psa: aead: Move AEAD driver entry points to psa_crypto_aead.c

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 0863901..eb6fae0 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -3509,222 +3509,6 @@
 /* AEAD */
 /****************************************************************/
 
-typedef struct
-{
-    const mbedtls_cipher_info_t *cipher_info;
-    union
-    {
-        unsigned dummy; /* Make the union non-empty even with no supported algorithms. */
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
-        mbedtls_ccm_context ccm;
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
-        mbedtls_gcm_context gcm;
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
-        mbedtls_chachapoly_context chachapoly;
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
-    } ctx;
-    psa_algorithm_t core_alg;
-    uint8_t full_tag_length;
-    uint8_t tag_length;
-} aead_operation_t;
-
-#define AEAD_OPERATION_INIT {0, {0}, 0, 0, 0}
-
-static void psa_aead_abort_internal( aead_operation_t *operation )
-{
-    switch( operation->core_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 */
-    }
-}
-
-static psa_status_t psa_aead_setup(
-    aead_operation_t *operation,
-    const psa_key_attributes_t *attributes,
-    const uint8_t *key_buffer,
-    psa_algorithm_t alg )
-{
-    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
-    size_t key_bits;
-    mbedtls_cipher_id_t cipher_id;
-
-    key_bits = attributes->core.bits;
-
-    operation->cipher_info =
-        mbedtls_cipher_info_from_psa( alg, attributes->core.type, key_bits,
-                                      &cipher_id );
-    if( operation->cipher_info == NULL )
-        return( PSA_ERROR_NOT_SUPPORTED );
-
-    switch( PSA_ALG_AEAD_WITH_SHORTENED_TAG( alg, 0 ) )
-    {
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
-        case PSA_ALG_AEAD_WITH_SHORTENED_TAG( PSA_ALG_CCM, 0 ):
-            operation->core_alg = PSA_ALG_CCM;
-            operation->full_tag_length = 16;
-            /* CCM allows the following tag lengths: 4, 6, 8, 10, 12, 14, 16.
-             * The call to mbedtls_ccm_encrypt_and_tag or
-             * mbedtls_ccm_auth_decrypt will validate the tag length. */
-            if( PSA_BLOCK_CIPHER_BLOCK_LENGTH( attributes->core.type ) != 16 )
-                return( PSA_ERROR_INVALID_ARGUMENT );
-
-            mbedtls_ccm_init( &operation->ctx.ccm );
-            status = mbedtls_to_psa_error(
-                mbedtls_ccm_setkey( &operation->ctx.ccm, cipher_id,
-                                    key_buffer, (unsigned int) key_bits ) );
-            if( status != PSA_SUCCESS )
-                return( status );
-            break;
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
-
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
-        case PSA_ALG_AEAD_WITH_SHORTENED_TAG( PSA_ALG_GCM, 0 ):
-            operation->core_alg = PSA_ALG_GCM;
-            operation->full_tag_length = 16;
-            /* GCM allows the following tag lengths: 4, 8, 12, 13, 14, 15, 16.
