crypto: Add Num3072 implementation

Num3072 is a specialized bignum implementation used in MuHash3072.

Co-authored-by: Pieter Wuille <pieter.wuille@gmail.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/src/crypto/muhash.h b/src/crypto/muhash.h
new file mode 100644
index 0000000000..e5f6f0464f
--- /dev/null
+++ b/src/crypto/muhash.h
@@ -0,0 +1,62 @@
+// Copyright (c) 2017-2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_CRYPTO_MUHASH_H
+#define BITCOIN_CRYPTO_MUHASH_H
+
+#if defined(HAVE_CONFIG_H)
+#include <config/bitcoin-config.h>
+#endif
+
+#include <serialize.h>
+#include <uint256.h>
+
+#include <stdint.h>
+
+class Num3072
+{
+private:
+    void FullReduce();
+    bool IsOverflow() const;
+    Num3072 GetInverse() const;
+
+public:
+
+#ifdef HAVE___INT128
+    typedef unsigned __int128 double_limb_t;
+    typedef uint64_t limb_t;
+    static constexpr int LIMBS = 48;
+    static constexpr int LIMB_SIZE = 64;
+#else
+    typedef uint64_t double_limb_t;
+    typedef uint32_t limb_t;
+    static constexpr int LIMBS = 96;
+    static constexpr int LIMB_SIZE = 32;
+#endif
+    limb_t limbs[LIMBS];
+
+    // Sanity check for Num3072 constants
+    static_assert(LIMB_SIZE * LIMBS == 3072, "Num3072 isn't 3072 bits");
+    static_assert(sizeof(double_limb_t) == sizeof(limb_t) * 2, "bad size for double_limb_t");
+    static_assert(sizeof(limb_t) * 8 == LIMB_SIZE, "LIMB_SIZE is incorrect");
+
+    // Hard coded values in MuHash3072 constructor and Finalize
+    static_assert(sizeof(limb_t) == 4 || sizeof(limb_t) == 8, "bad size for limb_t");
+
+    void Multiply(const Num3072& a);
+    void Divide(const Num3072& a);
+    void SetToOne();
+    void Square();
+
+    Num3072() { this->SetToOne(); };
+
+    SERIALIZE_METHODS(Num3072, obj)
+    {
+        for (auto& limb : obj.limbs) {
+            READWRITE(limb);
+        }
+    }
+};
+
+#endif // BITCOIN_CRYPTO_MUHASH_H