246 lines
7.6 KiB
C
246 lines
7.6 KiB
C
/*
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* Copyright (c) 2013, Kenneth MacKay
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _CRYPTO_ECC_H
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#define _CRYPTO_ECC_H
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/* One digit is u64 qword. */
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#define ECC_CURVE_NIST_P192_DIGITS 3
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#define ECC_CURVE_NIST_P256_DIGITS 4
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#define ECC_MAX_DIGITS (512 / 64)
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#define ECC_DIGITS_TO_BYTES_SHIFT 3
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/**
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* struct ecc_point - elliptic curve point in affine coordinates
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*
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* @x: X coordinate in vli form.
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* @y: Y coordinate in vli form.
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* @ndigits: Length of vlis in u64 qwords.
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*/
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struct ecc_point {
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u64 *x;
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u64 *y;
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u8 ndigits;
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};
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#define ECC_POINT_INIT(x, y, ndigits) (struct ecc_point) { x, y, ndigits }
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/**
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* struct ecc_curve - definition of elliptic curve
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*
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* @name: Short name of the curve.
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* @g: Generator point of the curve.
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* @p: Prime number, if Barrett's reduction is used for this curve
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* pre-calculated value 'mu' is appended to the @p after ndigits.
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* Use of Barrett's reduction is heuristically determined in
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* vli_mmod_fast().
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* @n: Order of the curve group.
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* @a: Curve parameter a.
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* @b: Curve parameter b.
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*/
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struct ecc_curve {
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char *name;
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struct ecc_point g;
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u64 *p;
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u64 *n;
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u64 *a;
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u64 *b;
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};
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/**
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* ecc_is_key_valid() - Validate a given ECDH private key
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*
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* @curve_id: id representing the curve to use
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* @ndigits: curve's number of digits
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* @private_key: private key to be used for the given curve
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* @private_key_len: private key length
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*
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* Returns 0 if the key is acceptable, a negative value otherwise
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*/
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int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
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const u64 *private_key, unsigned int private_key_len);
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/**
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* ecc_gen_privkey() - Generates an ECC private key.
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* The private key is a random integer in the range 0 < random < n, where n is a
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* prime that is the order of the cyclic subgroup generated by the distinguished
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* point G.
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* @curve_id: id representing the curve to use
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* @ndigits: curve number of digits
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* @private_key: buffer for storing the generated private key
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*
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* Returns 0 if the private key was generated successfully, a negative value
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* if an error occurred.
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*/
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int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey);
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/**
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* ecc_make_pub_key() - Compute an ECC public key
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*
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* @curve_id: id representing the curve to use
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* @ndigits: curve's number of digits
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* @private_key: pregenerated private key for the given curve
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* @public_key: buffer for storing the generated public key
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*
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* Returns 0 if the public key was generated successfully, a negative value
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* if an error occurred.
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*/
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int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits,
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const u64 *private_key, u64 *public_key);
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/**
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* crypto_ecdh_shared_secret() - Compute a shared secret
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*
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* @curve_id: id representing the curve to use
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* @ndigits: curve's number of digits
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* @private_key: private key of part A
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* @public_key: public key of counterpart B
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* @secret: buffer for storing the calculated shared secret
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*
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* Note: It is recommended that you hash the result of crypto_ecdh_shared_secret
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* before using it for symmetric encryption or HMAC.
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*
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* Returns 0 if the shared secret was generated successfully, a negative value
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* if an error occurred.
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*/
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int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
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const u64 *private_key, const u64 *public_key,
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u64 *secret);
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/**
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* ecc_is_pubkey_valid_partial() - Partial public key validation
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*
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* @curve: elliptic curve domain parameters
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* @pk: public key as a point
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*
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* Valdiate public key according to SP800-56A section 5.6.2.3.4 ECC Partial
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* Public-Key Validation Routine.
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*
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* Note: There is no check that the public key is in the correct elliptic curve
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* subgroup.
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*
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* Return: 0 if validation is successful, -EINVAL if validation is failed.
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*/
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int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve,
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struct ecc_point *pk);
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/**
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* vli_is_zero() - Determine is vli is zero
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*
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* @vli: vli to check.
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* @ndigits: length of the @vli
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*/
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bool vli_is_zero(const u64 *vli, unsigned int ndigits);
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/**
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* vli_cmp() - compare left and right vlis
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*
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* @left: vli
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* @right: vli
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* @ndigits: length of both vlis
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*
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* Returns sign of @left - @right, i.e. -1 if @left < @right,
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* 0 if @left == @right, 1 if @left > @right.
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*/
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int vli_cmp(const u64 *left, const u64 *right, unsigned int ndigits);
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/**
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* vli_sub() - Subtracts right from left
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*
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* @result: where to write result
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* @left: vli
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* @right vli
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* @ndigits: length of all vlis
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*
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* Note: can modify in-place.
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*
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* Return: carry bit.
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*/
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u64 vli_sub(u64 *result, const u64 *left, const u64 *right,
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unsigned int ndigits);
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/**
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* vli_from_be64() - Load vli from big-endian u64 array
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*
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* @dest: destination vli
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* @src: source array of u64 BE values
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* @ndigits: length of both vli and array
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*/
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void vli_from_be64(u64 *dest, const void *src, unsigned int ndigits);
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/**
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* vli_from_le64() - Load vli from little-endian u64 array
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*
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* @dest: destination vli
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* @src: source array of u64 LE values
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* @ndigits: length of both vli and array
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*/
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void vli_from_le64(u64 *dest, const void *src, unsigned int ndigits);
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/**
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* vli_mod_inv() - Modular inversion
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*
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* @result: where to write vli number
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* @input: vli value to operate on
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* @mod: modulus
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* @ndigits: length of all vlis
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*/
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void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod,
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unsigned int ndigits);
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/**
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* vli_mod_mult_slow() - Modular multiplication
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*
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* @result: where to write result value
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* @left: vli number to multiply with @right
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* @right: vli number to multiply with @left
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* @mod: modulus
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* @ndigits: length of all vlis
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*
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* Note: Assumes that mod is big enough curve order.
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*/
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void vli_mod_mult_slow(u64 *result, const u64 *left, const u64 *right,
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const u64 *mod, unsigned int ndigits);
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/**
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* ecc_point_mult_shamir() - Add two points multiplied by scalars
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*
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* @result: resulting point
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* @x: scalar to multiply with @p
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* @p: point to multiply with @x
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* @y: scalar to multiply with @q
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* @q: point to multiply with @y
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* @curve: curve
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*
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* Returns result = x * p + x * q over the curve.
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* This works faster than two multiplications and addition.
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*/
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void ecc_point_mult_shamir(const struct ecc_point *result,
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const u64 *x, const struct ecc_point *p,
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const u64 *y, const struct ecc_point *q,
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const struct ecc_curve *curve);
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#endif
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