diff --git a/programs/psa/aead_demo.c b/programs/psa/aead_demo.c
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+/**
+ * PSA API multi-part AEAD demonstration.
+ *
+ * This program AEAD-encrypts a message, using the algorithm and key size
+ * specified on the command line, using the multi-part API.
+ *
+ * It comes with a companion program cipher/aead_demo.c, which does the same
+ * operations with the legacy Cipher API. The goal is that comparing the two
+ * programs will help people migrating to the PSA Crypto API.
+ *
+ * When used with multi-part AEAD operations, the `mbedtls_cipher_context`
+ * serves a triple purpose (1) hold the key, (2) store the algorithm when no
+ * operation is active, and (3) save progress information for the current
+ * operation. With PSA those roles are held by disinct objects: (1) a
+ * psa_key_id_t to hold the key, a (2) psa_algorithm_t to represent the
+ * algorithm, and (3) a psa_operation_t for multi-part progress.
+ *
+ * On the other hand, with PSA, the algorithms encodes the desired tag length;
+ * with Cipher the desired tag length needs to be tracked separately.
+ *
+ * This program and its companion cipher/aead_demo.c illustrate this by doing the
+ * same sequence of multi-part AEAD computation with both APIs; looking at the
+ * two side by side should make the differences and similarities clear.
+ */
+
+/*
+ *  Copyright The Mbed TLS Contributors
+ *  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.
+ */
+
+/* First include Mbed TLS headers to get the Mbed TLS configuration and
+ * platform definitions that we'll use in this program. Also include
+ * standard C headers for functions we'll use here. */
+#include "mbedtls/build_info.h"
+
+#include "psa/crypto.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+/* If the build options we need are not enabled, compile a placeholder. */
+#if !defined(MBEDTLS_PSA_CRYPTO_C) || \
+    !defined(MBEDTLS_AES_C) || !defined(MBEDTLS_GCM_C) || \
+    !defined(MBEDTLS_CHACHAPOLY_C) || \
+    defined(MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER)
+int main( void )
+{
+    printf( "MBEDTLS_PSA_CRYPTO_C and/or "
+            "MBEDTLS_AES_C and/or MBEDTLS_GCM_C and/or "
+            "MBEDTLS_CHACHAPOLY_C not defined, and/or "
+            "MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER defined\r\n" );
+    return( 0 );
+}
+#else
+
+/* The real program starts here. */
+
+const char usage[] = "Usage: aead_demo [aes128-gcm|aes256-gcm|aes128-gcm_8|chachapoly]";
+
+/* Dummy data for encryption: IV/nonce, additional data, 2-part message */
+const unsigned char iv1[12] = { 0x00 };
+const unsigned char add_data1[] = { 0x01, 0x02 };
+const unsigned char msg1_part1[] = { 0x03, 0x04 };
+const unsigned char msg1_part2[] = { 0x05, 0x06, 0x07 };
+
+/* Dummy data (2nd message) */
+const unsigned char iv2[12] = { 0x10 };
+const unsigned char add_data2[] = { 0x11, 0x12 };
+const unsigned char msg2_part1[] = { 0x13, 0x14 };
+const unsigned char msg2_part2[] = { 0x15, 0x16, 0x17 };
+
+/* This must at least the sum of the length of the 2 parts for each message.
+ * This is a macro for the sake of compilers with insufficient C99 support. */
+#define MSG_MAX_SIZE 5
+
+/* Dummy key material - never do this in production!
+ * 32-byte is enough to all the key size supported by this program. */
+const unsigned char key_bytes[32] = { 0x2a };
+
+/* Print the contents of a buffer in hex */
+void print_buf( const char *title, uint8_t *buf, size_t len )
+{
+    printf( "%s:", title );
+    for( size_t i = 0; i < len; i++ )
+        printf( " %02x", buf[i] );
+    printf( "\n" );
+}
+
+/* Run a PSA function and bail out if it fails. */
+#define PSA_CHECK( expr )                                       \
+    do                                                          \
+    {                                                           \
+        status = ( expr );                                      \
+        if( status != PSA_SUCCESS )                             \
+        {                                                       \
+            printf( "Error %d at line %d: %s\n",                \
+                    (int) status,                               \
+                    __LINE__,                                   \
+                    #expr );                                    \
+            goto exit;                                          \
+        }                                                       \
+    }                                                           \
+    while( 0 )
+
+/*
+ * Prepare encryption material:
+ * - interpret command-line argument
+ * - set up key
+ * - outputs: key and algorithm, which together hold all the information
+ */
+static psa_status_t aead_prepare( const char *info,
+                                  psa_key_id_t *key,
+                                  psa_algorithm_t *alg )
+{
+    psa_status_t status;
+
+    /* Convert arg to alg + key_bits + key_type */
+    size_t key_bits;
+    psa_key_type_t key_type;
+    if( strcmp( info, "aes128-gcm" ) == 0 ) {
+        *alg = PSA_ALG_GCM;
+        key_bits = 128;
+        key_type = PSA_KEY_TYPE_AES;
+    } else if( strcmp( info, "aes256-gcm" ) == 0 ) {
+        *alg = PSA_ALG_GCM;
+        key_bits = 256;
+        key_type = PSA_KEY_TYPE_AES;
+    } else if( strcmp( info, "aes128-gcm_8" ) == 0 ) {
+        *alg = PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_GCM, 8);
+        key_bits = 128;
+        key_type = PSA_KEY_TYPE_AES;
+    } else if( strcmp( info, "chachapoly" ) == 0 ) {
+        *alg = PSA_ALG_CHACHA20_POLY1305;
+        key_bits = 256;
+        key_type = PSA_KEY_TYPE_CHACHA20;
+    } else {
+        puts( usage );
+        return( PSA_ERROR_INVALID_ARGUMENT );
+    }
+
+    /* Prepare key attibutes */
+    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
+    psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_ENCRYPT );
+    psa_set_key_algorithm( &attributes, *alg );
+    psa_set_key_type( &attributes, key_type );
+    psa_set_key_bits( &attributes, key_bits ); // optional
+
+    /* Import key */
+    PSA_CHECK( psa_import_key( &attributes, key_bytes, key_bits / 8, key ) );
+
+exit:
+    return( status );
+}
+
+/*
+ * Print out some information.
