49 lines
1.1 KiB
C++
49 lines
1.1 KiB
C++
/*
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Xtea.cpp - Xtea encryption/decryption
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Written by Frank Kienast in November, 2010
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https://github.com/franksmicro/Arduino/tree/master/libraries/Xtea
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*/
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#include <stdint.h>
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#include "Xtea.h"
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#define NUM_ROUNDS 32
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Xtea::Xtea(unsigned long key[4])
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{
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_key[0] = key[0];
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_key[1] = key[1];
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_key[2] = key[2];
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_key[3] = key[3];
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}
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void Xtea::encrypt(unsigned long v[2])
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{
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unsigned int i;
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unsigned long v0=v[0], v1=v[1], sum=0, delta=0x9E3779B9;
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for (i=0; i < NUM_ROUNDS; i++)
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{
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v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + _key[sum & 3]);
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sum += delta;
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v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + _key[(sum>>11) & 3]);
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}
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v[0]=v0; v[1]=v1;
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}
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void Xtea::decrypt(unsigned long v[2])
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{
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unsigned int i;
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uint32_t v0=v[0], v1=v[1], delta=0x9E3779B9, sum=delta*NUM_ROUNDS;
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for (i=0; i < NUM_ROUNDS; i++)
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{
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v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + _key[(sum>>11) & 3]);
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sum -= delta;
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v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + _key[sum & 3]);
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}
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v[0]=v0; v[1]=v1;
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}
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