diff --git a/ChangeLog b/ChangeLog
index 4a4d628..17d2aae 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -8,6 +8,59 @@
 
 = mbed TLS 2.20.0 branch released 2020-01-15
 
+Default behavior changes
+   * The initial seeding of a CTR_DRBG instance makes a second call to the
+     entropy function to obtain entropy for a nonce if the entropy size is less
+     than 3/2 times the key size. In case you want to disable the extra call to
+     grab entropy, you can call mbedtls_ctr_drbg_set_nonce_len() to force the
+     nonce length to 0.
+
+Security
+   * Enforce that mbedtls_entropy_func() gathers a total of
+     MBEDTLS_ENTROPY_BLOCK_SIZE bytes or more from strong sources. In the
+     default configuration, on a platform with a single entropy source, the
+     entropy module formerly only grabbed 32 bytes, which is good enough for
+     security if the source is genuinely strong, but less than the expected 64
+     bytes (size of the entropy accumulator).
+   * Zeroize local variables in mbedtls_internal_aes_encrypt() and
+     mbedtls_internal_aes_decrypt() before exiting the function. The value of
+     these variables can be used to recover the last round key. To follow best
+     practice and to limit the impact of buffer overread vulnerabilities (like
+     Heartbleed) we need to zeroize them before exiting the function.
+     Issue reported by Tuba Yavuz, Farhaan Fowze, Ken (Yihang) Bai,
+     Grant Hernandez, and Kevin Butler (University of Florida) and
+     Dave Tian (Purdue University).
+   * Fix side channel vulnerability in ECDSA. Our bignum implementation is not
+     constant time/constant trace, so side channel attacks can retrieve the
+     blinded value, factor it (as it is smaller than RSA keys and not guaranteed
+     to have only large prime factors), and then, by brute force, recover the
+     key. Reported by Alejandro Cabrera Aldaya and Billy Brumley.
+   * Fix side channel vulnerability in ECDSA key generation. Obtaining precise
+     timings on the comparison in the key generation enabled the attacker to
+     learn leading bits of the ephemeral key used during ECDSA signatures and to
+     recover the private key. Reported by Jeremy Dubeuf.
+   * Catch failure of AES functions in mbedtls_ctr_drbg_random(). Uncaught
+     failures could happen with alternative implementations of AES. Bug
+     reported and fix proposed by Johan Uppman Bruce and Christoffer Lauri,
+     Sectra.
+
+Features
+   * Key derivation inputs in the PSA API can now either come from a key object
+     or from a buffer regardless of the step type.
+   * The CTR_DRBG module can grab a nonce from the entropy source during the
+     initial seeding. The default nonce length is chosen based on the key size
+     to achieve the security strength defined by NIST SP 800-90A. You can
+     change it with mbedtls_ctr_drbg_set_nonce_len().
+   * Add ENUMERATED tag support to the ASN.1 module. Contributed by
+     msopiha-linaro in ARMmbed/mbed-crypto#307.
+
+API changes
+   * In the PSA API, forbid zero-length keys. To pass a zero-length input to a
+     key derivation function, use a buffer instead (this is now always
+     possible).
+   * Rename psa_asymmetric_sign() to psa_sign_hash() and
+     psa_asymmetric_verify() to psa_verify_hash().
+
 Bugfix
    * Fix an incorrect size in a debugging message. Reported and fix
      submitted by irwir. Fixes #2717.
@@ -15,6 +68,34 @@
      Reported and fix submitted by irwir. Fixes #2800.
    * Remove a useless assignment. Reported and fix submitted by irwir.
      Fixes #2801.
+   * Fix a buffer overflow in the PSA HMAC code when using a long key with an
+     unsupported algorithm. Fixes ARMmbed/mbed-crypto#254.
+   * Fix mbedtls_asn1_get_int to support any number of leading zeros. Credit
+     to OSS-Fuzz for finding a bug in an intermediate version of the fix.
+   * Fix mbedtls_asn1_get_bitstring_null to correctly parse bitstrings of at
+     most 2 bytes.
+   * mbedtls_ctr_drbg_set_entropy_len() and
+     mbedtls_hmac_drbg_set_entropy_len() now work if you call them before
+     mbedtls_ctr_drbg_seed() or mbedtls_hmac_drbg_seed().
+   * Fix some false-positive uninitialized variable warnings. Fix contributed
+     by apple-ihack-geek in #2663.
+
+Changes
+   * Remove the technical possibility to define custom mbedtls_md_info
+     structures, which was exposed only in an internal header.
+   * psa_close_key(0) and psa_destroy_key(0) now succeed (doing nothing, as
+     before).
+   * Variables containing error codes are now initialized to an error code
+     rather than success, so that coding mistakes or memory corruption tends to
+     cause functions to return this error code rather than a success. There are
+     no known instances where this changes the behavior of the library: this is
+     merely a robustness improvement. ARMmbed/mbed-crypto#323
+   * Remove a useless call to mbedtls_ecp_group_free(). Contributed by
+     Alexander Krizhanovsky in ARMmbed/mbed-crypto#210.
+   * Speed up PBKDF2 by caching the digest calculation. Contributed by Jack
+     Lloyd and Fortanix Inc in ARMmbed/mbed-crypto#277.
+   * Small performance improvement of mbedtls_mpi_div_mpi(). Contributed by
+     Alexander Krizhanovsky in ARMmbed/mbed-crypto#308.
 
