From 672f5c7f3dad8ae12b2d0ce0940ccb7c8e257bf8 Mon Sep 17 00:00:00 2001
From: Jeffrey Walton <noloader@gmail.com>
Date: Sun, 20 Jan 2019 22:43:00 -0500
Subject: [PATCH] Update documentation

---
 scrypt.cpp | 18 ++++++++++++++----
 scrypt.h   |  4 +++-
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/scrypt.cpp b/scrypt.cpp
index 0098d71a..27e604ee 100644
--- a/scrypt.cpp
+++ b/scrypt.cpp
@@ -183,6 +183,16 @@ void Scrypt::ValidateParameters(size_t derivedLen, word64 cost, word64 blockSize
         }
     }
 
+    // https://github.com/weidai11/cryptopp/issues/787
+    CRYPTOPP_ASSERT(parallelization <= std::numeric_limits<int>::max());
+    if (parallelization > static_cast<word64>(std::numeric_limits<int>::max()))
+    {
+        std::ostringstream oss;
+        oss << " parallelization " << parallelization << " is larger than ";
+        oss << numeric_limits<int>::max();
+        throw InvalidArgument("Scrypt: " + oss.str());
+    }
+
     CRYPTOPP_ASSERT(IsPowerOf2(cost));
     if (IsPowerOf2(cost) == false)
         throw InvalidArgument("Scrypt: cost must be a power of 2");
@@ -257,10 +267,10 @@ size_t Scrypt::DeriveKey(byte*derived, size_t derivedLen, const byte*secret, siz
     // 1: (B_0 ... B_{p-1}) <-- PBKDF2(P, S, 1, p * MFLen)
     PBKDF2_SHA256(B, B.size(), secret, secretLen, salt, saltLen, 1);
 
-	// Visual Studio and OpenMP 2.0 fixup. We must use int, not size_t.
-	int maxParallel=0;
-	if (!SafeConvert(parallel, maxParallel))
-		maxParallel = std::numeric_limits<int>::max();
+    // Visual Studio and OpenMP 2.0 fixup. We must use int, not size_t.
+    int maxParallel=0;
+    if (!SafeConvert(parallel, maxParallel))
+        maxParallel = std::numeric_limits<int>::max();
 
     #ifdef _OPENMP
     int threads = STDMIN(omp_get_max_threads(), maxParallel);
diff --git a/scrypt.h b/scrypt.h
index 129c5dc3..8c6f394f 100644
--- a/scrypt.h
+++ b/scrypt.h
@@ -76,7 +76,9 @@ public:
     /// \details The parameter <tt>blockSize</tt> ("r" in the documents) specifies the block
     ///   size.
     /// \details The <tt>parallelization</tt> parameter ("p" in the documents) is a positive
-    ///   integer less than or equal to <tt>((2^32-1) * 32) / (128 * r)</tt>.
+    ///   integer less than or equal to <tt>((2^32-1) * 32) / (128 * r)</tt>. Due to Microsoft
+    ///   and its OpenMP 2.0 implementation <tt>parallelization</tt> is limited to
+    ///   <tt>std::numeric_limits<int>::max()</tt>.
     /// \details Scrypt always returns 1 because it only performs 1 iteration. Other
     ///   derivation functions, like PBKDF's, will return more interesting values.
     /// \details The Crypto++ implementation of Scrypt is limited by C++ datatypes. For