diff --git a/library/psa_crypto_aead.c b/library/psa_crypto_aead.c
index 07c52d4..47b0e7b 100644
--- a/library/psa_crypto_aead.c
+++ b/library/psa_crypto_aead.c
@@ -20,39 +20,40 @@
 
 #include "common.h"
 
+
 #if defined(MBEDTLS_PSA_CRYPTO_C)
 
 #include "psa_crypto_aead.h"
 #include "psa_crypto_core.h"
 
+#include <string.h>
+#include "mbedtls/platform.h"
+#if !defined(MBEDTLS_PLATFORM_C)
+#define mbedtls_calloc calloc
+#define mbedtls_free   free
+#endif
+
 #include "mbedtls/ccm.h"
 #include "mbedtls/chachapoly.h"
 #include "mbedtls/cipher.h"
 #include "mbedtls/gcm.h"
+#include "mbedtls/error.h"
 
-
-static void psa_aead_abort_internal( psa_aead_operation_t *operation )
+/* Constant-time buffer comparison. This is duplication of code from
+ * psa_crypto.c, but has nowhere private I can put it for the minute. Really
+   belongs in the constant time module, when that gets implemented */
+static inline int safer_memcmp( const uint8_t *a, const uint8_t *b, size_t n )
 {
-    switch( operation->alg )
-    {
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
-        case PSA_ALG_CCM:
-            mbedtls_ccm_free( &operation->ctx.ccm );
-            break;
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
-        case PSA_ALG_GCM:
-            mbedtls_gcm_free( &operation->ctx.gcm );
-            break;
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
-        case PSA_ALG_CHACHA20_POLY1305:
-            mbedtls_chachapoly_free( &operation->ctx.chachapoly );
-            break;
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
-    }
+    size_t i;
+    unsigned char diff = 0;
+
+    for( i = 0; i < n; i++ )
+        diff |= a[i] ^ b[i];
+
+    return( diff );
 }
 
+
 static psa_status_t psa_aead_setup(
     psa_aead_operation_t *operation,
     const psa_key_attributes_t *attributes,
@@ -65,6 +66,12 @@
     mbedtls_cipher_id_t cipher_id;
     size_t full_tag_length = 0;
 
+    if( operation->key_set || operation->nonce_set ||
+        operation->ad_started || operation->body_started )
+    {
+        return( PSA_ERROR_BAD_STATE );
+    }
+
     key_bits = attributes->core.bits;
 
     cipher_info = mbedtls_cipher_info_from_psa( alg,
@@ -143,6 +150,8 @@
                                                  key_bits,
                                                  alg );
 
+    operation->key_set = 1;
+
     return( PSA_SUCCESS );
 }
 
@@ -230,7 +239,7 @@
         *ciphertext_length = plaintext_length + operation.tag_length;
 
 exit:
-    psa_aead_abort_internal( &operation );
+    mbedtls_psa_aead_abort( &operation );
 
     return( status );
 }
@@ -336,12 +345,715 @@
         *plaintext_length = ciphertext_length - operation.tag_length;
 
 exit:
-    psa_aead_abort_internal( &operation );
+    mbedtls_psa_aead_abort( &operation );
 
     if( status == PSA_SUCCESS )
         *plaintext_length = ciphertext_length - operation.tag_length;
     return( status );
 }
 
