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Fix an overflow in EC key derivation.

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Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
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Pol Henarejos 2022-03-24 20:42:43 +01:00
parent 483dc5e953
commit c2a474df98
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GPG key ID: C0095B7870A4CCD3
1 changed files with 19 additions and 2 deletions
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21
src/hsm/sc_hsm.c
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@ -1225,7 +1225,8 @@ int load_private_key_ecdsa(mbedtls_ecdsa_context *ctx, file_t *fkey) {
}
release_dkek();
mbedtls_ecp_group_id gid = kdata[0];
if (mbedtls_ecp_read_key(gid, ctx, kdata+1, key_size-1) != 0) {
int r = mbedtls_ecp_read_key(gid, ctx, kdata+1, key_size-1);
if (r != 0) {
free(kdata);
mbedtls_ecdsa_free(ctx);
return HSM_EXEC_ERROR;
@ -1553,6 +1554,22 @@ static int cmd_cipher_sym() {
return SW_OK();
}
#define MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED -0x006E
#define MOD_ADD( N ) \
while( mbedtls_mpi_cmp_mpi( &(N), &grp->P ) >= 0 ) \
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_abs( &(N), &(N), &grp->P ) )
static inline int mbedtls_mpi_add_mod( const mbedtls_ecp_group *grp,
mbedtls_mpi *X,
const mbedtls_mpi *A,
const mbedtls_mpi *B )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( X, A, B ) );
MOD_ADD( *X );
cleanup:
return( ret );
}
static int cmd_derive_asym() {
uint8_t key_id = P1(apdu);
uint8_t dest_id = P2(apdu);
@ -1584,7 +1601,7 @@ static int cmd_derive_asym() {
mbedtls_mpi_free(&nd);
return SW_DATA_INVALID();
}
r = mbedtls_mpi_add_mpi(&nd, &ctx.d, &a);
r = mbedtls_mpi_add_mod(&ctx.grp, &nd, &ctx.d, &a);
if (r != 0) {
mbedtls_ecdsa_free(&ctx);
mbedtls_mpi_free(&a);