MicroECC
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micro-ecc/uECC.c view on Meta::CPAN
struct uECC_Curve_t {
wordcount_t num_words;
wordcount_t num_bytes;
bitcount_t num_n_bits;
uECC_word_t p[uECC_MAX_WORDS];
uECC_word_t n[uECC_MAX_WORDS];
uECC_word_t G[uECC_MAX_WORDS * 2];
uECC_word_t b[uECC_MAX_WORDS];
void (*double_jacobian)(uECC_word_t * X1,
uECC_word_t * Y1,
uECC_word_t * Z1,
uECC_Curve curve);
#if uECC_SUPPORT_COMPRESSED_POINT
void (*mod_sqrt)(uECC_word_t *a, uECC_Curve curve);
#endif
void (*x_side)(uECC_word_t *result, const uECC_word_t *x, uECC_Curve curve);
#if (uECC_OPTIMIZATION_LEVEL > 0)
void (*mmod_fast)(uECC_word_t *result, uECC_word_t *product);
#endif
};
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
static void bcopy(uint8_t *dst,
const uint8_t *src,
unsigned num_bytes) {
while (0 != num_bytes) {
num_bytes--;
dst[num_bytes] = src[num_bytes];
}
}
#endif
static cmpresult_t uECC_vli_cmp_unsafe(const uECC_word_t *left,
const uECC_word_t *right,
wordcount_t num_words);
#if (uECC_PLATFORM == uECC_arm || uECC_PLATFORM == uECC_arm_thumb || \
uECC_PLATFORM == uECC_arm_thumb2)
#include "asm_arm.inc"
#endif
#if (uECC_PLATFORM == uECC_avr)
#include "asm_avr.inc"
#endif
#if default_RNG_defined
static uECC_RNG_Function g_rng_function = &default_RNG;
#else
static uECC_RNG_Function g_rng_function = 0;
#endif
void uECC_set_rng(uECC_RNG_Function rng_function) {
g_rng_function = rng_function;
}
uECC_RNG_Function uECC_get_rng(void) {
return g_rng_function;
}
int uECC_curve_private_key_size(uECC_Curve curve) {
return BITS_TO_BYTES(curve->num_n_bits);
}
int uECC_curve_public_key_size(uECC_Curve curve) {
return 2 * curve->num_bytes;
}
#if !asm_clear
uECC_VLI_API void uECC_vli_clear(uECC_word_t *vli, wordcount_t num_words) {
wordcount_t i;
for (i = 0; i < num_words; ++i) {
vli[i] = 0;
}
}
#endif /* !asm_clear */
/* Constant-time comparison to zero - secure way to compare long integers */
/* Returns 1 if vli == 0, 0 otherwise. */
uECC_VLI_API uECC_word_t uECC_vli_isZero(const uECC_word_t *vli, wordcount_t num_words) {
uECC_word_t bits = 0;
wordcount_t i;
for (i = 0; i < num_words; ++i) {
bits |= vli[i];
}
return (bits == 0);
}
/* Returns nonzero if bit 'bit' of vli is set. */
uECC_VLI_API uECC_word_t uECC_vli_testBit(const uECC_word_t *vli, bitcount_t bit) {
return (vli[bit >> uECC_WORD_BITS_SHIFT] & ((uECC_word_t)1 << (bit & uECC_WORD_BITS_MASK)));
}
/* Counts the number of words in vli. */
static wordcount_t vli_numDigits(const uECC_word_t *vli, const wordcount_t max_words) {
wordcount_t i;
/* Search from the end until we find a non-zero digit.