+/* Set the key and algorithm for a multipart authenticated encryption
+ * operation. */
+psa_status_t mbedtls_psa_aead_encrypt_setup( psa_aead_operation_t *operation,
+                                             const psa_key_attributes_t *attributes,
+                                             const uint8_t *key_buffer, size_t key_buffer_size,
+                                             psa_algorithm_t alg )
+{
+    psa_status_t status;
+
+    (void) key_buffer_size;
+
+    status = psa_aead_setup( operation, attributes, key_buffer, alg );
+
+    if( status == PSA_SUCCESS )
+    {
+        operation->is_encrypt = 1;
+    }
+
+    return ( status );
+}
+
+/* Set the key and algorithm for a multipart authenticated decryption
+ * operation. */
+psa_status_t mbedtls_psa_aead_decrypt_setup( psa_aead_operation_t *operation,
+                                             const psa_key_attributes_t *attributes,
+                                             const uint8_t *key_buffer, size_t key_buffer_size,
+                                             psa_algorithm_t alg )
+{
+    psa_status_t status;
+
+    (void) key_buffer_size;
+
+    status = psa_aead_setup( operation, attributes, key_buffer, alg );
+
+    if( status == PSA_SUCCESS )
+    {
+        operation->is_encrypt = 0;
+    }
+
+    return ( status );
+}
+
+/* Generate a random nonce / IV for multipart AEAD operation */
+psa_status_t mbedtls_psa_aead_generate_nonce( psa_aead_operation_t *operation,
+                                              uint8_t *nonce,
+                                              size_t nonce_size,
+                                              size_t *nonce_length )
+{
+    psa_status_t status;
+    size_t required_nonce_size = nonce_size;
+
+    if( !operation->key_set || operation->nonce_set ||
+        operation->ad_started || operation->body_started )
+    {
+        return( PSA_ERROR_BAD_STATE );
+    }
+
+    required_nonce_size = PSA_AEAD_NONCE_LENGTH(operation->key_type, operation->alg);
+
+    if( nonce_size == 0 || nonce_size < required_nonce_size )
+    {
+        return( PSA_ERROR_BUFFER_TOO_SMALL );
+    }
+
+    status = psa_generate_random( nonce, required_nonce_size );
+
+    if( status != PSA_SUCCESS )
+    {
+        return status;
+    }
+
+    status = mbedtls_psa_aead_set_nonce( operation, nonce, required_nonce_size );
+
+    if( status == PSA_SUCCESS )
+    {
+        *nonce_length = required_nonce_size;
+    }
+
+    return status;
+}
+
+/* Set a nonce for the multipart AEAD operation*/
+psa_status_t mbedtls_psa_aead_set_nonce( psa_aead_operation_t *operation,
+                                         const uint8_t *nonce,
+                                         size_t nonce_length )
+{
+    psa_status_t status;
+
+    if( !operation->key_set || operation->nonce_set ||
+        operation->ad_started || operation->body_started )
+    {
+        return( PSA_ERROR_BAD_STATE );
+    }
+
+    /* Restricting to a nominal safe length for nonces even though some
+       algorithms can handle longer nonces, but not without collision */
+    if( nonce_length > PSA_AEAD_NONCE_MAX_SIZE )
+    {
+        return( PSA_ERROR_INVALID_ARGUMENT );
+    }
+
+    #if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
+    if( operation->alg == PSA_ALG_GCM )
+    {
+        /* GCM sets nonce once additional data has been supplied */
+        memcpy(operation->nonce, nonce, nonce_length);
+
+        /* We know that nonce size cannot exceed the uint8_t size */
+        operation->nonce_length = ( uint8_t ) nonce_length;
+        status = PSA_SUCCESS;
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
+    if( operation->alg == PSA_ALG_CCM )
+    {
+        /* Multipart CCM not supported as yet, so CCM is basically operating
+           in oneshot mode. Store the nonce as we need this later */
+        memcpy(operation->nonce, nonce, nonce_length);
+
+        /* We know that nonce size cannot exceed the uint8_t size */
+        operation->nonce_length = ( uint8_t ) nonce_length;
+        status = PSA_SUCCESS;
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
+    if( operation->alg == PSA_ALG_CHACHA20_POLY1305 )
+    {
+        if( nonce_length != 12 && nonce_length != 8)
+        {
+            return( PSA_ERROR_INVALID_ARGUMENT );
+        }
+
+        status = mbedtls_to_psa_error(mbedtls_chachapoly_starts( &operation->ctx.chachapoly,
+                                                                 nonce,
+                                                                 operation->is_encrypt ?
+                                                                 MBEDTLS_CHACHAPOLY_ENCRYPT :
