bool android_pubkey_encode(const RSA* key, uint8_t* key_buffer, size_t size) {
RSAPublicKey* key_struct = (RSAPublicKey*)key_buffer;
bool ret = false;
BN_CTX* ctx = BN_CTX_new();
BIGNUM* r32 = BN_new();
BIGNUM* n0inv = BN_new();
BIGNUM* rr = BN_new();
if (sizeof(RSAPublicKey) > size ||
RSA_size(key) != ANDROID_PUBKEY_MODULUS_SIZE) {
goto cleanup;
}
// Store the modulus size.
key_struct->modulus_size_words = ANDROID_PUBKEY_MODULUS_SIZE_WORDS;
// Compute and store n0inv = -1 / N[0] mod 2^32.
if (!ctx || !r32 || !n0inv || !BN_set_bit(r32, 32) ||
!BN_mod(n0inv, key->n, r32, ctx) ||
!BN_mod_inverse(n0inv, n0inv, r32, ctx) || !BN_sub(n0inv, r32, n0inv)) {
goto cleanup;
}
key_struct->n0inv = (uint32_t)BN_get_word(n0inv);
// Store the modulus.
if (!android_pubkey_encode_bignum(key->n, key_struct->modulus)) {
goto cleanup;
}
// Compute and store rr = (2^(rsa_size)) ^ 2 mod N.
if (!ctx || !rr || !BN_set_bit(rr, ANDROID_PUBKEY_MODULUS_SIZE * 8) ||
!BN_mod_sqr(rr, rr, key->n, ctx) ||
!android_pubkey_encode_bignum(rr, key_struct->rr)) {
goto cleanup;
}
// Store the exponent.
key_struct->exponent = (uint32_t)BN_get_word(key->e);
ret = true;
cleanup:
BN_free(rr);
BN_free(n0inv);
BN_free(r32);
BN_CTX_free(ctx);
return ret;
}
int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP *group,
EC_POINT *point, const BIGNUM *x_,
int y_bit, BN_CTX *ctx) {
BN_CTX *new_ctx = NULL;
BIGNUM *tmp1, *tmp2, *x, *y;
int ret = 0;
ERR_clear_error();
if (ctx == NULL) {
ctx = new_ctx = BN_CTX_new();
if (ctx == NULL) {
return 0;
}
}
y_bit = (y_bit != 0);
BN_CTX_start(ctx);
tmp1 = BN_CTX_get(ctx);
tmp2 = BN_CTX_get(ctx);
x = BN_CTX_get(ctx);
y = BN_CTX_get(ctx);
if (y == NULL) {
goto err;
}
/* Recover y. We have a Weierstrass equation
* y^2 = x^3 + a*x + b,
* so y is one of the square roots of x^3 + a*x + b. */
/* tmp1 := x^3 */
if (!BN_nnmod(x, x_, &group->field, ctx)) {
goto err;
}
if (group->meth->field_decode == 0) {
/* field_{sqr,mul} work on standard representation */
if (!group->meth->field_sqr(group, tmp2, x_, ctx) ||
!group->meth->field_mul(group, tmp1, tmp2, x_, ctx)) {
goto err;
}
} else {
if (!BN_mod_sqr(tmp2, x_, &group->field, ctx) ||
!BN_mod_mul(tmp1, tmp2, x_, &group->field, ctx)) {
goto err;
}
}
/* tmp1 := tmp1 + a*x */
if (group->a_is_minus3) {
if (!BN_mod_lshift1_quick(tmp2, x, &group->field) ||
!BN_mod_add_quick(tmp2, tmp2, x, &group->field) ||
!BN_mod_sub_quick(tmp1, tmp1, tmp2, &group->field)) {
goto err;
}
} else {
if (group->meth->field_decode) {
if (!group->meth->field_decode(group, tmp2, &group->a, ctx) ||
!BN_mod_mul(tmp2, tmp2, x, &group->field, ctx)) {
goto err;
}
} else {
/* field_mul works on standard representation */
if (!group->meth->field_mul(group, tmp2, &group->a, x, ctx)) {
goto err;
}
}
if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) {
goto err;
}
}
/* tmp1 := tmp1 + b */
if (group->meth->field_decode) {
if (!group->meth->field_decode(group, tmp2, &group->b, ctx) ||
!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) {
goto err;
}
} else {
if (!BN_mod_add_quick(tmp1, tmp1, &group->b, &group->field)) {
goto err;
}
}
if (!BN_mod_sqrt(y, tmp1, &group->field, ctx)) {
unsigned long err = ERR_peek_last_error();
if (ERR_GET_LIB(err) == ERR_LIB_BN &&
ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) {
ERR_clear_error();
OPENSSL_PUT_ERROR(EC, ec_GFp_simple_set_compressed_coordinates, EC_R_INVALID_COMPRESSED_POINT);
} else {
OPENSSL_PUT_ERROR(EC, ec_GFp_simple_set_compressed_coordinates, ERR_R_BN_LIB);
}
goto err;
}
if (y_bit != BN_is_odd(y)) {
if (BN_is_zero(y)) {
int kron;
kron = BN_kronecker(x, &group->field, ctx);
if (kron == -2) {
goto err;
}
if (kron == 1) {
OPENSSL_PUT_ERROR(EC, ec_GFp_simple_set_compressed_coordinates,
EC_R_INVALID_COMPRESSION_BIT);
} else {
/* BN_mod_sqrt() should have cought this error (not a square) */
OPENSSL_PUT_ERROR(EC, ec_GFp_simple_set_compressed_coordinates,
EC_R_INVALID_COMPRESSED_POINT);
}
goto err;
}
if (!BN_usub(y, &group->field, y)) {
goto err;
}
}
if (y_bit != BN_is_odd(y)) {
OPENSSL_PUT_ERROR(EC, ec_GFp_simple_set_compressed_coordinates,
ERR_R_INTERNAL_ERROR);
goto err;
}
if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx))
goto err;
ret = 1;
err:
BN_CTX_end(ctx);
if (new_ctx != NULL)
BN_CTX_free(new_ctx);
return ret;
}
BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
/* Returns 'ret' such that
* ret^2 == a (mod p),
* using the Tonelli/Shanks algorithm (cf. Henri Cohen, "A Course
* in Algebraic Computational Number Theory", algorithm 1.5.1).