We do it in reverse because we expect that most digits will be nonzero. */
for (i = max_words - 1; i >= 0 && vli[i] == 0; --i) {
}
return (i + 1);
}
/* Counts the number of bits required to represent vli. */
uECC_VLI_API bitcount_t uECC_vli_numBits(const uECC_word_t *vli, const wordcount_t max_words) {
uECC_word_t i;
uECC_word_t digit;
wordcount_t num_digits = vli_numDigits(vli, max_words);
if (num_digits == 0) {
return 0;
}
digit = vli[num_digits - 1];
for (i = 0; digit; ++i) {
digit >>= 1;
}
return (((bitcount_t)(num_digits - 1) << uECC_WORD_BITS_SHIFT) + i);
}
micro-ecc/uECC.c view on Meta::CPAN
/* result may overlap point. */
static void EccPoint_mult(uECC_word_t * result,
const uECC_word_t * point,
const uECC_word_t * scalar,
const uECC_word_t * initial_Z,
bitcount_t num_bits,
uECC_Curve curve) {
/* R0 and R1 */
uECC_word_t Rx[2][uECC_MAX_WORDS];
uECC_word_t Ry[2][uECC_MAX_WORDS];
uECC_word_t z[uECC_MAX_WORDS];
bitcount_t i;
uECC_word_t nb;
wordcount_t num_words = curve->num_words;
uECC_vli_set(Rx[1], point, num_words);
uECC_vli_set(Ry[1], point + num_words, num_words);
XYcZ_initial_double(Rx[1], Ry[1], Rx[0], Ry[0], initial_Z, curve);
for (i = num_bits - 2; i > 0; --i) {
nb = !uECC_vli_testBit(scalar, i);
XYcZ_addC(Rx[1 - nb], Ry[1 - nb], Rx[nb], Ry[nb], curve);
XYcZ_add(Rx[nb], Ry[nb], Rx[1 - nb], Ry[1 - nb], curve);
}
nb = !uECC_vli_testBit(scalar, 0);
XYcZ_addC(Rx[1 - nb], Ry[1 - nb], Rx[nb], Ry[nb], curve);
/* Find final 1/Z value. */
uECC_vli_modSub(z, Rx[1], Rx[0], curve->p, num_words); /* X1 - X0 */
uECC_vli_modMult_fast(z, z, Ry[1 - nb], curve); /* Yb * (X1 - X0) */
uECC_vli_modMult_fast(z, z, point, curve); /* xP * Yb * (X1 - X0) */
uECC_vli_modInv(z, z, curve->p, num_words); /* 1 / (xP * Yb * (X1 - X0)) */
/* yP / (xP * Yb * (X1 - X0)) */
uECC_vli_modMult_fast(z, z, point + num_words, curve);
uECC_vli_modMult_fast(z, z, Rx[1 - nb], curve); /* Xb * yP / (xP * Yb * (X1 - X0)) */
/* End 1/Z calculation */
XYcZ_add(Rx[nb], Ry[nb], Rx[1 - nb], Ry[1 - nb], curve);
apply_z(Rx[0], Ry[0], z, curve);
uECC_vli_set(result, Rx[0], num_words);
uECC_vli_set(result + num_words, Ry[0], num_words);
}
static uECC_word_t regularize_k(const uECC_word_t * const k,
uECC_word_t *k0,
uECC_word_t *k1,
uECC_Curve curve) {
wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
bitcount_t num_n_bits = curve->num_n_bits;
uECC_word_t carry = uECC_vli_add(k0, k, curve->n, num_n_words) ||
(num_n_bits < ((bitcount_t)num_n_words * uECC_WORD_SIZE * 8) &&
uECC_vli_testBit(k0, num_n_bits));
uECC_vli_add(k1, k0, curve->n, num_n_words);
return carry;
}
static uECC_word_t EccPoint_compute_public_key(uECC_word_t *result,
uECC_word_t *private_key,
uECC_Curve curve) {
uECC_word_t tmp1[uECC_MAX_WORDS];
uECC_word_t tmp2[uECC_MAX_WORDS];
uECC_word_t *p2[2] = {tmp1, tmp2};
uECC_word_t carry;
/* Regularize the bitcount for the private key so that attackers cannot use a side channel
attack to learn the number of leading zeros. */
carry = regularize_k(private_key, tmp1, tmp2, curve);
EccPoint_mult(result, curve->G, p2[!carry], 0, curve->num_n_bits + 1, curve);
if (EccPoint_isZero(result, curve)) {
return 0;
}
return 1;
}
#if uECC_WORD_SIZE == 1
uECC_VLI_API void uECC_vli_nativeToBytes(uint8_t *bytes,
int num_bytes,
const uint8_t *native) {
wordcount_t i;
for (i = 0; i < num_bytes; ++i) {
bytes[i] = native[(num_bytes - 1) - i];
}
}
uECC_VLI_API void uECC_vli_bytesToNative(uint8_t *native,
const uint8_t *bytes,
int num_bytes) {
uECC_vli_nativeToBytes(native, num_bytes, bytes);
}
#else
uECC_VLI_API void uECC_vli_nativeToBytes(uint8_t *bytes,
int num_bytes,
const uECC_word_t *native) {
wordcount_t i;
for (i = 0; i < num_bytes; ++i) {
unsigned b = num_bytes - 1 - i;
bytes[i] = native[b / uECC_WORD_SIZE] >> (8 * (b % uECC_WORD_SIZE));
}
}
uECC_VLI_API void uECC_vli_bytesToNative(uECC_word_t *native,
const uint8_t *bytes,
int num_bytes) {
wordcount_t i;
uECC_vli_clear(native, (num_bytes + (uECC_WORD_SIZE - 1)) / uECC_WORD_SIZE);
for (i = 0; i < num_bytes; ++i) {
unsigned b = num_bytes - 1 - i;
native[b / uECC_WORD_SIZE] |=
(uECC_word_t)bytes[i] << (8 * (b % uECC_WORD_SIZE));
}
}
#endif /* uECC_WORD_SIZE */
/* Generates a random integer in the range 0 < random < top.
