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Diffstat (limited to 'lib/crypto/Random.cpp')
| -rw-r--r-- | lib/crypto/Random.cpp | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/lib/crypto/Random.cpp b/lib/crypto/Random.cpp new file mode 100644 index 00000000..549a9a91 --- /dev/null +++ b/lib/crypto/Random.cpp @@ -0,0 +1,165 @@ +// distribution boxbackup-0.10 (svn version: 494) +// +// Copyright (c) 2003 - 2006 +// Ben Summers and contributors. All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions +// are met: +// 1. Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// 2. Redistributions in binary form must reproduce the above copyright +// notice, this list of conditions and the following disclaimer in the +// documentation and/or other materials provided with the distribution. +// 3. All use of this software and associated advertising materials must +// display the following acknowledgment: +// This product includes software developed by Ben Summers. +// 4. The names of the Authors may not be used to endorse or promote +// products derived from this software without specific prior written +// permission. +// +// [Where legally impermissible the Authors do not disclaim liability for +// direct physical injury or death caused solely by defects in the software +// unless it is modified by a third party.] +// +// THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR +// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED +// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE +// DISCLAIMED. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, +// INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES +// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR +// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, +// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN +// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +// POSSIBILITY OF SUCH DAMAGE. +// +// +// +// -------------------------------------------------------------------------- +// +// File +// Name: Random.cpp +// Purpose: Random numbers +// Created: 31/12/03 +// +// -------------------------------------------------------------------------- + +#include "Box.h" + +#include <openssl/rand.h> +#include <stdio.h> + +#include "Random.h" +#include "CipherException.h" + +#include "MemLeakFindOn.h" + + +// -------------------------------------------------------------------------- +// +// Function +// Name: Random::Initialise() +// Purpose: Add additional randomness to the standard library initialisation +// Created: 18/6/04 +// +// -------------------------------------------------------------------------- +void Random::Initialise() +{ +#ifdef HAVE_RANDOM_DEVICE + if(::RAND_load_file(RANDOM_DEVICE, 1024) != 1024) + { + THROW_EXCEPTION(CipherException, RandomInitFailed) + } +#else + ::fprintf(stderr, "No random device -- additional seeding of random number generator not performed.\n"); +#endif +} + + +// -------------------------------------------------------------------------- +// +// Function +// Name: Random::Generate(void *, int) +// Purpose: Generate Length bytes of random data +// Created: 31/12/03 +// +// -------------------------------------------------------------------------- +void Random::Generate(void *pOutput, int Length) +{ + if(RAND_pseudo_bytes((uint8_t*)pOutput, Length) == -1) + { + THROW_EXCEPTION(CipherException, PseudoRandNotAvailable) + } +} + + +// -------------------------------------------------------------------------- +// +// Function +// Name: Random::GenerateHex(int) +// Purpose: Generate Length bytes of hex encoded data. Note that the +// maximum length requested is limited. (Returns a string +// 2 x Length characters long.) +// Created: 1/11/04 +// +// -------------------------------------------------------------------------- +std::string Random::GenerateHex(int Length) +{ + uint8_t r[256]; + if(Length > (int)sizeof(r)) + { + THROW_EXCEPTION(CipherException, LengthRequestedTooLongForRandomHex) + } + Random::Generate(r, Length); + + std::string o; + static const char *h = "0123456789abcdef"; + for(int l = 0; l < Length; ++l) + { + o += h[r[l] >> 4]; + o += h[r[l] & 0xf]; + } + + return o; +} + + +// -------------------------------------------------------------------------- +// +// Function +// Name: Random::RandomInt(int) +// Purpose: Return a random integer between 0 and MaxValue inclusive. +// Created: 21/1/04 +// +// -------------------------------------------------------------------------- +uint32_t Random::RandomInt(uint32_t MaxValue) +{ + uint32_t v = 0; + + // Generate a mask + uint32_t mask = 0; + while(mask < MaxValue) + { + mask = (mask << 1) | 1; + } + + do + { + // Generate a random number + uint32_t r = 0; + Random::Generate(&r, sizeof(r)); + + // Mask off relevant bits + v = r & mask; + + // Check that it's in the right range. + } while(v > MaxValue); + + // NOTE: don't do a mod, because this doesn't give a correct random distribution + + return v; +} + + + |