* 'p' must be prime!
*/
{
BIGNUM *ret = in;
int err = 1;
int r;
BIGNUM *A, *b, *q, *t, *x, *y;
int e, i, j;
if (!BN_is_odd(p) || BN_abs_is_word(p, 1))
{
if (BN_abs_is_word(p, 2))
{
if (ret == NULL)
ret = BN_new();
if (ret == NULL)
goto end;
if (!BN_set_word(ret, BN_is_bit_set(a, 0)))
{
if (ret != in)
BN_free(ret);
return NULL;
}
bn_check_top(ret);
return ret;
}
BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);
return(NULL);
}
if (BN_is_zero(a) || BN_is_one(a))
{
if (ret == NULL)
ret = BN_new();
if (ret == NULL)
goto end;
if (!BN_set_word(ret, BN_is_one(a)))
{
if (ret != in)
BN_free(ret);
return NULL;
}
bn_check_top(ret);
return ret;
}
BN_CTX_start(ctx);
A = BN_CTX_get(ctx);
b = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
t = BN_CTX_get(ctx);
x = BN_CTX_get(ctx);
y = BN_CTX_get(ctx);
if (y == NULL) goto end;
if (ret == NULL)
ret = BN_new();
if (ret == NULL) goto end;
/* A = a mod p */
if (!BN_nnmod(A, a, p, ctx)) goto end;
/* now write |p| - 1 as 2^e*q where q is odd */
e = 1;
while (!BN_is_bit_set(p, e))
e++;
/* we'll set q later (if needed) */
if (e == 1)
{
/* The easy case: (|p|-1)/2 is odd, so 2 has an inverse
* modulo (|p|-1)/2, and square roots can be computed
* directly by modular exponentiation.
* We have
* 2 * (|p|+1)/4 == 1 (mod (|p|-1)/2),
* so we can use exponent (|p|+1)/4, i.e. (|p|-3)/4 + 1.
*/
if (!BN_rshift(q, p, 2)) goto end;
q->neg = 0;
if (!BN_add_word(q, 1)) goto end;
if (!BN_mod_exp(ret, A, q, p, ctx)) goto end;
err = 0;
goto vrfy;
}
if (e == 2)
{
/* |p| == 5 (mod 8)
*
* In this case 2 is always a non-square since
* Legendre(2,p) = (-1)^((p^2-1)/8) for any odd prime.
* So if a really is a square, then 2*a is a non-square.
* Thus for
* b := (2*a)^((|p|-5)/8),
* i := (2*a)*b^2
* we have
* i^2 = (2*a)^((1 + (|p|-5)/4)*2)
* = (2*a)^((p-1)/2)
* = -1;
* so if we set
* x := a*b*(i-1),
* then
* x^2 = a^2 * b^2 * (i^2 - 2*i + 1)
* = a^2 * b^2 * (-2*i)
* = a*(-i)*(2*a*b^2)
* = a*(-i)*i
* = a.
*
* (This is due to A.O.L. Atkin,
* <URL: http://listserv.nodak.edu/scripts/wa.exe?A2=ind9211&L=nmbrthry&O=T&P=562>,
* November 1992.)
*/
/* t := 2*a */
if (!BN_mod_lshift1_quick(t, A, p)) goto end;
/* b := (2*a)^((|p|-5)/8) */
if (!BN_rshift(q, p, 3)) goto end;
q->neg = 0;
if (!BN_mod_exp(b, t, q, p, ctx)) goto end;
/* y := b^2 */
if (!BN_mod_sqr(y, b, p, ctx)) goto end;
/* t := (2*a)*b^2 - 1*/
if (!BN_mod_mul(t, t, y, p, ctx)) goto end;
if (!BN_sub_word(t, 1)) goto end;
/* x = a*b*t */
if (!BN_mod_mul(x, A, b, p, ctx)) goto end;
if (!BN_mod_mul(x, x, t, p, ctx)) goto end;
if (!BN_copy(ret, x)) goto end;
err = 0;
goto vrfy;
}
/* e > 2, so we really have to use the Tonelli/Shanks algorithm.
* First, find some y that is not a square. */
if (!BN_copy(q, p)) goto end; /* use 'q' as temp */
q->neg = 0;
i = 2;
do
{
/* For efficiency, try small numbers first;
* if this fails, try random numbers.
