+# unprepend
+# v hbv
+# length int
+# => hb
+# unappend
+# v hbv
+# length int
+# => hb
+# chopto
+# v hbv
+# length int
+# => hb
+# pkcs5
+# meth enum(PadMethod, "hbytes pad subcommand")
+# obj ...
+# blockcipher
+# encrypt charfrom("de","encrypt/decrypt")
+# v hbv
+# alg enum(BlockCipherAlgInfo, "alg")
+# mode enum(BlockCipherModeInfo, "mode")
+# ?iv hb
+# => hb
+# hash
+# alg enum(HashAlgInfo, "hash alg")
+# message hb
+# => hb
+# hmac
+# alg enum(HashAlgInfo, "hash alg for hmac")
+# message hb
+# key hb
+# maclen int
+# => hb