93 lines
2.1 KiB
C++
93 lines
2.1 KiB
C++
/*
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WDL - rng.cpp
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Copyright (C) 2005 and later, Cockos Incorporated
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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/*
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This file provides the implementation of a decent random number generator,
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that internally uses a 256-bit state, and SHA-1 to iterate.
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*/
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#ifdef _WIN32
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#include <windows.h>
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#else
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#include <stdlib.h>
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#include <memory.h>
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#include <string.h>
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#endif
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#include "rng.h"
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#include "sha.h"
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static unsigned char state[32];
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void WDL_RNG_addentropy(void *buf, int buflen)
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{
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WDL_SHA1 tmp;
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tmp.add(state,sizeof(state));
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tmp.result(state);
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tmp.reset();
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tmp.add((unsigned char *)buf,buflen);
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tmp.result(state+sizeof(state) - WDL_SHA1SIZE);
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}
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static void rngcycle()
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{
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int i;
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for (i = 0; i < (int)sizeof(state) && state[i]++; i++);
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}
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int WDL_RNG_int32()
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{
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WDL_SHA1 tmp;
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tmp.add(state,sizeof(state));
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rngcycle();
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union {
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char buf[WDL_SHA1SIZE];
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int a;
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} b;
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tmp.result(b.buf);
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return b.a;
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}
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void WDL_RNG_bytes(void *buf, int buflen)
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{
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char *b=(char *)buf;
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while (buflen > 0)
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{
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char tb[WDL_SHA1SIZE];
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WDL_SHA1 tmp;
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tmp.add(state,sizeof(state));
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rngcycle();
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tmp.result(tb);
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const int l=buflen < WDL_SHA1SIZE ? buflen : WDL_SHA1SIZE;
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memcpy(b,tb,l);
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buflen-=l;
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b+=l;
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}
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}
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