Have Blinder capture the Modular_Reducer by reference

randombit · Jan 28, 2025 · e67f697 · e67f697
1 parent 3c2fd2c
commit e67f697
Show file tree

Hide file tree

Showing 6 changed files with 11 additions and 12 deletions.
diff --git a/src/lib/prov/pkcs11/p11_rsa.cpp b/src/lib/prov/pkcs11/p11_rsa.cpp
@@ -116,9 +116,9 @@ class PKCS11_RSA_Decryption_Operation final : public PK_Ops::Decryption {
                                       RandomNumberGenerator& rng) :
             m_key(key),
             m_mechanism(MechanismWrapper::create_rsa_crypt_mechanism(padding)),
+            m_barrett_mod_n(Modular_Reducer::for_public_modulus(m_key.get_n())),
             m_blinder(
-               m_key.get_n(),
-               Modular_Reducer::for_public_modulus(m_key.get_n()),
+               m_barrett_mod_n,
                rng,
                [this](const BigInt& k) { return power_mod(k, m_key.get_e(), m_key.get_n()); },
                [this](const BigInt& k) { return inverse_mod_rsa_public_modulus(k, m_key.get_n()); }) {
@@ -161,6 +161,7 @@ class PKCS11_RSA_Decryption_Operation final : public PK_Ops::Decryption {
    private:
       const PKCS11_RSA_PrivateKey& m_key;
       MechanismWrapper m_mechanism;
+      Modular_Reducer m_barrett_mod_n;
       size_t m_bits = 0;
       Blinder m_blinder;
 };

diff --git a/src/lib/pubkey/blinding/blinding.cpp b/src/lib/pubkey/blinding/blinding.cpp
@@ -9,16 +9,15 @@
 
 namespace Botan {
 
-Blinder::Blinder(const BigInt& modulus,
-                 const Modular_Reducer& reducer,
+Blinder::Blinder(const Modular_Reducer& reducer,
                  RandomNumberGenerator& rng,
                  std::function<BigInt(const BigInt&)> fwd,
                  std::function<BigInt(const BigInt&)> inv) :
       m_reducer(reducer),
       m_rng(rng),
       m_fwd_fn(std::move(fwd)),
       m_inv_fn(std::move(inv)),
-      m_modulus_bits(modulus.bits()),
+      m_modulus_bits(reducer.get_modulus().bits()),
       m_e{},
       m_d{},
       m_counter{} {

diff --git a/src/lib/pubkey/blinding/blinding.h b/src/lib/pubkey/blinding/blinding.h
@@ -41,15 +41,17 @@ class Blinder final {
       BigInt unblind(const BigInt& x) const;
 
       /**
-      * @param modulus the modulus
+      * @param reducer precomputed Barrett reduction for the modulus
       * @param rng the RNG to use for generating the nonce
       * @param fwd_func a function that calculates the modular
       * exponentiation of the public exponent and the given value (the nonce)
       * @param inv_func a function that calculates the modular inverse
       * of the given value (the nonce)
+      *
+      * @note Lifetime: The rng and reducer arguments are captured by
+      * reference and must live as long as the Blinder does
       */
-      Blinder(const BigInt& modulus,
-              const Modular_Reducer& reducer,
+      Blinder(const Modular_Reducer& reducer,
               RandomNumberGenerator& rng,
               std::function<BigInt(const BigInt&)> fwd_func,
               std::function<BigInt(const BigInt&)> inv_func);
@@ -63,7 +65,7 @@ class Blinder final {
    private:
       BigInt blinding_nonce() const;
 
-      Modular_Reducer m_reducer;
+      const Modular_Reducer& m_reducer;
       RandomNumberGenerator& m_rng;
       std::function<BigInt(const BigInt&)> m_fwd_fn;
       std::function<BigInt(const BigInt&)> m_inv_fn;

diff --git a/src/lib/pubkey/dh/dh.cpp b/src/lib/pubkey/dh/dh.cpp
@@ -110,7 +110,6 @@ class DH_KA_Operation final : public PK_Ops::Key_Agreement_with_KDF {
             m_key(key),
             m_key_bits(m_key->private_key().bits()),
             m_blinder(
-               m_key->group().get_p(),
                m_key->group()._reducer_mod_p(),
                rng,
                [](const BigInt& k) { return k; },

diff --git a/src/lib/pubkey/elgamal/elgamal.cpp b/src/lib/pubkey/elgamal/elgamal.cpp
@@ -156,7 +156,6 @@ class ElGamal_Decryption_Operation final : public PK_Ops::Decryption_with_EME {
             PK_Ops::Decryption_with_EME(eme),
             m_key(key),
             m_blinder(
-               m_key->group().get_p(),
                m_key->group()._reducer_mod_p(),
                rng,
                [](const BigInt& k) { return k; },

diff --git a/src/lib/pubkey/rsa/rsa.cpp b/src/lib/pubkey/rsa/rsa.cpp
@@ -451,7 +451,6 @@ class RSA_Private_Operation {
             m_public(rsa.public_data()),
             m_private(rsa.private_data()),
             m_blinder(
-               m_public->get_n(),
                m_public->reducer_mod_n(),
                rng,
                [this](const BigInt& k) { return m_public->public_op(k); },