+ *
+ * All of this information was present in the command line argument, but his
+ * function demonstrates how each piece can be recovered from (key, alg).
+ */
+static void aead_info( psa_key_id_t key, psa_algorithm_t alg )
+{
+    psa_key_attributes_t attr = PSA_KEY_ATTRIBUTES_INIT;
+    (void) psa_get_key_attributes( key, &attr );
+    psa_key_type_t key_type = psa_get_key_type( &attr );
+    size_t key_bits = psa_get_key_bits( &attr );
+    psa_algorithm_t base_alg = PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG( alg );
+    size_t tag_len = PSA_AEAD_TAG_LENGTH( key_type, key_bits, alg );
+
+    const char *type_str = key_type == PSA_KEY_TYPE_AES ? "AES"
+                         : key_type == PSA_KEY_TYPE_CHACHA20 ? "Chacha"
+                         : "???";
+    const char *base_str = base_alg == PSA_ALG_GCM ? "GCM"
+                         : base_alg == PSA_ALG_CHACHA20_POLY1305 ? "ChachaPoly"
+                         : "???";
+
+    printf( "%s, %u, %s, %u\n",
+            type_str, (unsigned) key_bits, base_str, (unsigned) tag_len );
+}
+
+/*
+ * Encrypt a 2-part message.
+ */
+static int aead_encrypt( psa_key_id_t key, psa_algorithm_t alg,
+        const unsigned char *iv, size_t iv_len,
+        const unsigned char *ad, size_t ad_len,
+        const unsigned char *pa, size_t pa_len,
+        const unsigned char *pb, size_t pb_len )
+{
+    psa_status_t status;
+    size_t olen, olen_tag;
+    unsigned char out[PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE(MSG_MAX_SIZE)];
+    unsigned char *p = out, *end = out + sizeof( out );
+    unsigned char tag[PSA_AEAD_TAG_MAX_SIZE];
+
+    psa_aead_operation_t op = PSA_AEAD_OPERATION_INIT;
+    PSA_CHECK( psa_aead_encrypt_setup( &op, key, alg ) );
+
+    PSA_CHECK( psa_aead_set_nonce( &op, iv, iv_len ) );
+    PSA_CHECK( psa_aead_update_ad( &op, ad, ad_len ) );
+    PSA_CHECK( psa_aead_update( &op, pa, pa_len, p, end - p, &olen ) );
+    p += olen;
+    PSA_CHECK( psa_aead_update( &op, pb, pb_len, p, end - p, &olen ) );
+    p += olen;
+    PSA_CHECK( psa_aead_finish( &op, p, end - p, &olen,
+                               tag, sizeof( tag ), &olen_tag ) );
+    p += olen;
+    memcpy( p, tag, olen_tag );
+    p += olen_tag;
+
+    olen = p - out;
+    print_buf( "out", out, olen );
+
+exit:
+    psa_aead_abort( &op ); // required on errors, harmless on success
+    return( status );
+}
+
+/*
+ * AEAD demo: set up key/alg, print out info, encrypt messages.
+ */
+static psa_status_t aead_demo( const char *info )
+{
+    psa_status_t status;
+
+    psa_key_id_t key;
+    psa_algorithm_t alg;
+
+    PSA_CHECK( aead_prepare( info, &key, &alg ) );
+
+    aead_info( key, alg );
+
+    PSA_CHECK( aead_encrypt( key, alg,
+                       iv1, sizeof( iv1 ), add_data1, sizeof( add_data1 ),
+                       msg1_part1, sizeof( msg1_part1 ),
+                       msg1_part2, sizeof( msg1_part2 ) ) );
+    PSA_CHECK( aead_encrypt( key, alg,
+                       iv2, sizeof( iv2 ), add_data2, sizeof( add_data2 ),
+                       msg2_part1, sizeof( msg2_part1 ),
+                       msg2_part2, sizeof( msg2_part2 ) ) );
+
+exit:
+    psa_destroy_key( key );
+
+    return( status );
+}
+
+/*
+ * Main function
+ */
+int main( int argc, char **argv )
+{
+    psa_status_t status = PSA_SUCCESS;
+
+    /* Check usage */
+    if( argc != 2 )
+    {
+        puts( usage );
+        return( EXIT_FAILURE );
+    }
+
+    /* Initialize the PSA crypto library. */
+    PSA_CHECK( psa_crypto_init( ) );
+
+    /* Run the demo */
+    PSA_CHECK( aead_demo( argv[1] ) );
+
+    /* Deinitialize the PSA crypto library. */
+    mbedtls_psa_crypto_free( );
+
+exit:
+    return( status == PSA_SUCCESS ? EXIT_SUCCESS : EXIT_FAILURE );
+}
+
+#endif