Both random and top have num_words words. */
uECC_VLI_API int uECC_generate_random_int(uECC_word_t *random,
const uECC_word_t *top,
wordcount_t num_words) {
uECC_word_t mask = (uECC_word_t)-1;
uECC_word_t tries;
bitcount_t num_bits = uECC_vli_numBits(top, num_words);
if (!g_rng_function) {
return 0;
}
for (tries = 0; tries < uECC_RNG_MAX_TRIES; ++tries) {
if (!g_rng_function((uint8_t *)random, num_words * uECC_WORD_SIZE)) {
return 0;
}
random[num_words - 1] &= mask >> ((bitcount_t)(num_words * uECC_WORD_SIZE * 8 - num_bits));
if (!uECC_vli_isZero(random, num_words) &&
uECC_vli_cmp(top, random, num_words) == 1) {
return 1;
}
}
return 0;
}
int uECC_make_key(uint8_t *public_key,
uint8_t *private_key,
uECC_Curve curve) {
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
uECC_word_t *_private = (uECC_word_t *)private_key;
uECC_word_t *_public = (uECC_word_t *)public_key;
#else
uECC_word_t _private[uECC_MAX_WORDS];
uECC_word_t _public[uECC_MAX_WORDS * 2];
#endif
uECC_word_t tries;
for (tries = 0; tries < uECC_RNG_MAX_TRIES; ++tries) {
if (!uECC_generate_random_int(_private, curve->n, BITS_TO_WORDS(curve->num_n_bits))) {
return 0;
}
if (EccPoint_compute_public_key(_public, _private, curve)) {
#if uECC_VLI_NATIVE_LITTLE_ENDIAN == 0
uECC_vli_nativeToBytes(private_key, BITS_TO_BYTES(curve->num_n_bits), _private);
uECC_vli_nativeToBytes(public_key, curve->num_bytes, _public);
uECC_vli_nativeToBytes(
public_key + curve->num_bytes, curve->num_bytes, _public + curve->num_words);
#endif
return 1;
}
}
return 0;
}
int uECC_shared_secret(const uint8_t *public_key,
const uint8_t *private_key,
uint8_t *secret,
uECC_Curve curve) {
uECC_word_t _public[uECC_MAX_WORDS * 2];
uECC_word_t _private[uECC_MAX_WORDS];
uECC_word_t tmp[uECC_MAX_WORDS];
uECC_word_t *p2[2] = {_private, tmp};
uECC_word_t *initial_Z = 0;
uECC_word_t carry;
wordcount_t num_words = curve->num_words;
wordcount_t num_bytes = curve->num_bytes;
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
bcopy((uint8_t *) _private, private_key, num_bytes);
bcopy((uint8_t *) _public, public_key, num_bytes*2);
#else
uECC_vli_bytesToNative(_private, private_key, BITS_TO_BYTES(curve->num_n_bits));
uECC_vli_bytesToNative(_public, public_key, num_bytes);
uECC_vli_bytesToNative(_public + num_words, public_key + num_bytes, num_bytes);
#endif
/* Regularize the bitcount for the private key so that attackers cannot use a side channel
attack to learn the number of leading zeros. */
carry = regularize_k(_private, _private, tmp, curve);
/* If an RNG function was specified, try to get a random initial Z value to improve
protection against side-channel attacks. */
if (g_rng_function) {
if (!uECC_generate_random_int(p2[carry], curve->p, num_words)) {
return 0;
}
initial_Z = p2[carry];
}
EccPoint_mult(_public, _public, p2[!carry], initial_Z, curve->num_n_bits + 1, curve);
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
bcopy((uint8_t *) secret, (uint8_t *) _public, num_bytes);
#else
uECC_vli_nativeToBytes(secret, num_bytes, _public);
