chore(backward): add backward compat tests for rerand

tests/Cargo.toml

@@ -10,6 +10,7 @@ tfhe-versionable = { path = "../utils/tfhe-versionable" }
 tfhe-backward-compat-data = { path = "../utils/tfhe-backward-compat-data", default-features = false, features = [
     "load",
 ] }
+rand = { workspace = true }
 cargo_toml = "0.22"
 
 

tests/backward_compatibility/high_level_api.rs

@@ -3,7 +3,9 @@ use crate::{load_and_unversionize, TestedModule};
 use std::path::Path;
 #[cfg(feature = "zk-pok")]
 use tfhe::integer::parameters::DynamicDistribution;
-use tfhe::prelude::{CiphertextList, FheDecrypt, FheEncrypt, ParameterSetConformant, SquashNoise};
+use tfhe::prelude::{
+    CiphertextList, FheDecrypt, FheEncrypt, ParameterSetConformant, ReRandomize, SquashNoise,
+};
 #[cfg(feature = "zk-pok")]
 use tfhe::shortint::parameters::{
     CompactCiphertextListExpansionKind, CompactPublicKeyEncryptionParameters,
@@ -17,7 +19,8 @@ use tfhe::{
     set_server_key, ClientKey, CompactCiphertextList, CompressedCiphertextList,
     CompressedCompactPublicKey, CompressedFheBool, CompressedFheInt8, CompressedFheUint8,
     CompressedPublicKey, CompressedServerKey, CompressedSquashedNoiseCiphertextList, FheBool,
-    FheInt8, FheUint8, SquashedNoiseFheBool, SquashedNoiseFheInt, SquashedNoiseFheUint,
+    FheInt8, FheUint8, ReRandomizationContext, SquashedNoiseFheBool, SquashedNoiseFheInt,
+    SquashedNoiseFheUint,
 };
 #[cfg(feature = "zk-pok")]
 use tfhe::{CompactPublicKey, ProvenCompactCiphertextList};
@@ -347,6 +350,7 @@ pub fn test_hl_pubkey(
         };
         FheUint8::encrypt(value, &public_key)
     };
+
     let decrypted: u8 = encrypted.decrypt(&client_key);
 
     if decrypted != value {
@@ -375,7 +379,7 @@ pub fn test_hl_serverkey(
     .map_err(|e| test.failure(e, format))?;
 
     let v1 = 73u8;
-    let ct1 = FheUint8::encrypt(v1, &client_key);
+    let mut ct1 = FheUint8::encrypt(v1, &client_key);
     let v2 = 102u8;
     let ct2 = FheUint8::encrypt(v2, &client_key);
 
@@ -386,7 +390,8 @@ pub fn test_hl_serverkey(
         load_and_unversionize(dir, test, format)?
     };
 
-    let has_noise_squashing = key.noise_squashing_key().is_some();
+    let has_noise_squashing = key.supports_noise_squashing();
+    let has_rerand = key.supports_ciphertext_re_randomization();
     set_server_key(key);
 
     if has_noise_squashing {
@@ -402,6 +407,47 @@ pub fn test_hl_serverkey(
         }
     }
 
