diff --git a/examples/Makefile-nrf52840 b/examples/Makefile-nrf52840
index 1b4ea8025..4dc53c82e 100644
--- a/examples/Makefile-nrf52840
+++ b/examples/Makefile-nrf52840
@@ -41,13 +41,14 @@ OBJCOPY                         = arm-none-eabi-objcopy
 
 BuildJobs                      ?= 10
 
-configure_OPTIONS               = \
-    --enable-ftd                  \
-    --enable-cli                  \
-    --enable-ncp                  \
-    --enable-diag                 \
-    --with-examples=nrf52840      \
-    --with-platform-info=NRF52840 \
+configure_OPTIONS                                 = \
+    --enable-ftd                                    \
+    --enable-cli                                    \
+    --enable-ncp                                    \
+    --enable-diag                                   \
+    --with-examples=nrf52840                        \
+    --with-platform-info=NRF52840                   \
+    MBEDTLS_CPPFLAGS="$(NRF52840_MBEDTLS_CPPFLAGS)" \
     $(NULL)
 
 ifeq ($(DEFAULT_LOGGING),1)
@@ -109,6 +110,13 @@ endif
 TopSourceDir                    := $(dir $(shell readlink $(firstword $(MAKEFILE_LIST))))..
 AbsTopSourceDir                 := $(dir $(realpath $(firstword $(MAKEFILE_LIST))))..
 
+NRF52840_MBEDTLS_CPPFLAGS  = -DMBEDTLS_CONFIG_FILE='\"mbedtls-config.h\"'
+NRF52840_MBEDTLS_CPPFLAGS += -DMBEDTLS_USER_CONFIG_FILE='\"nrf52840-mbedtls-config.h\"'
+NRF52840_MBEDTLS_CPPFLAGS += -I$(AbsTopSourceDir)/examples/platforms/nrf52840/crypto
+NRF52840_MBEDTLS_CPPFLAGS += -I$(AbsTopSourceDir)/third_party/mbedtls
+NRF52840_MBEDTLS_CPPFLAGS += -I$(AbsTopSourceDir)/third_party/mbedtls/repo/include
+NRF52840_MBEDTLS_CPPFLAGS += -I$(AbsTopSourceDir)/third_party/mbedtls/repo/include/mbedtls
+
 CONFIG_FILE      = OPENTHREAD_PROJECT_CORE_CONFIG_FILE='\"openthread-core-nrf52840-config.h\"'
 CONFIG_FILE_PATH = $(AbsTopSourceDir)/examples/platforms/nrf52840/
 
diff --git a/examples/platforms/nrf52840/crypto/nrf52840-mbedtls-config.h b/examples/platforms/nrf52840/crypto/nrf52840-mbedtls-config.h
new file mode 100644
index 000000000..9673989ea
--- /dev/null
+++ b/examples/platforms/nrf52840/crypto/nrf52840-mbedtls-config.h
@@ -0,0 +1,29 @@
+/*
+ *  Copyright (c) 2017, The OpenThread Authors.
+ *  All rights reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions are met:
+ *  1. Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *  3. Neither the name of the copyright holder nor the
+ *     names of its contributors may be used to endorse or promote products
+ *     derived from this software without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *  POSSIBILITY OF SUCH DAMAGE.
+ */
+
+ #define MBEDTLS_SHA256_ALT
diff --git a/examples/platforms/nrf52840/crypto/sha256_alt.h b/examples/platforms/nrf52840/crypto/sha256_alt.h
new file mode 100644
index 000000000..e4233dda0
--- /dev/null
+++ b/examples/platforms/nrf52840/crypto/sha256_alt.h
@@ -0,0 +1,114 @@
+/*
+ *  Copyright (c) 2017, The OpenThread Authors.
+ *  All rights reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions are met:
+ *  1. Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *  3. Neither the name of the copyright holder nor the
+ *     names of its contributors may be used to endorse or promote products
+ *     derived from this software without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *  POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef MBEDTLS_SHA256_ALT_H
+#define MBEDTLS_SHA256_ALT_H
+
+#ifdef MBEDTLS_SHA256_ALT
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief          SHA-256 context structure
+ */
+typedef union
+{
+    struct
+    {
+        uint32_t total[2];          /*!< number of bytes processed  */
+        uint32_t state[8];          /*!< intermediate digest state  */
+        unsigned char buffer[64];   /*!< data block being processed */
+        int is224;                  /*!< 0 => SHA-256, else SHA-224 */
+    };
+    uint8_t reserved[256];
+}
+mbedtls_sha256_context;
+
+/**
+ * @brief Initialize SHA-256 context
+ *
+ * @param [in,out] ctx SHA-256 context to be initialized
+ */
+void mbedtls_sha256_init(mbedtls_sha256_context *ctx);
+
+/**
+ * @brief Clear SHA-256 context
+ *
+ * @param [in,out] ctx SHA-256 context to be cleared
+ */
+void mbedtls_sha256_free(mbedtls_sha256_context *ctx);
+
+/**
+ * @brief Clone (the state of) a SHA-256 context
+ *
+ * @param [out] dst The destination context
+ * @param [in] src The context to be cloned
+ */
+void mbedtls_sha256_clone(mbedtls_sha256_context *dst,
+                          const mbedtls_sha256_context *src);
+
+/**
+ * @brief SHA-256 context setup
+ *
+ * @param [in,out] ctx context to be initialized
+ * @param [in] is224 0 = use SHA256, 1 = use SHA224
+ */
+void mbedtls_sha256_starts(mbedtls_sha256_context *ctx, int is224);
+
+/**
+ * @brief SHA-256 process buffer
+ *
+ * @param [in,out] ctx SHA-256 context
+ * @param [in] input buffer holding the  data
+ * @param [in] ilen length of the input data
+ */
+void mbedtls_sha256_update(mbedtls_sha256_context *ctx, const unsigned char *input, size_t ilen);
+
+/**
+ * @brief SHA-256 final digest
+ *
+ * @param [in,out] ctx SHA-256 context
+ * @param [out] output SHA-224/256 checksum result
+ */
+void mbedtls_sha256_finish(mbedtls_sha256_context *ctx, unsigned char output[32]);
+
+/* Internal use */
+void mbedtls_sha256_process(mbedtls_sha256_context *ctx, const unsigned char data[64]);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* MBEDTLS_SHA256_ALT */
+
+/* MBEDTLS_SHA256_ALT was used to redifine context structure. Undefine it now to enable default mbedTLS implementation. */
+#undef MBEDTLS_SHA256_ALT
+
+#endif /* MBEDTLS_SHA256_ALT_H */