diff --git a/src/disc/wii.rs b/src/disc/wii.rs
index 49a1d88..0ab370f 100644
--- a/src/disc/wii.rs
+++ b/src/disc/wii.rs
@@ -230,13 +230,14 @@ impl DiscBase for DiscWii {
             .find(|v| v.part_type == WiiPartType::Data)
             .ok_or(Error::DiscFormat("Failed to locate data partition".to_string()))?;
         let data_off = part.part_header.data_off;
+        let has_crypto = disc_io.has_wii_crypto();
         let result = Box::new(WiiPartReadStream {
             stream: wrap_windowed(
                 disc_io.begin_read_stream(data_off)?,
                 data_off,
                 part.part_header.data_size,
             )?,
-            crypto: if disc_io.has_wii_crypto() {
+            crypto: if has_crypto {
                 Aes128::new(&part.part_header.ticket.enc_key.into()).into()
             } else {
                 Option::None
diff --git a/src/io/iso.rs b/src/io/iso.rs
index 62723cc..6a4a21a 100644
--- a/src/io/iso.rs
+++ b/src/io/iso.rs
@@ -5,7 +5,11 @@ use std::{
     path::{Path, PathBuf},
 };
 
-use crate::{io::DiscIO, streams::ReadStream, Result};
+use crate::{
+    io::DiscIO,
+    streams::{ByteReadStream, ReadStream},
+    Result,
+};
 
 pub(crate) struct DiscIOISO {
     pub(crate) filename: PathBuf,
@@ -18,9 +22,28 @@ impl DiscIOISO {
 }
 
 impl DiscIO for DiscIOISO {
-    fn begin_read_stream(&self, offset: u64) -> io::Result<Box<dyn ReadStream>> {
+    fn begin_read_stream(&mut self, offset: u64) -> io::Result<Box<dyn ReadStream>> {
         let mut file = File::open(&*self.filename)?;
         file.seek(SeekFrom::Start(offset))?;
         io::Result::Ok(Box::from(file))
     }
 }
+
+pub(crate) struct DiscIOISOStream<T: ReadStream + Sized> {
+    pub(crate) stream: T,
+}
+
+impl<T: ReadStream + Sized> DiscIOISOStream<T> {
+    pub(crate) fn new(stream: T) -> Result<DiscIOISOStream<T>> {
+        Result::Ok(DiscIOISOStream { stream })
+    }
+}
+
+impl<T: ReadStream + Sized> DiscIO for DiscIOISOStream<T> {
+    fn begin_read_stream<'a>(&'a mut self, offset: u64) -> io::Result<Box<dyn ReadStream + 'a>> {
+        let size = self.stream.stable_stream_len()?;
+        let mut stream = self.stream.new_window(0, size)?;
+        stream.seek(SeekFrom::Start(offset))?;
+        Ok(Box::from(stream))
+    }
+}
diff --git a/src/io/mod.rs b/src/io/mod.rs
index 83d8646..d534590 100644
--- a/src/io/mod.rs
+++ b/src/io/mod.rs
@@ -3,8 +3,11 @@
 use std::{fs, io, path::Path};
 
 use crate::{
-    io::{iso::DiscIOISO, nfs::DiscIONFS},
-    streams::ReadStream,
+    io::{
+        iso::{DiscIOISO, DiscIOISOStream},
+        nfs::DiscIONFS,
+    },
+    streams::{ByteReadStream, ReadStream},
     Error, Result,
 };
 
@@ -15,7 +18,7 @@ pub(crate) mod nfs;
 pub trait DiscIO {
     /// Opens a new read stream for the disc file(s).
     /// Generally does _not_ need to be used directly.
-    fn begin_read_stream(&self, offset: u64) -> io::Result<Box<dyn ReadStream + '_>>;
+    fn begin_read_stream(&mut self, offset: u64) -> io::Result<Box<dyn ReadStream + '_>>;
 
