diff --git a/include/psa/crypto_struct.h b/include/psa/crypto_struct.h
index 3ff3f93ef..5ac187504 100644
--- a/include/psa/crypto_struct.h
+++ b/include/psa/crypto_struct.h
@@ -158,7 +158,7 @@ struct psa_cipher_operation_s
     unsigned int key_set : 1;
     unsigned int iv_required : 1;
     unsigned int iv_set : 1;
-    unsigned int accelerator_set : 1;
+    unsigned int accelerator_set : 1; /* Indicates a driver is used instead of software fallback. */
     uint8_t iv_size;
     uint8_t block_size;
     union
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index cdae05ec4..4ba9baffe 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -4225,7 +4225,7 @@ psa_status_t psa_cipher_generate_iv( psa_cipher_operation_t *operation,
         goto exit;
     }
 
-    if( operation->iv_set || ! operation->iv_required || ! operation->key_set )
+    if( operation->iv_set || ! operation->iv_required )
     {
         return( PSA_ERROR_BAD_STATE );
     }
@@ -4266,7 +4266,7 @@ psa_status_t psa_cipher_set_iv( psa_cipher_operation_t *operation,
         goto exit;
     }
 
-    if( operation->iv_set || ! operation->iv_required || ! operation->key_set )
+    if( operation->iv_set || ! operation->iv_required )
     {
         return( PSA_ERROR_BAD_STATE );
     }
@@ -4394,7 +4394,11 @@ psa_status_t psa_cipher_update( psa_cipher_operation_t *operation,
         goto exit;
     }
 
-    if( operation->alg == 0 || ! operation->key_set )
+    if( operation->alg == 0 )
+    {
+        return( PSA_ERROR_BAD_STATE );
+    }
+    if( operation->iv_required && ! operation->iv_set )
     {
         return( PSA_ERROR_BAD_STATE );
     }
@@ -4466,10 +4470,6 @@ psa_status_t psa_cipher_finish( psa_cipher_operation_t *operation,
         return( status );
     }
 
-    if( ! operation->key_set )
-    {
-        return( PSA_ERROR_BAD_STATE );
-    }
     if( operation->iv_required && ! operation->iv_set )
     {
         return( PSA_ERROR_BAD_STATE );
diff --git a/library/psa_crypto_driver_wrappers.c b/library/psa_crypto_driver_wrappers.c
index 140c3d4b8..11aeef830 100644
--- a/library/psa_crypto_driver_wrappers.c
+++ b/library/psa_crypto_driver_wrappers.c
@@ -411,10 +411,10 @@ psa_status_t psa_driver_wrapper_cipher_encrypt(
                                                       output_length );
             /* Declared with fallback == true */
             if( status != PSA_ERROR_NOT_SUPPORTED )
-                return status;
+                return( status );
 #endif /* PSA_CRYPTO_DRIVER_TEST */
             /* Fell through, meaning no accelerator supports this operation */
-            return PSA_ERROR_NOT_SUPPORTED;
+            return( PSA_ERROR_NOT_SUPPORTED );
         /* Add cases for opaque driver here */
 #if defined(PSA_CRYPTO_DRIVER_TEST)
         case PSA_CRYPTO_TEST_DRIVER_LIFETIME:
@@ -430,7 +430,7 @@ psa_status_t psa_driver_wrapper_cipher_encrypt(
 #endif /* PSA_CRYPTO_DRIVER_TEST */
         default:
             /* Key is declared with a lifetime not known to us */
-            return status;
+            return( status );
     }
 #else /* PSA_CRYPTO_DRIVER_PRESENT */
     (void) slot;
@@ -441,7 +441,7 @@ psa_status_t psa_driver_wrapper_cipher_encrypt(
     (void) output_size;
     (void) output_length;
 
-    return PSA_ERROR_NOT_SUPPORTED;
+    return( PSA_ERROR_NOT_SUPPORTED );
 #endif /* PSA_CRYPTO_DRIVER_PRESENT */
 }
 