*/
if (i < 22)
{
if (!BN_set_word(y, i)) goto end;
}
else
{
if (!BN_pseudo_rand(y, BN_num_bits(p), 0, 0)) goto end;
if (BN_ucmp(y, p) >= 0)
{
if (!(p->neg ? BN_add : BN_sub)(y, y, p)) goto end;
}
/* now 0 <= y < |p| */
if (BN_is_zero(y))
if (!BN_set_word(y, i)) goto end;
}
r = BN_kronecker(y, q, ctx); /* here 'q' is |p| */
if (r < -1) goto end;
if (r == 0)
{
/* m divides p */
BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);
goto end;
}
}
while (r == 1 && ++i < 82);
if (r != -1)
{
/* Many rounds and still no non-square -- this is more likely
* a bug than just bad luck.
* Even if p is not prime, we should have found some y
* such that r == -1.
*/
BNerr(BN_F_BN_MOD_SQRT, BN_R_TOO_MANY_ITERATIONS);
goto end;
}
/* Here's our actual 'q': */
if (!BN_rshift(q, q, e)) goto end;
/* Now that we have some non-square, we can find an element
* of order 2^e by computing its q'th power. */
if (!BN_mod_exp(y, y, q, p, ctx)) goto end;
if (BN_is_one(y))
{
BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);
goto end;
}
/* Now we know that (if p is indeed prime) there is an integer
* k, 0 <= k < 2^e, such that
*
* a^q * y^k == 1 (mod p).
*
* As a^q is a square and y is not, k must be even.
* q+1 is even, too, so there is an element
*
* X := a^((q+1)/2) * y^(k/2),
*
* and it satisfies
*
* X^2 = a^q * a * y^k
* = a,
*
* so it is the square root that we are looking for.
*/
/* t := (q-1)/2 (note that q is odd) */
if (!BN_rshift1(t, q)) goto end;
/* x := a^((q-1)/2) */
if (BN_is_zero(t)) /* special case: p = 2^e + 1 */
{
if (!BN_nnmod(t, A, p, ctx)) goto end;
if (BN_is_zero(t))
{
/* special case: a == 0 (mod p) */
BN_zero(ret);
err = 0;
goto end;
}
else
if (!BN_one(x)) goto end;
}
else
{
if (!BN_mod_exp(x, A, t, p, ctx)) goto end;
if (BN_is_zero(x))
{
/* special case: a == 0 (mod p) */
BN_zero(ret);
err = 0;
goto end;
}
}
/* b := a*x^2 (= a^q) */
if (!BN_mod_sqr(b, x, p, ctx)) goto end;
if (!BN_mod_mul(b, b, A, p, ctx)) goto end;
/* x := a*x (= a^((q+1)/2)) */
if (!BN_mod_mul(x, x, A, p, ctx)) goto end;
while (1)
{
/* Now b is a^q * y^k for some even k (0 <= k < 2^E
* where E refers to the original value of e, which we
* don't keep in a variable), and x is a^((q+1)/2) * y^(k/2).
*
* We have a*b = x^2,
* y^2^(e-1) = -1,
* b^2^(e-1) = 1.
*/
if (BN_is_one(b))
{
if (!BN_copy(ret, x)) goto end;
err = 0;
goto vrfy;
}
/* find smallest i such that b^(2^i) = 1 */
i = 1;
if (!BN_mod_sqr(t, b, p, ctx)) goto end;
while (!BN_is_one(t))
{
i++;
if (i == e)
{
BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE);
goto end;
}
if (!BN_mod_mul(t, t, t, p, ctx)) goto end;
}
/* t := y^2^(e - i - 1) */
if (!BN_copy(t, y)) goto end;
for (j = e - i - 1; j > 0; j--)
{
if (!BN_mod_sqr(t, t, p, ctx)) goto end;
}
if (!BN_mod_mul(y, t, t, p, ctx)) goto end;
if (!BN_mod_mul(x, x, t, p, ctx)) goto end;
if (!BN_mod_mul(b, b, y, p, ctx)) goto end;
e = i;
}
vrfy:
if (!err)
{
/* verify the result -- the input might have been not a square
* (test added in 0.9.8) */
if (!BN_mod_sqr(x, ret, p, ctx))
err = 1;
if (!err && 0 != BN_cmp(x, A))
{
BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE);
err = 1;
}
}
end:
if (err)
{
if (ret != NULL && ret != in)
{
BN_clear_free(ret);
}
ret = NULL;
}
BN_CTX_end(ctx);
bn_check_top(ret);
return ret;
}
int ec_GFp_simple_point_get_affine_coordinates(const EC_GROUP *group,
const EC_POINT *point,
BIGNUM *x, BIGNUM *y,
BN_CTX *ctx)
{
BN_CTX *new_ctx = NULL;
BIGNUM *Z, *Z_1, *Z_2, *Z_3;
const BIGNUM *Z_;
int ret = 0;
if (EC_POINT_is_at_infinity(group, point)) {
ECerr(EC_F_EC_GFP_SIMPLE_POINT_GET_AFFINE_COORDINATES,
EC_R_POINT_AT_INFINITY);