 = mbed TLS 2.19.1 branch released 2019-09-16
 
diff --git a/crypto b/crypto
index d27a884..1146b4e 160000
--- a/crypto
+++ b/crypto
@@ -1 +1 @@
-Subproject commit d27a88438fe785f0906c01e3216044d1c98be875
+Subproject commit 1146b4e06011b69a6437e6b728f2af043a06ec19
diff --git a/doxygen/input/doc_mainpage.h b/doxygen/input/doc_mainpage.h
index d5ead37..5b5aefb 100644
--- a/doxygen/input/doc_mainpage.h
+++ b/doxygen/input/doc_mainpage.h
@@ -24,7 +24,7 @@
  */
 
 /**
- * @mainpage mbed TLS v2.19.1 source code documentation
+ * @mainpage mbed TLS v2.20.0 source code documentation
  *
  * This documentation describes the internal structure of mbed TLS.  It was
  * automatically generated from specially formatted comment blocks in
diff --git a/doxygen/mbedtls.doxyfile b/doxygen/mbedtls.doxyfile
index eb2d96e..47a9740 100644
--- a/doxygen/mbedtls.doxyfile
+++ b/doxygen/mbedtls.doxyfile
@@ -28,7 +28,7 @@
 # identify the project. Note that if you do not use Doxywizard you need
 # to put quotes around the project name if it contains spaces.
 
-PROJECT_NAME           = "mbed TLS v2.19.1"
+PROJECT_NAME           = "mbed TLS v2.20.0"
 
 # The PROJECT_NUMBER tag can be used to enter a project or revision number.
 # This could be handy for archiving the generated documentation or
diff --git a/include/mbedtls/version.h b/include/mbedtls/version.h
index ae694ee..d4e5d54 100644
--- a/include/mbedtls/version.h
+++ b/include/mbedtls/version.h
@@ -39,17 +39,17 @@
  * Major, Minor, Patchlevel
  */
 #define MBEDTLS_VERSION_MAJOR  2
-#define MBEDTLS_VERSION_MINOR  19
-#define MBEDTLS_VERSION_PATCH  1
+#define MBEDTLS_VERSION_MINOR  20
+#define MBEDTLS_VERSION_PATCH  0
 
 /**
  * The single version number has the following structure:
  *    MMNNPP00
  *    Major version | Minor version | Patch version
  */
-#define MBEDTLS_VERSION_NUMBER         0x02130100
-#define MBEDTLS_VERSION_STRING         "2.19.1"
-#define MBEDTLS_VERSION_STRING_FULL    "mbed TLS 2.19.1"
+#define MBEDTLS_VERSION_NUMBER         0x02140000
+#define MBEDTLS_VERSION_STRING         "2.20.0"
+#define MBEDTLS_VERSION_STRING_FULL    "mbed TLS 2.20.0"
 