#endif
return !EccPoint_isZero(_public, curve);
}
#if uECC_SUPPORT_COMPRESSED_POINT
void uECC_compress(const uint8_t *public_key, uint8_t *compressed, uECC_Curve curve) {
wordcount_t i;
for (i = 0; i < curve->num_bytes; ++i) {
compressed[i+1] = public_key[i];
}
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
compressed[0] = 2 + (public_key[curve->num_bytes] & 0x01);
#else
compressed[0] = 2 + (public_key[curve->num_bytes * 2 - 1] & 0x01);
#endif
}
void uECC_decompress(const uint8_t *compressed, uint8_t *public_key, uECC_Curve curve) {
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
uECC_word_t *point = (uECC_word_t *)public_key;
#else
uECC_word_t point[uECC_MAX_WORDS * 2];
#endif
uECC_word_t *y = point + curve->num_words;
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
bcopy(public_key, compressed+1, curve->num_bytes);
#else
uECC_vli_bytesToNative(point, compressed + 1, curve->num_bytes);
#endif
curve->x_side(y, point, curve);
curve->mod_sqrt(y, curve);
if ((y[0] & 0x01) != (compressed[0] & 0x01)) {
uECC_vli_sub(y, curve->p, y, curve->num_words);
}
#if uECC_VLI_NATIVE_LITTLE_ENDIAN == 0
uECC_vli_nativeToBytes(public_key, curve->num_bytes, point);
uECC_vli_nativeToBytes(public_key + curve->num_bytes, curve->num_bytes, y);
#endif
}
#endif /* uECC_SUPPORT_COMPRESSED_POINT */
int uECC_valid_point(const uECC_word_t *point, uECC_Curve curve) {
uECC_word_t tmp1[uECC_MAX_WORDS];
uECC_word_t tmp2[uECC_MAX_WORDS];
wordcount_t num_words = curve->num_words;
/* The point at infinity is invalid. */
if (EccPoint_isZero(point, curve)) {
return 0;
}
/* x and y must be smaller than p. */
if (uECC_vli_cmp_unsafe(curve->p, point, num_words) != 1 ||
uECC_vli_cmp_unsafe(curve->p, point + num_words, num_words) != 1) {
return 0;
}
uECC_vli_modSquare_fast(tmp1, point + num_words, curve);
curve->x_side(tmp2, point, curve); /* tmp2 = x^3 + ax + b */
/* Make sure that y^2 == x^3 + ax + b */
return (int)(uECC_vli_equal(tmp1, tmp2, num_words));
}
int uECC_valid_public_key(const uint8_t *public_key, uECC_Curve curve) {
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
uECC_word_t *_public = (uECC_word_t *)public_key;
#else
uECC_word_t _public[uECC_MAX_WORDS * 2];
#endif
#if uECC_VLI_NATIVE_LITTLE_ENDIAN == 0
uECC_vli_bytesToNative(_public, public_key, curve->num_bytes);
uECC_vli_bytesToNative(
_public + curve->num_words, public_key + curve->num_bytes, curve->num_bytes);
#endif
return uECC_valid_point(_public, curve);
}
int uECC_compute_public_key(const uint8_t *private_key, uint8_t *public_key, uECC_Curve curve) {
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
uECC_word_t *_private = (uECC_word_t *)private_key;
uECC_word_t *_public = (uECC_word_t *)public_key;
#else
uECC_word_t _private[uECC_MAX_WORDS];
uECC_word_t _public[uECC_MAX_WORDS * 2];
#endif
#if uECC_VLI_NATIVE_LITTLE_ENDIAN == 0
uECC_vli_bytesToNative(_private, private_key, BITS_TO_BYTES(curve->num_n_bits));
#endif
/* Make sure the private key is in the range [1, n-1]. */