return 0;
}
if (ctx == NULL) {
ctx = new_ctx = BN_CTX_new();
if (ctx == NULL)
return 0;
}
BN_CTX_start(ctx);
Z = BN_CTX_get(ctx);
Z_1 = BN_CTX_get(ctx);
Z_2 = BN_CTX_get(ctx);
Z_3 = BN_CTX_get(ctx);
if (Z_3 == NULL)
goto err;
/* transform (X, Y, Z) into (x, y) := (X/Z^2, Y/Z^3) */
if (group->meth->field_decode) {
if (!group->meth->field_decode(group, Z, point->Z, ctx))
goto err;
Z_ = Z;
} else {
Z_ = point->Z;
}
if (BN_is_one(Z_)) {
if (group->meth->field_decode) {
if (x != NULL) {
if (!group->meth->field_decode(group, x, point->X, ctx))
goto err;
}
if (y != NULL) {
if (!group->meth->field_decode(group, y, point->Y, ctx))
goto err;
}
} else {
if (x != NULL) {
if (!BN_copy(x, point->X))
goto err;
}
if (y != NULL) {
if (!BN_copy(y, point->Y))
goto err;
}
}
} else {
if (!BN_mod_inverse(Z_1, Z_, group->field, ctx)) {
ECerr(EC_F_EC_GFP_SIMPLE_POINT_GET_AFFINE_COORDINATES,
ERR_R_BN_LIB);
goto err;
}
if (group->meth->field_encode == 0) {
/* field_sqr works on standard representation */
if (!group->meth->field_sqr(group, Z_2, Z_1, ctx))
goto err;
} else {
if (!BN_mod_sqr(Z_2, Z_1, group->field, ctx))
goto err;
}
if (x != NULL) {
/*
* in the Montgomery case, field_mul will cancel out Montgomery
* factor in X:
*/
if (!group->meth->field_mul(group, x, point->X, Z_2, ctx))
goto err;
}
if (y != NULL) {
if (group->meth->field_encode == 0) {
/*
* field_mul works on standard representation
*/
if (!group->meth->field_mul(group, Z_3, Z_2, Z_1, ctx))
goto err;
} else {
if (!BN_mod_mul(Z_3, Z_2, Z_1, group->field, ctx))
goto err;
}
/*
* in the Montgomery case, field_mul will cancel out Montgomery
* factor in Y:
*/
if (!group->meth->field_mul(group, y, point->Y, Z_3, ctx))
goto err;
}
}
ret = 1;
err:
BN_CTX_end(ctx);
BN_CTX_free(new_ctx);
return ret;
}
int ec_GFp_simple_group_check_discriminant(const EC_GROUP *group, BN_CTX *ctx)
{
int ret = 0;
BIGNUM *a, *b, *order, *tmp_1, *tmp_2;
const BIGNUM *p = group->field;
BN_CTX *new_ctx = NULL;
if (ctx == NULL) {
ctx = new_ctx = BN_CTX_new();
if (ctx == NULL) {
ECerr(EC_F_EC_GFP_SIMPLE_GROUP_CHECK_DISCRIMINANT,
ERR_R_MALLOC_FAILURE);
goto err;
}
}
BN_CTX_start(ctx);
a = BN_CTX_get(ctx);
b = BN_CTX_get(ctx);
tmp_1 = BN_CTX_get(ctx);
tmp_2 = BN_CTX_get(ctx);
order = BN_CTX_get(ctx);
if (order == NULL)
goto err;
if (group->meth->field_decode) {
if (!group->meth->field_decode(group, a, group->a, ctx))
goto err;
if (!group->meth->field_decode(group, b, group->b, ctx))
goto err;
} else {
if (!BN_copy(a, group->a))
goto err;
if (!BN_copy(b, group->b))
goto err;
}
/*-
* check the discriminant:
* y^2 = x^3 + a*x + b is an elliptic curve <=> 4*a^3 + 27*b^2 != 0 (mod p)
* 0 =< a, b < p
*/
if (BN_is_zero(a)) {
if (BN_is_zero(b))
goto err;
} else if (!BN_is_zero(b)) {
if (!BN_mod_sqr(tmp_1, a, p, ctx))
goto err;
if (!BN_mod_mul(tmp_2, tmp_1, a, p, ctx))
goto err;
if (!BN_lshift(tmp_1, tmp_2, 2))
goto err;
/* tmp_1 = 4*a^3 */
if (!BN_mod_sqr(tmp_2, b, p, ctx))
goto err;
if (!BN_mul_word(tmp_2, 27))
goto err;
/* tmp_2 = 27*b^2 */
if (!BN_mod_add(a, tmp_1, tmp_2, p, ctx))
goto err;
if (BN_is_zero(a))
goto err;
}
ret = 1;
err:
if (ctx != NULL)
BN_CTX_end(ctx);
BN_CTX_free(new_ctx);
return ret;
}
int ec_GFp_simple_field_sqr(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
BN_CTX *ctx)
{
return BN_mod_sqr(r, a, group->field, ctx);
}
int test_sqrt(BIO *bp, BN_CTX *ctx)
{
BIGNUM *a,*p,*r;
int i, j;
int ret = 0;
a = BN_new();
p = BN_new();
r = BN_new();
if (a == NULL || p == NULL || r == NULL) goto err;
for (i = 0; i < 16; i++)
{
if (i < 8)
{
unsigned primes[8] = { 2, 3, 5, 7, 11, 13, 17, 19 };