+    if let Some(rerand_cpk_filename) = test.rerand_cpk_filename.as_ref() {
+        if has_rerand {
+            let rerand_cpk_file = dir.join(rerand_cpk_filename.to_string());
+            let public_key = CompressedCompactPublicKey::unversionize(
+                load_versioned_auxiliary(rerand_cpk_file).map_err(|e| test.failure(e, format))?,
+            )
+            .map_err(|e| test.failure(e, format))?
+            .decompress();
+
+            let nonce: [u8; 256 / 8] = rand::random();
+            let mut re_rand_context = ReRandomizationContext::new(
+                *b"TFHE_Rrd",
+                [b"FheUint8".as_slice(), nonce.as_slice()],
+                *b"TFHE_Enc",
+            );
+
+            re_rand_context.add_ciphertext(&ct1);
+            let mut seed_gen = re_rand_context.finalize();
+
+            ct1.re_randomize(&public_key, seed_gen.next_seed().unwrap())
+                .unwrap();
+
+            #[allow(clippy::eq_op)]
+            let rrd = &ct1 & &ct1;
+            let res: u8 = rrd.decrypt(&client_key);
+            if res != v1 {
+                return Err(test.failure(
+                    format!(
+                    "Invalid result for rerand using loaded server key, expected {v1} got {res}",
+                ),
+                    format,
+                ));
+            }
+        } else {
+            return Err(test.failure(
+                "Test requires rerand key but server key does not have it".to_string(),
+                format,
+            ));
+        }
+    }
+
     let ct_sum = ct1 + ct2;
     let sum: u8 = ct_sum.decrypt(&client_key);
 

tfhe/src/high_level_api/keys/server.rs

@@ -141,12 +141,20 @@ impl ServerKey {
         self.key.re_randomization_cpk_casting_key()
     }
 
+    pub fn supports_ciphertext_re_randomization(&self) -> bool {
+        self.re_randomization_cpk_casting_key().is_some()
+    }
+
     pub fn noise_squashing_key(
         &self,
     ) -> Option<&crate::integer::noise_squashing::NoiseSquashingKey> {
         self.key.noise_squashing_key.as_ref()
     }
 
+    pub fn supports_noise_squashing(&self) -> bool {
+        self.noise_squashing_key().is_some()
+    }
+
     pub(in crate::high_level_api) fn message_modulus(&self) -> MessageModulus {
         self.key.message_modulus()
     }

utils/tfhe-backward-compat-data/data/1_4/high_level_api/client_key_for_rerand.cbor

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:0ef52bb82a792d2530c7e46f80dccba6a9f5c6d7b94d5f87bdd4637ceeed8197
+size 3338

utils/tfhe-backward-compat-data/data/1_4/high_level_api/client_key_with_noise_squashing.bcode

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:11975834f2209a223da64547d50547f8f01798a5110388f5384c8631bdd82b19
+oid sha256:8e58e8549f1ab58bed9f77ec936b995cb0238f43b813dbc64651b96aab6d9452
-size 82427
+size 82428

utils/tfhe-backward-compat-data/data/1_4/high_level_api/client_key_with_noise_squashing.cbor

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:db5483f4fcf34659639acaaa25e755ded39794f762bba8ff18ef462073747435
+oid sha256:d422e48c8327dfe2cdada7da850b12aacc81d198b408e650e8dfcab3ec164487
-size 7336
+size 7370

utils/tfhe-backward-compat-data/data/1_4/high_level_api/cpk_for_rerand.cbor

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:a29e1f621ff00d68c39860be58660c3359801cdd6cdd55c09fffd80c4b86ba2f
+size 747

utils/tfhe-backward-compat-data/data/1_4/high_level_api/server_key_for_rerand.bcode

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:1d1f9127b621084669da234edfb15d6ec0a9811b4a11920f214f6a70710bcefd
+size 856624

utils/tfhe-backward-compat-data/data/1_4/high_level_api/server_key_for_rerand.cbor

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:827caa582a73af08043012732444f4ea89eaa445095b4cfc0b8dfb2a193f504d
+size 972494

utils/tfhe-backward-compat-data/data/1_4/high_level_api/server_key_with_noise_squashing.bcode

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:4acc2ef58e90faae1d8e0f5ebc0db83740f08e6b9be7cdc1dbe0034c37ee2102
+oid sha256:523fb601cb28251fce9fbf4a784b890336bda2cfd1b3db64c996cb89fc38f212
-size 15614959
+size 15614960

utils/tfhe-backward-compat-data/data/1_4/high_level_api/server_key_with_noise_squashing.cbor

