diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 910de1f..233a19e 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -43,6 +43,7 @@
 
 #include "psa/crypto.h"
 
+#include "psa_crypto_invasive.h"
 /* Include internal declarations that are useful for implementing persistently
  * stored keys. */
 #include "psa_crypto_storage.h"
@@ -146,12 +147,23 @@
     return( PSA_KEY_TYPE_IS_UNSTRUCTURED( type ) );
 }
 
+enum rng_state
+{
+    RNG_NOT_INITIALIZED = 0,
+    RNG_INITIALIZED,
+    RNG_SEEDED,
+};
+
 typedef struct
 {
-    int initialized;
+    void (* entropy_init )( mbedtls_entropy_context *ctx );
+    void (* entropy_free )( mbedtls_entropy_context *ctx );
     mbedtls_entropy_context entropy;
     mbedtls_ctr_drbg_context ctr_drbg;
     key_slot_t key_slots[PSA_KEY_SLOT_COUNT];
+    unsigned initialized : 1;
+    enum rng_state rng_state : 2;
+    unsigned key_slots_initialized : 1;
 } psa_global_data_t;
 
 static psa_global_data_t global_data;
@@ -4439,23 +4451,42 @@
 /* Module setup */
 /****************************************************************/
 
+psa_status_t mbedtls_psa_crypto_configure_entropy_sources(
+    void (* entropy_init )( mbedtls_entropy_context *ctx ),
+    void (* entropy_free )( mbedtls_entropy_context *ctx ) )
+{
+    if( global_data.rng_state != RNG_NOT_INITIALIZED )
+        return( PSA_ERROR_BAD_STATE );
+    global_data.entropy_init = entropy_init;
+    global_data.entropy_free = entropy_free;
+    return( PSA_SUCCESS );
+}
+
 void mbedtls_psa_crypto_free( void )
 {
     psa_key_slot_t key;
     key_slot_t *slot;
     psa_status_t status;
-
-    for( key = 1; key <= PSA_KEY_SLOT_COUNT; key++ )
+    if( global_data.key_slots_initialized )
     {
-        status = psa_get_key_slot( key, &slot );
-        if( status != PSA_SUCCESS )
-            continue;
-        psa_remove_key_data_from_memory( slot );
-        /* Zeroize the slot to wipe metadata such as policies. */
-        mbedtls_zeroize( slot, sizeof( *slot ) );
+        for( key = 1; key <= PSA_KEY_SLOT_COUNT; key++ )
+        {
+            status = psa_get_key_slot( key, &slot );
+            if( status != PSA_SUCCESS )
+                continue;
+            psa_remove_key_data_from_memory( slot );
+            /* Zeroize the slot to wipe metadata such as policies. */
+            mbedtls_zeroize( slot, sizeof( *slot ) );
+        }
     }
-    mbedtls_ctr_drbg_free( &global_data.ctr_drbg );
-    mbedtls_entropy_free( &global_data.entropy );
+    if( global_data.rng_state != RNG_NOT_INITIALIZED )
+    {
+        mbedtls_ctr_drbg_free( &global_data.ctr_drbg );
+        global_data.entropy_free( &global_data.entropy );
+    }
+    /* Wipe all remaining data, including configuration.
+     * In particular, this sets all state indicator to the value
+     * indicating "uninitialized". */
     mbedtls_zeroize( &global_data, sizeof( global_data ) );
 }
 
@@ -4464,20 +4495,35 @@
     int ret;
     const unsigned char drbg_seed[] = "PSA";
 
+    /* Double initialization is explicitly allowed. */
     if( global_data.initialized != 0 )
         return( PSA_SUCCESS );
 
-    mbedtls_zeroize( &global_data, sizeof( global_data ) );
-    mbedtls_entropy_init( &global_data.entropy );
-    mbedtls_ctr_drbg_init( &global_data.ctr_drbg );
+    /* Set default configuration if
+     * mbedtls_psa_crypto_configure_entropy_sources() hasn't been called. */
+    if( global_data.entropy_init == NULL )
+        global_data.entropy_init = mbedtls_entropy_init;
+    if( global_data.entropy_free == NULL )
+        global_data.entropy_free = mbedtls_entropy_free;
 