if (!BN_set_word(p, primes[i])) goto err;
}
else
{
if (!BN_set_word(a, 32)) goto err;
if (!BN_set_word(r, 2*i + 1)) goto err;
if (!BN_generate_prime(p, 256, 0, a, r, genprime_cb, NULL)) goto err;
putc('\n', stderr);
}
p->neg = rand_neg();
for (j = 0; j < num2; j++)
{
/* construct 'a' such that it is a square modulo p,
* but in general not a proper square and not reduced modulo p */
if (!BN_bntest_rand(r, 256, 0, 3)) goto err;
if (!BN_nnmod(r, r, p, ctx)) goto err;
if (!BN_mod_sqr(r, r, p, ctx)) goto err;
if (!BN_bntest_rand(a, 256, 0, 3)) goto err;
if (!BN_nnmod(a, a, p, ctx)) goto err;
if (!BN_mod_sqr(a, a, p, ctx)) goto err;
if (!BN_mul(a, a, r, ctx)) goto err;
if (rand_neg())
if (!BN_sub(a, a, p)) goto err;
if (!BN_mod_sqrt(r, a, p, ctx)) goto err;
if (!BN_mod_sqr(r, r, p, ctx)) goto err;
if (!BN_nnmod(a, a, p, ctx)) goto err;
if (BN_cmp(a, r) != 0)
{
fprintf(stderr, "BN_mod_sqrt failed: a = ");
BN_print_fp(stderr, a);
fprintf(stderr, ", r = ");
BN_print_fp(stderr, r);
fprintf(stderr, ", p = ");
BN_print_fp(stderr, p);
fprintf(stderr, "\n");
goto err;
}
putc('.', stderr);
fflush(stderr);
}
putc('\n', stderr);
fflush(stderr);
}
ret = 1;
err:
if (a != NULL) BN_free(a);
if (p != NULL) BN_free(p);
if (r != NULL) BN_free(r);
return ret;
}
BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx) {
// Compute a square root of |a| mod |p| using the Tonelli/Shanks algorithm
// (cf. Henri Cohen, "A Course in Algebraic Computational Number Theory",
// algorithm 1.5.1). |p| is assumed to be a prime.
BIGNUM *ret = in;
int err = 1;
int r;
BIGNUM *A, *b, *q, *t, *x, *y;
int e, i, j;
if (!BN_is_odd(p) || BN_abs_is_word(p, 1)) {
if (BN_abs_is_word(p, 2)) {
if (ret == NULL) {
ret = BN_new();
}
if (ret == NULL) {
goto end;
}
if (!BN_set_word(ret, BN_is_bit_set(a, 0))) {
if (ret != in) {
BN_free(ret);
}
return NULL;
}
return ret;
}
OPENSSL_PUT_ERROR(BN, BN_R_P_IS_NOT_PRIME);
return (NULL);
}
if (BN_is_zero(a) || BN_is_one(a)) {
if (ret == NULL) {
ret = BN_new();
}
if (ret == NULL) {
goto end;
}
if (!BN_set_word(ret, BN_is_one(a))) {
if (ret != in) {
BN_free(ret);
}
return NULL;
}
return ret;
}
BN_CTX_start(ctx);
A = BN_CTX_get(ctx);
b = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
t = BN_CTX_get(ctx);
x = BN_CTX_get(ctx);
y = BN_CTX_get(ctx);
if (y == NULL) {
goto end;
}
if (ret == NULL) {
ret = BN_new();
}
if (ret == NULL) {
goto end;
}
// A = a mod p
if (!BN_nnmod(A, a, p, ctx)) {
goto end;
}
// now write |p| - 1 as 2^e*q where q is odd
e = 1;
while (!BN_is_bit_set(p, e)) {
e++;
}
// we'll set q later (if needed)
if (e == 1) {
// The easy case: (|p|-1)/2 is odd, so 2 has an inverse
// modulo (|p|-1)/2, and square roots can be computed
// directly by modular exponentiation.
// We have
// 2 * (|p|+1)/4 == 1 (mod (|p|-1)/2),
// so we can use exponent (|p|+1)/4, i.e. (|p|-3)/4 + 1.
if (!BN_rshift(q, p, 2)) {
goto end;
}
q->neg = 0;
if (!BN_add_word(q, 1) ||
!BN_mod_exp_mont(ret, A, q, p, ctx, NULL)) {
goto end;
}
err = 0;
goto vrfy;
}
if (e == 2) {
// |p| == 5 (mod 8)
//
// In this case 2 is always a non-square since
// Legendre(2,p) = (-1)^((p^2-1)/8) for any odd prime.
// So if a really is a square, then 2*a is a non-square.
// Thus for
// b := (2*a)^((|p|-5)/8),
// i := (2*a)*b^2
// we have
// i^2 = (2*a)^((1 + (|p|-5)/4)*2)
// = (2*a)^((p-1)/2)
// = -1;
// so if we set
// x := a*b*(i-1),
// then
// x^2 = a^2 * b^2 * (i^2 - 2*i + 1)
// = a^2 * b^2 * (-2*i)
// = a*(-i)*(2*a*b^2)
// = a*(-i)*i
// = a.
//
// (This is due to A.O.L. Atkin,
// <URL:
//http://listserv.nodak.edu/scripts/wa.exe?A2=ind9211&L=nmbrthry&O=T&P=562>,
// November 1992.)