-             * The call to mbedtls_gcm_crypt_and_tag or
-             * mbedtls_gcm_auth_decrypt will validate the tag length. */
-            if( PSA_BLOCK_CIPHER_BLOCK_LENGTH( attributes->core.type ) != 16 )
-                return( PSA_ERROR_INVALID_ARGUMENT );
-
-            mbedtls_gcm_init( &operation->ctx.gcm );
-            status = mbedtls_to_psa_error(
-                mbedtls_gcm_setkey( &operation->ctx.gcm, cipher_id,
-                                    key_buffer, (unsigned int) key_bits ) );
-            if( status != PSA_SUCCESS )
-                return( status );
-            break;
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
-
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
-        case PSA_ALG_AEAD_WITH_SHORTENED_TAG( PSA_ALG_CHACHA20_POLY1305, 0 ):
-            operation->core_alg = PSA_ALG_CHACHA20_POLY1305;
-            operation->full_tag_length = 16;
-            /* We only support the default tag length. */
-            if( alg != PSA_ALG_CHACHA20_POLY1305 )
-                return( PSA_ERROR_NOT_SUPPORTED );
-
-            mbedtls_chachapoly_init( &operation->ctx.chachapoly );
-            status = mbedtls_to_psa_error(
-                mbedtls_chachapoly_setkey( &operation->ctx.chachapoly,
-                                           key_buffer ) );
-            if( status != PSA_SUCCESS )
-                return( status );
-            break;
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
-
-        default:
-            return( PSA_ERROR_NOT_SUPPORTED );
-    }
-
-    if( PSA_AEAD_TAG_LENGTH( alg ) > operation->full_tag_length )
-        return( PSA_ERROR_INVALID_ARGUMENT );
-
-    operation->tag_length = PSA_AEAD_TAG_LENGTH( alg );
-
-    return( PSA_SUCCESS );
-}
-
-static psa_status_t psa_aead_encrypt_internal(
-    const psa_key_attributes_t *attributes,
-    const uint8_t *key_buffer, size_t key_buffer_size,
-    psa_algorithm_t alg,
-    const uint8_t *nonce, size_t nonce_length,
-    const uint8_t *additional_data, size_t additional_data_length,
-    const uint8_t *plaintext, size_t plaintext_length,
-    uint8_t *ciphertext, size_t ciphertext_size, size_t *ciphertext_length )
-{
-    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
-    aead_operation_t operation = AEAD_OPERATION_INIT;
-    uint8_t *tag;
-    (void) key_buffer_size;
-
-    status = psa_aead_setup( &operation, attributes, key_buffer, alg );
-    if( status != PSA_SUCCESS )
-        goto exit;
-
-    /* For all currently supported modes, the tag is at the end of the
-     * ciphertext. */
-    if( ciphertext_size < ( plaintext_length + operation.tag_length ) )
-    {
-        status = PSA_ERROR_BUFFER_TOO_SMALL;
-        goto exit;
-    }
-    tag = ciphertext + plaintext_length;
-
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
-    if( operation.core_alg == PSA_ALG_GCM )
-    {
-        status = mbedtls_to_psa_error(
-            mbedtls_gcm_crypt_and_tag( &operation.ctx.gcm,
-                                       MBEDTLS_GCM_ENCRYPT,
-                                       plaintext_length,
-                                       nonce, nonce_length,
-                                       additional_data, additional_data_length,
-                                       plaintext, ciphertext,
-                                       operation.tag_length, tag ) );
-    }
-    else
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
-    if( operation.core_alg == PSA_ALG_CCM )
-    {
-        status = mbedtls_to_psa_error(
-            mbedtls_ccm_encrypt_and_tag( &operation.ctx.ccm,
-                                         plaintext_length,
-                                         nonce, nonce_length,
-                                         additional_data,
-                                         additional_data_length,
-                                         plaintext, ciphertext,
-                                         tag, operation.tag_length ) );
-    }
-    else
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
-    if( operation.core_alg == PSA_ALG_CHACHA20_POLY1305 )
-    {
-        if( nonce_length != 12 || operation.tag_length != 16 )
-        {
-            status = PSA_ERROR_NOT_SUPPORTED;
-            goto exit;
-        }
-        status = mbedtls_to_psa_error(
-            mbedtls_chachapoly_encrypt_and_tag( &operation.ctx.chachapoly,
-                                                plaintext_length,
-                                                nonce,
-                                                additional_data,
-                                                additional_data_length,
