Add tests for ECDSA verify with short r, s values
This is intended to test transcoding the signature to the format expected by
PSA (fixed-length encoding of r, s) when r and s have respectively:
- full length with initial null byte
- full length without initial null byte
- non-full length with initial null byte
- non-full length without initial null byte
The signatures were generated using:
programs/pkey/pk_sign tests/data_files/server5.key foo
where foo is an empty file, and with a variant of one of the following patches
applied:
diff --git a/library/ecdsa.c b/library/ecdsa.c
index abac015cebc6..e4a27b044516 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -305,7 +305,9 @@ static int ecdsa_sign_restartable( mbedtls_ecp_group *grp,
ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
goto cleanup;
}
+ printf("\ngenerating r...\n");
+gen:
MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, pk, f_rng, p_rng ) );
#if defined(MBEDTLS_ECP_RESTARTABLE)
@@ -317,6 +319,11 @@ mul:
MBEDTLS_MPI_CHK( mbedtls_ecp_mul_restartable( grp, &R, pk, &grp->G,
f_rng, p_rng, ECDSA_RS_ECP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pr, &R.X, &grp->N ) );
+
+ size_t bits = mbedtls_mpi_bitlen( pr );
+ printf("%zu ", bits);
+ if( bits != 255 )
+ goto gen;
}
while( mbedtls_mpi_cmp_int( pr, 0 ) == 0 );
or:
diff --git a/library/ecdsa.c b/library/ecdsa.c
index abac015cebc6..d704376e0c42 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -305,7 +305,9 @@ static int ecdsa_sign_restartable( mbedtls_ecp_group *grp,
ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
goto cleanup;
}
+ printf("\ngenerating r...\n");
+gen:
MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, pk, f_rng, p_rng ) );
#if defined(MBEDTLS_ECP_RESTARTABLE)
@@ -353,6 +355,11 @@ modn:
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( s, pk, &grp->N ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, s, &e ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( s, s, &grp->N ) );
+
+ size_t bits = mbedtls_mpi_bitlen( s );
+ printf("%zu ", bits);
+ if( bits != 247 )
+ goto gen;
}
while( mbedtls_mpi_cmp_int( s, 0 ) == 0 );
with the value edited manually between each run to get the desired bit length.
2baae9ef71