// t := 2*a
if (!BN_mod_lshift1_quick(t, A, p)) {
goto end;
}
// b := (2*a)^((|p|-5)/8)
if (!BN_rshift(q, p, 3)) {
goto end;
}
q->neg = 0;
if (!BN_mod_exp_mont(b, t, q, p, ctx, NULL)) {
goto end;
}
// y := b^2
if (!BN_mod_sqr(y, b, p, ctx)) {
goto end;
}
// t := (2*a)*b^2 - 1
if (!BN_mod_mul(t, t, y, p, ctx) ||
!BN_sub_word(t, 1)) {
goto end;
}
// x = a*b*t
if (!BN_mod_mul(x, A, b, p, ctx) ||
!BN_mod_mul(x, x, t, p, ctx)) {
goto end;
}
if (!BN_copy(ret, x)) {
goto end;
}
err = 0;
goto vrfy;
}
// e > 2, so we really have to use the Tonelli/Shanks algorithm.
// First, find some y that is not a square.
if (!BN_copy(q, p)) {
goto end; // use 'q' as temp
}
q->neg = 0;
i = 2;
do {
// For efficiency, try small numbers first;
// if this fails, try random numbers.
if (i < 22) {
if (!BN_set_word(y, i)) {
goto end;
}
} else {
if (!BN_pseudo_rand(y, BN_num_bits(p), 0, 0)) {
goto end;
}
if (BN_ucmp(y, p) >= 0) {
if (!(p->neg ? BN_add : BN_sub)(y, y, p)) {
goto end;
}
}
// now 0 <= y < |p|
if (BN_is_zero(y)) {
if (!BN_set_word(y, i)) {
goto end;
}
}
}
r = bn_jacobi(y, q, ctx); // here 'q' is |p|
if (r < -1) {
goto end;
}
if (r == 0) {
// m divides p
OPENSSL_PUT_ERROR(BN, BN_R_P_IS_NOT_PRIME);
goto end;
}
} while (r == 1 && ++i < 82);
if (r != -1) {
// Many rounds and still no non-square -- this is more likely
// a bug than just bad luck.
// Even if p is not prime, we should have found some y
// such that r == -1.
OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_ITERATIONS);
goto end;
}
// Here's our actual 'q':
if (!BN_rshift(q, q, e)) {
goto end;
}
// Now that we have some non-square, we can find an element
// of order 2^e by computing its q'th power.
if (!BN_mod_exp_mont(y, y, q, p, ctx, NULL)) {
goto end;
}
if (BN_is_one(y)) {
OPENSSL_PUT_ERROR(BN, BN_R_P_IS_NOT_PRIME);
goto end;
}
// Now we know that (if p is indeed prime) there is an integer
// k, 0 <= k < 2^e, such that
//
// a^q * y^k == 1 (mod p).
//
// As a^q is a square and y is not, k must be even.
// q+1 is even, too, so there is an element
//
// X := a^((q+1)/2) * y^(k/2),
//
// and it satisfies
//
// X^2 = a^q * a * y^k
// = a,
//
// so it is the square root that we are looking for.
// t := (q-1)/2 (note that q is odd)
if (!BN_rshift1(t, q)) {
goto end;
}
// x := a^((q-1)/2)
if (BN_is_zero(t)) // special case: p = 2^e + 1
{
if (!BN_nnmod(t, A, p, ctx)) {
goto end;
}
if (BN_is_zero(t)) {
// special case: a == 0 (mod p)
BN_zero(ret);
err = 0;
goto end;
} else if (!BN_one(x)) {
goto end;
}
} else {
if (!BN_mod_exp_mont(x, A, t, p, ctx, NULL)) {
goto end;
}
if (BN_is_zero(x)) {
// special case: a == 0 (mod p)
BN_zero(ret);
err = 0;
goto end;
}
}
// b := a*x^2 (= a^q)
if (!BN_mod_sqr(b, x, p, ctx) ||
!BN_mod_mul(b, b, A, p, ctx)) {
goto end;
}
// x := a*x (= a^((q+1)/2))
if (!BN_mod_mul(x, x, A, p, ctx)) {
goto end;
}
while (1) {
// Now b is a^q * y^k for some even k (0 <= k < 2^E
// where E refers to the original value of e, which we
// don't keep in a variable), and x is a^((q+1)/2) * y^(k/2).
//
// We have a*b = x^2,
// y^2^(e-1) = -1,
// b^2^(e-1) = 1.