-                                                plaintext,
-                                                ciphertext,
-                                                tag ) );
-    }
-    else
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
-    {
-        (void) tag;
-        return( PSA_ERROR_NOT_SUPPORTED );
-    }
-
-    if( status == PSA_SUCCESS )
-        *ciphertext_length = plaintext_length + operation.tag_length;
-
-exit:
-    psa_aead_abort_internal( &operation );
-
-    return( status );
-}
-
 psa_status_t psa_aead_encrypt( mbedtls_svc_key_id_t key,
                                psa_algorithm_t alg,
                                const uint8_t *nonce,
@@ -3751,7 +3535,7 @@
       .core = slot->attr
     };
 
-    status = psa_aead_encrypt_internal(
+    status = mbedtls_psa_aead_encrypt(
         &attributes, slot->key.data, slot->key.bytes,
         alg,
         nonce, nonce_length,
@@ -3767,114 +3551,6 @@
     return( status );
 }
 
-/* Locate the tag in a ciphertext buffer containing the encrypted data
- * followed by the tag. Return the length of the part preceding the tag in
- * *plaintext_length. This is the size of the plaintext in modes where
- * the encrypted data has the same size as the plaintext, such as
- * CCM and GCM. */
-static psa_status_t psa_aead_unpadded_locate_tag( size_t tag_length,
-                                                  const uint8_t *ciphertext,
-                                                  size_t ciphertext_length,
-                                                  size_t plaintext_size,
-                                                  const uint8_t **p_tag )
-{
-    size_t payload_length;
-    if( tag_length > ciphertext_length )
-        return( PSA_ERROR_INVALID_ARGUMENT );
-    payload_length = ciphertext_length - tag_length;
-    if( payload_length > plaintext_size )
-        return( PSA_ERROR_BUFFER_TOO_SMALL );
-    *p_tag = ciphertext + payload_length;
-    return( PSA_SUCCESS );
-}
-
-static psa_status_t psa_aead_decrypt_internal(
-    const psa_key_attributes_t *attributes,
-    const uint8_t *key_buffer, size_t key_buffer_size,
-    psa_algorithm_t alg,
-    const uint8_t *nonce, size_t nonce_length,
-    const uint8_t *additional_data, size_t additional_data_length,
-    const uint8_t *ciphertext, size_t ciphertext_length,
-    uint8_t *plaintext, size_t plaintext_size, size_t *plaintext_length )
-{
-    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
-    aead_operation_t operation = AEAD_OPERATION_INIT;
-    const uint8_t *tag = NULL;
-    (void) key_buffer_size;
-
-    status = psa_aead_setup( &operation, attributes, key_buffer, alg );
-    if( status != PSA_SUCCESS )
-        goto exit;
-
-    status = psa_aead_unpadded_locate_tag( operation.tag_length,
-                                           ciphertext, ciphertext_length,
-                                           plaintext_size, &tag );
-    if( status != PSA_SUCCESS )
-        goto exit;
-
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
-    if( operation.core_alg == PSA_ALG_GCM )
-    {
-        status = mbedtls_to_psa_error(
-            mbedtls_gcm_auth_decrypt( &operation.ctx.gcm,
-                                      ciphertext_length - operation.tag_length,
-                                      nonce, nonce_length,
-                                      additional_data,
-                                      additional_data_length,
-                                      tag, operation.tag_length,
-                                      ciphertext, plaintext ) );
-    }
-    else
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
-    if( operation.core_alg == PSA_ALG_CCM )
-    {
-        status = mbedtls_to_psa_error(
-            mbedtls_ccm_auth_decrypt( &operation.ctx.ccm,
-                                      ciphertext_length - operation.tag_length,
-                                      nonce, nonce_length,
-                                      additional_data,
-                                      additional_data_length,
-                                      ciphertext, plaintext,
-                                      tag, operation.tag_length ) );
-    }
-    else
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
-#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
-    if( operation.core_alg == PSA_ALG_CHACHA20_POLY1305 )
-    {
-        if( nonce_length != 12 || operation.tag_length != 16 )
-        {
-            status = PSA_ERROR_NOT_SUPPORTED;
-            goto exit;
-        }
-        status = mbedtls_to_psa_error(
-            mbedtls_chachapoly_auth_decrypt( &operation.ctx.chachapoly,
