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This comment expands all tabs using an 8-character tab-width. You should ignore this commit when using git blame or use git blame -w. In the early days, I used to use tabs where possible for indentation, since emacs did this automatically. In recent years, I have switched to only using spaces, which means qpdf source code has been a mixture of spaces and tabs. I have avoided cleaning this up because of not wanting gratuitous whitespaces change to cloud the output of git blame, but I changed my mind after discussing with users who view qpdf source code in editors/IDEs that have other tab widths by default and in light of the fact that I am planning to start applying automatic code formatting soon.
59 lines
1.3 KiB
C++
59 lines
1.3 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 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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{
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key_len = QIntC::to_int(
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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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{
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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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{
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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(unsigned char *in_data, size_t len, unsigned char* out_data)
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{
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if (out_data == 0)
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{
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// Convert in place
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out_data = in_data;
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}
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for (size_t i = 0; i < len; ++i)
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{
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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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