+ This flag is used to indicate that Initial Vector (IV)
+ in encryption will be included in the ciphertext
+ which the recipient must use in decryption. The IV
+ MUST be set after the last ciphertext block. With
+ this flag it is possible to use SILC protocol on
+ unreliable transport such as UDP/IP which may cause
+ packet reordering and packet losses. By default,
+ this flag is not set and thus IV is not included
+ in the ciphertext. Setting this flag increases the
+ ciphertext size by one ciphertext block. Responder
+ MAY override this flag for the initiator.