-                                             ciphertext_length - operation.tag_length,
-                                             nonce,
-                                             additional_data,
-                                             additional_data_length,
-                                             tag,
-                                             ciphertext,
-                                             plaintext ) );
-    }
-    else
-#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
-    {
-        return( PSA_ERROR_NOT_SUPPORTED );
-    }
-
-    if( status == PSA_SUCCESS )
-        *plaintext_length = ciphertext_length - operation.tag_length;
-
-exit:
-    psa_aead_abort_internal( &operation );
-
-    if( status == PSA_SUCCESS )
-        *plaintext_length = ciphertext_length - operation.tag_length;
-    return( status );
-}
-
 psa_status_t psa_aead_decrypt( mbedtls_svc_key_id_t key,
                                psa_algorithm_t alg,
                                const uint8_t *nonce,
@@ -3901,7 +3577,7 @@
       .core = slot->attr
     };
 
-    status = psa_aead_decrypt_internal(
+    status = mbedtls_psa_aead_decrypt(
         &attributes, slot->key.data, slot->key.bytes,
         alg,
         nonce, nonce_length,
@@ -3917,8 +3593,6 @@
     return( status );
 }
 
-
-
 /****************************************************************/
 /* Generators */
 /****************************************************************/
diff --git a/library/psa_crypto_aead.c b/library/psa_crypto_aead.c
index f453533..18ea176 100644
--- a/library/psa_crypto_aead.c
+++ b/library/psa_crypto_aead.c
@@ -23,6 +23,336 @@
 #if defined(MBEDTLS_PSA_CRYPTO_C)
 
 #include "psa_crypto_aead.h"
+#include "psa_crypto_core.h"
+
+#include "mbedtls/ccm.h"
+#include "mbedtls/chachapoly.h"
+#include "mbedtls/cipher.h"
+#include "mbedtls/gcm.h"
+
+typedef struct
+{
+    const mbedtls_cipher_info_t *cipher_info;
+    union
+    {
+        unsigned dummy; /* Make the union non-empty even with no supported algorithms. */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
+        mbedtls_ccm_context ccm;
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
+        mbedtls_gcm_context gcm;
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
+        mbedtls_chachapoly_context chachapoly;
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
+    } ctx;
+    psa_algorithm_t core_alg;
+    uint8_t full_tag_length;
+    uint8_t tag_length;
+} aead_operation_t;
+
+#define AEAD_OPERATION_INIT {0, {0}, 0, 0, 0}
+
+static void psa_aead_abort_internal( aead_operation_t *operation )
+{
+    switch( operation->core_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 */
+    }
+}
+
+static psa_status_t psa_aead_setup(
+    aead_operation_t *operation,
+    const psa_key_attributes_t *attributes,
+    const uint8_t *key_buffer,
+    psa_algorithm_t alg )
+{
+    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+    size_t key_bits;
+    mbedtls_cipher_id_t cipher_id;
+
+    key_bits = attributes->core.bits;
+
+    operation->cipher_info =
+        mbedtls_cipher_info_from_psa( alg, attributes->core.type, key_bits,
+                                      &cipher_id );
+    if( operation->cipher_info == NULL )
+        return( PSA_ERROR_NOT_SUPPORTED );
+
+    switch( PSA_ALG_AEAD_WITH_SHORTENED_TAG( alg, 0 ) )
+    {
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
+        case PSA_ALG_AEAD_WITH_SHORTENED_TAG( PSA_ALG_CCM, 0 ):
+            operation->core_alg = PSA_ALG_CCM;
+            operation->full_tag_length = 16;
+            /* CCM allows the following tag lengths: 4, 6, 8, 10, 12, 14, 16.
+             * The call to mbedtls_ccm_encrypt_and_tag or
+             * mbedtls_ccm_auth_decrypt will validate the tag length. */
+            if( PSA_BLOCK_CIPHER_BLOCK_LENGTH( attributes->core.type ) != 16 )
+                return( PSA_ERROR_INVALID_ARGUMENT );
+
+            mbedtls_ccm_init( &operation->ctx.ccm );
+            status = mbedtls_to_psa_error(
+                mbedtls_ccm_setkey( &operation->ctx.ccm, cipher_id,
+                                    key_buffer, (unsigned int) key_bits ) );
+            if( status != PSA_SUCCESS )
+                return( status );
+            break;
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
+
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
+        case PSA_ALG_AEAD_WITH_SHORTENED_TAG( PSA_ALG_GCM, 0 ):
+            operation->core_alg = PSA_ALG_GCM;
+            operation->full_tag_length = 16;
+            /* GCM allows the following tag lengths: 4, 8, 12, 13, 14, 15, 16.
