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68 lines
2.0 KiB
68 lines
2.0 KiB
#include "fe25519.h" |
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#include "sc25519.h" |
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#include "ge25519.h" |
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/* Multiples of the base point in Niels' representation */ |
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static const ge25519_niels ge25519_base_multiples_niels[] = { |
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#ifdef SMALLTABLES |
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#include "ge25519_base_niels_smalltables.data" |
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#else |
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#include "ge25519_base_niels.data" |
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#endif |
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}; |
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/* d */ |
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static const fe25519 ecd = {{0x75EB4DCA135978A3, 0x00700A4D4141D8AB, 0x8CC740797779E898, 0x52036CEE2B6FFE73}}; |
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void ge25519_scalarmult_base(ge25519_p3 *r, const sc25519 *s) |
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{ |
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signed char b[64]; |
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int i; |
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ge25519_niels t; |
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fe25519 d; |
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sc25519_window4(b,s); |
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#ifdef SMALLTABLES |
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ge25519_p1p1 tp1p1; |
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choose_t((ge25519_niels *)r, 0, (signed long long) b[1], ge25519_base_multiples_niels); |
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fe25519_sub(&d, &r->y, &r->x); |
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fe25519_add(&r->y, &r->y, &r->x); |
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r->x = d; |
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r->t = r->z; |
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fe25519_setint(&r->z,2); |
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for(i=3;i<64;i+=2) |
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{ |
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choose_t(&t, (unsigned long long) i/2, (signed long long) b[i], ge25519_base_multiples_niels); |
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ge25519_nielsadd2(r, &t); |
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} |
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ge25519_dbl_p1p1(&tp1p1,(ge25519_p2 *)r); |
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ge25519_p1p1_to_p2((ge25519_p2 *)r, &tp1p1); |
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ge25519_dbl_p1p1(&tp1p1,(ge25519_p2 *)r); |
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ge25519_p1p1_to_p2((ge25519_p2 *)r, &tp1p1); |
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ge25519_dbl_p1p1(&tp1p1,(ge25519_p2 *)r); |
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ge25519_p1p1_to_p2((ge25519_p2 *)r, &tp1p1); |
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ge25519_dbl_p1p1(&tp1p1,(ge25519_p2 *)r); |
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ge25519_p1p1_to_p3(r, &tp1p1); |
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choose_t(&t, (unsigned long long) 0, (signed long long) b[0], ge25519_base_multiples_niels); |
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fe25519_mul(&t.t2d, &t.t2d, &ecd); |
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ge25519_nielsadd2(r, &t); |
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for(i=2;i<64;i+=2) |
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{ |
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choose_t(&t, (unsigned long long) i/2, (signed long long) b[i], ge25519_base_multiples_niels); |
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ge25519_nielsadd2(r, &t); |
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} |
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#else |
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choose_t((ge25519_niels *)r, 0, (signed long long) b[0], ge25519_base_multiples_niels); |
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fe25519_sub(&d, &r->y, &r->x); |
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fe25519_add(&r->y, &r->y, &r->x); |
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r->x = d; |
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r->t = r->z; |
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fe25519_setint(&r->z,2); |
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for(i=1;i<64;i++) |
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{ |
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choose_t(&t, (unsigned long long) i, (signed long long) b[i], ge25519_base_multiples_niels); |
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ge25519_nielsadd2(r, &t); |
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} |
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#endif |
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}
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