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:f2b6cd9d2170c7782b525a01dc8021c3b55d11d67f66215bbf16cc4e84b98b22
+oid sha256:147dd3b499ce1385aeba3d54e60b12eff302ddbd98d3b218cb9972a0321251f2
-size 17632539
+size 17632589

utils/tfhe-backward-compat-data/data/high_level_api.ron

@@ -357,6 +357,7 @@
         metadata: HlServerKey((
             test_filename: "compressed_server_key",
             client_key_filename: "client_key.cbor",
+            rerand_cpk_filename: None,
             compressed: true,
         )),
     ),
@@ -366,6 +367,7 @@
         metadata: HlServerKey((
             test_filename: "server_key_with_compression",
             client_key_filename: "client_key.cbor",
+            rerand_cpk_filename: None,
             compressed: false,
         )),
     ),
@@ -448,6 +450,7 @@
         metadata: HlServerKey((
             test_filename: "server_key_ms_noise_reduction",
             client_key_filename: "client_key_ms_noise_reduction.cbor",
+            rerand_cpk_filename: None,
             compressed: false,
         )),
     ),
@@ -504,6 +507,7 @@
         metadata: HlServerKey((
             test_filename: "server_key_with_noise_squashing",
             client_key_filename: "client_key_with_noise_squashing",
+            rerand_cpk_filename: None,
             compressed: false,
         )),
     ),
@@ -513,6 +517,7 @@
         metadata: HlServerKey((
             test_filename: "server_key_with_noise_squashing_compressed",
             client_key_filename: "client_key_with_noise_squashing",
+            rerand_cpk_filename: None,
             compressed: true,
         )),
     ),
@@ -613,6 +618,7 @@
         metadata: HlServerKey((
             test_filename: "server_key_ms_mean_compensation",
             client_key_filename: "client_key_ms_mean_compensation.cbor",
+            rerand_cpk_filename: None,
             compressed: false,
         )),
     ),
@@ -673,6 +679,7 @@
         metadata: HlServerKey((
             test_filename: "server_key_with_noise_squashing",
             client_key_filename: "client_key_with_noise_squashing",
+            rerand_cpk_filename: None,
             compressed: false,
         )),
     ),
@@ -685,4 +692,14 @@
             clear_value: 42,
         )),
     ),
+    (
+        tfhe_version_min: "1.4",
+        tfhe_module: "high_level_api",
+        metadata: HlServerKey((
+            test_filename: "server_key_for_rerand",
+            client_key_filename: "client_key_for_rerand",
+            rerand_cpk_filename: Some("cpk_for_rerand"),
+            compressed: false,
+        )),
+    ),
 ]

utils/tfhe-backward-compat-data/src/data_0_10.rs

@@ -165,12 +165,14 @@ const HL_CLIENTKEY_TEST: HlClientKeyTest = HlClientKeyTest {
 const HL_COMPRESSED_SERVERKEY_TEST: HlServerKeyTest = HlServerKeyTest {
     test_filename: Cow::Borrowed("compressed_server_key"),
     client_key_filename: Cow::Borrowed("client_key.cbor"),
+    rerand_cpk_filename: None,
     compressed: true,
 };
 
 const HL_SERVERKEY_WITH_COMPRESSION_TEST: HlServerKeyTest = HlServerKeyTest {
     test_filename: Cow::Borrowed("server_key_with_compression"),
     client_key_filename: Cow::Borrowed("client_key.cbor"),
+    rerand_cpk_filename: None,
     compressed: false,
 };
 

utils/tfhe-backward-compat-data/src/data_1_0.rs

@@ -171,6 +171,7 @@ const HL_CLIENTKEY_MS_NOISE_REDUCTION_TEST: HlClientKeyTest = HlClientKeyTest {
 const HL_SERVERKEY_MS_NOISE_REDUCTION_TEST: HlServerKeyTest = HlServerKeyTest {
     test_filename: Cow::Borrowed("server_key_ms_noise_reduction"),
     client_key_filename: Cow::Borrowed("client_key_ms_noise_reduction.cbor"),
+    rerand_cpk_filename: None,
     compressed: false,
 };
 