+    /* Initialize the random generator. */
+    global_data.entropy_init( &global_data.entropy );
+    mbedtls_ctr_drbg_init( &global_data.ctr_drbg );
+    global_data.rng_state = RNG_INITIALIZED;
     ret = mbedtls_ctr_drbg_seed( &global_data.ctr_drbg,
                                  mbedtls_entropy_func,
                                  &global_data.entropy,
                                  drbg_seed, sizeof( drbg_seed ) - 1 );
     if( ret != 0 )
         goto exit;
+    global_data.rng_state = RNG_SEEDED;
 
+    /* Initialize the key slots. Zero-initialization has made all key
+     * slots empty, so there is nothing to do. In a future version we will
+     * load data from storage. */
+    global_data.key_slots_initialized = 1;
+
+    /* All done. */
     global_data.initialized = 1;
 
 exit:
diff --git a/library/psa_crypto_invasive.h b/library/psa_crypto_invasive.h
new file mode 100644
index 0000000..642652a
--- /dev/null
+++ b/library/psa_crypto_invasive.h
@@ -0,0 +1,79 @@
+/**
+ * \file psa_crypto_invasive.h
+ *
+ * \brief PSA cryptography module: invasive interfaces for test only.
+ *
+ * The interfaces in this file are intended for testing purposes only.
+ * They MUST NOT be made available to clients over IPC in integrations
+ * with isolation, and they SHOULD NOT be made available in library
+ * integrations except when building the library for testing.
+ */
+/*
+ *  Copyright (C) 2018, ARM Limited, All Rights Reserved
+ *  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)
+ */
+
+#ifndef PSA_CRYPTO_INVASIVE_H
+#define PSA_CRYPTO_INVASIVE_H
+
+#if defined(MBEDTLS_CONFIG_FILE)
+#include MBEDTLS_CONFIG_FILE
+#else
+#include "mbedtls/config.h"
+#endif
+
+#include "psa/crypto.h"
+
+#include "mbedtls/entropy.h"
+
+/** \brief Configure entropy sources.
+ *
+ * This function may only be called before a call to psa_crypto_init(),
+ * or after a call to mbedtls_psa_crypto_free() and before any
+ * subsequent call to psa_crypto_init().
+ *
+ * This function is only intended for test purposes. The functionality
+ * it provides is also useful for system integrators, but
+ * system integrators should configure entropy drivers instead of
+ * breaking through to the Mbed TLS API.
+ *
+ * \param entropy_init  Function to initialize the entropy context
+ *                      and set up the desired entropy sources.
+ *                      It is called by psa_crypto_init().
+ *                      By default this is mbedtls_entropy_init().
+ *                      This function cannot report failures directly.
+ *                      To indicate a failure, set the entropy context
+ *                      to a state where mbedtls_entropy_func() will
+ *                      return an error.
+ * \param entropy_free  Function to free the entropy context
+ *                      and associated resources.
+ *                      It is called by mbedtls_psa_crypto_free().
+ *                      By default this is mbedtls_entropy_free().
+ *
+ * \retval PSA_SUCCESS
+ *         Success.
+ * \retval PSA_ERROR_NOT_PERMITTED
+ *         The caller does not have the permission to configure
+ *         entropy sources.
+ * \retval PSA_ERROR_BAD_STATE
+ *         The library has already been initialized.
+ */
+psa_status_t mbedtls_psa_crypto_configure_entropy_sources(
+    void (* entropy_init )( mbedtls_entropy_context *ctx ),
+    void (* entropy_free )( mbedtls_entropy_context *ctx ) );
+
+#endif /* PSA_CRYPTO_INVASIVE_H */
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 95d60ff..56ce933 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -113,6 +113,7 @@
 add_test_suite(psa_crypto)
 add_test_suite(psa_crypto_entropy)
 add_test_suite(psa_crypto_hash)
+add_test_suite(psa_crypto_init)
 add_test_suite(psa_crypto_metadata)
 add_test_suite(psa_crypto_persistent_key)
 add_test_suite(psa_crypto_storage_file)
diff --git a/tests/suites/test_suite_psa_crypto.data b/tests/suites/test_suite_psa_crypto.data
index 6087412..91739f5 100644
--- a/tests/suites/test_suite_psa_crypto.data
+++ b/tests/suites/test_suite_psa_crypto.data
@@ -1,9 +1,6 @@
 PSA compile-time sanity checks
 static_checks:
 
