module CTR:Nocrypto.Cipher_block.S.CTR
type
key
val of_secret : Cstruct.t -> key
val key_sizes : int array
val block_size : int
val stream : key:key ->
ctr:Cstruct.t -> ?off:int -> int -> Cstruct.t
stream ~key ~ctr ~off n
is the first n
bytes obtained by
encrypting and concatenating blocks c(0), c(1), ...
, where c(0)
is
ctr
, and c(n + 1)
is c(n) + 1
interpreted in big-endian.
If off
is greater than 0
then the result is the last n
bytes of
an off + n
bytes long stream. Thus,
stream ~key ~ctr ~off:0 n || stream ~key ~ctr ~off:n n ==
.
stream ~key ~ctr ~off:0 (n*2)
ctr
has to be block-sized, and off
and n
need to be
non-negative.
val encrypt : key:key ->
ctr:Cstruct.t -> ?off:int -> Cstruct.t -> Cstruct.t
encrypt ~key ~ctr ~off msg
is
(stream ~key ~ctr ~off (len msg)) xor msg
.val decrypt : key:key ->
ctr:Cstruct.t -> ?off:int -> Cstruct.t -> Cstruct.t