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Reworked the API

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This commit is contained in:
Matthias Schiffer 2012-12-07 19:07:37 +01:00
parent f67c3f36b9
commit bccf64ec1b
4 changed files with 96 additions and 58 deletions
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44
include/libuecc/ecc.h
View file

@ -27,14 +27,14 @@
#ifndef _LIBUECC_ECC_H_ #ifndef _LIBUECC_ECC_H_
#define _LIBUECC_ECC_H_ #define _LIBUECC_ECC_H_
typedef struct _ecc_public_key_256 { typedef union _ecc_int_256 {
unsigned char p[32]; unsigned char p[32];
} ecc_public_key_256;
typedef struct _ecc_secret_key_256 { /* old name */
unsigned char s[32]; unsigned char s[32];
} ecc_secret_key_256; } ecc_int_256, ecc_secret_key_256, ecc_public_key_256;
/* a point on the curve unpacked for efficient calculation */
typedef struct _ecc_25519_work { typedef struct _ecc_25519_work {
unsigned int X[32]; unsigned int X[32];
unsigned int Y[32]; unsigned int Y[32];
@ -43,20 +43,36 @@ typedef struct _ecc_25519_work {
} ecc_25519_work; } ecc_25519_work;
void ecc_25519_load(ecc_25519_work *out, const ecc_public_key_256 *in); void ecc_25519_load_xy(ecc_25519_work *out, const ecc_int_256 *x, const ecc_int_256 *y);
void ecc_25519_store(ecc_public_key_256 *out, const ecc_25519_work *in); void ecc_25519_store_xy(ecc_int_256 *x, ecc_int_256 *y, const ecc_25519_work *in);
void ecc_25519_load_packed(ecc_25519_work *out, const ecc_int_256 *in);
void ecc_25519_store_packed(ecc_int_256 *out, const ecc_25519_work *in);
int ecc_25519_is_identity(const ecc_25519_work *in); int ecc_25519_is_identity(const ecc_25519_work *in);
void ecc_25519_add(ecc_25519_work *out, const ecc_25519_work *in1, const ecc_25519_work *in2); void ecc_25519_add(ecc_25519_work *out, const ecc_25519_work *in1, const ecc_25519_work *in2);
void ecc_25519_double(ecc_25519_work *out, const ecc_25519_work *in); void ecc_25519_double(ecc_25519_work *out, const ecc_25519_work *in);
void ecc_25519_scalarmult(ecc_25519_work *out, const ecc_secret_key_256 *n, const ecc_25519_work *base); void ecc_25519_scalarmult(ecc_25519_work *out, const ecc_int_256 *n, const ecc_25519_work *base);
void ecc_25519_scalarmult_base(ecc_25519_work *out, const ecc_secret_key_256 *n); void ecc_25519_scalarmult_base(ecc_25519_work *out, const ecc_int_256 *n);
int ecc_25519_secret_is_zero(const ecc_secret_key_256 *in); /* operations on elements of the prime field F_q for q = 2^252 + 27742317777372353535851937790883648493 */
void ecc_25519_secret_add(ecc_secret_key_256 *out, const ecc_secret_key_256 *in1, const ecc_secret_key_256 *in2); int ecc_25519_gf_is_zero(const ecc_int_256 *in);
void ecc_25519_secret_sub(ecc_secret_key_256 *out, const ecc_secret_key_256 *in1, const ecc_secret_key_256 *in2); void ecc_25519_gf_add(ecc_int_256 *out, const ecc_int_256 *in1, const ecc_int_256 *in2);
void ecc_25519_secret_reduce(ecc_secret_key_256 *out, const ecc_secret_key_256 *in); void ecc_25519_gf_sub(ecc_int_256 *out, const ecc_int_256 *in1, const ecc_int_256 *in2);
void ecc_25519_secret_mult(ecc_secret_key_256 *out, const ecc_secret_key_256 *in1, const ecc_secret_key_256 *in2); void ecc_25519_gf_reduce(ecc_int_256 *out, const ecc_int_256 *in);
void ecc_25519_secret_sanitize(ecc_secret_key_256 *out, const ecc_secret_key_256 *in); void ecc_25519_gf_mult(ecc_int_256 *out, const ecc_int_256 *in1, const ecc_int_256 *in2);
void ecc_25519_gf_sanitize_secret(ecc_int_256 *out, const ecc_int_256 *in);
/* defines for the old names */
#define ecc_25519_load ecc_25519_load_packed
#define ecc_25519_store ecc_25519_store_packed
#define ecc_25519_secret_is_zero ecc_25519_gf_is_zero
#define ecc_25519_secret_add ecc_25519_gf_add
#define ecc_25519_secret_sub ecc_25519_gf_sub
#define ecc_25519_secret_reduce ecc_25519_gf_reduce
#define ecc_25519_secret_mult ecc_25519_gf_mult
#define ecc_25519_secret_sanitize ecc_25519_gf_sanitize_secret
#endif /* _LIBUECC_ECC_H_ */ #endif /* _LIBUECC_ECC_H_ */

