feat: use tfhe-rs parameters supporting compression

Also, add a small binary to generate keys in fhevm-engine-common.

fhevm-engine/.gitignore

@@ -1 +1,2 @@
 target
+**/fhevm-keys

fhevm-engine/fhevm-engine-common/src/bin/generate_keys.rs

@@ -0,0 +1,15 @@
+use fhevm_engine_common::generate_fhe_keys;
+
+fn main() {
+    let output_dir = "fhevm-keys";
+    println!("Generating keys...");
+    let keys = generate_fhe_keys();
+    println!("Creating directory {output_dir}");
+    std::fs::create_dir_all(output_dir).unwrap();
+    println!("Creating file {output_dir}/cks");
+    std::fs::write(format!("{output_dir}/cks"), keys.client_key).unwrap();
+    println!("Creating file {output_dir}/pks");
+    std::fs::write(format!("{output_dir}/pks"), keys.compact_public_key).unwrap();
+    println!("Creating file {output_dir}/sks");
+    std::fs::write(format!("{output_dir}/sks"), keys.server_key).unwrap();
+}

fhevm-engine/fhevm-engine-common/src/lib.rs

@@ -1,5 +1,14 @@
-pub mod types;
+use tfhe::{
+    generate_keys,
+    shortint::parameters::{
+        list_compression::COMP_PARAM_MESSAGE_2_CARRY_2_KS_PBS_TUNIFORM_2M64,
+        PARAM_MESSAGE_2_CARRY_2_KS_PBS_TUNIFORM_2M64,
+    },
+    CompactPublicKey, ConfigBuilder,
+};
+
 pub mod tfhe_ops;
+pub mod types;
 
 pub struct FhevmKeys {
     pub server_key: Vec<u8>,
@@ -8,10 +17,19 @@ pub struct FhevmKeys {
 }
 
 pub fn generate_fhe_keys() -> FhevmKeys {
-    let (client_key, server_key) = tfhe::generate_keys(tfhe::ConfigBuilder::default().build());
-    let compact_key = tfhe::CompactPublicKey::new(&client_key);
+    let config =
+        ConfigBuilder::with_custom_parameters(PARAM_MESSAGE_2_CARRY_2_KS_PBS_TUNIFORM_2M64)
+            .enable_compression(COMP_PARAM_MESSAGE_2_CARRY_2_KS_PBS_TUNIFORM_2M64)
+            .build();
+    let (client_key, server_key) = generate_keys(config);
+    let public_key = CompactPublicKey::new(&client_key);
+
     let client_key = bincode::serialize(&client_key).unwrap();
     let server_key = bincode::serialize(&server_key).unwrap();
-    let compact_public_key = bincode::serialize(&compact_key).unwrap();
-    FhevmKeys { server_key, client_key, compact_public_key }
-}
+    let compact_public_key = bincode::serialize(&public_key).unwrap();
+    FhevmKeys {
+        server_key,
+        client_key,
+        compact_public_key,
+    }
+}