+                                                                 MBEDTLS_CHACHAPOLY_DECRYPT ) );
+        }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
+    {
+        ( void ) nonce;
+        ( void ) nonce_length;
+
+        return ( PSA_ERROR_NOT_SUPPORTED );
+    }
+
+    if( status == PSA_SUCCESS )
+    {
+        operation->nonce_set = 1;
+    }
+
+    return( status );
+}
+ /* Declare the lengths of the message and additional data for AEAD. */
+psa_status_t mbedtls_psa_aead_set_lengths( psa_aead_operation_t *operation,
+                                           size_t ad_length,
+                                           size_t plaintext_length )
+{
+
+    if( !operation->key_set || operation->lengths_set )
+    {
+        return( PSA_ERROR_BAD_STATE );
+    }
+
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
+    if( operation->alg == PSA_ALG_GCM )
+    {
+#if SIZE_MAX > UINT32_MAX
+        if( ( (uint64_t) ad_length ) >> 61 != 0 ||
+            ( (uint64_t) plaintext_length ) > 0xFFFFFFFE0ull )
+        {
+            return ( PSA_ERROR_INVALID_ARGUMENT );
+        }
+#endif
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
+    if( operation->alg == PSA_ALG_CCM )
+    {
+        if( ad_length > 0xFF00 )
+        {
+            return ( PSA_ERROR_INVALID_ARGUMENT );
+        }
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
+    if( operation->alg == PSA_ALG_CHACHA20_POLY1305 )
+    {
+        /* No length restrictions for ChaChaPoly. */
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
+    {
+        ( void ) ad_length;
+        ( void ) plaintext_length;
+
+        return ( PSA_ERROR_NOT_SUPPORTED );
+    }
+
+    operation->ad_remaining = ad_length;
+    operation->body_remaining = plaintext_length;
+    operation->lengths_set = 1;
+
+    return ( PSA_SUCCESS );
+}
+
+/* Pass additional data to an active multipart AEAD operation. */
+psa_status_t mbedtls_psa_aead_update_ad( psa_aead_operation_t *operation,
+                                         const uint8_t *input,
+                                         size_t input_length )
+{
+    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+
+    if( !operation->nonce_set || !operation->key_set )
+    {
+        return( PSA_ERROR_BAD_STATE );
+    }
+
+    if( operation->lengths_set )
+    {
+        if ( operation->ad_remaining < input_length )
+        {
+            return( PSA_ERROR_INVALID_ARGUMENT );
+        }
+
+        operation->ad_remaining -= input_length;
+    }
+
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
+    if( operation->alg == PSA_ALG_GCM )
+    {
+        if( !operation->lengths_set || operation->ad_started )
+        {
+            return( PSA_ERROR_BAD_STATE );
+        }
+
+        /* GCM currently requires all the additional data to be passed in in
+         * one contigious buffer, so until that is re-done, we have to enforce
+         * this, as we cannot allocate a buffer to collate multiple calls into.
+           */
+        if( input_length != operation->ad_remaining )
+        {
+            return ( PSA_ERROR_INVALID_ARGUMENT );
+        }
+
+        status = mbedtls_to_psa_error( mbedtls_gcm_starts( &operation->ctx.gcm,
+                                                          operation->is_encrypt ?
+                                                           MBEDTLS_GCM_ENCRYPT : MBEDTLS_GCM_DECRYPT,
+                                                          operation->nonce,
+                                                          operation->nonce_length,
+                                                          input,
+                                                          input_length ) );
+
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
+    if( operation->alg == PSA_ALG_CCM )
+    {
+        /* CCM requires all additional data to be passed in in one go at the
+           minute, as we are basically operating in oneshot mode. */
+        if( !operation->lengths_set || operation->ad_started )
+        {
+            return( PSA_ERROR_BAD_STATE );
+        }
+
+        /* Save the additional data for later, this will be passed in
+           when we have the body. */
+        operation->ad_buffer = ( uint8_t * ) mbedtls_calloc(1, input_length );
+
+        if( operation->ad_buffer )
+        {
+            memcpy( operation->ad_buffer, input, input_length );
+            operation->ad_length = input_length;
+        }
+        else
+        {
+            return ( PSA_ERROR_INSUFFICIENT_MEMORY );
+        }
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
