mirror of https://github.com/qpdf/qpdf.git
56 lines
1.0 KiB
C++
56 lines
1.0 KiB
C++
#include <qpdf/RC4.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::RC4(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 = (int)strlen((char*)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] = 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::process(unsigned char *in_data, int 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 (int i = 0; i < len; ++i)
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{
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key.x = (key.x + 1) % 256;
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key.y = (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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