+             * The call to mbedtls_gcm_crypt_and_tag or
+             * mbedtls_gcm_auth_decrypt will validate the tag length. */
+            if( PSA_BLOCK_CIPHER_BLOCK_LENGTH( attributes->core.type ) != 16 )
+                return( PSA_ERROR_INVALID_ARGUMENT );
+
+            mbedtls_gcm_init( &operation->ctx.gcm );
+            status = mbedtls_to_psa_error(
+                mbedtls_gcm_setkey( &operation->ctx.gcm, cipher_id,
+                                    key_buffer, (unsigned int) key_bits ) );
+            if( status != PSA_SUCCESS )
+                return( status );
+            break;
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
+
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
+        case PSA_ALG_AEAD_WITH_SHORTENED_TAG( PSA_ALG_CHACHA20_POLY1305, 0 ):
+            operation->core_alg = PSA_ALG_CHACHA20_POLY1305;
+            operation->full_tag_length = 16;
+            /* We only support the default tag length. */
+            if( alg != PSA_ALG_CHACHA20_POLY1305 )
+                return( PSA_ERROR_NOT_SUPPORTED );
+
+            mbedtls_chachapoly_init( &operation->ctx.chachapoly );
+            status = mbedtls_to_psa_error(
+                mbedtls_chachapoly_setkey( &operation->ctx.chachapoly,
+                                           key_buffer ) );
+            if( status != PSA_SUCCESS )
+                return( status );
+            break;
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
+
+        default:
+            return( PSA_ERROR_NOT_SUPPORTED );
+    }
+
+    if( PSA_AEAD_TAG_LENGTH( alg ) > operation->full_tag_length )
+        return( PSA_ERROR_INVALID_ARGUMENT );
+
+    operation->tag_length = PSA_AEAD_TAG_LENGTH( alg );
+
+    return( PSA_SUCCESS );
+}
+
+psa_status_t mbedtls_psa_aead_encrypt(
+    const psa_key_attributes_t *attributes,
+    const uint8_t *key_buffer, size_t key_buffer_size,
+    psa_algorithm_t alg,
+    const uint8_t *nonce, size_t nonce_length,
+    const uint8_t *additional_data, size_t additional_data_length,
+    const uint8_t *plaintext, size_t plaintext_length,
+    uint8_t *ciphertext, size_t ciphertext_size, size_t *ciphertext_length )
+{
+    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+    aead_operation_t operation = AEAD_OPERATION_INIT;
+    uint8_t *tag;
+    (void) key_buffer_size;
+
+    status = psa_aead_setup( &operation, attributes, key_buffer, alg );
+    if( status != PSA_SUCCESS )
+        goto exit;
+
+    /* For all currently supported modes, the tag is at the end of the
+     * ciphertext. */
+    if( ciphertext_size < ( plaintext_length + operation.tag_length ) )
+    {
+        status = PSA_ERROR_BUFFER_TOO_SMALL;
+        goto exit;
+    }
+    tag = ciphertext + plaintext_length;
+
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
+    if( operation.core_alg == PSA_ALG_GCM )
+    {
+        status = mbedtls_to_psa_error(
+            mbedtls_gcm_crypt_and_tag( &operation.ctx.gcm,
+                                       MBEDTLS_GCM_ENCRYPT,
+                                       plaintext_length,
+                                       nonce, nonce_length,
+                                       additional_data, additional_data_length,
+                                       plaintext, ciphertext,
+                                       operation.tag_length, tag ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
+    if( operation.core_alg == PSA_ALG_CCM )
+    {
+        status = mbedtls_to_psa_error(
+            mbedtls_ccm_encrypt_and_tag( &operation.ctx.ccm,
+                                         plaintext_length,
+                                         nonce, nonce_length,
+                                         additional_data,
+                                         additional_data_length,
+                                         plaintext, ciphertext,
+                                         tag, operation.tag_length ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
+    if( operation.core_alg == PSA_ALG_CHACHA20_POLY1305 )
+    {
+        if( nonce_length != 12 || operation.tag_length != 16 )
+        {
+            status = PSA_ERROR_NOT_SUPPORTED;
+            goto exit;
+        }
+        status = mbedtls_to_psa_error(