-PSA init/deinit
-init_deinit:
-
 PSA fill 250 slots
 fill_slots:250
 
@@ -1829,12 +1826,6 @@
 depends_on:MBEDTLS_ECP_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED:MBEDTLS_ECDSA_C
 generate_key:PSA_KEY_TYPE_ECC_KEYPAIR(PSA_ECC_CURVE_SECP256R1):128:PSA_KEY_USAGE_EXPORT | PSA_KEY_USAGE_SIGN | PSA_KEY_USAGE_VERIFY:PSA_ALG_ECDSA_ANY:PSA_ERROR_INVALID_ARGUMENT
 
-PSA validate module initialization: random
-validate_module_init_generate_random:
-
-PSA validate module initialization: key based
-validate_module_init_key_based:
-
 persistent key can be accessed after in-memory deletion: AES, 128 bits, CTR
 depends_on:MBEDTLS_PK_C:MBEDTLS_PK_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_PSA_CRYPTO_STORAGE_C
 persistent_key_load_key_from_storage:"2b7e151628aed2a6abf7158809cf4f3c":PSA_KEY_TYPE_AES:128:PSA_KEY_USAGE_EXPORT:PSA_ALG_CTR:IMPORT_KEY:PSA_SUCCESS
diff --git a/tests/suites/test_suite_psa_crypto.function b/tests/suites/test_suite_psa_crypto.function
index 53295be..2fa060b 100644
--- a/tests/suites/test_suite_psa_crypto.function
+++ b/tests/suites/test_suite_psa_crypto.function
@@ -872,22 +872,6 @@
 /* END_CASE */
 
 /* BEGIN_CASE */
-void init_deinit( )
-{
-    psa_status_t status;
-    int i;
-    for( i = 0; i <= 1; i++ )
-    {
-        status = psa_crypto_init( );
-        TEST_ASSERT( status == PSA_SUCCESS );
-        status = psa_crypto_init( );
-        TEST_ASSERT( status == PSA_SUCCESS );
-        mbedtls_psa_crypto_free( );
-    }
-}
-/* END_CASE */
-
-/* BEGIN_CASE */
 void fill_slots( int max_arg )
 {
     /* Fill all the slots until we run out of memory or out of slots,
@@ -4018,26 +4002,6 @@
 }
 /* END_CASE */
 
