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-rw-r--r--src/CMakeLists.txt2
-rw-r--r--src/ec25519.c32
-rw-r--r--src/ec25519_secret.c181
3 files changed, 198 insertions, 17 deletions
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 1bad208..edcee42 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,6 +1,6 @@
include_directories(${LIBUECC_SOURCE_DIR}/include)
-add_library(uecc STATIC ec25519.c)
+add_library(uecc STATIC ec25519.c ec25519_secret.c)
install(TARGETS uecc
ARCHIVE DESTINATION lib
diff --git a/src/ec25519.c b/src/ec25519.c
index effbfc6..7887f61 100644
--- a/src/ec25519.c
+++ b/src/ec25519.c
@@ -74,7 +74,7 @@ static void squeeze(unsigned int a[32]) {
static const unsigned int minusp[32] = {
19, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 128
-} ;
+};
static void freeze(unsigned int a[32]) {
unsigned int aorig[32];
@@ -156,13 +156,13 @@ static int check_equal(const unsigned int x[32], const unsigned int y[32]) {
return (1-(1 & ((differentbits - 1) >> 16)));
}
-static void selectw(ec_25519_work *out, const ec_25519_work *r, const ec_25519_work *s, unsigned int b) {
+static void selectw(ecc_25519_work *out, const ecc_25519_work *r, const ecc_25519_work *s, unsigned int b) {
unsigned int j;
unsigned int t;
unsigned int bminus1;
bminus1 = b - 1;
- for (j = 0;j < 32;++j) {
+ for (j = 0; j < 32; ++j) {
t = bminus1 & (r->X[j] ^ s->X[j]);
out->X[j] = s->X[j] ^ t;
@@ -340,7 +340,7 @@ static void recip(unsigned int out[32], const unsigned int z[32]) {
/* 2^255 - 21 */ mult(out, t1, z11);
}
-void ec_25519_load(ec_25519_work *out, const ec_public_key_256 *in) {
+void ecc_25519_load(ecc_25519_work *out, const ecc_public_key_256 *in) {
int i;
unsigned int X2[32], d_X2[32] = {0x04, 0x6d, 0x07} /* 486660 */, a_X2[32] = {0x08, 0x6d, 0x07} /* 486664 */, _1_a_X2[32], d_X2_a_X2[32], Y[32], Yt[32];
@@ -362,7 +362,7 @@ void ec_25519_load(ec_25519_work *out, const ec_public_key_256 *in) {
select(out->Y, Y, Yt, (in->p[31] >> 7) ^ (Y[0] & 1));
}
-void ec_25519_store(ec_public_key_256 *out, const ec_25519_work *in) {
+void ecc_25519_store(ecc_public_key_256 *out, const ecc_25519_work *in) {
unsigned int x[32], y[32], z[32];
int i;
@@ -380,9 +380,9 @@ void ec_25519_store(ec_public_key_256 *out, const ec_25519_work *in) {
out->p[31] |= (y[0] << 7);
}
-static const ec_25519_work infty = {{0}, {0}, {1}};
+static const ecc_25519_work infty = {{0}, {0}, {1}};
-void ec_25519_double(ec_25519_work *out, const ec_25519_work *in) {
+void ecc_25519_double(ecc_25519_work *out, const ecc_25519_work *in) {
unsigned int A[32], B[32], C[32], D[32], E[32], U[32], t0[32], t1[32], t2[32], t3[32], t4[32], t5[32];
square(A, in->X);
@@ -403,7 +403,7 @@ void ec_25519_double(ec_25519_work *out, const ec_25519_work *in) {
selectw(out, &infty, out, check_zero(out->X)*check_zero(out->Y));
}
-void ec_25519_add(ec_25519_work *out, const ec_25519_work *in1, const ec_25519_work *in2) {
+void ecc_25519_add(ecc_25519_work *out, const ecc_25519_work *in1, const ecc_25519_work *in2) {
unsigned int A[32], B[32], C[32], D[32], E[32], H[32], I[32], t0[32], t1[32], t2[32], t3[32], t4[32], t5[32], t6[32], t7[32], t8[32];
mult(A, in1->Z, in2->Z);