@@ -478,10 +478,10 @@ psa_status_t psa_driver_wrapper_cipher_decrypt(
                                                       output_length );
             /* Declared with fallback == true */
             if( status != PSA_ERROR_NOT_SUPPORTED )
-                return status;
+                return( status );
 #endif /* PSA_CRYPTO_DRIVER_TEST */
             /* Fell through, meaning no accelerator supports this operation */
-            return PSA_ERROR_NOT_SUPPORTED;
+            return( PSA_ERROR_NOT_SUPPORTED );
         /* Add cases for opaque driver here */
 #if defined(PSA_CRYPTO_DRIVER_TEST)
         case PSA_CRYPTO_TEST_DRIVER_LIFETIME:
@@ -497,7 +497,7 @@ psa_status_t psa_driver_wrapper_cipher_decrypt(
 #endif /* PSA_CRYPTO_DRIVER_TEST */
         default:
             /* Key is declared with a lifetime not known to us */
-            return status;
+            return( status );
     }
 #else /* PSA_CRYPTO_DRIVER_PRESENT */
     (void) slot;
@@ -508,7 +508,7 @@ psa_status_t psa_driver_wrapper_cipher_decrypt(
     (void) output_size;
     (void) output_length;
 
-    return PSA_ERROR_NOT_SUPPORTED;
+    return( PSA_ERROR_NOT_SUPPORTED );
 #endif /* PSA_CRYPTO_DRIVER_PRESENT */
 }
 
@@ -526,7 +526,7 @@ psa_status_t psa_driver_wrapper_cipher_encrypt_setup(
 
     /* Check for operation already allocated */
     if( operation->ctx.driver.ctx != NULL )
-        return PSA_ERROR_BAD_STATE;
+        return( PSA_ERROR_BAD_STATE );
 
     switch( location )
     {
@@ -554,7 +554,7 @@ psa_status_t psa_driver_wrapper_cipher_encrypt_setup(
                     operation->ctx.driver.ctx = NULL;
                 }
 
-                return status;
+                return( status );
             }
             else
             {
@@ -563,13 +563,13 @@ psa_status_t psa_driver_wrapper_cipher_encrypt_setup(
             }
 #endif /* PSA_CRYPTO_DRIVER_TEST */
             /* Fell through, meaning no accelerator supports this operation */
-            return PSA_ERROR_NOT_SUPPORTED;
+            return( PSA_ERROR_NOT_SUPPORTED );
         /* Add cases for opaque driver here */
 #if defined(PSA_CRYPTO_DRIVER_TEST)
         case PSA_CRYPTO_TEST_DRIVER_LIFETIME:
             operation->ctx.driver.ctx = mbedtls_calloc( 1, sizeof(test_opaque_cipher_operation_t) );
             if( operation->ctx.driver.ctx == NULL )
-                return PSA_ERROR_INSUFFICIENT_MEMORY;
+                return( PSA_ERROR_INSUFFICIENT_MEMORY );
 
             status = test_opaque_cipher_encrypt_setup( operation->ctx.driver.ctx,
                                                        &attributes,
@@ -584,18 +584,18 @@ psa_status_t psa_driver_wrapper_cipher_encrypt_setup(
                 operation->ctx.driver.ctx = NULL;
             }
 
-            return status;
+            return( status );
 #endif /* PSA_CRYPTO_DRIVER_TEST */
         default:
             /* Key is declared with a lifetime not known to us */
-            return PSA_ERROR_BAD_STATE;
+            return( PSA_ERROR_BAD_STATE );
     }
 #else /* PSA_CRYPTO_DRIVER_PRESENT */
     (void)slot;
     (void)alg;
     (void)operation;
 
-    return PSA_ERROR_NOT_SUPPORTED;
+    return( PSA_ERROR_NOT_SUPPORTED );
 #endif /* PSA_CRYPTO_DRIVER_PRESENT */
 }
 