if (BN_is_one(b)) {
if (!BN_copy(ret, x)) {
goto end;
}
err = 0;
goto vrfy;
}
// find smallest i such that b^(2^i) = 1
i = 1;
if (!BN_mod_sqr(t, b, p, ctx)) {
goto end;
}
while (!BN_is_one(t)) {
i++;
if (i == e) {
OPENSSL_PUT_ERROR(BN, BN_R_NOT_A_SQUARE);
goto end;
}
if (!BN_mod_mul(t, t, t, p, ctx)) {
goto end;
}
}
// t := y^2^(e - i - 1)
if (!BN_copy(t, y)) {
goto end;
}
for (j = e - i - 1; j > 0; j--) {
if (!BN_mod_sqr(t, t, p, ctx)) {
goto end;
}
}
if (!BN_mod_mul(y, t, t, p, ctx) ||
!BN_mod_mul(x, x, t, p, ctx) ||
!BN_mod_mul(b, b, y, p, ctx)) {
goto end;
}
e = i;
}
vrfy:
if (!err) {
// verify the result -- the input might have been not a square
// (test added in 0.9.8)
if (!BN_mod_sqr(x, ret, p, ctx)) {
err = 1;
}
if (!err && 0 != BN_cmp(x, A)) {
OPENSSL_PUT_ERROR(BN, BN_R_NOT_A_SQUARE);
err = 1;
}
}
end:
if (err) {
if (ret != in) {
BN_clear_free(ret);
}
ret = NULL;
}
BN_CTX_end(ctx);
return ret;
}
void do_mul_exp(BIGNUM *r, BIGNUM *a, BIGNUM *b, BIGNUM *c, BN_CTX *ctx)
{
int i,k;
double tm;
long num;
num=BASENUM;
for (i=NUM_START; i<NUM_SIZES; i++)
{
#ifdef C_PRIME
# ifdef TEST_SQRT
if (!BN_set_word(a, 64)) goto err;
if (!BN_set_word(b, P_MOD_64)) goto err;
# define ADD a
# define REM b
# else
# define ADD NULL
# define REM NULL
# endif
if (!BN_generate_prime(c,sizes[i],0,ADD,REM,genprime_cb,NULL)) goto err;
putc('\n', stderr);
fflush(stderr);
#endif
for (k=0; k<num; k++)
{
if (k%50 == 0) /* Average over num/50 different choices of random numbers. */
{
if (!BN_pseudo_rand(a,sizes[i],1,0)) goto err;
if (!BN_pseudo_rand(b,sizes[i],1,0)) goto err;
#ifndef C_PRIME
if (!BN_pseudo_rand(c,sizes[i],1,1)) goto err;
#endif
#ifdef TEST_SQRT
if (!BN_mod_sqr(a,a,c,ctx)) goto err;
if (!BN_mod_sqr(b,b,c,ctx)) goto err;
#else
if (!BN_nnmod(a,a,c,ctx)) goto err;
if (!BN_nnmod(b,b,c,ctx)) goto err;
#endif
if (k == 0)
Time_F(START);
}
#if defined(TEST_EXP)
if (!BN_mod_exp(r,a,b,c,ctx)) goto err;
#elif defined(TEST_MUL)
{
int i = 0;
for (i = 0; i < 50; i++)
if (!BN_mod_mul(r,a,b,c,ctx)) goto err;
}
#elif defined(TEST_SQR)
{
int i = 0;
for (i = 0; i < 50; i++)
{
if (!BN_mod_sqr(r,a,c,ctx)) goto err;
if (!BN_mod_sqr(r,b,c,ctx)) goto err;
}
}
#elif defined(TEST_GCD)
if (!BN_gcd(r,a,b,ctx)) goto err;
if (!BN_gcd(r,b,c,ctx)) goto err;
if (!BN_gcd(r,c,a,ctx)) goto err;
#elif defined(TEST_KRON)
if (-2 == BN_kronecker(a,b,ctx)) goto err;
if (-2 == BN_kronecker(b,c,ctx)) goto err;
if (-2 == BN_kronecker(c,a,ctx)) goto err;
#elif defined(TEST_INV)
if (!BN_mod_inverse(r,a,c,ctx)) goto err;
if (!BN_mod_inverse(r,b,c,ctx)) goto err;
#else /* TEST_SQRT */
if (!BN_mod_sqrt(r,a,c,ctx)) goto err;
if (!BN_mod_sqrt(r,b,c,ctx)) goto err;
#endif
}
tm=Time_F(STOP);
printf(
#if defined(TEST_EXP)
"modexp %4d ^ %4d %% %4d"
#elif defined(TEST_MUL)
"50*modmul %4d %4d %4d"
#elif defined(TEST_SQR)
"100*modsqr %4d %4d %4d"
#elif defined(TEST_GCD)
"3*gcd %4d %4d %4d"
#elif defined(TEST_KRON)
"3*kronecker %4d %4d %4d"
#elif defined(TEST_INV)
"2*inv %4d %4d mod %4d"
#else /* TEST_SQRT */
"2*sqrt [prime == %d (mod 64)] %4d %4d mod %4d"
#endif
" -> %8.3fms %5.1f (%ld)\n",
#ifdef TEST_SQRT
P_MOD_64,
#endif
sizes[i],sizes[i],sizes[i],tm*1000.0/num,tm*mul_c[i]/num, num);
num/=7;
if (num <= 0) num=1;
}
return;
err:
ERR_print_errors_fp(stderr);
}
int
ecdh_im_compute_key(PACE_CTX * ctx, const BUF_MEM * s, const BUF_MEM * in,
BN_CTX *bn_ctx)
{
int ret = 0;
BUF_MEM * x_mem = NULL;
BIGNUM * a = NULL, *b = NULL, *p = NULL;
BIGNUM * x = NULL, *y = NULL, *v = NULL, *u = NULL;
