30 lines
726 B
C
30 lines
726 B
C
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/* Montgomery <-> Edwards isomorphism
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* Daniel Beer <dlbeer@gmail.com>, 18 Jan 2014
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*
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* This file is in the public domain.
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*/
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#ifndef MORPH25519_H_
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#define MORPH25519_H_
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#include <stdint.h>
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/* Convert an Edwards Y to a Montgomery X (Edwards X is not used).
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* Resulting coordinate is normalized.
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*/
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void morph25519_e2m(uint8_t *montgomery_x, const uint8_t *edwards_y);
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/* Return a parity bit for the Edwards X coordinate */
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static inline int morph25519_eparity(const uint8_t *edwards_x)
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{
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return edwards_x[0] & 1;
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}
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/* Convert a Montgomery X and a parity bit to an Edwards X/Y. Returns
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* non-zero if successful.
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*/
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uint8_t morph25519_m2e(uint8_t *ex, uint8_t *ey,
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const uint8_t *mx, int parity);
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#endif
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