diff --git a/Cargo.lock b/Cargo.lock
index 8593ddb..7247052 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1336,6 +1336,7 @@ version = "0.1.0"
 dependencies = [
  "chacha20",
  "common",
+ "lz4_flex",
  "risc0-zkvm",
 ]
 
@@ -1435,6 +1436,7 @@ dependencies = [
  "chacha20",
  "common",
  "hex-literal 1.0.0",
+ "lz4_flex",
  "methods",
  "risc0-zkvm",
  "serde",
@@ -1886,6 +1888,15 @@ version = "0.4.27"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "13dc2df351e3202783a1fe0d44375f7295ffb4049267b0f3018346dc122a1d94"
 
+[[package]]
+name = "lz4_flex"
+version = "0.11.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75761162ae2b0e580d7e7c390558127e5f01b4194debd6221fd8c207fc80e3f5"
+dependencies = [
+ "twox-hash",
+]
+
 [[package]]
 name = "lzma-sys"
 version = "0.1.20"
@@ -3059,7 +3070,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys 0.4.15",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
diff --git a/Cargo.toml b/Cargo.toml
index 649d4b3..4bc527d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,6 +15,8 @@ common = { path = "common" }
 chacha20 = "0.9.1"
 hex-literal = "1.0.0"
 
+lz4_flex = "0.11"
+
 risc0-zkvm = { version = "2.0",  default-features = false, features = ['std'] }
 risc0-build = "2.0"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
diff --git a/host/Cargo.toml b/host/Cargo.toml
index 0b049f8..98608d9 100644
--- a/host/Cargo.toml
+++ b/host/Cargo.toml
@@ -12,6 +12,7 @@ hex-literal.workspace = true
 risc0-zkvm = { workspace = true,  default-features = true }
 tracing-subscriber.workspace = true
 serde.workspace = true
+lz4_flex.workspace = true 
 
 [features]
 cuda = ["risc0-zkvm/cuda"]
diff --git a/host/src/main.rs b/host/src/main.rs
index a59c700..b14f6d6 100644
--- a/host/src/main.rs
+++ b/host/src/main.rs
@@ -1,6 +1,7 @@
 use chacha20::cipher::{KeyIvInit, StreamCipher};
 use chacha20::ChaCha20;
 
+use lz4_flex::decompress_size_prepended;
 // These constants represent the RISC-V ELF and the image ID generated by risc0-build.
 // The ELF is used for proving and the ID is used for verification.
 use methods::GUEST_ENCRYPT_ELF;
@@ -74,7 +75,10 @@ fn main() {
     // decrypt ciphertext by applying keystream again
     cipher.apply_keystream(&mut output_buffer);
 
-    assert_eq!(output_buffer, plaintext);
+    let decompressed_output =
+        decompress_size_prepended(&output_buffer).expect("Unable to decompress output");
+
+    assert_eq!(decompressed_output, plaintext);
     println!("Decryption of zkVM ciphertext matches input!");
     println!(
         "Output size to publish to DA = {} bytes (seal), {} bytes (ciphertext)",
diff --git a/methods/guest/Cargo.toml b/methods/guest/Cargo.toml
index f2964e3..0e98988 100644
--- a/methods/guest/Cargo.toml
+++ b/methods/guest/Cargo.toml
@@ -6,5 +6,7 @@ edition.workspace = true
 [dependencies]
 common.workspace = true
 
+lz4_flex.workspace = true 
+
 risc0-zkvm = { workspace = true,  default-features = false, features = ['std'] }
 chacha20.workspace = true
diff --git a/methods/guest/src/main.rs b/methods/guest/src/main.rs
index a6572da..ffe54c7 100644
--- a/methods/guest/src/main.rs
+++ b/methods/guest/src/main.rs
@@ -1,5 +1,6 @@
 use chacha20::cipher::{KeyIvInit, StreamCipher};
 use chacha20::ChaCha20;
+use lz4_flex::compress_prepend_size;
 use risc0_zkvm::{
     guest::env,
     sha::{Impl, Sha256},
@@ -25,15 +26,16 @@ fn main() {
     // TODO:
     // - Hash key and/or nonce & commit?
 
+    let mut compressed_input = compress_prepend_size(&buffer);
     // Key and IV must be references to the `GenericArray` type.
     // Here we use the `Into` trait to convert arrays into it.
     let mut cipher = ChaCha20::new(&key.into(), &nonce.into());
 
     // Write ciphertext into buffer by applying keystream to plaintext
-    cipher.apply_keystream(&mut buffer);
+    cipher.apply_keystream(&mut compressed_input);
 
     // write public output to the journal
-    env::commit_slice(&buffer);
+    env::commit_slice(&compressed_input);
 
     let end = env::cycle_count();
     eprintln!("*-*-*-* CYCLE COUNT: {}", end - start);