@@ -429,8 +429,8 @@ void ec_25519_add(ec_25519_work *out, const ec_25519_work *in1, const ec_25519_w
selectw(out, in2, out, check_zero(t2));
}
-void ec_25519_scalarmult(ec_25519_work *out, const ec_secret_key_256 *n, const ec_25519_work *base) {
- ec_25519_work Q2, Q2p, cur;
+void ecc_25519_scalarmult(ecc_25519_work *out, const ecc_secret_key_256 *n, const ecc_25519_work *base) {
+ ecc_25519_work Q2, Q2p, cur;
int i, b, pos;
for (i = 0; i < 32; i++) {
@@ -439,12 +439,12 @@ void ec_25519_scalarmult(ec_25519_work *out, const ec_secret_key_256 *n, const e
cur.Z[i] = (i == 0);
}
- for (pos = 254;pos >= 0;--pos) {
+ for (pos = 255; pos >= 0; --pos) {
b = n->s[pos / 8] >> (pos & 7);
b &= 1;
- ec_25519_double(&Q2, &cur);
- ec_25519_add(&Q2p, &Q2, base);
+ ecc_25519_double(&Q2, &cur);
+ ecc_25519_add(&Q2p, &Q2, base);
selectw(&cur, &Q2, &Q2p, b);
}
@@ -455,7 +455,7 @@ void ec_25519_scalarmult(ec_25519_work *out, const ec_secret_key_256 *n, const e
}
}
-static const ec_25519_work default_base = {
+static const ecc_25519_work default_base = {
{0x51, 0x89, 0xfa, 0x46, 0xa0, 0xc0, 0x8b, 0x3d,
0x30, 0x60, 0xf1, 0x7d, 0x2a, 0xec, 0xcd, 0xf3,
0x24, 0x50, 0x96, 0x62, 0x21, 0xfc, 0xe6, 0x18,
@@ -467,6 +467,6 @@ static const ec_25519_work default_base = {
{1}
};
-void ec_25519_scalarmult_base(ec_25519_work *out, const ec_secret_key_256 *n) {
- ec_25519_scalarmult(out, n, &default_base);
+void ecc_25519_scalarmult_base(ecc_25519_work *out, const ecc_secret_key_256 *n) {
+ ecc_25519_scalarmult(out, n, &default_base);
}
diff --git a/src/ec25519_secret.c b/src/ec25519_secret.c
new file mode 100644
index 0000000..0a58629
--- /dev/null
+++ b/src/ec25519_secret.c
@@ -0,0 +1,181 @@
+/*
+ Copyright (c) 2012, Matthias Schiffer <mschiffer@universe-factory.net>
+ Partly based on public domain code by Matthew Dempsky and D. J. Bernstein.
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are met:
+
+ 1. Redistributions of source code must retain the above copyright notice,
+ this list of conditions and the following disclaimer.
+ 2. Redistributions in binary form must reproduce the above copyright notice,
+ this list of conditions and the following disclaimer in the documentation
+ and/or other materials provided with the distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/*
+ Simple finite field operations on the prime field F_p for
+ p = 2^252 + 27742317777372353535851937790883648493, which
+ is the order of the base point used for ec25519
+*/
+
+#include <libuecc/ecc.h>
+
+
+#define IS_NEGATIVE(n) ((int)((((unsigned)n) >> (8*sizeof(n)-1))&1))
+
+
+static const unsigned char q[32] = {
+ 0xed, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58,
+ 0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10
+};
+
+
+static void select(unsigned char out[32], const unsigned char r[32], const unsigned char s[32], unsigned int b) {
+ unsigned int j;
+ unsigned int t;
+ unsigned int bminus1;
+
+ bminus1 = b - 1;
+ for (j = 0;j < 32;++j) {
+ t = bminus1 & (r[j] ^ s[j]);
+ out[j] = s[j] ^ t;
+ }
+}
+
+void ecc_25519_add_secret(ecc_secret_key_256 *out, const ecc_secret_key_256 *in1, const ecc_secret_key_256 *in2) {
+ unsigned int j;
+ int u1, u2, u3;
+ unsigned char out1[32], out2[32], out3[32];