@@ -613,7 +613,7 @@ psa_status_t psa_driver_wrapper_cipher_decrypt_setup(
 
     /* Check for operation already allocated */
     if( operation->ctx.driver.ctx != NULL )
-        return PSA_ERROR_BAD_STATE;
+        return( PSA_ERROR_BAD_STATE );
 
     switch( location )
     {
@@ -623,7 +623,7 @@ psa_status_t psa_driver_wrapper_cipher_decrypt_setup(
 #if defined(PSA_CRYPTO_DRIVER_TEST)
             operation->ctx.driver.ctx = mbedtls_calloc( 1, sizeof(test_transparent_cipher_operation_t) );
             if( operation->ctx.driver.ctx == NULL )
-                return PSA_ERROR_INSUFFICIENT_MEMORY;
+                return( PSA_ERROR_INSUFFICIENT_MEMORY );
 
             status = test_transparent_cipher_decrypt_setup( operation->ctx.driver.ctx,
                                                             &attributes,
@@ -641,7 +641,7 @@ psa_status_t psa_driver_wrapper_cipher_decrypt_setup(
                     operation->ctx.driver.ctx = NULL;
                 }
 
-                return status;
+                return( status );
             }
             else
             {
@@ -650,7 +650,7 @@ psa_status_t psa_driver_wrapper_cipher_decrypt_setup(
             }
 #endif /* PSA_CRYPTO_DRIVER_TEST */
             /* Fell through, meaning no accelerator supports this operation */
-            return PSA_ERROR_NOT_SUPPORTED;
+            return( PSA_ERROR_NOT_SUPPORTED );
         /* Add cases for opaque driver here */
 #if defined(PSA_CRYPTO_DRIVER_TEST)
         case PSA_CRYPTO_TEST_DRIVER_LIFETIME:
@@ -671,18 +671,18 @@ psa_status_t psa_driver_wrapper_cipher_decrypt_setup(
                 operation->ctx.driver.ctx = NULL;
             }
 
-            return status;
+            return( status );
 #endif /* PSA_CRYPTO_DRIVER_TEST */
         default:
             /* Key is declared with a lifetime not known to us */
-            return PSA_ERROR_BAD_STATE;
+            return( PSA_ERROR_BAD_STATE );
     }
 #else /* PSA_CRYPTO_DRIVER_PRESENT */
     (void)slot;
     (void)alg;
     (void)operation;
 
-    return PSA_ERROR_NOT_SUPPORTED;
+    return( PSA_ERROR_NOT_SUPPORTED );
 #endif /* PSA_CRYPTO_DRIVER_PRESENT */
 }
 
@@ -695,7 +695,7 @@ psa_status_t psa_driver_wrapper_cipher_generate_iv(
 #if defined(PSA_CRYPTO_DRIVER_PRESENT) && defined(PSA_CRYPTO_ACCELERATOR_DRIVER_PRESENT)
     /* Check for operation already allocated */
     if( operation->ctx.driver.ctx == NULL )
-        return PSA_ERROR_INVALID_ARGUMENT;
+        return( PSA_ERROR_INVALID_ARGUMENT );
 
     switch( operation->ctx.driver.id )
     {
@@ -715,7 +715,7 @@ psa_status_t psa_driver_wrapper_cipher_generate_iv(
 #endif /* PSA_CRYPTO_DRIVER_TEST */
         default:
             /* Key is attached to a driver not known to us */
-            return PSA_ERROR_BAD_STATE;
+            return( PSA_ERROR_BAD_STATE );
     }
 #else /* PSA_CRYPTO_DRIVER_PRESENT */
     (void) operation;
@@ -723,7 +723,7 @@ psa_status_t psa_driver_wrapper_cipher_generate_iv(
     (void) iv_size;
     (void) iv_length;
 
-    return PSA_ERROR_NOT_SUPPORTED;
+    return( PSA_ERROR_NOT_SUPPORTED );
 #endif /* PSA_CRYPTO_DRIVER_PRESENT */
 }
 