 #if defined(MBEDTLS_VERSION_C)
 
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 5e36a5b..d990d43 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -174,14 +174,14 @@
 if(USE_SHARED_MBEDTLS_LIBRARY)
 
     add_library(mbedx509 SHARED ${src_x509})
-    set_target_properties(mbedx509 PROPERTIES VERSION 2.19.1 SOVERSION 1)
+    set_target_properties(mbedx509 PROPERTIES VERSION 2.20.0 SOVERSION 1)
     target_link_libraries(mbedx509 ${libs} mbedcrypto)
     target_include_directories(mbedx509
         PUBLIC ${MBEDTLS_DIR}/include/
         PUBLIC ${MBEDTLS_DIR}/crypto/include/)
 
     add_library(mbedtls SHARED ${src_tls})
-    set_target_properties(mbedtls PROPERTIES VERSION 2.19.1 SOVERSION 13)
+    set_target_properties(mbedtls PROPERTIES VERSION 2.20.0 SOVERSION 13)
     target_link_libraries(mbedtls ${libs} mbedx509)
     target_include_directories(mbedtls
         PUBLIC ${MBEDTLS_DIR}/include/
diff --git a/library/Makefile b/library/Makefile
index bc9363d..6fc110c 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -37,7 +37,7 @@
 
 SOEXT_TLS=so.13
 SOEXT_X509=so.1
-SOEXT_CRYPTO=so.3
+SOEXT_CRYPTO=so.4
 
 # Set AR_DASH= (empty string) to use an ar implementation that does not accept
 # the - prefix for command line options (e.g. llvm-ar)
diff --git a/tests/suites/test_suite_ssl.data b/tests/suites/test_suite_ssl.data
index 83ef691..59b4769 100644
--- a/tests/suites/test_suite_ssl.data
+++ b/tests/suites/test_suite_ssl.data
@@ -35,34 +35,16 @@
 ssl_mock_sanity:
 
 Test mock blocking TCP connection
-ssl_mock_tcp:1:0:0
+ssl_mock_tcp:1
 
-Test mock non-blocking TCP connection: would not block
-ssl_mock_tcp:0:0:0
-
-Test mock non-blocking TCP connection: client would block
-ssl_mock_tcp:0:0xB509:0
-
-Test mock non-blocking TCP connection: server would block
-ssl_mock_tcp:0:0x0FB1:0
-
-Test mock non-blocking TCP connection: both peers would block
-ssl_mock_tcp:0:0x1111:0xEEEE
+Test mock non-blocking TCP connection
+ssl_mock_tcp:0
 
 Test mock blocking TCP connection (interleaving)
-ssl_mock_tcp_interleaving:1:0:0
+ssl_mock_tcp_interleaving:1
 
-Test mock non-blocking TCP connection: would not block (interleaving)
-ssl_mock_tcp_interleaving:0:0:0
-
-Test mock non-blocking TCP connection: client would block (interleaving)
-ssl_mock_tcp_interleaving:0:0xB509:0
-
-Test mock non-blocking TCP connection: server would block (interleaving)
-ssl_mock_tcp_interleaving:0:0x0FB1:0
-
-Test mock non-blocking TCP connection: both peers would block (interleaving)
-ssl_mock_tcp_interleaving:0:0x1111:0xEEEE
+Test mock non-blocking TCP connection (interleaving)
+ssl_mock_tcp_interleaving:0
 
 SSL DTLS replay: initial state, seqnum 0
 ssl_dtls_replay:"":"000000000000":0
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index a57e256..a936d83 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -77,20 +77,33 @@
         return ( input_len == 0 ) ? 0 : -1;
     }
 
