mirrors/i2pd
2
0
Fork 0
mirror of https://github.com/PurpleI2P/i2pd synced 2024-11-10 00:00:29 +03:00
Code Issues Packages Projects Releases Wiki Activity

encode key

Browse Source
This commit is contained in:
orignal 2019-12-06 20:29:03 -05:00
parent e6956d9bb0
commit 95df3e4b39
2 changed files with 37 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

73
libi2pd/Elligator.cpp
View File

@ -5,12 +5,6 @@ namespace i2p
{
namespace crypto
{
static const uint8_t u_[32] =
{
0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
Elligator2::Elligator2 ()
{
@ -21,44 +15,29 @@ namespace crypto
BN_sub_word (p, 19);
p38 = BN_dup (p); BN_add_word (p38, 3); BN_div_word (p38, 8); // (p+3)/8
p12 = BN_dup (p); BN_sub_word (p12, 1); BN_div_word (p12, 2); // (p-1)/2
n1 = BN_dup (p); BN_sub_word (n1, 1); // p-1
n2 = BN_dup (p); BN_sub_word (n2, 2); // p-2
p14 = BN_dup (p); BN_sub_word (p14, 1); BN_div_word (p14, 4); // (p-1)/4
A = BN_new (); BN_set_word (A, 486662);
auto A = BN_new (); BN_set_word (A, 486662);
nA = BN_new (); BN_sub (nA, p, A);
BN_CTX * ctx = BN_CTX_new ();
// calculate sqrt(-1)
sqrtn1 = BN_new ();
BN_mod_exp (sqrtn1, n1, p38, p, ctx); // (-1)^((p+3)/8)
auto p14 = BN_dup (p); BN_sub_word (p14, 1); BN_div_word (p14, 4); // (p-1)/4
auto tmp = BN_new (); BN_set_word (tmp, 2);
BN_mod_exp (tmp, tmp, p14, p, ctx); // 2^((p-1)/4
BN_mod_mul (sqrtn1, tmp, sqrtn1, p, ctx); // 2^((p-1)/4 * (-1)^((p+3)/8)
BN_free (p14);
BN_set_word (sqrtn1, 2);
BN_mod_exp (sqrtn1, sqrtn1, p14, p, ctx); // 2^((p-1)/4
u = BN_new (); BN_bin2bn (u_, 32, u); // TODO: endianess
u = BN_new (); BN_set_word (u, 2);
iu = BN_new (); BN_mod_inverse (iu, u, p, ctx);
// calculate d = -121665*inv(121666)
d = BN_new ();
BN_set_word (tmp, 121666);
BN_mod_inverse (tmp, tmp, p, ctx);
BN_set_word (d, 121665);
BN_set_negative (d, 1);
BN_mod_mul (d, d, tmp, p, ctx);
BN_free (tmp);
//printf ("%s\n", BN_bn2hex (d));
//printf ("%s\n", BN_bn2hex (iu));
BN_CTX_free (ctx);
}
Elligator2::~Elligator2 ()
{
BN_free (p); BN_free (p38); BN_free (p12);
BN_free (n1);BN_free (n2); BN_free (sqrtn1);
BN_free (A); BN_free (nA);
BN_free (u); BN_free (iu); BN_free (d);
BN_free (p); BN_free (p38); BN_free (p12); BN_free (p14);
BN_free (sqrtn1); BN_free (A); BN_free (nA);
BN_free (u); BN_free (iu);
}
void Elligator2::Encode (const uint8_t * key, uint8_t * encoded) const
@ -66,24 +45,36 @@ namespace crypto
BN_CTX * ctx = BN_CTX_new ();
BN_CTX_start (ctx);
BIGNUM * a = BN_CTX_get (ctx); BN_bin2bn (key, 32, a);
BIGNUM * b = BN_CTX_get (ctx);
BN_add (a, A, b);
BIGNUM * c = BN_CTX_get (ctx);
BN_mod_exp (c, b, n2, p, ctx);
BN_mod_mul (b, c, a, p, ctx);
BN_sub (b, p, b);
BIGNUM * x = BN_CTX_get (ctx); BN_bin2bn (key, 32, x);
BIGNUM * xA = BN_CTX_get (ctx); BN_add (xA, x, A); // x + A
BN_sub (xA, p, xA); // p - (x + A)
//BN_mod_exp (c, b, n2, p, ctx);
BIGNUM * r = BN_CTX_get (ctx);
BN_mod_inverse (r, xA, p, ctx);
BN_mod_mul (r, r, x, p, ctx);
BN_mod_mul (r, r, iu, p, ctx);
BN_mod_mul (c, b, iu, p, ctx);
// TODO:
bn2buf (b, encoded, 32);
SquareRoot (r, r, ctx);
bn2buf (r, encoded, 32);
BN_CTX_end (ctx);
BN_CTX_free (ctx);
}
void Elligator2::SquareRoot (const BIGNUM * x, BIGNUM * r, BN_CTX * ctx) const
{
BIGNUM * t = BN_CTX_get (ctx);
BN_mod_exp (t, x, p14, p, ctx); // t = x^((p-1)/4)
BN_mod_exp (r, x, p38, p, ctx); // r = x^((p+3)/8)
BN_add_word (t, 1);
if (!BN_cmp (t, p))
BN_mod_mul (r, r, sqrtn1, p, ctx);
if (BN_cmp (r, p12) > 0) // r > (p-1)/2
BN_sub (r, p, r);
}
static std::unique_ptr<Elligator2> g_Elligator;
std::unique_ptr<Elligator2>& GetElligator ()
{

6
libi2pd/Elligator.h
View File

@ -19,9 +19,13 @@ namespace crypto
void Encode (const uint8_t * key, uint8_t * encoded) const;
private:
void SquareRoot (const BIGNUM * x, BIGNUM * r, BN_CTX * ctx) const;
private:
BIGNUM * p, * n1, * n2, * p38, * p12, * sqrtn1, * A, * nA, * u, * iu, * d;
BIGNUM * p, * p38, * p12, * p14, * sqrtn1, * A, * nA, * u, * iu;
};
std::unique_ptr<Elligator2>& GetElligator ();