diff --git a/aead/src/buffer.rs b/aead/src/buffer.rs
new file mode 100644
index 00000000..8e983aea
--- /dev/null
+++ b/aead/src/buffer.rs
@@ -0,0 +1,97 @@
+use crate::{Error, Result};
+
+#[cfg(feature = "alloc")]
+use alloc::vec::Vec;
+
+#[cfg(feature = "bytes")]
+use bytes::BytesMut;
+
+#[cfg(feature = "arrayvec")]
+use arrayvec::ArrayVec;
+
+/// In-place encryption/decryption byte buffers.
+///
+/// This trait defines the set of methods needed to support in-place operations
+/// on a `Vec`-like data type.
+pub trait Buffer: AsMut<[u8]> {
+    /// Resizes buffer to the requested length.
+    ///
+    /// If buffer is smaller than `len`, fills it with zeros. Otherwise, truncates it to `len`.
+    fn resize(&mut self, len: usize) -> Result<()>;
+
+    /// Extend this buffer from the given slice
+    fn extend_from_slice(&mut self, other: &[u8]) -> Result<()>;
+
+    /// Truncate this buffer to the given size
+    fn truncate(&mut self, len: usize);
+}
+
+#[cfg(feature = "alloc")]
+impl Buffer for Vec<u8> {
+    fn resize(&mut self, len: usize) -> Result<()> {
+        Vec::resize(self, len, 0);
+        Ok(())
+    }
+
+    fn extend_from_slice(&mut self, other: &[u8]) -> Result<()> {
+        Vec::extend_from_slice(self, other);
+        Ok(())
+    }
+
+    fn truncate(&mut self, len: usize) {
+        Vec::truncate(self, len);
+    }
+}
+
+#[cfg(feature = "bytes")]
+impl Buffer for BytesMut {
+    fn resize(&mut self, len: usize) -> Result<()> {
+        BytesMut::resize(self, len, 0);
+        Ok(())
+    }
+
+    fn extend_from_slice(&mut self, other: &[u8]) -> Result<()> {
+        BytesMut::extend_from_slice(self, other);
+        Ok(())
+    }
+
+    fn truncate(&mut self, len: usize) {
+        BytesMut::truncate(self, len);
+    }
+}
+
+#[cfg(feature = "arrayvec")]
+impl<const N: usize> Buffer for ArrayVec<u8, N> {
+    fn resize(&mut self, len: usize) -> Result<()> {
+        if let Some(ext_len) = len.checked_sub(self.len()) {
+            let buf = &[0u8; N][..ext_len];
+            self.try_extend_from_slice(buf).map_err(|_| Error)
+        } else {
+            self.truncate(len);
+            Ok(())
+        }
+    }
+
+    fn extend_from_slice(&mut self, other: &[u8]) -> Result<()> {
+        ArrayVec::try_extend_from_slice(self, other).map_err(|_| Error)
+    }
+
+    fn truncate(&mut self, len: usize) {
+        ArrayVec::truncate(self, len);
+    }
+}
+
+#[cfg(feature = "heapless")]
+impl<const N: usize> Buffer for heapless::Vec<u8, N> {
+    fn resize(&mut self, len: usize) -> Result<()> {
+        heapless::Vec::resize(self, len, 0).map_err(|_| Error)
+    }
+
+    fn extend_from_slice(&mut self, other: &[u8]) -> Result<()> {
+        heapless::Vec::extend_from_slice(self, other).map_err(|_| Error)
+    }
+
+    fn truncate(&mut self, len: usize) {
+        heapless::Vec::truncate(self, len);
+    }
+}
diff --git a/aead/src/lib.rs b/aead/src/lib.rs
index c8e26a52..4fe253b3 100644
--- a/aead/src/lib.rs
+++ b/aead/src/lib.rs
@@ -16,15 +16,12 @@
 #[cfg(feature = "alloc")]
 extern crate alloc;
 
-#[cfg(feature = "bytes")]
-use bytes::BytesMut;
-
-#[cfg(feature = "arrayvec")]
-use arrayvec::ArrayVec;
-
 #[cfg(feature = "dev")]
 pub mod dev;
 
+mod buffer;
+pub use buffer::Buffer;
+
 pub use crypto_common::{
     self,
     array::{self, typenum::consts},
@@ -486,90 +483,3 @@ impl<'msg> From<&'msg [u8]> for Payload<'msg, '_> {
         Self { msg, aad: b"" }
     }
 }
-
-/// In-place encryption/decryption byte buffers.
-///
-/// This trait defines the set of methods needed to support in-place operations
-/// on a `Vec`-like data type.
-pub trait Buffer: AsMut<[u8]> {
-    /// Resizes buffer to the requested length.
-    ///
-    /// If buffer is smaller than `len`, fills it with zeros. Otherwise, truncates it to `len`.
-    fn resize(&mut self, len: usize) -> Result<()>;
-
-    /// Extend this buffer from the given slice
-    fn extend_from_slice(&mut self, other: &[u8]) -> Result<()>;
-
-    /// Truncate this buffer to the given size
-    fn truncate(&mut self, len: usize);
-}
-
-#[cfg(feature = "alloc")]
-impl Buffer for Vec<u8> {
-    fn resize(&mut self, len: usize) -> Result<()> {
-        Vec::resize(self, len, 0);
-        Ok(())
-    }
-
-    fn extend_from_slice(&mut self, other: &[u8]) -> Result<()> {
-        Vec::extend_from_slice(self, other);
-        Ok(())
-    }
-
-    fn truncate(&mut self, len: usize) {
-        Vec::truncate(self, len);
-    }
-}
-
-#[cfg(feature = "bytes")]
-impl Buffer for BytesMut {
-    fn resize(&mut self, len: usize) -> Result<()> {
-        BytesMut::resize(self, len, 0);
-        Ok(())
-    }
-
-    fn extend_from_slice(&mut self, other: &[u8]) -> Result<()> {
-        BytesMut::extend_from_slice(self, other);
-        Ok(())
-    }
-
-    fn truncate(&mut self, len: usize) {
-        BytesMut::truncate(self, len);
-    }
-}
-
-#[cfg(feature = "arrayvec")]
-impl<const N: usize> Buffer for ArrayVec<u8, N> {
-    fn resize(&mut self, len: usize) -> Result<()> {
-        if let Some(ext_len) = len.checked_sub(self.len()) {
-            let buf = &[0u8; N][..ext_len];
-            self.try_extend_from_slice(buf).map_err(|_| Error)
-        } else {
-            self.truncate(len);
-            Ok(())
-        }
-    }
-
-    fn extend_from_slice(&mut self, other: &[u8]) -> Result<()> {
-        ArrayVec::try_extend_from_slice(self, other).map_err(|_| Error)
-    }
-
-    fn truncate(&mut self, len: usize) {
-        ArrayVec::truncate(self, len);
-    }
-}
-
-#[cfg(feature = "heapless")]
-impl<const N: usize> Buffer for heapless::Vec<u8, N> {
-    fn resize(&mut self, len: usize) -> Result<()> {
-        heapless::Vec::resize(self, len, 0).map_err(|_| Error)
-    }
-
-    fn extend_from_slice(&mut self, other: &[u8]) -> Result<()> {
-        heapless::Vec::extend_from_slice(self, other).map_err(|_| Error)
-    }
-
-    fn truncate(&mut self, len: usize) {
-        heapless::Vec::truncate(self, len);
-    }
-}