-/* BEGIN_CASE */
-void validate_module_init_generate_random( )
-{
-    psa_status_t status;
-    uint8_t random[10] = { 0 };
-    status = psa_generate_random( random, sizeof( random ) );
-    TEST_ASSERT( status == PSA_ERROR_BAD_STATE );
-}
-/* END_CASE */
-
-/* BEGIN_CASE */
-void validate_module_init_key_based( )
-{
-    psa_status_t status;
-    uint8_t data[10] = { 0 };
-    status = psa_import_key( 1, PSA_KEY_TYPE_RAW_DATA, data, sizeof( data ) );
-    TEST_ASSERT( status == PSA_ERROR_BAD_STATE );
-}
-/* END_CASE */
-
 /* BEGIN_CASE depends_on:MBEDTLS_PSA_CRYPTO_STORAGE_C */
 void persistent_key_load_key_from_storage( data_t *data, int type_arg,
                                            int bits, int usage_arg,
diff --git a/tests/suites/test_suite_psa_crypto_init.data b/tests/suites/test_suite_psa_crypto_init.data
new file mode 100644
index 0000000..c57a764
--- /dev/null
+++ b/tests/suites/test_suite_psa_crypto_init.data
@@ -0,0 +1,56 @@
+Create NV seed file
+create_nv_seed:
+
+PSA init/deinit
+init_deinit:2
+
+PSA deinit without init
+deinit_without_init:0
+
+PSA deinit twice
+deinit_without_init:1
+
+No random without init
+validate_module_init_generate_random:0
+
+No key slot access without init
+validate_module_init_key_based:0
+
+No random after deinit
+validate_module_init_generate_random:1
+
+No key slot access after deinit
+validate_module_init_key_based:1
+
+Custom entropy sources: all standard
+custom_entropy_sources:0x0000ffff:PSA_SUCCESS
+
+Custom entropy sources: none
+custom_entropy_sources:0:PSA_ERROR_INSUFFICIENT_ENTROPY
+
+Fake entropy: never returns anything
+fake_entropy_source:MBEDTLS_ENTROPY_BLOCK_SIZE:0:0:0:0:PSA_ERROR_INSUFFICIENT_ENTROPY
+
+Fake entropy: less than the block size
+fake_entropy_source:MBEDTLS_ENTROPY_BLOCK_SIZE:MBEDTLS_ENTROPY_BLOCK_SIZE - 1:-1:-1:-1:PSA_ERROR_INSUFFICIENT_ENTROPY
+
+Fake entropy: one block eventually
+fake_entropy_source:MBEDTLS_ENTROPY_BLOCK_SIZE:0:0:0:MBEDTLS_ENTROPY_BLOCK_SIZE:PSA_SUCCESS
+
+Fake entropy: one block in two steps
+fake_entropy_source:MBEDTLS_ENTROPY_BLOCK_SIZE:MBEDTLS_ENTROPY_BLOCK_SIZE - 1:1:-1:-1:PSA_SUCCESS
+
+Fake entropy: more than one block in two steps
+fake_entropy_source:MBEDTLS_ENTROPY_BLOCK_SIZE:MBEDTLS_ENTROPY_BLOCK_SIZE - 1:MBEDTLS_ENTROPY_BLOCK_SIZE - 1:-1:-1:PSA_SUCCESS
+
+NV seed only: less than minimum
+entropy_from_nv_seed:MBEDTLS_ENTROPY_MIN_PLATFORM - 1:PSA_ERROR_INSUFFICIENT_ENTROPY
+
+NV seed only: less than one block
+entropy_from_nv_seed:MBEDTLS_ENTROPY_BLOCK_SIZE - 1:PSA_ERROR_INSUFFICIENT_ENTROPY
+
+NV seed only: just enough
+entropy_from_nv_seed:ENTROPY_MIN_NV_SEED_SIZE:PSA_SUCCESS
+
+Recreate NV seed file
+create_nv_seed:
diff --git a/tests/suites/test_suite_psa_crypto_init.function b/tests/suites/test_suite_psa_crypto_init.function
new file mode 100644
index 0000000..3596504
--- /dev/null
+++ b/tests/suites/test_suite_psa_crypto_init.function
@@ -0,0 +1,294 @@
+/* BEGIN_HEADER */
+#include <stdint.h>
+
+#if defined(MBEDTLS_PSA_CRYPTO_SPM)
+#include "spm/psa_defs.h"
+#endif
+#include "psa/crypto.h"
+
+/* Some tests in this module configure entropy sources. */
+#include "psa_crypto_invasive.h"
+
+#include "mbedtls/entropy.h"
+#include "mbedtls/entropy_poll.h"
+#include "mbedtls/platform.h"
+
+#define MIN( x, y ) ( ( x ) < ( y ) ? ( x ) : ( y ) )
+#define MAX( x, y ) ( ( x ) > ( y ) ? ( x ) : ( y ) )
+
+#define ENTROPY_MIN_NV_SEED_SIZE                                        \
+    MAX(MBEDTLS_ENTROPY_MIN_PLATFORM, MBEDTLS_ENTROPY_BLOCK_SIZE)
+
+typedef struct
+{
+    size_t threshold; /* Minimum bytes to make mbedtls_entropy_func happy */
+    size_t max_steps;
+    size_t *length_sequence;
+    size_t step;
+} fake_entropy_state_t;
+static int fake_entropy_source( void *state_arg,
+                                unsigned char *output, size_t len,
+                                size_t *olen )
+{
+    fake_entropy_state_t *state = state_arg;
+    size_t i;
+
+    if( state->step >= state->max_steps )
+        return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
+
+    *olen = MIN( len, state->length_sequence[state->step] );
+    for( i = 0; i < *olen; i++ )
+        output[i] = i;
+    ++state->step;
