35 lines
635 B
C
35 lines
635 B
C
#include "os.h"
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#include <mp.h>
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#include <libsec.h>
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static uint8_t nine[32] = {9};
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void
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curve25519_dh_new(uint8_t x[32], uint8_t y[32])
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{
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uint8_t b;
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/* new public/private key pair */
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genrandom(x, 32);
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b = x[31];
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x[0] &= ~7; /* clear bit 0,1,2 */
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x[31] = 0x40 | (b & 0x7f); /* set bit 254, clear bit 255 */
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curve25519(y, x, nine);
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/* bit 255 is always 0, so make it random */
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y[31] |= b & 0x80;
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}
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void
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curve25519_dh_finish(uint8_t x[32], uint8_t y[32], uint8_t z[32])
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{
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/* remove the random bit */
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y[31] &= 0x7f;
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/* calculate dhx key */
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curve25519(z, x, y);
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jehanne_memset(x, 0, 32);
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jehanne_memset(y, 0, 32);
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}
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