diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index f94830d..c266f9f 100644
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -1229,17 +1229,59 @@
 
 /** The type of the state data structure for multipart cipher operations.
  *
+ * Before calling any function on a cipher operation object, the application
+ * must initialize it by any of the following means:
+ * - Set the structure to all-bits-zero, for example:
+ *   \code
+ *   psa_cipher_operation_t operation;
+ *   memset(&operation, 0, sizeof(operation));
+ *   \endcode
+ * - Initialize the structure to logical zero values, for example:
+ *   \code
+ *   psa_cipher_operation_t operation = {0};
+ *   \endcode
+ * - Initialize the structure to the initializer #PSA_CIPHER_OPERATION_INIT,
+ *   for example:
+ *   \code
+ *   psa_cipher_operation_t operation = PSA_CIPHER_OPERATION_INIT;
+ *   \endcode
+ * - Assign the result of the function psa_cipher_operation_init()
+ *   to the structure, for example:
+ *   \code
+ *   psa_cipher_operation_t operation;
+ *   operation = psa_cipher_operation_init();
+ *   \endcode
+ *
  * This is an implementation-defined \c struct. Applications should not
  * make any assumptions about the content of this structure except
  * as directed by the documentation of a specific implementation. */
 typedef struct psa_cipher_operation_s psa_cipher_operation_t;
 
+/** \def PSA_CIPHER_OPERATION_INIT
+ *
+ * This macro returns a suitable initializer for a cipher operation object of
+ * type #psa_cipher_operation_t.
+ */
+#ifdef __DOXYGEN_ONLY__
+/* This is an example definition for documentation purposes.
+ * Implementations should define a suitable value in `crypto_struct.h`.
+ */
+#define PSA_CIPHER_OPERATION_INIT {0}
+#endif
+
+/** Return an initial value for a cipher operation object.
+ */
+static psa_cipher_operation_t psa_cipher_operation_init(void);
+
 /** Set the key for a multipart symmetric encryption operation.
  *
  * The sequence of operations to encrypt a message with a symmetric cipher
  * is as follows:
  * -# Allocate an operation object which will be passed to all the functions
  *    listed here.
+ * -# Initialize the operation object with one of the methods described in the
+ *    documentation for #psa_cipher_operation_t, e.g.
+ *    PSA_CIPHER_OPERATION_INIT.
  * -# Call psa_cipher_encrypt_setup() to specify the algorithm and key.
  *    The key remains associated with the operation even if the content
  *    of the key slot changes.
@@ -1252,7 +1294,7 @@
  * -# Call psa_cipher_finish().
  *
  * The application may call psa_cipher_abort() at any time after the operation
- * has been initialized with psa_cipher_encrypt_setup().
+ * has been initialized.
  *
  * After a successful call to psa_cipher_encrypt_setup(), the application must
  * eventually terminate the operation. The following events terminate an
@@ -1261,7 +1303,9 @@
  *   or psa_cipher_update().
  * - A call to psa_cipher_finish() or psa_cipher_abort().
  *
- * \param[out] operation        The operation object to use.
+ * \param[in,out] operation     The operation object to set up. It must have
+ *                              been initialized as per the documentation for
+ *                              #psa_cipher_operation_t and not yet in use.
  * \param handle                Handle to the key to use for the operation.
  * \param alg                   The cipher algorithm to compute
  *                              (\c PSA_ALG_XXX value such that
@@ -1295,6 +1339,9 @@
  * is as follows:
  * -# Allocate an operation object which will be passed to all the functions
  *    listed here.
+ * -# Initialize the operation object with one of the methods described in the
+ *    documentation for #psa_cipher_operation_t, e.g.
+ *    PSA_CIPHER_OPERATION_INIT.
  * -# Call psa_cipher_decrypt_setup() to specify the algorithm and key.
  *    The key remains associated with the operation even if the content
  *    of the key slot changes.
@@ -1307,7 +1354,7 @@
  * -# Call psa_cipher_finish().
  *
  * The application may call psa_cipher_abort() at any time after the operation
- * has been initialized with psa_cipher_decrypt_setup().
+ * has been initialized.
  *
  * After a successful call to psa_cipher_decrypt_setup(), the application must
  * eventually terminate the operation. The following events terminate an
@@ -1315,7 +1362,9 @@
  * - A failed call to psa_cipher_update().
  * - A call to psa_cipher_finish() or psa_cipher_abort().
  *
- * \param[out] operation        The operation object to use.
+ * \param[in,out] operation     The operation object to set up. It must have
+ *                              been initialized as per the documentation for
+ *                              #psa_cipher_operation_t and not yet in use.
  * \param handle                Handle to the key to use for the operation.
  * \param alg                   The cipher algorithm to compute
  *                              (\c PSA_ALG_XXX value such that