Add signature generation operation classes. Remove sign() from

PK_Signing_Key, though for the moment the class remains because there
are a few pieces of code that use it to detect if signatures are
supported, or for passing to functions in look_pk

2 files changed, 57 insertions, 5 deletions

diff --git a/src/pubkey/rw/rw.cpp b/src/pubkey/rw/rw.cpp
index 72fa29afa..de50313d2 100644
--- a/src/pubkey/rw/rw.cpp
+++ b/src/pubkey/rw/rw.cpp
@@ -123,4 +123,37 @@ bool RW_PrivateKey::check_key(RandomNumberGenerator& rng, bool strong) const
    return true;
    }
 
+RW_Signature_Operation::RW_Signature_Operation(const RW_PrivateKey& rw) :
+   q(rw.get_q()),
+   c(rw.get_c()),
+   n(rw.get_n()),
+   powermod_d1_p(rw.get_d1(), rw.get_p()),
+   powermod_d2_q(rw.get_d2(), rw.get_q()),
+   mod_p(rw.get_p())
+   {
+   }
+
+SecureVector<byte> RW_Signature_Operation::sign(const byte msg[],
+                                                u32bit msg_len,
+                                                RandomNumberGenerator&)
+   {
+   BigInt i(msg, msg_len);
+
+   if(i >= n || i % 16 != 12)
+      throw Invalid_Argument("Rabin-Williams: invalid input");
+
+   if(jacobi(i, n) != 1)
+      i >>= 1;
+
+   BigInt j1 = powermod_d1_p(i);
+   BigInt j2 = powermod_d2_q(i);
+   j1 = mod_p.reduce(sub_mul(j1, j2, c));
+
+   BigInt r = mul_add(j1, q, j2);
+
+   r = std::min(r, n - r);
+
+   return BigInt::encode_1363(r, n.bytes());
+   }
+
 }
diff --git a/src/pubkey/rw/rw.h b/src/pubkey/rw/rw.h
index efdca04e7..a46cb5bb3 100644
--- a/src/pubkey/rw/rw.h
+++ b/src/pubkey/rw/rw.h
@@ -49,11 +49,6 @@ class BOTAN_DLL RW_PrivateKey : public RW_PublicKey,
                                 public IF_Scheme_PrivateKey
    {
    public:
-      SecureVector<byte> sign(const byte[], u32bit,
-                              RandomNumberGenerator& rng) const;
-
-      bool check_key(RandomNumberGenerator& rng, bool) const;
-
       RW_PrivateKey(const AlgorithmIdentifier& alg_id,
                     const MemoryRegion<byte>& key_bits,
                     RandomNumberGenerator& rng) :
@@ -66,6 +61,30 @@ class BOTAN_DLL RW_PrivateKey : public RW_PublicKey,
          IF_Scheme_PrivateKey(rng, p, q, e, d, n) {}
 
       RW_PrivateKey(RandomNumberGenerator& rng, u32bit bits, u32bit = 2);
+
+      bool check_key(RandomNumberGenerator& rng, bool) const;
+
+      SecureVector<byte> sign(const byte[], u32bit,
+                              RandomNumberGenerator& rng) const;
+   };
+
+class BOTAN_DLL RW_Signature_Operation : public PK_Ops::Signature_Operation
+   {
+   public:
+      RW_Signature_Operation(const RW_PrivateKey& rw);
+
+      u32bit max_input_bits() const { return (n.bits() - 1); }
+
+      SecureVector<byte> sign(const byte msg[], u32bit msg_len,
+                              RandomNumberGenerator& rng);
+   private:
+      const BigInt& q;
+      const BigInt& c;
+      const BigInt& n;
+
+      Fixed_Exponent_Power_Mod powermod_d1_p, powermod_d2_q;
+      Modular_Reducer mod_p;
+      u32bit n_bits;
    };
 
 }