Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Bignum: Extract secp384r1 fast reduction from the prototype #7222

Merged
merged 7 commits into from
Mar 27, 2023
Merged

Bignum: Extract secp384r1 fast reduction from the prototype #7222

Changes from 1 commit
Commits
Show all changes
7 commits
Select commit Hold shift + click to select a range
6fb105f
ecp_curves: Ported prototypes
minosgalanakis Feb 22, 2023
619385d
test_suite_ecp: Added ecp_mod_p384_raw() test case.
minosgalanakis Mar 6, 2023
f359c91
ecp test generator: Added EcpPp384R1Raw().
minosgalanakis Mar 6, 2023
37f4cb6
ecp_curves: Minor rework for p384
minosgalanakis Mar 9, 2023
4af90bb
EcpP384R1Raw: Added test case for 2nd round of carry reduction.
minosgalanakis Mar 20, 2023
68d64a1
ecp_curves: Re-introduced `mbedtls_ecp_fix_negative()`
minosgalanakis Mar 22, 2023
f9fca53
ecp_curves: Updated ecp_mod_p384_raw documentation
minosgalanakis Mar 23, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
33 changes: 33 additions & 0 deletions library/ecp_curves.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5299,6 +5299,39 @@ int mbedtls_ecp_mod_p384_raw(mbedtls_mpi_uint *X, size_t X_limbs)
MBEDTLS_ECP_DP_SECP256R1_ENABLED ||
MBEDTLS_ECP_DP_SECP384R1_ENABLED */

#if defined(MBEDTLS_TEST_HOOKS) && defined(MBEDTLS_ECP_C)
MBEDTLS_STATIC_TESTABLE
void mbedtls_ecp_fix_negative(mbedtls_mpi *N, signed char c, size_t bits)
{
size_t i;

/* Set N := 2^bits - 1 - N. We know that 0 <= N < 2^bits, so
* set the absolute value to 0xfff...fff - N. There is no carry
* since we're subtracting from all-bits-one. */
for (i = 0; i <= bits / 8 / sizeof(mbedtls_mpi_uint); i++) {
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Repeating bits / 8 / sizeof(mbedtls_mpi_uint) - can we have a variable for this please?

Copy link
Contributor Author

@minosgalanakis minosgalanakis Mar 23, 2023 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This function is not new, it was just moved further down the code. I would rather not modify it since it falls out of the scope of this PR

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Okay

N->p[i] = ~(mbedtls_mpi_uint) 0 - N->p[i];
}
/* Add 1, taking care of the carry. */
i = 0;
do {
++N->p[i];
} while (N->p[i++] == 0 && i <= bits / 8 / sizeof(mbedtls_mpi_uint));
/* Invert the sign.
* Now N = N0 - 2^bits where N0 is the initial value of N. */
N->s = -1;

/* Add |c| * 2^bits to the absolute value. Since c and N are
* negative, this adds c * 2^bits. */
mbedtls_mpi_uint msw = (mbedtls_mpi_uint) -c;
#if defined(MBEDTLS_HAVE_INT64)
if (bits == 224) {
msw <<= 32;
}
#endif
N->p[bits / 8 / sizeof(mbedtls_mpi_uint)] += msw;
}
#endif /* MBEDTLS_TEST_HOOKS & MBEDTLS_ECP_C */

#if defined(MBEDTLS_ECP_DP_SECP521R1_ENABLED)
/* Size of p521 in terms of mbedtls_mpi_uint */
#define P521_WIDTH (521 / 8 / sizeof(mbedtls_mpi_uint) + 1)
Expand Down