+            mbedtls_chachapoly_encrypt_and_tag( &operation.ctx.chachapoly,
+                                                plaintext_length,
+                                                nonce,
+                                                additional_data,
+                                                additional_data_length,
+                                                plaintext,
+                                                ciphertext,
+                                                tag ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
+    {
+        (void) tag;
+        return( PSA_ERROR_NOT_SUPPORTED );
+    }
+
+    if( status == PSA_SUCCESS )
+        *ciphertext_length = plaintext_length + operation.tag_length;
+
+exit:
+    psa_aead_abort_internal( &operation );
+
+    return( status );
+}
+
+/* Locate the tag in a ciphertext buffer containing the encrypted data
+ * followed by the tag. Return the length of the part preceding the tag in
+ * *plaintext_length. This is the size of the plaintext in modes where
+ * the encrypted data has the same size as the plaintext, such as
+ * CCM and GCM. */
+static psa_status_t psa_aead_unpadded_locate_tag( size_t tag_length,
+                                                  const uint8_t *ciphertext,
+                                                  size_t ciphertext_length,
+                                                  size_t plaintext_size,
+                                                  const uint8_t **p_tag )
+{
+    size_t payload_length;
+    if( tag_length > ciphertext_length )
+        return( PSA_ERROR_INVALID_ARGUMENT );
+    payload_length = ciphertext_length - tag_length;
+    if( payload_length > plaintext_size )
+        return( PSA_ERROR_BUFFER_TOO_SMALL );
+    *p_tag = ciphertext + payload_length;
+    return( PSA_SUCCESS );
+}
+
+psa_status_t mbedtls_psa_aead_decrypt(
+    const psa_key_attributes_t *attributes,
+    const uint8_t *key_buffer, size_t key_buffer_size,
+    psa_algorithm_t alg,
+    const uint8_t *nonce, size_t nonce_length,
+    const uint8_t *additional_data, size_t additional_data_length,
+    const uint8_t *ciphertext, size_t ciphertext_length,
+    uint8_t *plaintext, size_t plaintext_size, size_t *plaintext_length )
+{
+    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+    aead_operation_t operation = AEAD_OPERATION_INIT;
+    const uint8_t *tag = NULL;
+    (void) key_buffer_size;
+
+    status = psa_aead_setup( &operation, attributes, key_buffer, alg );
+    if( status != PSA_SUCCESS )
+        goto exit;
+
+    status = psa_aead_unpadded_locate_tag( operation.tag_length,
+                                           ciphertext, ciphertext_length,
+                                           plaintext_size, &tag );
+    if( status != PSA_SUCCESS )
+        goto exit;
+
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)
+    if( operation.core_alg == PSA_ALG_GCM )
+    {
+        status = mbedtls_to_psa_error(
+            mbedtls_gcm_auth_decrypt( &operation.ctx.gcm,
+                                      ciphertext_length - operation.tag_length,
+                                      nonce, nonce_length,
+                                      additional_data,
+                                      additional_data_length,
+                                      tag, operation.tag_length,
+                                      ciphertext, plaintext ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)
+    if( operation.core_alg == PSA_ALG_CCM )
+    {
+        status = mbedtls_to_psa_error(
+            mbedtls_ccm_auth_decrypt( &operation.ctx.ccm,
+                                      ciphertext_length - operation.tag_length,
+                                      nonce, nonce_length,
+                                      additional_data,
+                                      additional_data_length,
+                                      ciphertext, plaintext,
+                                      tag, operation.tag_length ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
+    if( operation.core_alg == PSA_ALG_CHACHA20_POLY1305 )
+    {
+        if( nonce_length != 12 || operation.tag_length != 16 )
+        {
