+default the key length is set to 128 bits and 12 rounds. Alternative key lengths
+can be set using L<EVP_CIPHER_CTX_set_key_length(3)>. The maximum key length is
+2040 bits.
+
+The following rc5 specific I<ctrl>s are supported (see
+L<EVP_CIPHER_CTX_ctrl(3)>).
+
+=over 4
+
+=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC5_ROUNDS, rounds, NULL)
+
+Sets the number of rounds to B<rounds>. This must be one of RC5_8_ROUNDS,
+RC5_12_ROUNDS or RC5_16_ROUNDS.
+
+=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC5_ROUNDS, 0, &rounds)
+
+Stores the number of rounds currently configured in B<*rounds> where B<*rounds>
+is an int.
+
+=back