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use nettle;
use packet;
use Packet;
/// Holds an MDC packet.
///
/// A modification detection code packet. This packet appears after a
/// SEIP packet. See [Section 5.14 of RFC 4880] for details.
///
/// [Section 5.14 of RFC 4880]: https://tools.ietf.org/html/rfc4880#section-5.14
#[derive(PartialEq, Eq, Hash, Clone, Debug)]
pub struct MDC {
/// CTB packet header fields.
pub(crate) common: packet::Common,
/// Our SHA-1 hash.
computed_hash: [u8; 20],
/// A 20-octet SHA-1 hash of the preceding plaintext data.
hash: [u8; 20],
}
impl MDC {
/// Creates an MDC packet.
pub fn new(hash: [u8; 20], computed_hash: [u8; 20]) -> Self {
MDC {
common: Default::default(),
computed_hash: computed_hash,
hash: hash,
}
}
/// Gets the packet's hash value.
pub fn hash(&self) -> &[u8] {
&self.hash[..]
}
/// Gets the computed hash value.
pub fn computed_hash(&self) -> &[u8] {
&self.computed_hash[..]
}
/// Returns whether the data protected by the MDC is valid.
pub fn valid(&self) -> bool {
if self.hash == [ 0; 20 ] {
// If the computed_hash and hash are uninitialized, then
// return false.
false
} else {
self.computed_hash == self.hash
}
}
}
impl From<MDC> for Packet {
fn from(s: MDC) -> Self {
Packet::MDC(s)
}
}
impl From<[u8; 20]> for MDC {
fn from(hash: [u8; 20]) -> Self {
MDC {
common: Default::default(),
// All 0s.
computed_hash: Default::default(),
hash: hash,
}
}
}
impl From<Box<nettle::Hash>> for MDC {
fn from(mut hash: Box<nettle::Hash>) -> Self {
let mut value : [u8; 20] = Default::default();
hash.digest(&mut value[..]);
value.into()
}
}