if (uECC_vli_isZero(_private, BITS_TO_WORDS(curve->num_n_bits))) {
return 0;
}
if (uECC_vli_cmp(curve->n, _private, BITS_TO_WORDS(curve->num_n_bits)) != 1) {
return 0;
}
/* Compute public key. */
if (!EccPoint_compute_public_key(_public, _private, curve)) {
return 0;
}
#if uECC_VLI_NATIVE_LITTLE_ENDIAN == 0
uECC_vli_nativeToBytes(public_key, curve->num_bytes, _public);
uECC_vli_nativeToBytes(
public_key + curve->num_bytes, curve->num_bytes, _public + curve->num_words);
#endif
return 1;
}
/* -------- ECDSA code -------- */
static void bits2int(uECC_word_t *native,
const uint8_t *bits,
unsigned bits_size,
uECC_Curve curve) {
unsigned num_n_bytes = BITS_TO_BYTES(curve->num_n_bits);
unsigned num_n_words = BITS_TO_WORDS(curve->num_n_bits);
int shift;
uECC_word_t carry;
uECC_word_t *ptr;
if (bits_size > num_n_bytes) {
bits_size = num_n_bytes;
}
uECC_vli_clear(native, num_n_words);
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
bcopy((uint8_t *) native, bits, bits_size);
#else
uECC_vli_bytesToNative(native, bits, bits_size);
#endif
if (bits_size * 8 <= (unsigned)curve->num_n_bits) {
return;
}
shift = bits_size * 8 - curve->num_n_bits;
carry = 0;
ptr = native + num_n_words;
while (ptr-- > native) {
uECC_word_t temp = *ptr;
*ptr = (temp >> shift) | carry;
carry = temp << (uECC_WORD_BITS - shift);
}
/* Reduce mod curve_n */
if (uECC_vli_cmp_unsafe(curve->n, native, num_n_words) != 1) {
uECC_vli_sub(native, native, curve->n, num_n_words);
}
}
static int uECC_sign_with_k(const uint8_t *private_key,
const uint8_t *message_hash,
unsigned hash_size,
uECC_word_t *k,
uint8_t *signature,
uECC_Curve curve) {
uECC_word_t tmp[uECC_MAX_WORDS];
uECC_word_t s[uECC_MAX_WORDS];
uECC_word_t *k2[2] = {tmp, s};
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
uECC_word_t *p = (uECC_word_t *)signature;
#else
uECC_word_t p[uECC_MAX_WORDS * 2];
#endif
uECC_word_t carry;
wordcount_t num_words = curve->num_words;
wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
bitcount_t num_n_bits = curve->num_n_bits;
/* Make sure 0 < k < curve_n */
if (uECC_vli_isZero(k, num_words) || uECC_vli_cmp(curve->n, k, num_n_words) != 1) {
return 0;
}
carry = regularize_k(k, tmp, s, curve);
EccPoint_mult(p, curve->G, k2[!carry], 0, num_n_bits + 1, curve);
if (uECC_vli_isZero(p, num_words)) {
return 0;
}
/* If an RNG function was specified, get a random number
to prevent side channel analysis of k. */
if (!g_rng_function) {
uECC_vli_clear(tmp, num_n_words);
tmp[0] = 1;
} else if (!uECC_generate_random_int(tmp, curve->n, num_n_words)) {
return 0;
}
/* Prevent side channel analysis of uECC_vli_modInv() to determine
bits of k / the private key by premultiplying by a random number */
uECC_vli_modMult(k, k, tmp, curve->n, num_n_words); /* k' = rand * k */
uECC_vli_modInv(k, k, curve->n, num_n_words); /* k = 1 / k' */
uECC_vli_modMult(k, k, tmp, curve->n, num_n_words); /* k = 1 / k */
#if uECC_VLI_NATIVE_LITTLE_ENDIAN == 0
uECC_vli_nativeToBytes(signature, curve->num_bytes, p); /* store r */
#endif
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
