From e7c0ad2cf0e9c0c88bb6da5d2176ea0dbe3978ab Mon Sep 17 00:00:00 2001
From: Cheng <cheng@>
Date: Wed, 27 Nov 2024 03:58:27 +0000
Subject: [PATCH] random generation in a range functor with seed in an instance
 of a class

---
 src/secrets.cpp | 29 +++++++++++++++++++++++++++++
 src/secrets.h   | 15 +++++++++++++++
 src/testbed.cpp | 31 ++++---------------------------
 3 files changed, 48 insertions(+), 27 deletions(-)

diff --git a/src/secrets.cpp b/src/secrets.cpp
index 9cec927..7b00c39 100644
--- a/src/secrets.cpp
+++ b/src/secrets.cpp
@@ -81,6 +81,35 @@ ristretto255::scalar DeriveSecret(const scalar &sc, uint_fast64_t i) {
 	return ristretto255::scalar(ristretto255::hash<512>(sc, i));
 }
 
+uint32_t randInRangeClass::rand() {
+	hash<256>& mybase(*this);
+	if (--i < 0) {
+		mybase = hash<256>(hsh<256>() << (mybase));
+		//hash of hash, to get 	a new block of eight pseudo random values.
+		i = 7;
+	}
+	return static_cast<uint32_t*>(static_cast<void*>(&(mybase.blob[0])))[i];
+}
+
+uint32_t randInRangeClass::operator()(uint32_t range) {
+	assert(range != 0);
+	if (range == 0) throw(sz_unexpected_error); //There are no valid values in the range zero to less than zero
+	uint64_t random32bit = this->rand(); //32-bit random number
+	uint64_t multiresult = random32bit * range;
+	uint32_t leftover = (uint32_t)multiresult;
+	if (leftover < range) {
+		// Discard potentially biased results
+		uint32_t threshold = (UINT32_MAX + 1 - range) % range;
+		while (leftover < threshold) {
+			random32bit = this->rand();
+			multiresult = random32bit * range;
+			leftover = (uint32_t)multiresult;
+		}
+	}
+	return multiresult >> 32;
+};
+
+
 namespace ristretto255 {
 	extended_public_key::extended_public_key(point&& p, hash<256>&& h) :
 		publickey(p),
diff --git a/src/secrets.h b/src/secrets.h
index f4ee6ab..a3729d8 100644
--- a/src/secrets.h
+++ b/src/secrets.h
@@ -14,6 +14,21 @@ constexpr int rounded_log2(const T val) noexcept {
 }
 std::string DeriveWordListSecret();
 
+class randInRangeClass :ristretto255::hash<256> {
+	// generates a pseudo random sequence determined by
+	// the initializer of this instance of the class
+	int i = 8;
+	uint32_t rand();  // pseudo random function in range zero to UINT32_MAX inclusive;
+public:
+	using hash::hash;
+	randInRangeClass() = delete;
+	uint32_t operator()(uint32_t range);
+	// pseudo random functor that returns a value
+	// in the range zero to less than argument.
+	// with the pseudo random sequence determined by
+	// the initializer of this instance of the class.
+};
+
 namespace ristretto255 {
 	class extended_public_key;
 	class extended_private_key {
diff --git a/src/testbed.cpp b/src/testbed.cpp
index c7f2e68..abdf19f 100644
--- a/src/testbed.cpp
+++ b/src/testbed.cpp
@@ -64,8 +64,6 @@ If using queumessage, the testbed code will complete while the dialog
 	*/
 
 	void testbed() {
-		hsh a_hsh=hsh().hashinto("the quick brown fox", "jumped over the lazy dog");
-		hash<256> a_hash = a_hsh;
 //		wxVersionInfo wx = wxWebView::GetBackendVersionInfo(wxASCII_STR(wxWebViewBackendDefault));
 //		wxLogMessage(wx.ToString());
 //		wx = wxWebView::GetBackendVersionInfo(wxASCII_STR(wxWebViewBackendEdge));
@@ -73,32 +71,11 @@ If using queumessage, the testbed code will complete while the dialog
 	//	queue_error_message("hello world");
 	//	throw MyException("hello world exception", __LINE__, __func__, SrcFilename);
 		ILogMessage("begin testbed");
-/*		auto text_secret{DeriveTextSecret(scalar(7), 1)};
-		if (text_secret == decltype(text_secret){"Rmc mLSu mDk DhfV 9gBK kKj"}) {
-			ILogMessage("\t\tObtained expected text secret from scalar(7)");
+	/*	randInRangeClass randInRange("the quicku brown fox");
+		for (int i = 0; i < 100; i++) {
+			wxLogMessage(wxT("%d "), randInRange(1000000000));
 		}
-		else {
-			errorCode = 18;
-			szError = "Fail\tUnexpected text secret from scalar(7)";
-			ILogError(szError.c_str());
-		}
-		auto start_time{ std::chrono::high_resolution_clock::now() };
-		extended_private_key s1(& text_secret[0]);
-		auto end_time{ std::chrono::high_resolution_clock::now() };
-		std::string str_s1{ &(base58(s1))[0] };
-		wxLogMessage("\t\textended private key: %s", str_s1);
-		const char * str_s2 = "jyRioJfob242toZDETkd7nG4YW6oYeGBEVEw4KLGWZaJfCPV2hQbT3AFUcnu6ZXEvDPPpSmM5ivMJ2awJxSBS5DoE";
-		if (str_s2 != str_s1) {
-			throw MyException("unexpected value of private key", __LINE__, __func__, SrcFilename);
-		}
-		auto s2 = base58<extended_private_key>::bin(str_s2);
-		if ( s1 != s2) {
-			throw MyException("Round trip for extended_private_key to and from base 58 representation failed", __LINE__, __func__, SrcFilename);
-		}
-
-		auto time_taken{ std::chrono::duration_cast<std::chrono::microseconds> (end_time - start_time) };
-		wxLogMessage("\t\tStrong secret derivation took %lld microseconds", time_taken.count());*/
-
+		*/
 		ILogMessage("end testbed");
 	}
 }