utils/tfhe-backward-compat-data/src/data_1_1.rs

@@ -207,12 +207,14 @@ const HL_CLIENTKEY_WITH_NOISE_SQUASHING_TEST: HlClientKeyTest = HlClientKeyTest
 const HL_SERVERKEY_MS_NOISE_REDUCTION_TEST: HlServerKeyTest = HlServerKeyTest {
     test_filename: Cow::Borrowed("server_key_with_noise_squashing"),
     client_key_filename: HL_CLIENTKEY_WITH_NOISE_SQUASHING_TEST.test_filename,
+    rerand_cpk_filename: None,
     compressed: false,
 };
 
 const HL_SERVERKEY_MS_NOISE_REDUCTION_COMPRESSED_TEST: HlServerKeyTest = HlServerKeyTest {
     test_filename: Cow::Borrowed("server_key_with_noise_squashing_compressed"),
     client_key_filename: HL_CLIENTKEY_WITH_NOISE_SQUASHING_TEST.test_filename,
+    rerand_cpk_filename: None,
     compressed: true,
 };
 

utils/tfhe-backward-compat-data/src/data_1_3.rs

@@ -14,7 +14,7 @@ use std::fs::create_dir_all;
 
 use crate::generate::{
     INSECURE_SMALL_TEST_NOISE_SQUASHING_PARAMS_MS_NOISE_REDUCTION,
-    INSECURE_SMALL_TEST_PARAMS_MS_NOISE_REDUCTION, TEST_PRAMS_NOISE_SQUASHING_COMPRESSION,
+    INSECURE_SMALL_TEST_PARAMS_MS_NOISE_REDUCTION, TEST_PARAMS_NOISE_SQUASHING_COMPRESSION,
 };
 
 use tfhe_1_3::boolean::engine::BooleanEngine;
@@ -310,6 +310,7 @@ const HL_CLIENTKEY_MS_MEAN_COMPENSATION: HlClientKeyTest = HlClientKeyTest {
 const HL_SERVERKEY_MS_MEAN_COMPENSATION: HlServerKeyTest = HlServerKeyTest {
     test_filename: Cow::Borrowed("server_key_ms_mean_compensation"),
     client_key_filename: Cow::Borrowed("client_key_ms_mean_compensation.cbor"),
+    rerand_cpk_filename: None,
     compressed: false,
 };
 
@@ -449,7 +450,7 @@ impl TfhersVersion for V1_3 {
             .enable_noise_squashing(
                 INSECURE_SMALL_TEST_NOISE_SQUASHING_PARAMS_MS_NOISE_REDUCTION.into(),
             )
-            .enable_noise_squashing_compression(TEST_PRAMS_NOISE_SQUASHING_COMPRESSION.into())
+            .enable_noise_squashing_compression(TEST_PARAMS_NOISE_SQUASHING_COMPRESSION.into())
             .build();
             let hl_client_key = ClientKey::generate(config);
             let hl_server_key = ServerKey::new(&hl_client_key);