-    /* Calculate the number of bytes that need to be placed at lower memory
-     * address */
-    if( buf->start + buf->content_length + input_len
-        > buf->capacity )
+     /* Check if the buffer has not come full circle and free space is not in
+      * the middle */
+    if( buf->start + buf->content_length < buf->capacity )
     {
-        overflow = ( buf->start + buf->content_length + input_len )
-                    % buf->capacity;
+
+        /* Calculate the number of bytes that need to be placed at lower memory
+        * address */
+        if( buf->start + buf->content_length + input_len
+            > buf->capacity )
+        {
+            overflow = ( buf->start + buf->content_length + input_len )
+                        % buf->capacity;
+        }
+
+        memcpy( buf->buffer + buf->start + buf->content_length, input,
+                    input_len - overflow );
+        memcpy( buf->buffer, input + input_len - overflow, overflow );
+
+    }
+    else
+    {
+        /* The buffer has come full circle and free space is in the middle */
+        memcpy( buf->buffer + buf->start + buf->content_length - buf->capacity,
+                input, input_len );
     }
 
-    memcpy( buf->buffer + buf->start + buf->content_length, input,
-            input_len - overflow );
-    memcpy( buf->buffer, input + input_len - overflow, overflow );
     buf->content_length += input_len;
-
     return input_len;
 }
 
@@ -146,7 +159,6 @@
 typedef struct mbedtls_mock_socket
 {
     int status;
-    uint32_t blocking_pattern;
     mbedtls_test_buffer *input;
     mbedtls_test_buffer *output;
     struct mbedtls_mock_socket *peer;
@@ -212,20 +224,7 @@
 {
     int ret = -1;
 
-    peer1->input = peer2->output =
-        (mbedtls_test_buffer*) mbedtls_calloc( 1, sizeof(mbedtls_test_buffer) );
-    if( peer1->input == NULL )
-    {
-        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
-        goto exit;
-    }
-    mbedtls_test_buffer_init( peer1->input );
-    if( 0 != ( ret = mbedtls_test_buffer_setup( peer1->input, bufsize ) ) )
-    {
-        goto exit;
-    }
-
-    peer1->output = peer2->input =
+    peer1->output =
         (mbedtls_test_buffer*) mbedtls_calloc( 1, sizeof(mbedtls_test_buffer) );
     if( peer1->output == NULL )
     {
@@ -238,8 +237,23 @@
         goto exit;
     }
 
+    peer2->output =
+        (mbedtls_test_buffer*) mbedtls_calloc( 1, sizeof(mbedtls_test_buffer) );
+    if( peer2->output == NULL )
+    {
+        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
+        goto exit;
+    }
+    mbedtls_test_buffer_init( peer2->output );
+    if( 0 != ( ret = mbedtls_test_buffer_setup( peer2->output, bufsize ) ) )
+    {
+        goto exit;
+    }
+
     peer1->peer = peer2;
     peer2->peer = peer1;
+    peer1->input = peer2->output;
+    peer2->input = peer1->output;
 
     peer1->status = peer2->status = MBEDTLS_MOCK_SOCKET_CONNECTED;
     ret = 0;
@@ -256,26 +270,6 @@
 }
 
 /*
- * Set the blocking pattern for the socket.
- *
- * For every bit of \p blocking_pattern set to one the socket will simulate a
- * "would block" event. The bits are processed starting with the least
- * significant bit and every call to a non-blocking I/O function consumes one.
- *
- * The behaviour of blocking I/O functions remains unchanged.
- */
-int mbedtls_mock_socket_set_block( mbedtls_mock_socket* socket,
-                                   uint32_t blocking_pattern )
-{
-    if( socket == NULL )
-        return -1;
-
-    socket->blocking_pattern = blocking_pattern;
-
-    return 0;
-}
-
-/*
  * Callbacks for simulating blocking I/O over connection-oriented transport.
  */
 
@@ -310,14 +304,11 @@
     if( socket == NULL || socket->status != MBEDTLS_MOCK_SOCKET_CONNECTED )
         return -1;
 
-    if( socket->blocking_pattern & 1 )
+    if( socket->output->capacity == socket->output->content_length )
     {
-        socket->blocking_pattern >>= 1;
         return MBEDTLS_ERR_SSL_WANT_WRITE;
     }
 