+    if( operation->alg == PSA_ALG_CHACHA20_POLY1305 )
+    {
+        status = mbedtls_to_psa_error( mbedtls_chachapoly_update_aad( &operation->ctx.chachapoly,
+                                                                      input,
+                                                                      input_length ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
+    {
+        (void) input;
+        (void) input_length;
+
+        return ( PSA_ERROR_NOT_SUPPORTED );
+    }
+
+    if( status == PSA_SUCCESS )
+    {
+        operation->ad_started = 1;
+    }
+
+    return ( status );
+}
+
+/* Encrypt or decrypt a message fragment in an active multipart AEAD
+ * operation.*/
+psa_status_t mbedtls_psa_aead_update( psa_aead_operation_t *operation,
+                                      const uint8_t *input,
+                                      size_t input_length,
+                                      uint8_t *output,
+                                      size_t output_size,
+                                      size_t *output_length )
+{
+    size_t update_output_size;
+    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+
+    if( !operation->nonce_set || !operation->key_set || !operation->ad_started )
+    {
+        return( PSA_ERROR_BAD_STATE );
+    }
+
+    update_output_size = PSA_AEAD_UPDATE_OUTPUT_SIZE(operation->key_type,
+                                                     operation->alg, input_length);
+
+    if(update_output_size > output_size )
+    {
+        return ( PSA_ERROR_BUFFER_TOO_SMALL );
+    }
+
+    if( operation->lengths_set)
+    {
+        /* Additional data length was supplied, but not all the additional
+           data was supplied.*/
+        if( operation->ad_remaining != 0 )
+        {
+            return ( PSA_ERROR_INVALID_ARGUMENT );
+        }
+
+        /* Too much data provided. */
+        if( operation->body_remaining < input_length )
+        {
+            return ( PSA_ERROR_INVALID_ARGUMENT );
+        }
+
+        operation->body_remaining -= input_length;
+    }
+
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
+    if( operation->alg == PSA_ALG_GCM )
+    {
+        /* For the time being set the requirement that all of the body data
+         * must be passed in in one update, rather than deal with the complexity
+         * of non block size aligned updates. This will be fixed in 3.0 when
+           we can change the signature of the GCM multipart functions */
+        if( !operation->lengths_set || operation->body_remaining != 0 )
+        {
+            return( PSA_ERROR_BAD_STATE );
+        }
+
+        if( operation->ad_started )
+        {
+            return( PSA_ERROR_BAD_STATE );
+        }
+
+        status =  mbedtls_to_psa_error( mbedtls_gcm_update( &operation->ctx.gcm,
+                                                        input_length,
+                                                        input,
+                                                        output ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
+    if( operation->alg == PSA_ALG_CCM )
+    {
+        /* CCM dooes not support multipart yet, so all the input has to be
+           passed in in one go. Store the data for the final step.*/
+        if( operation->ad_started )
+        {
+            return( PSA_ERROR_BAD_STATE );
+        }
+
+        /* Save the additional data for later, this will be passed in
+           when we have the body. */
+        operation->data_buffer = ( uint8_t * ) mbedtls_calloc(1, input_length );
+
+        if( operation->data_buffer )
+        {
+            memcpy( operation->data_buffer, input, input_length );
+            operation->data_length = input_length;
+        }
+        else
+        {
+            return ( PSA_ERROR_INSUFFICIENT_MEMORY );
+        }
+
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
+    if( operation->alg == PSA_ALG_CHACHA20_POLY1305 )
+    {
+        status = mbedtls_to_psa_error( mbedtls_chachapoly_update( &operation->ctx.chachapoly,
+                                                                  input_length,
+                                                                  input,
+                                                                  output ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
+    {
+        (void) input;
+        (void) input_length;
+
+        return ( PSA_ERROR_NOT_SUPPORTED );
+    }
+
+    if( status == PSA_SUCCESS )
+    {
+        *output_length = update_output_size;
+        operation->body_started = 1;
+    }
+
+    return( status );
+}
+
+/* Common checks for both mbedtls_psa_aead_finish() and
