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51 lines
1.2 KiB
C++
51 lines
1.2 KiB
C++
#include <qpdf/RC4_native.hh>
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#include <qpdf/QIntC.hh>
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#include <string.h>
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static void
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swap_byte(unsigned char& a, unsigned char& b)
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{
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unsigned char t;
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t = a;
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a = b;
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b = t;
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}
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RC4_native::RC4_native(unsigned char const* key_data, int key_len)
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{
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if (key_len == -1) {
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key_len =
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QIntC::to_int(strlen(reinterpret_cast<char const*>(key_data)));
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}
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for (int i = 0; i < 256; ++i) {
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key.state[i] = static_cast<unsigned char>(i);
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}
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key.x = 0;
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key.y = 0;
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int i1 = 0;
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int i2 = 0;
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for (int i = 0; i < 256; ++i) {
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i2 = (key_data[i1] + key.state[i] + i2) % 256;
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swap_byte(key.state[i], key.state[i2]);
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i1 = (i1 + 1) % key_len;
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}
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}
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void
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RC4_native::process(
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unsigned char const* in_data, size_t len, unsigned char* out_data)
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{
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for (size_t i = 0; i < len; ++i) {
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key.x = static_cast<unsigned char>((key.x + 1) % 256);
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key.y = static_cast<unsigned char>((key.state[key.x] + key.y) % 256);
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swap_byte(key.state[key.x], key.state[key.y]);
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int xor_index = (key.state[key.x] + key.state[key.y]) % 256;
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out_data[i] = in_data[i] ^ key.state[xor_index];
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}
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}
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