BIGNUM * tmp = NULL, *tmp2 = NULL, *bn_inv = NULL;
BIGNUM * two = NULL, *three = NULL, *four = NULL, *six = NULL;
BIGNUM * twentyseven = NULL;
EC_KEY *static_key = NULL, *ephemeral_key = NULL;
EC_POINT *g = NULL;
BN_CTX_start(bn_ctx);
check((ctx && ctx->static_key && s && ctx->ka_ctx), "Invalid arguments");
static_key = EVP_PKEY_get1_EC_KEY(ctx->static_key);
if (!static_key)
goto err;
/* Setup all the variables*/
a = BN_CTX_get(bn_ctx);
b = BN_CTX_get(bn_ctx);
p = BN_CTX_get(bn_ctx);
x = BN_CTX_get(bn_ctx);
y = BN_CTX_get(bn_ctx);
v = BN_CTX_get(bn_ctx);
two = BN_CTX_get(bn_ctx);
three = BN_CTX_get(bn_ctx);
four = BN_CTX_get(bn_ctx);
six = BN_CTX_get(bn_ctx);
twentyseven = BN_CTX_get(bn_ctx);
tmp = BN_CTX_get(bn_ctx);
tmp2 = BN_CTX_get(bn_ctx);
bn_inv = BN_CTX_get(bn_ctx);
if (!bn_inv)
goto err;
/* Encrypt the Nonce using the symmetric key in */
x_mem = cipher_no_pad(ctx->ka_ctx, NULL, in, s, 1);
if (!x_mem)
goto err;
/* Fetch the curve parameters */
if (!EC_GROUP_get_curve_GFp(EC_KEY_get0_group(static_key), p, a, b, bn_ctx))
goto err;
/* Assign constants */
if ( !BN_set_word(two,2)||
!BN_set_word(three,3)||
!BN_set_word(four,4)||
!BN_set_word(six,6)||
!BN_set_word(twentyseven,27)
) goto err;
/* Check prerequisites for curve parameters */
check(
/* p > 3;*/
(BN_cmp(p, three) == 1) &&
/* p mod 3 = 2; (p has the form p=q^n, q prime) */
BN_nnmod(tmp, p, three, bn_ctx) &&
(BN_cmp(tmp, two) == 0),
"Unsuited curve");
/* Convert encrypted nonce to BIGNUM */
u = BN_bin2bn((unsigned char *) x_mem->data, x_mem->length, u);
if (!u)
goto err;
if ( /* v = (3a - u^4) / 6u mod p */
!BN_mod_mul(tmp, three, a, p, bn_ctx) ||
!BN_mod_exp(tmp2, u, four, p, bn_ctx) ||
!BN_mod_sub(v, tmp, tmp2, p, bn_ctx) ||
!BN_mod_mul(tmp, u, six, p, bn_ctx) ||
/* For division within a galois field we need to compute
* the multiplicative inverse of a number */
!BN_mod_inverse(bn_inv, tmp, p, bn_ctx) ||
!BN_mod_mul(v, v, bn_inv, p, bn_ctx) ||
/* x = (v^2 - b - ((u^6)/27)) */
!BN_mod_sqr(tmp, v, p, bn_ctx) ||
!BN_mod_sub(tmp2, tmp, b, p, bn_ctx) ||
!BN_mod_exp(tmp, u, six, p, bn_ctx) ||
!BN_mod_inverse(bn_inv, twentyseven, p, bn_ctx) ||
!BN_mod_mul(tmp, tmp, bn_inv, p, bn_ctx) ||
!BN_mod_sub(x, tmp2, tmp, p, bn_ctx) ||
/* x -> x^(1/3) = x^((2p^n -1)/3) */
!BN_mul(tmp, two, p, bn_ctx) ||
!BN_sub(tmp, tmp, BN_value_one()) ||
/* Division is defined, because p^n = 2 mod 3 */
!BN_div(tmp, y, tmp, three, bn_ctx) ||
!BN_mod_exp(tmp2, x, tmp, p, bn_ctx) ||
!BN_copy(x, tmp2) ||
/* x += (u^2)/3 */
!BN_mod_sqr(tmp, u, p, bn_ctx) ||
!BN_mod_inverse(bn_inv, three, p, bn_ctx) ||
!BN_mod_mul(tmp2, tmp, bn_inv, p, bn_ctx) ||
!BN_mod_add(tmp, x, tmp2, p, bn_ctx) ||
!BN_copy(x, tmp) ||
/* y = ux + v */
!BN_mod_mul(y, u, x, p, bn_ctx) ||
!BN_mod_add(tmp, y, v, p, bn_ctx) ||
!BN_copy(y, tmp)
)
goto err;
/* Initialize ephemeral parameters with parameters from the static key */
ephemeral_key = EC_KEY_dup(static_key);
if (!ephemeral_key)
goto err;
EVP_PKEY_set1_EC_KEY(ctx->ka_ctx->key, ephemeral_key);
/* configure the new EC_KEY */
g = EC_POINT_new(EC_KEY_get0_group(ephemeral_key));
if (!g)
goto err;
if (!EC_POINT_set_affine_coordinates_GFp(EC_KEY_get0_group(ephemeral_key), g,
x, y, bn_ctx))
goto err;
ret = 1;
err:
if (x_mem)
BUF_MEM_free(x_mem);
if (u)
BN_free(u);
BN_CTX_end(bn_ctx);
if (g)
EC_POINT_clear_free(g);
/* Decrement reference count, keys are still available via PACE_CTX */
if (static_key)
EC_KEY_free(static_key);
if (ephemeral_key)
EC_KEY_free(ephemeral_key);
return ret;
}
