73 lines
1.8 KiB
C++
73 lines
1.8 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2015 Danny Robson <danny@nerdcruft.net>
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*/
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#include "hotp.hpp"
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#include "../endian.hpp"
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#include <cstring>
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using util::hash::HOTP;
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//-----------------------------------------------------------------------------
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HOTP::HOTP (const char *_key, uint64_t _counter):
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HOTP (_key, strlen (_key), _counter)
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{ ; }
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//-----------------------------------------------------------------------------
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HOTP::HOTP (const void *_key, size_t _len, uint64_t _counter):
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m_counter (_counter),
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m_hash ((const uint8_t*)_key, _len)
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{ ; }
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//-----------------------------------------------------------------------------
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unsigned
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HOTP::value (void)
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{
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auto c = htob (m_counter);
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m_hash.update (&c, sizeof (c));
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m_hash.finish ();
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auto h = m_hash.digest ();
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auto t = truncate (h);
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m_hash.reset ();
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++m_counter;
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return t % 1000000;
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}
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//-----------------------------------------------------------------------------
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uint32_t
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HOTP::truncate (SHA1::digest_t d)
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{
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// offset into the digest by the last 4 bits
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size_t o= d[d.size () - 1] & 0x0F;
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// mask the highest bit per the specification
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uint32_t v = (d[o + 0] & 0x7f) << 24 |
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(d[o + 1] & 0xff) << 16 |
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(d[o + 2] & 0xff) << 8 |
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(d[o + 3] & 0xff) << 0;
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return v;
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}
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