+            status = PSA_ERROR_NOT_SUPPORTED;
+            goto exit;
+        }
+        status = mbedtls_to_psa_error(
+            mbedtls_chachapoly_auth_decrypt( &operation.ctx.chachapoly,
+                                             ciphertext_length - operation.tag_length,
+                                             nonce,
+                                             additional_data,
+                                             additional_data_length,
+                                             tag,
+                                             ciphertext,
+                                             plaintext ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
+    {
+        return( PSA_ERROR_NOT_SUPPORTED );
+    }
+
+    if( status == PSA_SUCCESS )
+        *plaintext_length = ciphertext_length - operation.tag_length;
+
+exit:
+    psa_aead_abort_internal( &operation );
+
+    if( status == PSA_SUCCESS )
+        *plaintext_length = ciphertext_length - operation.tag_length;
+    return( status );
+}
 
 #endif /* MBEDTLS_PSA_CRYPTO_C */
 
diff --git a/library/psa_crypto_aead.h b/library/psa_crypto_aead.h
index 1219e7c..aab0f83 100644
--- a/library/psa_crypto_aead.h
+++ b/library/psa_crypto_aead.h
@@ -23,4 +23,129 @@
 
 #include <psa/crypto.h>
 
+/**
+ * \brief Process an authenticated encryption operation.
+ *
+ * \note The signature of this function is that of a PSA driver
+ *       aead_encrypt entry point. This function behaves as an aead_encrypt
+ *       entry point as defined in the PSA driver interface specification for
+ *       transparent drivers.
+ *
+ * \param[in]  attributes         The attributes of the key to use for the
+ *                                operation.
+ * \param[in]  key_buffer         The buffer containing the key context.
+ * \param      key_buffer_size    Size of the \p key_buffer buffer in bytes.
+ * \param      alg                The AEAD algorithm to compute.
+ * \param[in]  nonce              Nonce or IV to use.
+ * \param      nonce_length       Size of the nonce buffer in bytes. This must
+ *                                be appropriate for the selected algorithm.
+ *                                The default nonce size is
+ *                                PSA_AEAD_NONCE_LENGTH(key_type, alg) where
+ *                                key_type is the type of key.
+ * \param[in]  additional_data    Additional data that will be authenticated
+ *                                but not encrypted.
+ * \param      additional_data_length  Size of additional_data in bytes.
+ * \param[in]  plaintext          Data that will be authenticated and encrypted.
+ * \param      plaintext_length   Size of plaintext in bytes.
+ * \param[out] ciphertext         Output buffer for the authenticated and
+ *                                encrypted data. The additional data is not
+ *                                part of this output. For algorithms where the
+ *                                encrypted data and the authentication tag are
+ *                                defined as separate outputs, the
+ *                                authentication tag is appended to the
+ *                                encrypted data.
+ * \param      ciphertext_size    Size of the ciphertext buffer in bytes. This
+ *                                must be appropriate for the selected algorithm
+ *                                and key:
+ *                                - A sufficient output size is
+ *                                  PSA_AEAD_ENCRYPT_OUTPUT_SIZE(key_type, alg,
+ *                                  plaintext_length) where key_type is the type
+ *                                  of key.
+ *                                - PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE(
+ *                                  plaintext_length) evaluates to the maximum
+ *                                  ciphertext size of any supported AEAD
+ *                                  encryption.
+ * \param[out] ciphertext_length  On success, the size of the output in the
+ *                                ciphertext buffer.
+ *
+ * \retval #PSA_SUCCESS Success.
+ * \retval #PSA_ERROR_NOT_SUPPORTED
+ *         \p alg is not supported.
+ * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
+ * \retval #PSA_ERROR_BUFFER_TOO_SMALL
+ *         ciphertext_size is too small.
+ * \retval #PSA_ERROR_CORRUPTION_DETECTED
+ */
+psa_status_t mbedtls_psa_aead_encrypt(
+    const psa_key_attributes_t *attributes,
+    const uint8_t *key_buffer, size_t key_buffer_size,
+    psa_algorithm_t alg,
+    const uint8_t *nonce, size_t nonce_length,
+    const uint8_t *additional_data, size_t additional_data_length,
+    const uint8_t *plaintext, size_t plaintext_length,
+    uint8_t *ciphertext, size_t ciphertext_size, size_t *ciphertext_length );
+
+/**
+ * \brief Process an authenticated decryption operation.
+ *
+ * \note The signature of this function is that of a PSA driver
+ *       aead_decrypt entry point. This function behaves as an aead_decrypt
+ *       entry point as defined in the PSA driver interface specification for
+ *       transparent drivers.
+ *
+ * \param[in]  attributes         The attributes of the key to use for the
+ *                                operation.
+ * \param[in]  key_buffer         The buffer containing the key context.
+ * \param      key_buffer_size    Size of the \p key_buffer buffer in bytes.
+ * \param      alg                The AEAD algorithm to compute.
+ * \param[in]  nonce              Nonce or IV to use.
+ * \param      nonce_length       Size of the nonce buffer in bytes. This must
+ *                                be appropriate for the selected algorithm.
+ *                                The default nonce size is
+ *                                PSA_AEAD_NONCE_LENGTH(key_type, alg) where
+ *                                key_type is the type of key.
+ * \param[in]  additional_data    Additional data that has been authenticated
+ *                                but not encrypted.
+ * \param      additional_data_length  Size of additional_data in bytes.
+ * \param[in]  ciphertext         Data that has been authenticated and
+ *                                encrypted. For algorithms where the encrypted
+ *                                data and the authentication tag are defined
+ *                                as separate inputs, the buffer contains
+ *                                encrypted data followed by the authentication
+ *                                tag.
+ * \param      ciphertext_length  Size of ciphertext in bytes.
+ * \param[out] plaintext          Output buffer for the decrypted data.
+ * \param      plaintext_size     Size of the plaintext buffer in bytes. This
+ *                                must be appropriate for the selected algorithm
+ *                                and key:
+ *                                - A sufficient output size is
+ *                                  PSA_AEAD_DECRYPT_OUTPUT_SIZE(key_type, alg,
+ *                                  ciphertext_length) where key_type is the
+ *                                  type of key.
+ *                                - PSA_AEAD_DECRYPT_OUTPUT_MAX_SIZE(
+ *                                  ciphertext_length) evaluates to the maximum
+ *                                  plaintext size of any supported AEAD
+ *                                  decryption.
+ * \param[out] plaintext_length   On success, the size of the output in the
+ *                                plaintext buffer.
+ *
+ * \retval #PSA_SUCCESS Success.
+ * \retval #PSA_ERROR_INVALID_SIGNATURE
+ *         The cipher is not authentic.
+ * \retval #PSA_ERROR_NOT_SUPPORTED
+ *         \p alg is not supported.
+ * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
+ * \retval #PSA_ERROR_BUFFER_TOO_SMALL
+ *         plaintext_size is too small.
+ * \retval #PSA_ERROR_CORRUPTION_DETECTED
+ */
+psa_status_t mbedtls_psa_aead_decrypt(
+    const psa_key_attributes_t *attributes,
+    const uint8_t *key_buffer, size_t key_buffer_size,
+    psa_algorithm_t alg,
+    const uint8_t *nonce, size_t nonce_length,
+    const uint8_t *additional_data, size_t additional_data_length,
+    const uint8_t *ciphertext, size_t ciphertext_length,
+    uint8_t *plaintext, size_t plaintext_size, size_t *plaintext_length );
+
 #endif /* PSA_CRYPTO_AEAD */