+
+ u1 = u2 = u3 = 0;
+ for (j = 0; j < 31; ++j) {
+ u1 += in1->s[j] + in2->s[j];
+ u2 += in1->s[j] + in2->s[j] - 8*q[j];
+ u3 += in1->s[j] + in2->s[j] - 16*q[j];
+
+ out1[j] = u1; out2[j] = u2; out3[j] = u3;
+ u1 = (u1+IS_NEGATIVE(u1))/256 - IS_NEGATIVE(u1);
+ u2 = (u2+IS_NEGATIVE(u2))/256 - IS_NEGATIVE(u2);
+ u3 = (u3+IS_NEGATIVE(u3))/256 - IS_NEGATIVE(u3);
+ }
+ u1 += in1->s[31] + in2->s[31];
+ u2 += in1->s[31] + in2->s[31] - 8*q[31];
+ u3 += in1->s[31] + in2->s[31] - 16*q[31];
+ out1[31] = u1; out2[31] = u2; out3[31] = u3;
+
+ select(out->s, out1, out2, (u1 >> 8) & 1);
+ select(out->s, out->s, out3, ((u1 >> 8) & (u2 >> 8)) & 1);
+}
+
+void ecc_25519_sub_secret(ecc_secret_key_256 *out, const ecc_secret_key_256 *in1, const ecc_secret_key_256 *in2) {
+ unsigned int j;
+ int u1, u2, u3;
+ unsigned char out1[32], out2[32], out3[32];
+
+ u1 = u2 = u3 = 0;
+ for (j = 0; j < 31; ++j) {
+ u1 += in1->s[j] - in2->s[j] + 16*q[j];
+ u2 += in1->s[j] - in2->s[j] + 8*q[j];
+ u3 += in1->s[j] - in2->s[j];
+
+ out1[j] = u1; out2[j] = u2; out3[j] = u3;
+ u1 = (u1+IS_NEGATIVE(u1))/256 - IS_NEGATIVE(u1);
+ u2 = (u2+IS_NEGATIVE(u2))/256 - IS_NEGATIVE(u2);
+ u3 = (u3+IS_NEGATIVE(u3))/256 - IS_NEGATIVE(u3);
+ }
+ u1 += in1->s[31] - in2->s[31] + 16*q[31];
+ u2 += in1->s[31] - in2->s[31] + 8*q[31];
+ u3 += in1->s[31] - in2->s[31];
+ out1[31] = u1; out2[31] = u2; out3[31] = u3;
+
+ select(out->s, out1, out2, (u1 >> 8) & 1);
+ select(out->s, out->s, out3, ((u1 >> 8) & (u2 >> 8)) & 1);
+}
+
+static void reduce(unsigned char a[32]) {
+ unsigned int j;
+ int nq = a[31] >> 4;
+ int u1, u2;
+ unsigned char out1[32], out2[32];
+
+ u1 = u2 = 0;
+ for (j = 0; j < 31; ++j) {
+ u1 += a[j] - nq*q[j];
+ u2 += a[j] - (nq-1)*q[j];
+
+ out1[j] = u1; out2[j] = u2;
+ u1 = (u1+IS_NEGATIVE(u1))/256 - IS_NEGATIVE(u1);
+ u2 = (u2+IS_NEGATIVE(u2))/256 - IS_NEGATIVE(u2);
+ }
+ u1 += a[31] - nq*q[31];
+ u2 += a[31] - (nq-1)*q[31];
+ out1[31] = u1; out2[31] = u2;
+
+ select(a, out1, out2, IS_NEGATIVE(u1));
+}
+
+/* Montgomery modular multiplication algorithm */
+static void montgomery(unsigned char out[32], const unsigned char a[32], const unsigned char b[32]) {
+ unsigned int a_i;
+ unsigned int i, j;
+ unsigned int r0;
+ unsigned int u;
+
+ for (i = 0; i < 32; i++)
+ out[i] = 0;
+
+ for (i = 0; i < 256; i++) {
+ a_i = a[i / 8] >> (i & 7);
+ a_i &= 1;
+
+ u = out[0] + a_i*b[0];
+ r0 = u & 1;
+ u += r0 * q[0];
+
+ for (j = 1; j < 32; ++j) {
+ u += (out[j] + a_i*b[j] + r0*q[j]) << 8;
+ out[j-1] = (u >> 1) & 255;
+ u >>= 8;
+ }
+
+ out[31] = u >> 1;
+ }
+}
+
+
+void ecc_25519_mult_secret(ecc_secret_key_256 *out, const ecc_secret_key_256 *in1, const ecc_secret_key_256 *in2) {
+ /* 2^512 mod p */
+ static const unsigned char C[32] = {
+ 0x01, 0x0f, 0x9c, 0x44, 0xe3, 0x11, 0x06, 0xa4,
+ 0x47, 0x93, 0x85, 0x68, 0xa7, 0x1b, 0x0e, 0xd0,
+ 0x65, 0xbe, 0xf5, 0x17, 0xd2, 0x73, 0xec, 0xce,
+ 0x3d, 0x9a, 0x30, 0x7c, 0x1b, 0x41, 0x99, 0x03
+ };
+
+ unsigned char B[32];
+ unsigned char R[32];
+ unsigned int i;
+
+ for (i = 0; i < 32; i++)
+ B[i] = in2->s[i];
+
+ reduce(B);
+
+ montgomery(R, in1->s, B);
+ montgomery(out->s, R, C);
+}
+
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