@@ -735,7 +735,7 @@ psa_status_t psa_driver_wrapper_cipher_set_iv(
 #if defined(PSA_CRYPTO_DRIVER_PRESENT) && defined(PSA_CRYPTO_ACCELERATOR_DRIVER_PRESENT)
     /* Check for operation already allocated */
     if( operation->ctx.driver.ctx == NULL )
-        return PSA_ERROR_INVALID_ARGUMENT;
+        return( PSA_ERROR_INVALID_ARGUMENT );
 
     switch( operation->ctx.driver.id )
     {
@@ -753,14 +753,14 @@ psa_status_t psa_driver_wrapper_cipher_set_iv(
 #endif /* PSA_CRYPTO_DRIVER_TEST */
         default:
             /* Key is attached to a driver not known to us */
-            return PSA_ERROR_BAD_STATE;
+            return( PSA_ERROR_BAD_STATE );
     }
 #else /* PSA_CRYPTO_DRIVER_PRESENT */
     (void) operation;
     (void) iv;
     (void) iv_length;
 
-    return PSA_ERROR_NOT_SUPPORTED;
+    return( PSA_ERROR_NOT_SUPPORTED );
 #endif /* PSA_CRYPTO_DRIVER_PRESENT */
 }
 
@@ -775,7 +775,7 @@ psa_status_t psa_driver_wrapper_cipher_update(
 #if defined(PSA_CRYPTO_DRIVER_PRESENT) && defined(PSA_CRYPTO_ACCELERATOR_DRIVER_PRESENT)
     /* Check for operation already allocated */
     if( operation->ctx.driver.ctx == NULL )
-        return PSA_ERROR_INVALID_ARGUMENT;
+        return( PSA_ERROR_INVALID_ARGUMENT );
 
     switch( operation->ctx.driver.id )
     {
@@ -799,7 +799,7 @@ psa_status_t psa_driver_wrapper_cipher_update(
 #endif /* PSA_CRYPTO_DRIVER_TEST */
         default:
             /* Key is attached to a driver not known to us */
-            return PSA_ERROR_BAD_STATE;
+            return( PSA_ERROR_BAD_STATE );
     }
 #else /* PSA_CRYPTO_DRIVER_PRESENT */
     (void) operation;
@@ -809,7 +809,7 @@ psa_status_t psa_driver_wrapper_cipher_update(
     (void) output_length;
     (void) output_size;
 
-    return PSA_ERROR_NOT_SUPPORTED;
+    return( PSA_ERROR_NOT_SUPPORTED );
 #endif /* PSA_CRYPTO_DRIVER_PRESENT */
 }
 
@@ -822,7 +822,7 @@ psa_status_t psa_driver_wrapper_cipher_finish(
 #if defined(PSA_CRYPTO_DRIVER_PRESENT) && defined(PSA_CRYPTO_ACCELERATOR_DRIVER_PRESENT)
     /* Check for operation already allocated */
     if( operation->ctx.driver.ctx == NULL )
-        return PSA_ERROR_INVALID_ARGUMENT;
+        return( PSA_ERROR_INVALID_ARGUMENT );
 
     switch( operation->ctx.driver.id )
     {
@@ -842,7 +842,7 @@ psa_status_t psa_driver_wrapper_cipher_finish(
 #endif /* PSA_CRYPTO_DRIVER_TEST */
         default:
             /* Key is attached to a driver not known to us */
-            return PSA_ERROR_BAD_STATE;
+            return( PSA_ERROR_BAD_STATE );
     }
 #else /* PSA_CRYPTO_DRIVER_PRESENT */
     (void) operation;
@@ -850,7 +850,7 @@ psa_status_t psa_driver_wrapper_cipher_finish(
     (void) output_size;
     (void) output_length;
 
-    return PSA_ERROR_NOT_SUPPORTED;
+    return( PSA_ERROR_NOT_SUPPORTED );
 #endif /* PSA_CRYPTO_DRIVER_PRESENT */
 }
 
