Fix information leak in ecp_gen_keypair_base

The function ecp_gen_keypair_base did not wipe the stack buffer used to
hold the private exponent before returning. This commit fixes this by not using
a stack buffer in the first place but instead calling mpi_fill_random directly
to acquire the necessary random MPI.
This commit is contained in:
Hanno Becker 2017-10-25 16:08:19 +01:00
parent 0727ca41b7
commit 754663f8c4

View file

@ -1854,7 +1854,6 @@ int ecp_gen_keypair( ecp_group *grp, mpi *d, ecp_point *Q,
{
/* SEC1 3.2.1: Generate d such that 1 <= n < N */
int count = 0;
unsigned char rnd[POLARSSL_ECP_MAX_BYTES];
/*
* Match the procedure given in RFC 6979 (deterministic ECDSA):
@ -1865,8 +1864,7 @@ int ecp_gen_keypair( ecp_group *grp, mpi *d, ecp_point *Q,
*/
do
{
MPI_CHK( f_rng( p_rng, rnd, n_size ) );
MPI_CHK( mpi_read_binary( d, rnd, n_size ) );
MPI_CHK( mpi_fill_random( d, n_size, f_rng, p_rng ) );
MPI_CHK( mpi_shift_r( d, 8 * n_size - grp->nbits ) );
/*