bcopy((uint8_t *) tmp, private_key, BITS_TO_BYTES(curve->num_n_bits));
#else
uECC_vli_bytesToNative(tmp, private_key, BITS_TO_BYTES(curve->num_n_bits)); /* tmp = d */
#endif
s[num_n_words - 1] = 0;
uECC_vli_set(s, p, num_words);
uECC_vli_modMult(s, tmp, s, curve->n, num_n_words); /* s = r*d */
bits2int(tmp, message_hash, hash_size, curve);
uECC_vli_modAdd(s, tmp, s, curve->n, num_n_words); /* s = e + r*d */
uECC_vli_modMult(s, s, k, curve->n, num_n_words); /* s = (e + r*d) / k */
if (uECC_vli_numBits(s, num_n_words) > (bitcount_t)curve->num_bytes * 8) {
return 0;
}
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
bcopy((uint8_t *) signature + curve->num_bytes, (uint8_t *) s, curve->num_bytes);
#else
uECC_vli_nativeToBytes(signature + curve->num_bytes, curve->num_bytes, s);
#endif
return 1;
}
int uECC_sign(const uint8_t *private_key,
const uint8_t *message_hash,
unsigned hash_size,
uint8_t *signature,
uECC_Curve curve) {
uECC_word_t k[uECC_MAX_WORDS];
uECC_word_t tries;
for (tries = 0; tries < uECC_RNG_MAX_TRIES; ++tries) {
if (!uECC_generate_random_int(k, curve->n, BITS_TO_WORDS(curve->num_n_bits))) {
return 0;
}
if (uECC_sign_with_k(private_key, message_hash, hash_size, k, signature, curve)) {
return 1;
}
}
return 0;
}
/* Compute an HMAC using K as a key (as in RFC 6979). Note that K is always
the same size as the hash result size. */
static void HMAC_init(const uECC_HashContext *hash_context, const uint8_t *K) {
uint8_t *pad = hash_context->tmp + 2 * hash_context->result_size;
unsigned i;
for (i = 0; i < hash_context->result_size; ++i)
pad[i] = K[i] ^ 0x36;
for (; i < hash_context->block_size; ++i)
pad[i] = 0x36;
hash_context->init_hash(hash_context);
hash_context->update_hash(hash_context, pad, hash_context->block_size);
}
static void HMAC_update(const uECC_HashContext *hash_context,
const uint8_t *message,
unsigned message_size) {
hash_context->update_hash(hash_context, message, message_size);
}
static void HMAC_finish(const uECC_HashContext *hash_context,
const uint8_t *K,
uint8_t *result) {
uint8_t *pad = hash_context->tmp + 2 * hash_context->result_size;
unsigned i;
for (i = 0; i < hash_context->result_size; ++i)
pad[i] = K[i] ^ 0x5c;
for (; i < hash_context->block_size; ++i)
pad[i] = 0x5c;
hash_context->finish_hash(hash_context, result);
hash_context->init_hash(hash_context);
hash_context->update_hash(hash_context, pad, hash_context->block_size);
hash_context->update_hash(hash_context, result, hash_context->result_size);
hash_context->finish_hash(hash_context, result);
}
/* V = HMAC_K(V) */
static void update_V(const uECC_HashContext *hash_context, uint8_t *K, uint8_t *V) {
HMAC_init(hash_context, K);
HMAC_update(hash_context, V, hash_context->result_size);
HMAC_finish(hash_context, K, V);
}
/* Deterministic signing, similar to RFC 6979. Differences are:
* We just use H(m) directly rather than bits2octets(H(m))
(it is not reduced modulo curve_n).
* We generate a value for k (aka T) directly rather than converting endianness.