utils/tfhe-backward-compat-data/src/data_1_4.rs

@@ -1,10 +1,13 @@
 use crate::generate::{
-    store_versioned_test_tfhe_1_4, TfhersVersion,
+    store_versioned_auxiliary_tfhe_1_4, store_versioned_test_tfhe_1_4, TfhersVersion,
-    INSECURE_SMALL_TEST_NOISE_SQUASHING_PARAMS_MULTI_BIT, INSECURE_SMALL_TEST_PARAMS_MULTI_BIT,
+    INSECURE_DEDICATED_CPK_TEST_PARAMS, INSECURE_SMALL_TEST_NOISE_SQUASHING_PARAMS_MULTI_BIT,
+    INSECURE_SMALL_TEST_PARAMS_MS_MEAN_COMPENSATION, INSECURE_SMALL_TEST_PARAMS_MULTI_BIT,
+    KS_TO_BIG_TEST_PARAMS, KS_TO_SMALL_TEST_PARAMS,
 };
 use crate::{
     HlClientKeyTest, HlServerKeyTest, HlSquashedNoiseUnsignedCiphertextTest,
-    TestClassicParameterSet, TestDistribution, TestMetadata, TestModulusSwitchNoiseReductionParams,
+    TestClassicParameterSet, TestCompactPublicKeyEncryptionParameters, TestDistribution,
+    TestKeySwitchingParams, TestMetadata, TestModulusSwitchNoiseReductionParams,
     TestModulusSwitchType, TestMultiBitParameterSet, TestNoiseSquashingParamsMultiBit,
     TestParameterSet, HL_MODULE_NAME,
 };
@@ -19,14 +22,19 @@ use tfhe_1_4::prelude::*;
 use tfhe_1_4::shortint::engine::ShortintEngine;
 use tfhe_1_4::shortint::parameters::noise_squashing::NoiseSquashingMultiBitParameters;
 use tfhe_1_4::shortint::parameters::{
-    CarryModulus, CiphertextModulus, CoreCiphertextModulus, DecompositionBaseLog,
+    CarryModulus, CiphertextModulus, CompactCiphertextListExpansionKind,
+    CompactPublicKeyEncryptionParameters, CoreCiphertextModulus, DecompositionBaseLog,
     DecompositionLevelCount, DynamicDistribution, EncryptionKeyChoice, GlweDimension,
     LweBskGroupingFactor, LweCiphertextCount, LweDimension, MaxNoiseLevel, MessageModulus,
     ModulusSwitchNoiseReductionParams, ModulusSwitchType, NoiseEstimationMeasureBound,
-    NoiseSquashingParameters, PolynomialSize, RSigmaFactor, StandardDev, Variance,
+    NoiseSquashingParameters, PolynomialSize, RSigmaFactor, ShortintKeySwitchingParameters,
+    StandardDev, SupportedCompactPkeZkScheme, Variance,
 };
 use tfhe_1_4::shortint::{AtomicPatternParameters, ClassicPBSParameters, MultiBitPBSParameters};
-use tfhe_1_4::{set_server_key, ClientKey, FheUint32, Seed, ServerKey};
+use tfhe_1_4::{
+    set_server_key, ClientKey, CompressedCompactPublicKey, ConfigBuilder, FheUint32, Seed,
+    ServerKey,
+};
 
 macro_rules! store_versioned_test {
     ($msg:expr, $dir:expr, $test_filename:expr $(,)? ) => {
@@ -34,6 +42,12 @@ macro_rules! store_versioned_test {
     };
 }
 
+macro_rules! store_versioned_auxiliary {
+    ($msg:expr, $dir:expr, $test_filename:expr $(,)? ) => {
+        store_versioned_auxiliary_tfhe_1_4($msg, $dir, $test_filename)
+    };
+}
+
 impl From<TestDistribution> for DynamicDistribution<u64> {
     fn from(value: TestDistribution) -> Self {
         match value {
@@ -220,6 +234,41 @@ impl From<TestNoiseSquashingParamsMultiBit> for NoiseSquashingParameters {
     }
 }
 