-    socket->blocking_pattern >>= 1;
-
     return mbedtls_test_buffer_put( socket->output, buf, len );
 }
 
@@ -328,14 +319,11 @@
     if( socket == NULL || socket->status != MBEDTLS_MOCK_SOCKET_CONNECTED )
         return -1;
 
-    if( socket->blocking_pattern & 1 )
+    if( socket->input->content_length == 0)
     {
-        socket->blocking_pattern >>= 1;
         return MBEDTLS_ERR_SSL_WANT_READ;
     }
 
-    socket->blocking_pattern >>= 1;
-
     return mbedtls_test_buffer_get( socket->input, buf, len );
 }
 
@@ -743,6 +731,16 @@
     TEST_ASSERT( mbedtls_test_buffer_put( &buf, NULL, 0 ) == 0 );
     TEST_ASSERT( mbedtls_test_buffer_get( &buf, NULL, 0 ) == 0 );
 
+    /* Make sure calling put several times in the row is safe */
+
+    TEST_ASSERT( mbedtls_test_buffer_put( &buf, input, sizeof( input ) )
+                                          == sizeof( input ) );
+    TEST_ASSERT( mbedtls_test_buffer_get( &buf, output, 2 ) == 2 );
+    TEST_ASSERT( mbedtls_test_buffer_put( &buf, input, 1 ) == 1 );
+    TEST_ASSERT( mbedtls_test_buffer_put( &buf, input, 2 ) == 1 );
+    TEST_ASSERT( mbedtls_test_buffer_put( &buf, input, 2 ) == 0 );
+
+
 exit:
 
     mbedtls_test_buffer_free( &buf );
@@ -905,9 +903,10 @@
  */
 
 /* BEGIN_CASE */
-void ssl_mock_tcp( int blocking, int client_pattern, int server_pattern )
+void ssl_mock_tcp( int blocking )
 {
     enum { MSGLEN = 105 };
+    enum { BUFLEN = MSGLEN / 5 };
     unsigned char message[MSGLEN];
     unsigned char received[MSGLEN];
     mbedtls_mock_socket client;
@@ -916,8 +915,6 @@
     int send_ret, recv_ret;
     mbedtls_ssl_send_t *send;
     mbedtls_ssl_recv_t *recv;
-    uint32_t client_block = client_pattern;
-    uint32_t server_block = server_pattern;
     unsigned i;
 
     if( blocking == 0 )
@@ -942,10 +939,7 @@
     }
 
     /* Make sure that sending a message takes a few  iterations. */
-    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server,
-                                                   MSGLEN / 5 ) );
-    TEST_ASSERT( 0 == mbedtls_mock_socket_set_block( &client, client_block ) );
-    TEST_ASSERT( 0 == mbedtls_mock_socket_set_block( &server, server_block ) );
+    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server, BUFLEN ) );
 
     /* Send the message to the server */
     send_ret = recv_ret = 1;
@@ -954,28 +948,56 @@
     {
         send_ret = send( &client, message + written, MSGLEN - written );
 
-        if( ( blocking == 0 ) && ( client_block & 1 ) )
+        TEST_ASSERT( send_ret >= 0 );
+        TEST_ASSERT( send_ret <= BUFLEN );
+        written += send_ret;
+
+        /* If the buffer is full we can test blocking and non-blocking send */
+        if ( send_ret == BUFLEN )
         {
-            TEST_ASSERT( send_ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+            int blocking_ret = send( &client, message , 1 );
+            if ( blocking )
+            {
+                TEST_ASSERT( blocking_ret == 0 );
+            }
+            else
+            {
+                TEST_ASSERT( blocking_ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+            }
         }
-        else
-        {
-            TEST_ASSERT( send_ret >= 0 );
-            written += send_ret;
-        }
-        client_block >>= 1;
 
