chore(shortint): add more granular 2_2 TUniform parameters

tfhe/src/shortint/parameters/key_switching.rs

@@ -43,9 +43,31 @@ pub const PARAM_KEYSWITCH_1_1_KS_PBS_TO_2_2_KS_PBS: ShortintKeySwitchingParamete
         destination_key: EncryptionKeyChoice::Big,
     };
 
+// The level and base log correspond to the level and base log of the 2_2 TUniform parameters, so
+// these parameters allow to keyswitch from one set of keys of the 2_2 TUniform parameters to
+// another set of keys. The ciphertext will be under the small key and a PBS with the destination
+// keys will be applied to finish the keyswitch.
 pub const PARAM_KEYSWITCH_MESSAGE_2_CARRY_2_KS_PBS_TUNIFORM_2M64: ShortintKeySwitchingParameters =
     ShortintKeySwitchingParameters {
         ks_level: DecompositionLevelCount(5),
         ks_base_log: DecompositionBaseLog(3),
         destination_key: EncryptionKeyChoice::Small,
     };
+
+// Parameters to keyswitch from input PKE 2_2 TUniform parameters to 2_2 KS_PBS compute parameters
+// arriving under the small key, requires a PBS to get to the big key
+pub const PARAM_KEYSWITCH_PKE_TO_SMALL_MESSAGE_2_CARRY_2_KS_PBS_TUNIFORM_2M64:
+    ShortintKeySwitchingParameters = ShortintKeySwitchingParameters {
+    ks_level: DecompositionLevelCount(5),
+    ks_base_log: DecompositionBaseLog(3),
+    destination_key: EncryptionKeyChoice::Small,
+};
+
+// Parameters to keyswitch from input PKE 2_2 TUniform parameters to 2_2 KS_PBS compute parameters
+// arriving under the big key, requires a PBS to get to the big key
+pub const PARAM_KEYSWITCH_PKE_TO_BIG_MESSAGE_2_CARRY_2_KS_PBS_TUNIFORM_2M64:
+    ShortintKeySwitchingParameters = ShortintKeySwitchingParameters {
+    ks_level: DecompositionLevelCount(1),
+    ks_base_log: DecompositionBaseLog(27),
+    destination_key: EncryptionKeyChoice::Big,
+};