+impl From<TestKeySwitchingParams> for ShortintKeySwitchingParameters {
+    fn from(value: TestKeySwitchingParams) -> Self {
+        Self {
+            ks_level: DecompositionLevelCount(value.ks_level),
+            ks_base_log: DecompositionBaseLog(value.ks_base_log),
+            destination_key: match &*value.destination_key {
+                "big" => EncryptionKeyChoice::Big,
+                "small" => EncryptionKeyChoice::Small,
+                _ => panic!("Invalid encryption key choice"),
+            },
+        }
+    }
+}
+
+impl From<TestCompactPublicKeyEncryptionParameters> for CompactPublicKeyEncryptionParameters {
+    fn from(value: TestCompactPublicKeyEncryptionParameters) -> Self {
+        Self {
+            encryption_lwe_dimension: LweDimension(value.encryption_lwe_dimension),
+            encryption_noise_distribution: value.encryption_noise_distribution.into(),
+            message_modulus: MessageModulus(value.message_modulus as u64),
+            carry_modulus: CarryModulus(value.carry_modulus as u64),
+            ciphertext_modulus: CoreCiphertextModulus::try_new(value.ciphertext_modulus).unwrap(),
+            expansion_kind: match &*value.expansion_kind {
+                "requires_casting" => CompactCiphertextListExpansionKind::RequiresCasting,
+                _ => panic!("Invalid expansion kind"),
+            },
+            zk_scheme: match &*value.zk_scheme {
+                "zkv1" => SupportedCompactPkeZkScheme::V1,
+                "zkv2" => SupportedCompactPkeZkScheme::V2,
+                _ => panic!("Invalid zk scheme"),
+            },
+        }
+    }
+}
+
 const TEST_FILENAME: Cow<'static, str> = Cow::Borrowed("client_key_with_noise_squashing");
 
 const HL_CLIENTKEY_WITH_NOISE_SQUASHING_TEST: HlClientKeyTest = HlClientKeyTest {
@@ -230,6 +279,7 @@ const HL_CLIENTKEY_WITH_NOISE_SQUASHING_TEST: HlClientKeyTest = HlClientKeyTest
 const HL_SERVERKEY_TEST: HlServerKeyTest = HlServerKeyTest {
     test_filename: Cow::Borrowed("server_key_with_noise_squashing"),
     client_key_filename: TEST_FILENAME,
+    rerand_cpk_filename: None,
     compressed: false,
 };
 
@@ -240,6 +290,13 @@ const HL_SQUASHED_NOISE_UNSIGNED_CIPHERTEXT_TEST: HlSquashedNoiseUnsignedCiphert
         clear_value: 42,
     };
 
+const HL_SERVERKEY_RERAND_TEST: HlServerKeyTest = HlServerKeyTest {
+    test_filename: Cow::Borrowed("server_key_for_rerand"),
+    client_key_filename: Cow::Borrowed("client_key_for_rerand"),
+    rerand_cpk_filename: Some(Cow::Borrowed("cpk_for_rerand")),
+    compressed: false,
+};
+
 pub struct V1_4;
 
 impl TfhersVersion for V1_4 {
@@ -264,34 +321,74 @@ impl TfhersVersion for V1_4 {
         let dir = Self::data_dir().join(HL_MODULE_NAME);
         create_dir_all(&dir).unwrap();
 
-        let config = tfhe_1_4::ConfigBuilder::with_custom_parameters(
+        // Test noise squahsing multibit
-            HL_CLIENTKEY_WITH_NOISE_SQUASHING_TEST.parameters,
+        {
-        )
+            let config = ConfigBuilder::with_custom_parameters(
-        .enable_noise_squashing(INSECURE_SMALL_TEST_NOISE_SQUASHING_PARAMS_MULTI_BIT.into())
+                HL_CLIENTKEY_WITH_NOISE_SQUASHING_TEST.parameters,
-        .build();
+            )
-        let hl_client_key = ClientKey::generate(config);
+            .enable_noise_squashing(INSECURE_SMALL_TEST_NOISE_SQUASHING_PARAMS_MULTI_BIT.into())
-        let hl_server_key = ServerKey::new(&hl_client_key);
+            .build();
-        set_server_key(hl_server_key.clone());
+            let hl_client_key = ClientKey::generate(config);
+            let hl_server_key = ServerKey::new(&hl_client_key);
+            set_server_key(hl_server_key.clone());
 
-        let input = FheUint32::encrypt(
+            let input = FheUint32::encrypt(
-            HL_SQUASHED_NOISE_UNSIGNED_CIPHERTEXT_TEST.clear_value as u32,
+                HL_SQUASHED_NOISE_UNSIGNED_CIPHERTEXT_TEST.clear_value as u32,
-            &hl_client_key,
+                &hl_client_key,
-        );
+            );
 