     /// If false, the file format does not use standard Wii partition encryption. (e.g. NFS)
     fn has_wii_crypto(&self) -> bool { true }
@@ -66,6 +69,16 @@ pub fn new_disc_io(filename: &Path) -> Result<Box<dyn DiscIO>> {
     }
 }
 
+pub fn new_disc_io_from_buf(buf: &[u8]) -> Result<Box<dyn DiscIO + '_>> {
+    Ok(Box::from(DiscIOISOStream::new(ByteReadStream { bytes: buf, position: 0 })?))
+}
+
+pub fn new_disc_io_from_stream<'a, T: 'a + ReadStream + Sized>(
+    stream: T,
+) -> Result<Box<dyn DiscIO + 'a>> {
+    Ok(Box::from(DiscIOISOStream::new(stream)?))
+}
+
 /// Helper function for checking a file extension.
 #[inline(always)]
 pub fn has_extension(filename: &Path, extension: &str) -> bool {
diff --git a/src/io/nfs.rs b/src/io/nfs.rs
index 5c1e705..22463c2 100644
--- a/src/io/nfs.rs
+++ b/src/io/nfs.rs
@@ -228,7 +228,7 @@ impl<'a> ReadStream for NFSReadStream<'a> {
 }
 
 impl DiscIO for DiscIONFS {
-    fn begin_read_stream(&self, offset: u64) -> io::Result<Box<dyn ReadStream + '_>> {
+    fn begin_read_stream(&mut self, offset: u64) -> io::Result<Box<dyn ReadStream + '_>> {
         io::Result::Ok(Box::from(NFSReadStream {
             disc_io: self,
             file: Option::None,
diff --git a/src/streams.rs b/src/streams.rs
index 3a666dd..1f6871e 100644
--- a/src/streams.rs
+++ b/src/streams.rs
@@ -173,3 +173,55 @@ impl<'a> WindowedReadStream for SharedWindowedReadStream<'a> {
 
     fn window(&self) -> (u64, u64) { (self.begin, self.end) }
 }
+
+pub struct ByteReadStream<'a> {
+    pub bytes: &'a [u8],
+    pub position: u64,
+}
+
+impl Read for ByteReadStream<'_> {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        let mut len = buf.len();
+        let total = self.bytes.len();
+        let pos = self.position as usize;
+        if len + pos > total {
+            if pos >= total {
+                return Err(io::Error::from(io::ErrorKind::UnexpectedEof));
+            }
+            len = total - pos;
+        }
+        buf.copy_from_slice(&self.bytes[pos..pos + len]);
+        self.position += len as u64;
+        Ok(len)
+    }
+}
+
+impl Seek for ByteReadStream<'_> {
+    fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
+        let new_pos = match pos {
+            SeekFrom::Start(v) => v,
+            SeekFrom::End(v) => (self.bytes.len() as i64 + v) as u64,
+            SeekFrom::Current(v) => (self.position as i64 + v) as u64,
+        };
+        if new_pos > self.bytes.len() as u64 {
+            Err(io::Error::from(io::ErrorKind::UnexpectedEof))
+        } else {
+            self.position = new_pos;
+            Ok(new_pos)
+        }
+    }
+
+    // fn stream_len(&mut self) -> io::Result<u64> { Ok(self.bytes.len() as u64) }
+
+    fn stream_position(&mut self) -> io::Result<u64> { Ok(self.position) }
+}
+
+impl ReadStream for ByteReadStream<'_> {
+    fn stable_stream_len(&mut self) -> io::Result<u64> { Ok(self.bytes.len() as u64) }
+
+    fn as_dyn(&mut self) -> &mut dyn ReadStream { self }
+}
+
+impl<'a> AsMut<dyn ReadStream + 'a> for ByteReadStream<'a> {
+    fn as_mut(&mut self) -> &mut (dyn ReadStream + 'a) { self as &mut (dyn ReadStream + 'a) }
+}