20 lines
574 B
C
20 lines
574 B
C
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#include <utsm/crypto.h>
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#include <utsm/config.h>
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static u64 next_stream_word(u64 x) {
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x ^= x << 13;
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x ^= x >> 7;
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x ^= x << 17;
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return x;
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}
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void utsm_crypt_line(const utsm_key_material *key, u64 tweak, const u8 *in, u8 *out) {
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u64 state = key->words[0] ^ key->words[1] ^ key->words[2] ^ key->words[3] ^ tweak;
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for (u64 i = 0; i < UTSM_CACHE_LINE_SIZE; i += 8) {
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state = next_stream_word(state + i + 0xa5a5a5a5a5a5a5a5ULL);
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for (u64 j = 0; j < 8; j++) {
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out[i + j] = in[i + j] ^ (u8)(state >> (j * 8));
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}
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}
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}
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