commit 52ff8e938719eaeb33d6bf552afab2ea67e3e1ce
author Janos Follath <janos.follath@arm.com> Tue Feb 26 13:56:04 2019 +0000
committer Janos Follath <janos.follath@arm.com> Tue Feb 26 16:49:52 2019 +0000
tree d0573174f066378dcec674e2400a70317ccd92ba
parent bf42408528f5db2ba1d94e10dd34a784a52c5b2d

Fix ECDH secret export for Mongomery curves

We only switched to little endian for Curve25519, but all Montgomery
curves require little endian byte order.

library/ecdh.c

diff --git a/library/ecdh.c b/library/ecdh.c
index 30c5f9f..eecae91 100644
--- a/library/ecdh.c
+++ b/library/ecdh.c
@@ -638,7 +638,7 @@
 
     *olen = ctx->grp.pbits / 8 + ( ( ctx->grp.pbits % 8 ) != 0 );
 
-    if( ctx->grp.id == MBEDTLS_ECP_DP_CURVE25519 )
+    if( mbedtls_ecp_get_type( &ctx->grp ) == MBEDTLS_ECP_TYPE_MONTGOMERY )
         return mbedtls_mpi_write_binary_le( &ctx->z, buf, *olen );
 
     return mbedtls_mpi_write_binary( &ctx->z, buf, *olen );