         recv_ret = recv( &server, received + read, MSGLEN - read );
-        if( ( blocking == 0 ) && ( server_block & 1 ) )
+
+        /* The result depends on whether any data was sent */
+        if ( send_ret > 0 )
         {
-            TEST_ASSERT( recv_ret == MBEDTLS_ERR_SSL_WANT_READ );
+            TEST_ASSERT( recv_ret > 0 );
+            TEST_ASSERT( recv_ret <= BUFLEN );
+            read += recv_ret;
+        }
+        else if( blocking )
+        {
+            TEST_ASSERT( recv_ret == 0 );
         }
         else
         {
-            TEST_ASSERT( recv_ret >= 0 );
-            read += recv_ret;
+            TEST_ASSERT( recv_ret == MBEDTLS_ERR_SSL_WANT_READ );
+            recv_ret = 0;
         }
-        server_block >>= 1;
+
+        /* If the buffer is empty we can test blocking and non-blocking read */
+        if ( recv_ret == BUFLEN )
+        {
+            int blocking_ret = recv( &server, received, 1 );
+            if ( blocking )
+            {
+                TEST_ASSERT( blocking_ret == 0 );
+            }
+            else
+            {
+                TEST_ASSERT( blocking_ret == MBEDTLS_ERR_SSL_WANT_READ );
+            }
+        }
     }
     TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
 
@@ -993,11 +1015,11 @@
  */
 
 /* BEGIN_CASE */
-void ssl_mock_tcp_interleaving( int blocking,
-                                int client_pattern, int server_pattern )
+void ssl_mock_tcp_interleaving( int blocking )
 {
     enum { ROUNDS = 2 };
     enum { MSGLEN = 105 };
+    enum { BUFLEN = MSGLEN / 5 };
     unsigned char message[ROUNDS][MSGLEN];
     unsigned char received[ROUNDS][MSGLEN];
     mbedtls_mock_socket client;
@@ -1009,8 +1031,6 @@
     unsigned i, j, progress;
     mbedtls_ssl_send_t *send;
     mbedtls_ssl_recv_t *recv;
-    uint32_t client_block = client_pattern;
-    uint32_t server_block = server_pattern;
 
     if( blocking == 0 )
     {
@@ -1037,10 +1057,7 @@
     }
 
     /* Make sure that sending a message takes a few  iterations. */
-    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server,
-                                                   MSGLEN / 5 ) );
-    TEST_ASSERT( 0 == mbedtls_mock_socket_set_block( &client, client_block ) );
-    TEST_ASSERT( 0 == mbedtls_mock_socket_set_block( &server, server_block ) );
+    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server, BUFLEN ) );
 
     /* Send the message from both sides, interleaving. */
     progress = 1;
@@ -1053,72 +1070,80 @@
      * of at least one byte on either side. */
     while( progress != 0 )
     {
-        send_ret[0] = send( &client, message[0] + written[0],
-                                               MSGLEN - written[0] );
-        if( ( blocking == 0 ) && ( client_block & 1 ) )
-        {
-            TEST_ASSERT( send_ret[0] == MBEDTLS_ERR_SSL_WANT_WRITE );
-        }
-        else
-        {
-            TEST_ASSERT( send_ret[0] >= 0 );
-            written[0] += send_ret[0];
-        }
-        client_block >>= 1;
+        mbedtls_mock_socket *socket;
 
-        send_ret[1] = send( &server, message[1] + written[1],
-                                               MSGLEN - written[1] );
-        if( ( blocking == 0 ) && ( server_block & 1 ) )
+        for( i = 0; i < ROUNDS; i++ )
         {
-            TEST_ASSERT( send_ret[1] == MBEDTLS_ERR_SSL_WANT_WRITE );
-        }
-        else
-        {
-            TEST_ASSERT( send_ret[1] >= 0 );
-            written[1] += send_ret[1];
-        }
-        server_block >>= 1;
+            /* First sending is from the client */
+            socket = ( i % 2 == 0 ) ? ( &client ) : ( &server );
 