Layout of hash_context->tmp: <K> | <V> | (1 byte overlapped 0x00 or 0x01) / <HMAC pad> */
int uECC_sign_deterministic(const uint8_t *private_key,
const uint8_t *message_hash,
unsigned hash_size,
const uECC_HashContext *hash_context,
uint8_t *signature,
uECC_Curve curve) {
uint8_t *K = hash_context->tmp;
uint8_t *V = K + hash_context->result_size;
wordcount_t num_bytes = curve->num_bytes;
wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
bitcount_t num_n_bits = curve->num_n_bits;
uECC_word_t tries;
unsigned i;
for (i = 0; i < hash_context->result_size; ++i) {
V[i] = 0x01;
K[i] = 0;
}
/* K = HMAC_K(V || 0x00 || int2octets(x) || h(m)) */
HMAC_init(hash_context, K);
V[hash_context->result_size] = 0x00;
HMAC_update(hash_context, V, hash_context->result_size + 1);
HMAC_update(hash_context, private_key, num_bytes);
HMAC_update(hash_context, message_hash, hash_size);
HMAC_finish(hash_context, K, K);
update_V(hash_context, K, V);
/* K = HMAC_K(V || 0x01 || int2octets(x) || h(m)) */
HMAC_init(hash_context, K);
V[hash_context->result_size] = 0x01;
HMAC_update(hash_context, V, hash_context->result_size + 1);
HMAC_update(hash_context, private_key, num_bytes);
HMAC_update(hash_context, message_hash, hash_size);
HMAC_finish(hash_context, K, K);
update_V(hash_context, K, V);
for (tries = 0; tries < uECC_RNG_MAX_TRIES; ++tries) {
uECC_word_t T[uECC_MAX_WORDS];
uint8_t *T_ptr = (uint8_t *)T;
wordcount_t T_bytes = 0;
for (;;) {
update_V(hash_context, K, V);
for (i = 0; i < hash_context->result_size; ++i) {
T_ptr[T_bytes++] = V[i];
if (T_bytes >= num_n_words * uECC_WORD_SIZE) {
goto filled;
}
}
}
filled:
if ((bitcount_t)num_n_words * uECC_WORD_SIZE * 8 > num_n_bits) {
uECC_word_t mask = (uECC_word_t)-1;
T[num_n_words - 1] &=
mask >> ((bitcount_t)(num_n_words * uECC_WORD_SIZE * 8 - num_n_bits));
}
if (uECC_sign_with_k(private_key, message_hash, hash_size, T, signature, curve)) {
return 1;
}
/* K = HMAC_K(V || 0x00) */
HMAC_init(hash_context, K);
V[hash_context->result_size] = 0x00;
HMAC_update(hash_context, V, hash_context->result_size + 1);
HMAC_finish(hash_context, K, K);
update_V(hash_context, K, V);
}
return 0;
}
static bitcount_t smax(bitcount_t a, bitcount_t b) {
return (a > b ? a : b);
}
int uECC_verify(const uint8_t *public_key,
const uint8_t *message_hash,
unsigned hash_size,
const uint8_t *signature,
uECC_Curve curve) {
uECC_word_t u1[uECC_MAX_WORDS], u2[uECC_MAX_WORDS];
uECC_word_t z[uECC_MAX_WORDS];
uECC_word_t sum[uECC_MAX_WORDS * 2];
uECC_word_t rx[uECC_MAX_WORDS];
uECC_word_t ry[uECC_MAX_WORDS];
uECC_word_t tx[uECC_MAX_WORDS];
uECC_word_t ty[uECC_MAX_WORDS];
uECC_word_t tz[uECC_MAX_WORDS];
const uECC_word_t *points[4];
const uECC_word_t *point;
bitcount_t num_bits;
bitcount_t i;
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
uECC_word_t *_public = (uECC_word_t *)public_key;
#else
uECC_word_t _public[uECC_MAX_WORDS * 2];
#endif
uECC_word_t r[uECC_MAX_WORDS], s[uECC_MAX_WORDS];
wordcount_t num_words = curve->num_words;
wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
rx[num_n_words - 1] = 0;
r[num_n_words - 1] = 0;
s[num_n_words - 1] = 0;
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
bcopy((uint8_t *) r, signature, curve->num_bytes);
bcopy((uint8_t *) s, signature + curve->num_bytes, curve->num_bytes);
#else
uECC_vli_bytesToNative(_public, public_key, curve->num_bytes);
uECC_vli_bytesToNative(
_public + num_words, public_key + curve->num_bytes, curve->num_bytes);
uECC_vli_bytesToNative(r, signature, curve->num_bytes);
uECC_vli_bytesToNative(s, signature + curve->num_bytes, curve->num_bytes);
#endif
/* r, s must not be 0. */
( run in 1.670 second using v1.01-cache-2.11-cpan-39bf76dae61 )