Skip to content

ecc: reject compressed EC points with incorrect length #10591

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

Open
MarkAtwood wants to merge 2 commits into
base: master
Choose a base branch
from
+47 −2
Open

ecc: reject compressed EC points with incorrect length #10591

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
456fe33
ecc: reject compressed EC points with incorrect length
MarkAtwood Mar 16, 2026
cf5a34d
ecc: harden compressed-point length checks
MarkAtwood Jun 5, 2026
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
21 changes: 21 additions & 0 deletions tests/api/test_ecc.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -760,6 +760,16 @@ int test_wc_ecc_import_x963(void)
WC_NO_ERR_TRACE(BAD_FUNC_ARG));
ExpectIntEQ(wc_ecc_import_x963(x963, x963Len + 1, &pubKey),
WC_NO_ERR_TRACE(ECC_BAD_ARG_E));
#ifdef HAVE_COMP_KEY
/* A bare compressed format byte (0x02) with no x coordinate must be
* rejected. inLen == 1 is odd, so the early even-length check does not
* catch this -- the compressed-point length validation must. */
{
byte trunc[1] = { 0x02 };
ExpectIntEQ(wc_ecc_import_x963(trunc, 1, &pubKey),
WC_NO_ERR_TRACE(ECC_BAD_ARG_E));
}
#endif

DoExpectIntEQ(wc_FreeRng(&rng), 0);
wc_ecc_free(&key);
Expand Down Expand Up @@ -1481,6 +1491,17 @@ int test_wc_ecc_pointFns(void)
WC_NO_ERR_TRACE(ECC_BAD_ARG_E));
ExpectIntEQ(wc_ecc_import_point_der(der, derSz + 1, idx, point),
WC_NO_ERR_TRACE(ECC_BAD_ARG_E));
#ifdef HAVE_COMP_KEY
/* A bare format byte (0x02) with no x coordinate must be rejected.
* The failing import zeroes point's coordinates, so re-import the
* valid DER afterward to restore state for subsequent tests. */
{
byte trunc[1] = { 0x02 };
ExpectIntEQ(wc_ecc_import_point_der(trunc, 1, idx, point),
WC_NO_ERR_TRACE(ECC_BAD_ARG_E));
}
ExpectIntEQ(wc_ecc_import_point_der(der, derSz, idx, point), 0);
#endif

/* Copy */
ExpectIntEQ(wc_ecc_copy_point(point, cpypt), 0);
Expand Down
28 changes: 26 additions & 2 deletions wolfcrypt/src/ecc.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9628,7 +9628,18 @@ int wc_ecc_import_point_der_ex(const byte* in, word32 inLen,

if (pointType == ECC_POINT_COMP_EVEN || pointType == ECC_POINT_COMP_ODD) {
#ifdef HAVE_COMP_KEY
compressed = 1;
/* Compressed point must be exactly 1 + field_element_size bytes.
* When shortKeySize is set, callers may pass the uncompressed
* length (2*size + 1) even for compressed data.
* Reject truncated inputs (e.g. a bare 0x02/0x03 byte). */
if (inLen == (word32)ecc_sets[curve_idx].size + 1) {
compressed = 1;
} else if (shortKeySize &&
inLen == (word32)ecc_sets[curve_idx].size * 2 + 1) {
compressed = 1;
} else {
err = ECC_BAD_ARG_E;
}
Comment thread
MarkAtwood marked this conversation as resolved.
Comment thread
MarkAtwood marked this conversation as resolved.
Comment thread
MarkAtwood marked this conversation as resolved.
#else
err = NOT_COMPILED_IN;
#endif
Expand Down Expand Up @@ -10902,7 +10913,20 @@ static int _ecc_import_x963_ex2(const byte* in, word32 inLen, ecc_key* key,

if (pointType == ECC_POINT_COMP_EVEN || pointType == ECC_POINT_COMP_ODD) {
#ifdef HAVE_COMP_KEY
compressed = 1;
/* Compressed point must be at least 2 bytes (format + x coordinate).
* When curve_id is known, verify exact expected length. */
if (inLen < 2) {
err = ECC_BAD_ARG_E;
} else if (curve_id > ECC_CURVE_DEF) {
int expSz = wc_ecc_get_curve_size_from_id(curve_id);
if (expSz <= 0 || inLen != (word32)expSz + 1) {
err = ECC_BAD_ARG_E;
} else {
compressed = 1;
}
} else {
compressed = 1;
}
#else
err = NOT_COMPILED_IN;
#endif
Expand Down
Loading