+.TP
+.B x25519
+This is Bernstein's Curve25519, a fast Diffie-Hellman using a specific
+elliptic curve.
+Use the
+.B x25519
+algorithm of the
+.B key add
+command
+(see
+.BR key (1))
+to generate the key.
+.TP
+.B x448
+This is Hamburg's Curve25519, a strong Diffie-Hellman using a specific
+elliptic curve.
+Use the
+.B x448
+algorithm of the
+.B key add
+command
+(see
+.BR key (1))
+to generate the key.
+.PP
+The bulk crypto transform is chosen based on the
+.B bulk
+attribute on the key, or, failing that,
+from the
+.I bulk
+stated in the
+.IR kemalgspec .
+Run
+.B catcrypt show bulk
+for a list of supported bulk crypto transforms.
+.TP
+.B gencomp
+A generic composition of
+a cipher secure against chosen-plaintext attack,
+and a message authentication code.
+Makes use of
+.B cipher
+and
+.B mac
+attributes.
+This is the default transform.
+.TP
+.B naclbox
+Use Salsa20 or ChaCha and Poly1305 to secure the bulk data.
+This is nearly the same as the NaCl
+.B crypto_secretbox
+construction,
+except that
+.B catcrypt
+uses Salsa20 or ChaCha rather than XSalsa20,
+because it doesn't need the latter's extended nonce.
+The
+.B cipher
+attribute may be set to one of
+.BR salsa20 ,
+.BR salsa20/12 ,
+.BR salsa20/8 ,
+.BR chacha20 ,
+.BR chacha12 ,
+or
+.BR chacha8 ;
+the default is
+.BR salsa20 .