-        let ns = input.squash_noise().unwrap();
+            let ns = input.squash_noise().unwrap();
 
-        store_versioned_test!(
+            store_versioned_test!(
-            &hl_client_key,
+                &hl_client_key,
-            &dir,
+                &dir,
-            &HL_CLIENTKEY_WITH_NOISE_SQUASHING_TEST.test_filename
+                &HL_CLIENTKEY_WITH_NOISE_SQUASHING_TEST.test_filename
-        );
+            );
-        store_versioned_test!(&hl_server_key, &dir, &HL_SERVERKEY_TEST.test_filename,);
+            store_versioned_test!(&hl_server_key, &dir, &HL_SERVERKEY_TEST.test_filename,);
 
-        store_versioned_test!(
+            store_versioned_test!(
-            &ns,
+                &ns,
-            &dir,
+                &dir,
-            &HL_SQUASHED_NOISE_UNSIGNED_CIPHERTEXT_TEST.test_filename,
+                &HL_SQUASHED_NOISE_UNSIGNED_CIPHERTEXT_TEST.test_filename,
-        );
+            );
+        }
+
+        // Test re-randomization
+        {
+            let params = INSECURE_SMALL_TEST_PARAMS_MS_MEAN_COMPENSATION;
+            let cpk_params = (
+                INSECURE_DEDICATED_CPK_TEST_PARAMS.into(),
+                KS_TO_SMALL_TEST_PARAMS.into(),
+            );
+            let re_rand_ks_params = KS_TO_BIG_TEST_PARAMS;
+
+            let config = ConfigBuilder::with_custom_parameters(params)
+                .use_dedicated_compact_public_key_parameters(cpk_params)
+                .enable_ciphertext_re_randomization(re_rand_ks_params.into())
+                .build();
+
+            let hl_client_key = ClientKey::generate(config);
+            let hl_server_key = ServerKey::new(&hl_client_key);
+            let hl_public_key = CompressedCompactPublicKey::new(&hl_client_key);
+
+            store_versioned_auxiliary!(
+                &hl_client_key,
+                &dir,
+                &HL_SERVERKEY_RERAND_TEST.client_key_filename
+            );
+
+            store_versioned_auxiliary!(
+                &hl_public_key,
+                &dir,
+                &HL_SERVERKEY_RERAND_TEST.rerand_cpk_filename.unwrap()
+            );
+
+            store_versioned_test!(
+                &hl_server_key,
+                &dir,
+                &HL_SERVERKEY_RERAND_TEST.test_filename,
+            );
+        }
 
         vec![
             TestMetadata::HlClientKey(HL_CLIENTKEY_WITH_NOISE_SQUASHING_TEST),
@@ -299,6 +396,7 @@ impl TfhersVersion for V1_4 {
             TestMetadata::HlSquashedNoiseUnsignedCiphertext(
                 HL_SQUASHED_NOISE_UNSIGNED_CIPHERTEXT_TEST,
             ),
+            TestMetadata::HlServerKey(HL_SERVERKEY_RERAND_TEST),
         ]
     }
 }

utils/tfhe-backward-compat-data/src/generate.rs

@@ -12,9 +12,10 @@ use tfhe_1_4_versionable::Versionize as VersionizeTfhe_1_4;
 use tfhe_versionable::{Versionize as VersionizeTfhe_0_10, Versionize as VersionizeTfhe_0_8};
 
 use crate::{
-    data_dir, dir_for_version, TestClassicParameterSet, TestCompressionParameterSet,
+    data_dir, dir_for_version, TestClassicParameterSet, TestCompactPublicKeyEncryptionParameters,
-    TestDistribution, TestMetadata, TestModulusSwitchNoiseReductionParams, TestModulusSwitchType,
+    TestCompressionParameterSet, TestDistribution, TestKeySwitchingParams, TestMetadata,
-    TestMultiBitParameterSet, TestNoiseSquashingCompressionParameters, TestNoiseSquashingParams,
+    TestModulusSwitchNoiseReductionParams, TestModulusSwitchType, TestMultiBitParameterSet,
+    TestNoiseSquashingCompressionParameters, TestNoiseSquashingParams,
     TestNoiseSquashingParamsMultiBit, TestParameterSet,
 };
 
