diff --git a/Cargo.toml b/Cargo.toml
index 3be22ff..e3d9556 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,6 +8,7 @@ edition = "2021"
 [dependencies]
 anyhow = "1.0"
 thiserror = "1.0"
+derive-new = "0.5"
 aes256ctr_poly1305aes = { path = "../aes256ctr_poly1305aes" } 
 base64 = "0.13"
 scrypt = { version = "0.8", default-features = false }
@@ -21,3 +22,4 @@ boomphf = "0.5"
 walkdir = "2"
 # commands
 clap = { version = "3", features = ["derive"] }
+
diff --git a/src/blob/mod.rs b/src/blob/mod.rs
index d88ac35..cf6d99e 100644
--- a/src/blob/mod.rs
+++ b/src/blob/mod.rs
@@ -1,5 +1,8 @@
+use anyhow::Result;
+use derive_new::new;
 use serde::{Deserialize, Serialize};
 
+use crate::backend::{FileType, ReadBackend};
 use crate::id::Id;
 
 #[derive(Clone, Copy, Debug, PartialEq, Serialize, Deserialize)]
@@ -10,34 +13,52 @@ pub enum BlobType {
     Tree,
 }
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, new)]
 pub struct Blob {
-    pub tpe: BlobType,
-    pub id: Id,
+    tpe: BlobType,
+    id: Id,
 }
 
-#[derive(Debug)]
+#[derive(Debug, new)]
 pub struct BlobInformation {
-    pub blob: Blob,
-    pub offset: u32,
-    pub length: u32,
+    blob: Blob,
+    offset: u32,
+    length: u32,
 }
 
-#[derive(Debug)]
+#[derive(Debug, new)]
 pub struct IndexEntry {
-    pub pack: Id,
-    pub bi: BlobInformation,
+    pack: Id,
+    bi: BlobInformation,
 }
 
 impl IndexEntry {
+    /// Get a blob described by IndexEntry from the backend
+    pub fn read_data<B: ReadBackend>(&self, be: &B) -> Result<Vec<u8>> {
+        Ok(be.read_partial(FileType::Pack, self.pack, self.offset(), self.length())?)
+    }
+
+    #[inline]
     pub fn id(&self) -> &Id {
         &self.bi.blob.id
     }
 
+    #[inline]
     pub fn tpe(&self) -> &BlobType {
         &self.bi.blob.tpe
     }
 
+    #[inline]
+    pub fn offset(&self) -> u32 {
+        self.bi.offset
+    }
+
+    #[inline]
+    pub fn length(&self) -> u32 {
+        self.bi.length
+    }
+
+    #[inline]
     pub fn blob(&self) -> &Blob {
         &self.bi.blob
     }
diff --git a/src/commands/cat.rs b/src/commands/cat.rs
index 162e767..b188f51 100644
--- a/src/commands/cat.rs
+++ b/src/commands/cat.rs
@@ -20,10 +20,10 @@ pub(super) fn execute(be: &impl ReadBackend, dbe: &impl ReadBackend, opts: Opts)
     let tpe = match opts.tpe.as_str() {
         // special treatment for catingg blobs: read the index and use it to locate the blob
         "blob" => {
-            let blob = AllIndexFiles::new(be)
-                .get_id(id)
-                .ok_or(anyhow!("blob not found in index"))?;
-            let dec = be.read_partial(FileType::Pack, blob.pack, blob.bi.offset, blob.bi.length)?;
+            let dec = AllIndexFiles::new(be)
+                .get_id(&id)
+                .ok_or(anyhow!("blob not found in index"))?
+                .read_data(be)?;
             print!("{}", String::from_utf8_lossy(&dec));
             return Ok(());
         }
diff --git a/src/index/mod.rs b/src/index/mod.rs
index bed6ce0..679e578 100644
--- a/src/index/mod.rs
+++ b/src/index/mod.rs
@@ -6,11 +6,11 @@ use crate::id::Id;
 pub trait ReadIndex {
     fn iter(&self) -> Box<dyn Iterator<Item = IndexEntry> + '_>;
 
-    fn get_id(&self, id: Id) -> Option<IndexEntry> {
-        self.iter().find(|e| e.bi.blob.id == id)
+    fn get_id(&self, id: &Id) -> Option<IndexEntry> {
+        self.iter().find(|e| e.id() == id)
     }
 
-    fn get_blob(&self, blob: Blob) -> Option<IndexEntry> {
-        self.iter().find(|e| e.bi.blob == blob)
+    fn get_blob(&self, blob: &Blob) -> Option<IndexEntry> {
+        self.iter().find(|e| e.blob() == blob)
     }
 }
diff --git a/src/repo/index.rs b/src/repo/index.rs
index 693e9d7..0f8f5b1 100644
--- a/src/repo/index.rs
+++ b/src/repo/index.rs
@@ -28,10 +28,7 @@ impl IntoIterator for IndexFile {
 
     fn into_iter(self) -> Self::IntoIter {
         Box::new(self.packs.into_iter().flat_map(|p| {
-            p.blobs.into_iter().map(move |b| IndexEntry {
-                pack: p.id,
-                bi: b.to_bi(),
-            })
+            p.blobs.into_iter().map(move |b| IndexEntry::new(p.id,b.to_bi()))
         }))
     }
 }
@@ -39,10 +36,7 @@ impl IntoIterator for IndexFile {
 impl ReadIndex for IndexFile {
     fn iter(&self) -> Box<dyn Iterator<Item = IndexEntry> + '_> {
         Box::new(self.packs.iter().flat_map(|p| {
-            p.blobs.iter().map(|b| IndexEntry {
-                pack: p.id,
-                bi: b.to_bi(),
-            })
+            p.blobs.iter().map(|b| IndexEntry::new(p.id,b.to_bi()))
         }))
     }
 }
@@ -64,13 +58,6 @@ struct BlobIndex {
 
 impl BlobIndex {
     pub fn to_bi(&self) -> BlobInformation {
-        BlobInformation {
-            blob: Blob {
-                id: self.id,
-                tpe: self.tpe,
-            },
-            offset: self.offset,
-            length: self.length,
-        }
+        BlobInformation::new(Blob::new(self.tpe, self.id), self.offset, self.length)
     }
 }