-        recv_ret[0] = recv( &server, received[0] + read[0],
-                                               MSGLEN - read[0] );
-        if( ( blocking == 0 ) && ( server_block & 1 ) )
-        {
-            TEST_ASSERT( recv_ret[0] == MBEDTLS_ERR_SSL_WANT_READ );
-        }
-        else
-        {
-            TEST_ASSERT( recv_ret[0] >= 0 );
-            read[0] += recv_ret[0];
-        }
-        server_block >>= 1;
+            send_ret[i] = send( socket, message[i] + written[i],
+                                               MSGLEN - written[i] );
+            TEST_ASSERT( send_ret[i] >= 0 );
+            TEST_ASSERT( send_ret[i] <= BUFLEN );
+            written[i] += send_ret[i];
 
-        recv_ret[1] = recv( &client, received[1] + read[1],
-                                               MSGLEN - read[1] );
-        if( ( blocking == 0 ) && ( client_block & 1 ) )
-        {
-            TEST_ASSERT( recv_ret[1] == MBEDTLS_ERR_SSL_WANT_READ );
+            /* If the buffer is full we can test blocking and non-blocking
+             * send */
+            if ( send_ret[i] == BUFLEN )
+            {
+                int blocking_ret = send( socket, message[i] , 1 );
+                if ( blocking )
+                {
+                    TEST_ASSERT( blocking_ret == 0 );
+                }
+                else
+                {
+                    TEST_ASSERT( blocking_ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+                }
+            }
         }
-        else
+
+        for( i = 0; i < ROUNDS; i++ )
         {
-            TEST_ASSERT( recv_ret[1] >= 0 );
-            read[1] += recv_ret[1];
+            /* First receiving is from the server */
+            socket = ( i % 2 == 0 ) ? ( &server ) : ( &client );
+
+            recv_ret[i] = recv( socket, received[i] + read[i],
+                                               MSGLEN - read[i] );
+
+            /* The result depends on whether any data was sent */
+            if ( send_ret[i] > 0 )
+            {
+                TEST_ASSERT( recv_ret[i] > 0 );
+                TEST_ASSERT( recv_ret[i] <= BUFLEN );
+                read[i] += recv_ret[i];
+            }
+            else if( blocking )
+            {
+                TEST_ASSERT( recv_ret[i] == 0 );
+            }
+            else
+            {
+                TEST_ASSERT( recv_ret[i] == MBEDTLS_ERR_SSL_WANT_READ );
+                recv_ret[i] = 0;
+            }
+
+            /* If the buffer is empty we can test blocking and non-blocking
+             * read */
+            if ( recv_ret[i] == BUFLEN )
+            {
+                int blocking_ret = recv( socket, received[i], 1 );
+                if ( blocking )
+                {
+                    TEST_ASSERT( blocking_ret == 0 );
+                }
+                else
+                {
+                    TEST_ASSERT( blocking_ret == MBEDTLS_ERR_SSL_WANT_READ );
+                }
+            }
         }
-        client_block >>= 1;
 
         progress = 0;
         for( i = 0; i < ROUNDS; i++ )
         {
-            if( ( send_ret[i] > 0 ) ||
-                    ( send_ret[i] == MBEDTLS_ERR_SSL_WANT_WRITE ) )
-            {
-                progress++;
-            }
-
-            if( ( recv_ret[i] > 0 ) ||
-                    ( recv_ret[i] == MBEDTLS_ERR_SSL_WANT_READ ) )
-            {
-                progress++;
-            }
+            progress += send_ret[i] + recv_ret[i];
         }
     }
 
diff --git a/tests/suites/test_suite_version.data b/tests/suites/test_suite_version.data
index b6dca23..ff0612b 100644
--- a/tests/suites/test_suite_version.data
+++ b/tests/suites/test_suite_version.data
@@ -1,8 +1,8 @@
 Check compiletime library version
-check_compiletime_version:"2.19.1"
+check_compiletime_version:"2.20.0"
 
 Check runtime library version
-check_runtime_version:"2.19.1"
+check_runtime_version:"2.20.0"
 
 Check for MBEDTLS_VERSION_C
 check_feature:"MBEDTLS_VERSION_C":0