+#define GC_INIT(cc, k, sz) (cc)->init((k), (sz))
+#define GC_CLASS(cc) (cc)->ops->c
+#define GC_ENCRYPT(c, s, t, sz) (c)->ops->encrypt((c), (s), (t), (sz))
+#define GC_DECRYPT(c, s, t, sz) (c)->ops->decrypt((c), (s), (t), (sz))
+#define GC_DESTROY(c) (c)->ops->destroy((c))
+#define GC_SETIV(c, iv) (c)->ops->setiv((c), (iv))
+#define GC_BDRY(c) (c)->ops->bdry((c))
+
+/*----- Key size management -----------------------------------------------*/
+
+/* --- Key size type constants --- *
+ *
+ * A key size limitation is an array of bytes. The first byte describes the
+ * kind of limitation on the key size %$k$%; the rest are argument bytes
+ * %$a_i$%, for %$i \ge 0$%. In all cases, %$a_0$% is the `recommended' key
+ * size.
+ *
+ * * @KSZ_ANY@ means there is no restriction.
+ *
+ * * @KSZ_RANGE@ requires that %$k \ge a_1$%, %$k \equiv 0 \pmod{a_3}$%,
+ * and, if %$a_2 \ne 0$%, %$k \le a_2$%.
+ *
+ * * @KSZ_SET@ requires that %$k \in {\,a_i\,}$%.
+ */
+
+enum {
+ KSZ_ANY, /* Allows any key at all */
+ KSZ_RANGE, /* Allows keys within a range */
+ KSZ_SET /* Allows specific sizes of keys */
+};
+
+/* --- @keysz@ --- *
+ *
+ * Arguments: @size_t sz@ = a proposed key size, or zero
+ * @const octet *ksz@ = pointer to key size table
+ *
+ * Returns: See below.
+ *
+ * Use: Returns a sensible key size. If @sz@ is nonzero, it is
+ * interpreted as an amount (in bytes) of key material which the
+ * caller has available, and the return value is either the
+ * largest allowable key size less than or equal to the caller's
+ * size, or zero if there is no valid key length small enough.
+ * If @sz@ is zero, the function returns a `recommended' key
+ * size.
+ */
+
+extern size_t keysz(size_t /*sz*/, const octet */*ksz*/);
+
+#define KSZ_CHECK(pre, sz) (keysz((sz), pre##_keysz) == (sz))
+#define KSZ_ASSERT(pre, sz) \
+ assert(((void)"Bad key size for " #pre, KSZ_CHECK(pre, sz)))
+
+/*----- Tables ------------------------------------------------------------*/
+
+extern const gccipher *const gciphertab[];
+
+/* --- @gcipher_byname@ --- *
+ *
+ * Arguments: @const char *p@ = pointer to name string
+ *
+ * Returns: The named cipher class, or null.
+ */
+
+extern const gccipher *gcipher_byname(const char */*p*/);
+