+   mbedtls_psa_aead_verify() */
+static psa_status_t mbedtls_psa_aead_finish_checks( psa_aead_operation_t *operation,
+                                                    size_t output_size,
+                                                    size_t tag_size,
+                                                    size_t *finish_output_size,
+                                                    size_t *output_tag_length )
+{
+    if( !operation->key_set || !operation->nonce_set
+        || !operation->ad_started || !operation->body_started)
+    {
+        return( PSA_ERROR_BAD_STATE );
+    }
+
+    if( operation->lengths_set )
+    {
+        if( operation->ad_remaining != 0 || operation->body_remaining != 0 )
+        {
+            return( PSA_ERROR_BAD_STATE );
+        }
+    }
+
+    *output_tag_length = operation->tag_length;
+
+    if( tag_size < *output_tag_length)
+    {
+        return ( PSA_ERROR_BUFFER_TOO_SMALL );
+    }
+
+    if( operation->is_encrypt )
+    {
+        *finish_output_size = PSA_AEAD_FINISH_OUTPUT_SIZE(operation->key_type,
+                                                          operation->alg);
+    }
+    else
+    {
+        *finish_output_size = PSA_AEAD_VERIFY_OUTPUT_SIZE(operation->key_type,
+                                                          operation->alg);
+    }
+
+    if( output_size < *finish_output_size )
+    {
+        return ( PSA_ERROR_BUFFER_TOO_SMALL );
+    }
+
+    return ( PSA_SUCCESS );
+
+}
+
+/* Finish encrypting a message in a multipart AEAD operation. */
+psa_status_t mbedtls_psa_aead_finish( psa_aead_operation_t *operation,
+                                      uint8_t *ciphertext,
+                                      size_t ciphertext_size,
+                                      size_t *ciphertext_length,
+                                      uint8_t *tag,
+                                      size_t tag_size,
+                                      size_t *tag_length )
+{
+    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+    size_t output_tag_length;
+    size_t finish_output_size;
+
+    status = mbedtls_psa_aead_finish_checks( operation, ciphertext_size, tag_size, &finish_output_size,
+                                             &output_tag_length);
+
+    if( status != PSA_SUCCESS )
+    {
+        return status;
+    }
+
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
+    if( operation->alg == PSA_ALG_GCM )
+    {
+        /* We will need to do final GCM pass in here when multipart is done. */
+        status =  mbedtls_to_psa_error( mbedtls_gcm_finish( &operation->ctx.gcm,
+                                                            tag,
+                                                            tag_size ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
+    if( operation->alg == PSA_ALG_CCM )
+    {
+        if( !operation->ad_buffer || !operation->data_buffer )
+        {
+            return( PSA_ERROR_BAD_STATE );
+        }
+
+        /* Perform oneshot CCM encryption with data already stored, as
+           CCM does not support multipart yet.*/
+        status = mbedtls_to_psa_error( mbedtls_ccm_encrypt_and_tag( &operation->ctx.ccm,
+                                                                    operation->data_length,
+                                                                    operation->nonce,
+                                                                    operation->nonce_length,
+                                                                    operation->ad_buffer,
+                                                                    operation->ad_length,
+                                                                    operation->data_buffer,
+                                                                    ciphertext,
+                                                                    tag, tag_size ) );
+
+        /* Even if the above operation fails, we no longer need the data */
+        mbedtls_free(operation->ad_buffer);
+        operation->ad_buffer = NULL;
+        operation->ad_length = 0;
+
+        mbedtls_free(operation->data_buffer);
+        operation->data_buffer = NULL;
+        operation->data_length = 0;
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
+    if( operation->alg == PSA_ALG_CHACHA20_POLY1305 )
+    {
+        status = mbedtls_to_psa_error( mbedtls_chachapoly_finish( &operation->ctx.chachapoly,
+                                                                  tag ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
+    {
+        ( void ) ciphertext;