@@ -181,7 +182,7 @@ pub const INSECURE_SMALL_TEST_NOISE_SQUASHING_PARAMS_MS_NOISE_REDUCTION: TestNoi
         ciphertext_modulus: 0,
     };
 
-pub const TEST_PRAMS_NOISE_SQUASHING_COMPRESSION: TestNoiseSquashingCompressionParameters =
+pub const TEST_PARAMS_NOISE_SQUASHING_COMPRESSION: TestNoiseSquashingCompressionParameters =
     TestNoiseSquashingCompressionParameters {
         packing_ks_level: 1,
         packing_ks_base_log: 61,
@@ -242,6 +243,30 @@ pub const INVALID_TEST_PARAMS: TestClassicParameterSet = TestClassicParameterSet
     modulus_switch_noise_reduction_params: TestModulusSwitchType::Standard,
 };
 
+pub const KS_TO_SMALL_TEST_PARAMS: TestKeySwitchingParams = TestKeySwitchingParams {
+    ks_level: 5,
+    ks_base_log: 3,
+    destination_key: Cow::Borrowed("small"),
+};
+
+/// Parameters used to create a rerand key
+pub const KS_TO_BIG_TEST_PARAMS: TestKeySwitchingParams = TestKeySwitchingParams {
+    ks_level: 1,
+    ks_base_log: 27,
+    destination_key: Cow::Borrowed("big"),
+};
+
+pub const INSECURE_DEDICATED_CPK_TEST_PARAMS: TestCompactPublicKeyEncryptionParameters =
+    TestCompactPublicKeyEncryptionParameters {
+        encryption_lwe_dimension: 32,
+        encryption_noise_distribution: TestDistribution::TUniform { bound_log2: 42 },
+        message_modulus: 4,
+        carry_modulus: 4,
+        ciphertext_modulus: 1 << 64,
+        expansion_kind: Cow::Borrowed("requires_casting"),
+        zk_scheme: Cow::Borrowed("zkv2"),
+    };
+
 pub fn save_cbor<Data: Serialize, P: AsRef<Path>>(msg: &Data, path: P) {
     let path = path.as_ref();
     if path.exists() {

utils/tfhe-backward-compat-data/src/lib.rs

@@ -159,6 +159,26 @@ pub enum TestDistribution {
     TUniform { bound_log2: u32 },
 }
 
+/// Re-definition of keyswitch parameters
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub struct TestKeySwitchingParams {
+    pub ks_level: usize,
+    pub ks_base_log: usize,
+    pub destination_key: Cow<'static, str>,
+}
+
+/// Re-definition of cpk parameters
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub struct TestCompactPublicKeyEncryptionParameters {
+    pub encryption_lwe_dimension: usize,
+    pub encryption_noise_distribution: TestDistribution,
+    pub message_modulus: usize,
+    pub carry_modulus: usize,
+    pub ciphertext_modulus: u128,
+    pub expansion_kind: Cow<'static, str>,
+    pub zk_scheme: Cow<'static, str>,
+}
+
 pub fn dir_for_version<P: AsRef<Path>>(data_dir: P, version: &str) -> PathBuf {
     let mut path = data_dir.as_ref().to_path_buf();
     path.push(version.replace('.', "_"));
@@ -349,6 +369,7 @@ impl TestType for HlClientKeyTest {
 pub struct HlServerKeyTest {
     pub test_filename: Cow<'static, str>,
     pub client_key_filename: Cow<'static, str>,
+    pub rerand_cpk_filename: Option<Cow<'static, str>>,
     pub compressed: bool,
 }