ECDH: Add new ECDH context for Everest Curve25519
diff --git a/3rdparty/everest/library/x25519.c b/3rdparty/everest/library/x25519.c
new file mode 100644
index 0000000..72cab6b
--- /dev/null
+++ b/3rdparty/everest/library/x25519.c
@@ -0,0 +1,187 @@
+/*
+ * ECDH with curve-optimized implementation multiplexing
+ *
+ * Copyright 2016-2018 INRIA and Microsoft Corporation
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * This file is part of mbed TLS (https://tls.mbed.org)
+ */
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#if defined(MBEDTLS_ECDH_C)
+
+#include <Hacl_Curve25519.h>
+#include <mbedtls/platform_util.h>
+
+#include "x25519.h"
+
+#include <string.h>
+
+/*
+ * Initialize context
+ */
+void mbedtls_x25519_init( mbedtls_x25519_context *ctx )
+{
+ memset( ctx, 0, sizeof( mbedtls_x25519_context ) );
+}
+
+/*
+ * Free context
+ */
+void mbedtls_x25519_free( mbedtls_x25519_context *ctx )
+{
+ if( ctx == NULL )
+ return;
+
+ mbedtls_platform_zeroize( ctx->our_secret, 32 );
+ mbedtls_platform_zeroize( ctx->peer_point, 32 );
+}
+
+int mbedtls_x25519_make_params( mbedtls_x25519_context *ctx, size_t *olen,
+ unsigned char *buf, size_t blen,
+ int( *f_rng )(void *, unsigned char *, size_t),
+ void *p_rng )
+{
+ int ret = 0;
+
+ uint8_t base[32] = {0};
+
+ if( ( ret = f_rng( p_rng, ctx->our_secret, 32 ) ) != 0 )
+ return ret;
+
+ *olen = 36;
+ if( blen < *olen )
+ return( MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL );
+
+ *buf++ = MBEDTLS_ECP_TLS_NAMED_CURVE;
+ *buf++ = MBEDTLS_ECP_TLS_CURVE25519 >> 8;
+ *buf++ = MBEDTLS_ECP_TLS_CURVE25519 & 0xFF;
+ *buf++ = 32;
+
+ base[0] = 9;
+ Hacl_Curve25519_crypto_scalarmult( buf, ctx->our_secret, base );
+
+ base[0] = 0;
+ if( memcmp( buf, base, 32) == 0 )
+ return MBEDTLS_ERR_ECP_RANDOM_FAILED;
+
+ return( 0 );
+}
+
+int mbedtls_x25519_read_params( mbedtls_x25519_context *ctx,
+ const unsigned char **buf, const unsigned char *end )
+{
+ if( end - *buf < 33 )
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+ if( ( *(*buf)++ != 32 ) )
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+ memcpy( ctx->peer_point, *buf, 32 );
+ *buf += 32;
+ return( 0 );
+}
+
+int mbedtls_x25519_get_params( mbedtls_x25519_context *ctx, const mbedtls_ecp_keypair *key,
+ int side )
+{
+ size_t olen = 0;
+
+ switch( side ) {
+ case MBEDTLS_ECDH_THEIRS:
+ mbedtls_ecp_point_write_binary( &key->grp, &key->Q, MBEDTLS_ECP_PF_COMPRESSED, &olen, ctx->peer_point, 32 );
+ /* untested; defensively throw an error for now. */
+ return(MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE);
+ case MBEDTLS_ECDH_OURS:
+ mbedtls_mpi_write_binary( &key->d, ctx->our_secret, 32 );
+ /* CMW: key->Q = key->d * base; do we need to set up ctx.peer_point here? */
+ /* untested; defensively throw an error for now. */
+ return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+ default:
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+ }
+}
+
+int mbedtls_x25519_calc_secret( mbedtls_x25519_context *ctx, size_t *olen,
+ unsigned char *buf, size_t blen,
+ int( *f_rng )(void *, unsigned char *, size_t),
+ void *p_rng )
+{
+ /* CMW: Is it okay that f_rng, p_rng are not used? */
+ (( void )f_rng);
+ (( void )p_rng);
+
+ *olen = 32;
+
+ if( blen < *olen )
+ return( MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL );
+
+ Hacl_Curve25519_crypto_scalarmult( buf, ctx->our_secret, ctx->peer_point);
+
+ /* Wipe the DH secret and don't let the peer chose a small subgroup point */
+ memset( ctx->our_secret, 0, 32 );
+ if( memcmp( buf, ctx->our_secret, 32) == 0 )
+ return MBEDTLS_ERR_ECP_RANDOM_FAILED;
+
+ return( 0 );
+}
+
+int mbedtls_x25519_make_public( mbedtls_x25519_context *ctx, size_t *olen,
+ unsigned char *buf, size_t blen,
+ int( *f_rng )(void *, unsigned char *, size_t),
+ void *p_rng )
+{
+ unsigned char base[32] = { 0 };
+
+ /* CMW: Is it okay that f_rng, p_rng are not used? */
+ (( void )f_rng);
+ (( void )p_rng);
+
+ if( ctx == NULL )
+ return(MBEDTLS_ERR_ECP_BAD_INPUT_DATA);
+
+ *olen = 33;
+ if( blen < *olen )
+ return(MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL);
+ *buf++ = 32;
+
+ base[0] = 9;
+ Hacl_Curve25519_crypto_scalarmult( buf, ctx->our_secret, base );
+
+ base[0] = 0;
+ if( memcmp( buf, base, 32 ) == 0 )
+ return MBEDTLS_ERR_ECP_RANDOM_FAILED;
+
+ return(0);
+}
+
+int mbedtls_x25519_read_public( mbedtls_x25519_context *ctx,
+ const unsigned char *buf, size_t blen )
+{
+ if( blen < 33 )
+ return(MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL);
+ if( (*buf++ != 32) )
+ return(MBEDTLS_ERR_ECP_BAD_INPUT_DATA);
+ memcpy( ctx->peer_point, buf, 32 );
+ return(0);
+}
+
+
+#endif /* MBEDTLS_ECDH_C */