+        ( void ) ciphertext_size;
+        ( void ) ciphertext_length;
+        ( void ) tag;
+        ( void ) tag_size;
+        ( void ) tag_length;
+
+        return ( PSA_ERROR_NOT_SUPPORTED );
+    }
+
+    if( status == PSA_SUCCESS )
+    {
+        *ciphertext_length = finish_output_size;
+        *tag_length = output_tag_length;
+    }
+
+    mbedtls_psa_aead_abort(operation);
+
+    return ( status );
+}
+
+/* Finish authenticating and decrypting a message in a multipart AEAD
+ * operation.*/
+psa_status_t mbedtls_psa_aead_verify( psa_aead_operation_t *operation,
+                                      uint8_t *plaintext,
+                                      size_t plaintext_size,
+                                      size_t *plaintext_length,
+                                      const uint8_t *tag,
+                                      size_t tag_length )
+{
+    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    size_t finish_output_size;
+    size_t output_tag_length;
+
+    int do_tag_check = 1;
+    uint8_t check_tag[16];
+
+    status = mbedtls_psa_aead_finish_checks( operation, plaintext_size, tag_length, &finish_output_size,
+                                             &output_tag_length);
+
+    if( status != PSA_SUCCESS )
+    {
+        return status;
+    }
+
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
+    if( operation->alg == PSA_ALG_GCM )
+    {
+        /* Call finish to get the tag for comparison */
+        status =  mbedtls_to_psa_error( mbedtls_gcm_finish( &operation->ctx.gcm,
+                                                            check_tag,
+                                                            16 ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
+    if( operation->alg == PSA_ALG_CCM )
+    {
+        if( !operation->ad_buffer || !operation->data_buffer )
+        {
+            return( PSA_ERROR_BAD_STATE );
+        }
+
+        /* Perform oneshot CCM decryption with data already stored, as
+           CCM does not support multipart yet.*/
+
+        ret = mbedtls_ccm_auth_decrypt( &operation->ctx.ccm, operation->data_length,
+                                       operation->nonce, operation->nonce_length,
+                                       operation->ad_buffer, operation->ad_length,
+                                       operation->data_buffer, plaintext,
+                                       tag, tag_length );
+
+        if( ret == MBEDTLS_ERR_CCM_AUTH_FAILED )
+        {
+            status = PSA_ERROR_INVALID_SIGNATURE;
+        }
+        else
+        {
+            status = mbedtls_to_psa_error( ret );
+            do_tag_check = 0;
+        }
+
+        /* Even if the above operation fails, we no longer need the data */
+        mbedtls_free(operation->ad_buffer);
+        operation->ad_buffer = NULL;
+        operation->ad_length = 0;
+
+        mbedtls_free(operation->data_buffer);
+        operation->data_buffer = NULL;
+        operation->data_length = 0;
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
+    if( operation->alg == PSA_ALG_CHACHA20_POLY1305 )
+    {
+        // call finish to get the tag for comparison.
+        status = mbedtls_to_psa_error( mbedtls_chachapoly_finish( &operation->ctx.chachapoly,
+                                                                  check_tag ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
+    {
+        ( void ) plaintext;
+        ( void ) plaintext_size;
+        ( void ) plaintext_length;
+        ( void ) tag;
+        ( void ) tag_length;
+
+        return ( PSA_ERROR_NOT_SUPPORTED );
+    }
+
+    if( status == PSA_SUCCESS )
+    {
+        if( do_tag_check && safer_memcmp(tag, check_tag, tag_length) != 0 )
+        {
+            status = MBEDTLS_ERR_GCM_AUTH_FAILED;
+        }
+    }
+
+    mbedtls_psa_aead_abort(operation);
+
+    return ( status );
+}
+
+/* Abort an AEAD operation */
+psa_status_t mbedtls_psa_aead_abort( psa_aead_operation_t *operation )
+{
+   switch( operation->alg )
+    {
+#if defined(MBEDTLS_CCM_C)
+        case MBEDTLS_PSA_BUILTIN_ALG_CCM:
+            mbedtls_ccm_free( &operation->ctx.ccm );
+            break;
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
+        case PSA_ALG_GCM:
+            mbedtls_gcm_free( &operation->ctx.gcm );
+            break;
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
+       case PSA_ALG_CHACHA20_POLY1305:
+           mbedtls_chachapoly_free( &operation->ctx.chachapoly );
+           break;
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
+    }
+
+    return( PSA_SUCCESS );
+}
+
 #endif /* MBEDTLS_PSA_CRYPTO_C */