+    return( 0 );
+};
+
+#define ENTROPY_SOURCE_PLATFORM                 0x00000001
+#define ENTROPY_SOURCE_TIMING                   0x00000002
+#define ENTROPY_SOURCE_HAVEGE                   0x00000004
+#define ENTROPY_SOURCE_HARDWARE                 0x00000008
+#define ENTROPY_SOURCE_NV_SEED                  0x00000010
+#define ENTROPY_SOURCE_FAKE                     0x40000000
+
+static uint32_t custom_entropy_sources_mask;
+static fake_entropy_state_t fake_entropy_state;
+
+/* This is a modified version of mbedtls_entropy_init() from entropy.c
+ * which chooses entropy sources dynamically. */
+static void custom_entropy_init( mbedtls_entropy_context *ctx )
+{
+    ctx->source_count = 0;
+    memset( ctx->source, 0, sizeof( ctx->source ) );
+
+#if defined(MBEDTLS_THREADING_C)
+    mbedtls_mutex_init( &ctx->mutex );
+#endif
+
+    ctx->accumulator_started = 0;
+#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
+    mbedtls_sha512_init( &ctx->accumulator );
+#else
+    mbedtls_sha256_init( &ctx->accumulator );
+#endif
+#if defined(MBEDTLS_HAVEGE_C)
+    mbedtls_havege_init( &ctx->havege_data );
+#endif
+
+#if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
+    if( custom_entropy_sources_mask & ENTROPY_SOURCE_PLATFORM )
+        mbedtls_entropy_add_source( ctx, mbedtls_platform_entropy_poll, NULL,
+                                    MBEDTLS_ENTROPY_MIN_PLATFORM,
+                                    MBEDTLS_ENTROPY_SOURCE_STRONG );
+#endif
+#if defined(MBEDTLS_TIMING_C)
+    if( custom_entropy_sources_mask & ENTROPY_SOURCE_TIMING )
+        mbedtls_entropy_add_source( ctx, mbedtls_hardclock_poll, NULL,
+                                    MBEDTLS_ENTROPY_MIN_HARDCLOCK,
+                                    MBEDTLS_ENTROPY_SOURCE_WEAK );
+#endif
+#if defined(MBEDTLS_HAVEGE_C)
+    if( custom_entropy_sources_mask & ENTROPY_SOURCE_HAVEGE )
+        mbedtls_entropy_add_source( ctx, mbedtls_havege_poll, &ctx->havege_data,
+                                    MBEDTLS_ENTROPY_MIN_HAVEGE,
+                                    MBEDTLS_ENTROPY_SOURCE_STRONG );
+#endif
+#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
+    if( custom_entropy_sources_mask & ENTROPY_SOURCE_HARDWARE )
+        mbedtls_entropy_add_source( ctx, mbedtls_hardware_poll, NULL,
+                                    MBEDTLS_ENTROPY_MIN_HARDWARE,
+                                    MBEDTLS_ENTROPY_SOURCE_STRONG );
+#endif
+#if defined(MBEDTLS_ENTROPY_NV_SEED)
+    if( custom_entropy_sources_mask & ENTROPY_SOURCE_NV_SEED )
+    {
+        mbedtls_entropy_add_source( ctx, mbedtls_nv_seed_poll, NULL,
+                                    MBEDTLS_ENTROPY_BLOCK_SIZE,
+                                    MBEDTLS_ENTROPY_SOURCE_STRONG );
+        ctx->initial_entropy_run = 0;
+    }
+    else
+    {
+        /* Skip the NV seed even though it's compiled in. */
+        ctx->initial_entropy_run = 1;
+    }
+#endif
+
+    if( custom_entropy_sources_mask & ENTROPY_SOURCE_FAKE )
+        mbedtls_entropy_add_source( ctx,
+                                    fake_entropy_source, &fake_entropy_state,
+                                    fake_entropy_state.threshold,
+                                    MBEDTLS_ENTROPY_SOURCE_STRONG );
+}
+
+/* END_HEADER */
+
+/* BEGIN_DEPENDENCIES
+ * depends_on:MBEDTLS_PSA_CRYPTO_C
+ * END_DEPENDENCIES
+ */
+
+/* BEGIN_CASE depends_on:MBEDTLS_ENTROPY_NV_SEED */
+void create_nv_seed( )
+{
+    static unsigned char seed[ENTROPY_MIN_NV_SEED_SIZE];
+    TEST_ASSERT( mbedtls_nv_seed_write( seed, sizeof( seed ) ) >= 0 );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void init_deinit( int count )
+{
+    psa_status_t status;
+    int i;
+    for( i = 0; i < count; i++ )
+    {
+        status = psa_crypto_init( );
+        TEST_ASSERT( status == PSA_SUCCESS );
+        status = psa_crypto_init( );
+        TEST_ASSERT( status == PSA_SUCCESS );
+        mbedtls_psa_crypto_free( );
+    }
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void deinit_without_init( int count )
+{
+    int i;
+    for( i = 0; i < count; i++ )
+    {
+        TEST_ASSERT( psa_crypto_init( ) == PSA_SUCCESS );
