argon2: move Memory to its own module (#158)

Also makes `Instance` accept `Memory` as a parameter.

This is in preparation for moving slice handling to `Memory`.

argon2/src/instance.rs

@@ -1,7 +1,8 @@
 //! Argon2 instance (i.e. state)
 
 use crate::{
-    Algorithm, Argon2, Block, Error, Version, BLOCK_SIZE, MAX_OUTLEN, MIN_OUTLEN, SYNC_POINTS,
+    Algorithm, Argon2, Block, Error, Memory, Version, BLOCK_SIZE, MAX_OUTLEN, MIN_OUTLEN,
+    SYNC_POINTS,
 };
 use blake2::{
     digest::{self, VariableOutput},
@@ -36,39 +37,6 @@ struct Position {
     index: u32,
 }
 
-/// Structure containing references to the memory blocks
-struct Memory<'a> {
-    /// Memory blocks
-    data: &'a mut [Block],
-
-    /// Size of the memory in blocks
-    size: usize,
-}
-
-impl<'a> Memory<'a> {
-    /// Instantiate a new memory struct
-    fn new(data: &'a mut [Block]) -> Self {
-        let size = data.len();
-
-        Self { data, size }
-    }
-
-    /// Get a copy of the block
-    fn get_block(&self, idx: usize) -> Block {
-        self.data[idx]
-    }
-
-    /// Get a mutable reference to the block
-    fn get_block_mut(&mut self, idx: usize) -> &mut Block {
-        &mut self.data[idx]
-    }
-
-    /// Size of the memory
-    fn len(&self) -> usize {
-        self.size
-    }
-}
-
 /// Argon2 instance: memory pointer, number of passes, amount of memory, type,
 /// and derived values.
 ///
@@ -107,7 +75,7 @@ impl<'a> Instance<'a> {
         context: &Argon2<'_>,
         alg: Algorithm,
         initial_hash: digest::Output<Blake2b>,
-        memory: &'a mut [Block],
+        memory: Memory<'a>,
         out: &mut [u8],
     ) -> Result<(), Error> {
         let mut instance = Self::new(context, alg, initial_hash, memory)?;
@@ -127,10 +95,8 @@ impl<'a> Instance<'a> {
         context: &Argon2<'_>,
         alg: Algorithm,
         mut initial_hash: digest::Output<Blake2b>,
-        memory: &'a mut [Block],
+        memory: Memory<'a>,
     ) -> Result<Self, Error> {
-        let memory = Memory::new(memory);
-
         let mut instance = Instance {
             version: context.version,
             memory,

argon2/src/lib.rs

@@ -79,14 +79,15 @@ extern crate alloc;
 mod block;
 mod error;
 mod instance;
+mod memory;
 
 pub use crate::error::Error;
 
 #[cfg(feature = "password-hash")]
 #[cfg_attr(docsrs, doc(cfg(feature = "password-hash")))]
 pub use password_hash::{self, PasswordHash, PasswordHasher, PasswordVerifier};
 
-use crate::{block::Block, instance::Instance};
+use crate::{block::Block, instance::Instance, memory::Memory};
 use blake2::{digest, Blake2b, Digest};
 use core::{
     convert::TryFrom,
@@ -485,7 +486,7 @@ impl<'key> Argon2<'key> {
         // TODO(tarcieri): support for stack-allocated memory blocks (i.e. no alloc)
         let mut memory = vec![Block::default(); memory_blocks];
 
-        Instance::hash(self, alg, initial_hash, &mut memory, out)
+        Instance::hash(self, alg, initial_hash, Memory::new(&mut memory), out)
     }
 
     /// Hashes all the inputs into `blockhash[PREHASH_DIGEST_LENGTH]`.

argon2/src/memory.rs

@@ -0,0 +1,36 @@
+//! Memory blocks
+
+use crate::Block;
+
+/// Structure containing references to the memory blocks
+pub(crate) struct Memory<'a> {
+    /// Memory blocks
+    data: &'a mut [Block],
+
+    /// Size of the memory in blocks
+    size: usize,
+}
+
+impl<'a> Memory<'a> {
+    /// Instantiate a new memory struct
+    pub(crate) fn new(data: &'a mut [Block]) -> Self {
+        let size = data.len();
+
+        Self { data, size }
+    }
+
+    /// Get a copy of the block
+    pub(crate) fn get_block(&self, idx: usize) -> Block {
+        self.data[idx]
+    }
+
+    /// Get a mutable reference to the block
+    pub(crate) fn get_block_mut(&mut self, idx: usize) -> &mut Block {
+        &mut self.data[idx]
+    }
+
+    /// Size of the memory
+    pub(crate) fn len(&self) -> usize {
+        self.size
+    }
+}