADCS %0, %0, 0\n"
: "=r" (carry) : "r" (x), "r" (y), "r" (z) : "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10"
"STMIA %2, {r3}\n"
: : "r" (x), "r" (y), "r" (z) : "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10"
);
return carry;
}
@ -111,7 +103,8 @@ STEP_4:
}
shift_right(D);
}
if (sub9_zxy(u, u, v) == 1) { // u >= v
sub9_zxy(u, u, v);
if ((u[8] & 0x80000000) == 0) { // u >= v
sub9_zxy(B, B, D);
}
else {