+        mbedtls_psa_crypto_free( );
+    }
+    mbedtls_psa_crypto_free( );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void validate_module_init_generate_random( int count )
+{
+    psa_status_t status;
+    uint8_t random[10] = { 0 };
+    int i;
+    for( i = 0; i < count; i++ )
+    {
+        status = psa_crypto_init( );
+        TEST_ASSERT( status == PSA_SUCCESS );
+        mbedtls_psa_crypto_free( );
+    }
+    status = psa_generate_random( random, sizeof( random ) );
+    TEST_ASSERT( status == PSA_ERROR_BAD_STATE );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void validate_module_init_key_based( int count )
+{
+    psa_status_t status;
+    uint8_t data[10] = { 0 };
+    int i;
+    for( i = 0; i < count; i++ )
+    {
+        status = psa_crypto_init( );
+        TEST_ASSERT( status == PSA_SUCCESS );
+        mbedtls_psa_crypto_free( );
+    }
+    status = psa_import_key( 1, PSA_KEY_TYPE_RAW_DATA, data, sizeof( data ) );
+    TEST_ASSERT( status == PSA_ERROR_BAD_STATE );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void custom_entropy_sources( int sources_arg, int expected_init_status_arg )
+{
+    psa_status_t expected_init_status = expected_init_status_arg;
+    uint8_t random[10] = { 0 };
+
+    custom_entropy_sources_mask = sources_arg;
+    TEST_ASSERT( mbedtls_psa_crypto_configure_entropy_sources(
+                     custom_entropy_init, mbedtls_entropy_free ) ==
+                 PSA_SUCCESS );
+
+    TEST_ASSERT( psa_crypto_init( ) == expected_init_status );
+    if( expected_init_status != PSA_SUCCESS )
+        goto exit;
+
+    TEST_ASSERT( psa_generate_random( random, sizeof( random ) ) ==
+                 PSA_SUCCESS );
+
+exit:
+    mbedtls_psa_crypto_free( );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void fake_entropy_source( int threshold,
+                          int amount1,
+                          int amount2,
+                          int amount3,
+                          int amount4,
+                          int expected_init_status_arg )
+{
+    psa_status_t expected_init_status = expected_init_status_arg;
+    uint8_t random[10] = { 0 };
+    size_t lengths[4];
+
+    fake_entropy_state.threshold = threshold;
+    fake_entropy_state.step = 0;
+    fake_entropy_state.max_steps = 0;
+    if( amount1 >= 0 )
+        lengths[fake_entropy_state.max_steps++] = amount1;
+    if( amount2 >= 0 )
+        lengths[fake_entropy_state.max_steps++] = amount2;
+    if( amount3 >= 0 )
+        lengths[fake_entropy_state.max_steps++] = amount3;
+    if( amount4 >= 0 )
+        lengths[fake_entropy_state.max_steps++] = amount4;
+    fake_entropy_state.length_sequence = lengths;
+
+    custom_entropy_sources_mask = ENTROPY_SOURCE_FAKE;
+    TEST_ASSERT( mbedtls_psa_crypto_configure_entropy_sources(
+                     custom_entropy_init, mbedtls_entropy_free ) ==
+                 PSA_SUCCESS );
+
+    TEST_ASSERT( psa_crypto_init( ) == expected_init_status );
+    if( expected_init_status != PSA_SUCCESS )
+        goto exit;
+
+    TEST_ASSERT( psa_generate_random( random, sizeof( random ) ) ==
+                 PSA_SUCCESS );
+
+exit:
+    mbedtls_psa_crypto_free( );
+}
+/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_ENTROPY_NV_SEED */
+void entropy_from_nv_seed( int seed_size_arg,
+                           int expected_init_status_arg )
+{
+    psa_status_t expected_init_status = expected_init_status_arg;
+    uint8_t random[10] = { 0 };
+    uint8_t *seed = NULL;
+    size_t seed_size = seed_size_arg;
+
+    ASSERT_ALLOC( seed, seed_size );
+    TEST_ASSERT( mbedtls_nv_seed_write( seed, seed_size ) >= 0 );
+
+    custom_entropy_sources_mask = ENTROPY_SOURCE_NV_SEED;
+    TEST_ASSERT( mbedtls_psa_crypto_configure_entropy_sources(
+                     custom_entropy_init, mbedtls_entropy_free ) ==
+                 PSA_SUCCESS );
+
+    TEST_ASSERT( psa_crypto_init( ) == expected_init_status );
+    if( expected_init_status != PSA_SUCCESS )
+        goto exit;
+
+    TEST_ASSERT( psa_generate_random( random, sizeof( random ) ) ==
+                 PSA_SUCCESS );
+
+exit:
+    mbedtls_free( seed );
+    mbedtls_psa_crypto_free( );
+}
+/* END_CASE */