@@ -861,7 +861,7 @@ psa_status_t psa_driver_wrapper_cipher_abort(
     psa_status_t status = PSA_ERROR_INVALID_ARGUMENT;
     /* Check for operation already allocated */
     if( operation->ctx.driver.ctx == NULL )
-        return PSA_ERROR_INVALID_ARGUMENT;
+        return( PSA_ERROR_INVALID_ARGUMENT );
 
     switch( operation->ctx.driver.id )
     {
@@ -873,7 +873,7 @@ psa_status_t psa_driver_wrapper_cipher_abort(
             operation->ctx.driver.ctx = NULL;
             operation->ctx.driver.id = 0;
 
-            return status;
+            return( status );
 #endif /* PSA_CRYPTO_DRIVER_TEST */
 #if defined(PSA_CRYPTO_DRIVER_TEST)
         case PSA_CRYPTO_OPAQUE_TEST_DRIVER_ID:
@@ -881,16 +881,16 @@ psa_status_t psa_driver_wrapper_cipher_abort(
             mbedtls_free( operation->ctx.driver.ctx );
             operation->ctx.driver.ctx = NULL;
 
-            return status;
+            return( status );
 #endif /* PSA_CRYPTO_DRIVER_TEST */
         default:
             /* Operation is attached to a driver not known to us */
-            return PSA_ERROR_BAD_STATE;
+            return( PSA_ERROR_BAD_STATE );
     }
 #else /* PSA_CRYPTO_DRIVER_PRESENT */
     (void)operation;
 
-    return PSA_ERROR_NOT_SUPPORTED;
+    return( PSA_ERROR_NOT_SUPPORTED );
 #endif /* PSA_CRYPTO_DRIVER_PRESENT */
 }
 
diff --git a/tests/include/test/drivers/cipher.h b/tests/include/test/drivers/cipher.h
index 96ab29556..ef787f794 100644
--- a/tests/include/test/drivers/cipher.h
+++ b/tests/include/test/drivers/cipher.h
@@ -52,7 +52,7 @@ typedef struct {
     /* If not PSA_SUCCESS, return this error code instead of processing the
      * function call. */
     psa_status_t forced_status;
-    /* Count the amount of times one of the keygen driver functions is called. */
+    /* Count the amount of times one of the cipher driver functions is called. */
     unsigned long hits;
 } test_driver_cipher_hooks_t;
 
diff --git a/tests/src/drivers/cipher.c b/tests/src/drivers/cipher.c
index 0a4a347dd..c8eb1d350 100644
--- a/tests/src/drivers/cipher.c
+++ b/tests/src/drivers/cipher.c
@@ -35,11 +35,11 @@
 
 #include <string.h>
 
-/* Test driver implements AES-CTR by default when it's status is not overridden.
+/* Test driver implements AES-CTR only. Its default behaviour (when its return
+ * status is not overridden through the hooks) is to take care of all AES-CTR
+ * operations, and return PSA_ERROR_NOT_SUPPORTED for all others.
  * Set test_driver_cipher_hooks.forced_status to PSA_ERROR_NOT_SUPPORTED to use
- * fallback even for AES-CTR.
- * Keep in mind this code is only exercised with the crypto drivers test target,
- * meaning the other test runs will only test the non-driver implementation. */
+ * fallback even for AES-CTR. */
 test_driver_cipher_hooks_t test_driver_cipher_hooks = TEST_DRIVER_CIPHER_INIT;
 
 psa_status_t test_transparent_cipher_encrypt(
@@ -112,10 +112,11 @@ psa_status_t test_transparent_cipher_encrypt_setup(
     if( operation->alg != 0 )
         return( PSA_ERROR_BAD_STATE );
 
-    /* write our struct, this will trigger memory corruption failures
-     * in test when we go outside of bounds, or when the function is called
-     * without first destroying the context object. */
-    memset( operation, 0, sizeof( test_transparent_cipher_operation_t ) );
+    /* Wiping the entire struct here, instead of member-by-member. This is useful
+     * for the test suite, since it gives a chance of catching memory corruption
+     * errors should the core not have allocated (enough) memory for our context
+     * struct. */
+    memset( operation, 0, sizeof( *operation ) );
 