2
src/CMakeLists.txt
View file

@ -1,6 +1,6 @@
include_directories(${LIBUECC_SOURCE_DIR}/include) include_directories(${LIBUECC_SOURCE_DIR}/include)
add_library(uecc STATIC ec25519.c ec25519_secret.c) add_library(uecc STATIC ec25519.c ec25519_gf.c)
install(TARGETS uecc install(TARGETS uecc
ARCHIVE DESTINATION lib ARCHIVE DESTINATION lib

60
src/ec25519.c
View file

@ -347,7 +347,40 @@ static void recip(unsigned int out[32], const unsigned int z[32]) {
/* 2^255 - 21 */ mult(out, t1, z11); /* 2^255 - 21 */ mult(out, t1, z11);
} }
void ecc_25519_load(ecc_25519_work *out, const ecc_public_key_256 *in) { void ecc_25519_load_xy(ecc_25519_work *out, const ecc_int_256 *x, const ecc_int_256 *y) {
int i;
for (i = 0; i < 32; i++) {
out->X[i] = x->p[i];
out->Y[i] = y->p[i];
out->Z[i] = (i == 0);
}
mult(out->T, out->X, out->Y);
}
void ecc_25519_store_xy(ecc_int_256 *x, ecc_int_256 *y, const ecc_25519_work *in) {
unsigned int X[32], Y[32], Z[32];
int i;
recip(Z, in->Z);
if (x) {
mult(X, Z, in->X);
freeze(X);
for (i = 0; i < 32; i++)
x->p[i] = X[i];
}
if (y) {
mult(Y, Z, in->Y);
freeze(Y);
for (i = 0; i < 32; i++)
y->p[i] = Y[i];
}
}
void ecc_25519_load_packed(ecc_25519_work *out, const ecc_int_256 *in) {
static const unsigned int zero[32] = {0}; static const unsigned int zero[32] = {0};
static const unsigned int one[32] = {1}; static const unsigned int one[32] = {1};
@ -377,22 +410,11 @@ void ecc_25519_load(ecc_25519_work *out, const ecc_public_key_256 *in) {
mult(out->T, out->X, out->Y); mult(out->T, out->X, out->Y);
} }
void ecc_25519_store(ecc_public_key_256 *out, const ecc_25519_work *in) { void ecc_25519_store_packed(ecc_int_256 *out, const ecc_25519_work *in) {
unsigned int x[32], y[32], z[32]; ecc_int_256 y;
int i;
recip(z, in->Z); ecc_25519_store_xy(out, &y, in);
out->p[31] |= (y.p[0] << 7);
mult(x, z, in->X);
mult(y, z, in->Y);
freeze(x);
freeze(y);
for (i = 0; i < 32; i++)
out->p[i] = x[i];
out->p[31] |= (y[0] << 7);
} }
static const ecc_25519_work id = {{0}, {1}, {1}, {0}}; static const ecc_25519_work id = {{0}, {1}, {1}, {0}};
@ -450,13 +472,13 @@ void ecc_25519_add(ecc_25519_work *out, const ecc_25519_work *in1, const ecc_255
mult(out->Z, F, G); mult(out->Z, F, G);
} }
void ecc_25519_scalarmult(ecc_25519_work *out, const ecc_secret_key_256 *n, const ecc_25519_work *base) { void ecc_25519_scalarmult(ecc_25519_work *out, const ecc_int_256 *n, const ecc_25519_work *base) {
ecc_25519_work Q2, Q2p; ecc_25519_work Q2, Q2p;
ecc_25519_work cur = id; ecc_25519_work cur = id;
int b, pos; int b, pos;
for (pos = 255; pos >= 0; --pos) { for (pos = 255; pos >= 0; --pos) {
b = n->s[pos / 8] >> (pos & 7); b = n->p[pos / 8] >> (pos & 7);
b &= 1; b &= 1;
ecc_25519_double(&Q2, &cur); ecc_25519_double(&Q2, &cur);
@ -483,6 +505,6 @@ static const ecc_25519_work default_base = {
0x47, 0x4b, 0x4c, 0x81, 0xa6, 0x02, 0xfd, 0x29} 0x47, 0x4b, 0x4c, 0x81, 0xa6, 0x02, 0xfd, 0x29}
}; };
void ecc_25519_scalarmult_base(ecc_25519_work *out, const ecc_secret_key_256 *n) { void ecc_25519_scalarmult_base(ecc_25519_work *out, const ecc_int_256 *n) {
ecc_25519_scalarmult(out, n, &default_base); ecc_25519_scalarmult(out, n, &default_base);
} }

