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Make default base and identity points accessible

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This commit is contained in:
Matthias Schiffer 2015-01-26 06:00:20 +01:00
parent 2320e02317
commit 1591dbfc4d
2 changed files with 28 additions and 23 deletions
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3
include/libuecc/ecc.h
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@ -55,6 +55,9 @@ typedef struct _ecc_25519_work {
* @{
*/
extern const ecc_25519_work_t ecc_25519_work_identity;
extern const ecc_25519_work_t ecc_25519_work_default_base;
int ecc_25519_load_xy(ecc_25519_work_t *out, const ecc_int256_t *x, const ecc_int256_t *y);
void ecc_25519_store_xy(ecc_int256_t *x, ecc_int256_t *y, const ecc_25519_work_t *in);

48
src/ec25519.c
View file

@ -40,6 +40,28 @@
#include <libuecc/ecc.h>
/** The identity element */
const ecc_25519_work_t ecc_25519_work_identity = {{0}, {1}, {1}, {0}};
/** The ec25519 default base */
const ecc_25519_work_t ecc_25519_work_default_base = {
{0xd4, 0x6b, 0xfe, 0x7f, 0x39, 0xfa, 0x8c, 0x22,
0xe1, 0x96, 0x23, 0xeb, 0x26, 0xb7, 0x8e, 0x6a,
0x34, 0x74, 0x8b, 0x66, 0xd6, 0xa3, 0x26, 0xdd,
0x19, 0x5e, 0x9f, 0x21, 0x50, 0x43, 0x7c, 0x54},
{0x58, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66},
{1},
{0x47, 0x56, 0x98, 0x99, 0xc7, 0x61, 0x0a, 0x82,
0x1a, 0xdf, 0x82, 0x22, 0x1f, 0x2c, 0x72, 0x88,
0xc3, 0x29, 0x09, 0x52, 0x78, 0xe9, 0x1e, 0xe4,
0x47, 0x4b, 0x4c, 0x81, 0xa6, 0x02, 0xfd, 0x29}
};
static const unsigned int zero[32] = {0};
static const unsigned int one[32] = {1};
@ -478,9 +500,6 @@ void ecc_25519_store_packed(ecc_int256_t *out, const ecc_25519_work_t *in) {
out->p[31] |= (y.p[0] << 7);
}
/** The identity element */
static const ecc_25519_work_t id = {{0}, {1}, {1}, {0}};
/** Checks if a point is the identity element of the Elliptic Curve group */
int ecc_25519_is_identity(const ecc_25519_work_t *in) {
unsigned int Y_Z[32];
@ -558,7 +577,7 @@ void ecc_25519_add(ecc_25519_work_t *out, const ecc_25519_work_t *in1, const ecc
**/
void ecc_25519_scalarmult_bits(ecc_25519_work_t *out, const ecc_int256_t *n, const ecc_25519_work_t *base, unsigned bits) {
ecc_25519_work_t Q2, Q2p;
ecc_25519_work_t cur = id;
ecc_25519_work_t cur = ecc_25519_work_identity;
int b, pos;
if (bits > 256)
@ -585,23 +604,6 @@ void ecc_25519_scalarmult(ecc_25519_work_t *out, const ecc_int256_t *n, const ec
ecc_25519_scalarmult_bits(out, n, base, 256);
}
/** The ec25519 default base */
static const ecc_25519_work_t default_base = {
{0xd4, 0x6b, 0xfe, 0x7f, 0x39, 0xfa, 0x8c, 0x22,
0xe1, 0x96, 0x23, 0xeb, 0x26, 0xb7, 0x8e, 0x6a,
0x34, 0x74, 0x8b, 0x66, 0xd6, 0xa3, 0x26, 0xdd,
0x19, 0x5e, 0x9f, 0x21, 0x50, 0x43, 0x7c, 0x54},
{0x58, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66},
{1},
{0x47, 0x56, 0x98, 0x99, 0xc7, 0x61, 0x0a, 0x82,
0x1a, 0xdf, 0x82, 0x22, 0x1f, 0x2c, 0x72, 0x88,
0xc3, 0x29, 0x09, 0x52, 0x78, 0xe9, 0x1e, 0xe4,
0x47, 0x4b, 0x4c, 0x81, 0xa6, 0x02, 0xfd, 0x29}
};
/**
* Does a scalar multiplication of the default base point (generator element) of the Elliptic Curve with an integer of a given bit length
*
@ -610,7 +612,7 @@ static const ecc_25519_work_t default_base = {
* See the notes about \ref ecc_25519_scalarmult_bits before using this function.
*/
void ecc_25519_scalarmult_base_bits(ecc_25519_work_t *out, const ecc_int256_t *n, unsigned bits) {
ecc_25519_scalarmult_bits(out, n, &default_base, bits);
ecc_25519_scalarmult_bits(out, n, &ecc_25519_work_default_base, bits);
}
/**
@ -619,5 +621,5 @@ void ecc_25519_scalarmult_base_bits(ecc_25519_work_t *out, const ecc_int256_t *n
* The order of the base point is \f$ 2^{252} + 27742317777372353535851937790883648493 \f$.
*/
void ecc_25519_scalarmult_base(ecc_25519_work_t *out, const ecc_int256_t *n) {
ecc_25519_scalarmult(out, n, &default_base);
ecc_25519_scalarmult(out, n, &ecc_25519_work_default_base);
}