     /* Test driver supports AES-CTR only, to verify operation calls. */
     if( alg != PSA_ALG_CTR ||
@@ -173,10 +174,11 @@ psa_status_t test_transparent_cipher_decrypt_setup(
     if( operation->alg != 0 )
         return( PSA_ERROR_BAD_STATE );
 
-    /* write our struct, this will trigger memory corruption failures
-     * in test when we go outside of bounds, or when the function is called
-     * without first destroying the context object. */
-    memset( operation, 0, sizeof( test_transparent_cipher_operation_t ) );
+    /* Wiping the entire struct here, instead of member-by-member. This is useful
+     * for the test suite, since it gives a chance of catching memory corruption
+     * errors should the core not have allocated (enough) memory for our context
+     * struct. */
+    memset( operation, 0, sizeof( *operation ) );
 
     /* Test driver supports AES-CTR only, to verify operation calls. */
     if( alg != PSA_ALG_CTR || psa_get_key_type( attributes ) != PSA_KEY_TYPE_AES )
@@ -225,9 +227,11 @@ psa_status_t test_transparent_cipher_abort(
 
     mbedtls_cipher_free( &operation->cipher );
 
-    /* write our struct, this will trigger memory corruption failures
-     * in test when we go outside of bounds. */
-    memset( operation, 0, sizeof( test_transparent_cipher_operation_t ) );
+    /* Wiping the entire struct here, instead of member-by-member. This is useful
+     * for the test suite, since it gives a chance of catching memory corruption
+     * errors should the core not have allocated (enough) memory for our context
+     * struct. */
+    memset( operation, 0, sizeof( *operation ) );
 
     test_driver_cipher_hooks.hits++;
     return( PSA_SUCCESS );
diff --git a/tests/suites/test_suite_psa_crypto_driver_wrappers.function b/tests/suites/test_suite_psa_crypto_driver_wrappers.function
index 1daf9bb3f..470c43864 100644
--- a/tests/suites/test_suite_psa_crypto_driver_wrappers.function
+++ b/tests/suites/test_suite_psa_crypto_driver_wrappers.function
@@ -236,6 +236,7 @@ void cipher_encrypt( int alg_arg, int key_type_arg,
                                 output + total_output_length,
                                 output_buffer_size - total_output_length,
                                 &function_output_length );
+    /* Finish will have called abort as well, so expecting two hits here */
     TEST_EQUAL( test_driver_cipher_hooks.hits, 2 );
     test_driver_cipher_hooks.hits = 0;
 
@@ -326,6 +327,7 @@ void cipher_encrypt_multipart( int alg_arg, int key_type_arg,
                                    output + total_output_length,
                                    output_buffer_size - total_output_length,
                                    &function_output_length ) );
+    /* Finish will have called abort as well, so expecting two hits here */
     TEST_EQUAL( test_driver_cipher_hooks.hits, 2 );
     test_driver_cipher_hooks.hits = 0 ;
     total_output_length += function_output_length;
@@ -413,6 +415,7 @@ void cipher_decrypt_multipart( int alg_arg, int key_type_arg,
                                    output + total_output_length,
                                    output_buffer_size - total_output_length,
                                    &function_output_length ) );
+    /* Finish will have called abort as well, so expecting two hits here */
     TEST_EQUAL( test_driver_cipher_hooks.hits, 2 );
     test_driver_cipher_hooks.hits = 0;
     total_output_length += function_output_length;
@@ -483,6 +486,7 @@ void cipher_decrypt( int alg_arg, int key_type_arg,
                                 output + total_output_length,
                                 output_buffer_size - total_output_length,
                                 &function_output_length );
+    /* Finish will have called abort as well, so expecting two hits here */
     TEST_EQUAL( test_driver_cipher_hooks.hits, 2 );
     test_driver_cipher_hooks.hits = 0;