48
src/ec25519_secret.c → src/ec25519_gf.c
View file

@ -57,43 +57,43 @@ static void select(unsigned char out[32], const unsigned char r[32], const unsig
} }
} }
int ecc_25519_secret_is_zero(const ecc_secret_key_256 *in) { int ecc_25519_gf_is_zero(const ecc_int_256 *in) {
int i; int i;
ecc_secret_key_256 r; ecc_int_256 r;
unsigned int bits; unsigned int bits;
ecc_25519_secret_reduce(&r, in); ecc_25519_gf_reduce(&r, in);
for (i = 0; i < 32; i++) for (i = 0; i < 32; i++)
bits |= r.s[i]; bits |= r.p[i];
return (((bits-1)>>8) & 1); return (((bits-1)>>8) & 1);
} }
void ecc_25519_secret_add(ecc_secret_key_256 *out, const ecc_secret_key_256 *in1, const ecc_secret_key_256 *in2) { void ecc_25519_gf_add(ecc_int_256 *out, const ecc_int_256 *in1, const ecc_int_256 *in2) {
unsigned int j; unsigned int j;
unsigned int u; unsigned int u;
int nq = 1 - (in1->s[31]>>4) - (in2->s[31]>>4); int nq = 1 - (in1->p[31]>>4) - (in2->p[31]>>4);
u = 0; u = 0;
for (j = 0; j < 32; ++j) { for (j = 0; j < 32; ++j) {
u += in1->s[j] + in2->s[j] + nq*q[j]; u += in1->p[j] + in2->p[j] + nq*q[j];
out->s[j] = u; out->p[j] = u;
u = ASR(u, 8); u = ASR(u, 8);
} }
} }
void ecc_25519_secret_sub(ecc_secret_key_256 *out, const ecc_secret_key_256 *in1, const ecc_secret_key_256 *in2) { void ecc_25519_gf_sub(ecc_int_256 *out, const ecc_int_256 *in1, const ecc_int_256 *in2) {
unsigned int j; unsigned int j;
unsigned int u; unsigned int u;
int nq = 8 - (in1->s[31]>>4) + (in2->s[31]>>4); int nq = 8 - (in1->p[31]>>4) + (in2->p[31]>>4);
u = 0; u = 0;
for (j = 0; j < 32; ++j) { for (j = 0; j < 32; ++j) {
u += in1->s[j] - in2->s[j] + nq*q[j]; u += in1->p[j] - in2->p[j] + nq*q[j];
out->s[j] = u; out->p[j] = u;
u = ASR(u, 8); u = ASR(u, 8);
} }
} }
@ -120,13 +120,13 @@ static void reduce(unsigned char a[32]) {
select(a, out1, out2, IS_NEGATIVE(u1)); select(a, out1, out2, IS_NEGATIVE(u1));
} }
void ecc_25519_secret_reduce(ecc_secret_key_256 *out, const ecc_secret_key_256 *in) { void ecc_25519_gf_reduce(ecc_int_256 *out, const ecc_int_256 *in) {
int i; int i;
for (i = 0; i < 32; i++) for (i = 0; i < 32; i++)
out->s[i] = in->s[i]; out->p[i] = in->p[i];
reduce(out->s); reduce(out->p);
} }
/* Montgomery modular multiplication algorithm */ /* Montgomery modular multiplication algorithm */
@ -154,7 +154,7 @@ static void montgomery(unsigned char out[32], const unsigned char a[32], const u
} }
void ecc_25519_secret_mult(ecc_secret_key_256 *out, const ecc_secret_key_256 *in1, const ecc_secret_key_256 *in2) { void ecc_25519_gf_mult(ecc_int_256 *out, const ecc_int_256 *in1, const ecc_int_256 *in2) {
/* 2^512 mod q */ /* 2^512 mod q */
static const unsigned char C[32] = { static const unsigned char C[32] = {
0x01, 0x0f, 0x9c, 0x44, 0xe3, 0x11, 0x06, 0xa4, 0x01, 0x0f, 0x9c, 0x44, 0xe3, 0x11, 0x06, 0xa4,
@ -168,21 +168,21 @@ void ecc_25519_secret_mult(ecc_secret_key_256 *out, const ecc_secret_key_256 *in
unsigned int i; unsigned int i;
for (i = 0; i < 32; i++) for (i = 0; i < 32; i++)
B[i] = in2->s[i]; B[i] = in2->p[i];
reduce(B); reduce(B);
montgomery(R, in1->s, B); montgomery(R, in1->p, B);
montgomery(out->s, R, C); montgomery(out->p, R, C);
} }
void ecc_25519_secret_sanitize(ecc_secret_key_256 *out, const ecc_secret_key_256 *in) { void ecc_25519_gf_sanitize_secret(ecc_int_256 *out, const ecc_int_256 *in) {
int i; int i;
for (i = 0; i < 32; i++) for (i = 0; i < 32; i++)
out->s[i] = in->s[i]; out->p[i] = in->p[i];
out->s[0] &= 0xf8; out->p[0] &= 0xf8;
out->s[31] &= 0x7f; out->p[31] &= 0x7f;
out->s[31] |= 0x40; out->p[31] |= 0x40;
} }