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52 lines
1.7 KiB
C
52 lines
1.7 KiB
C
/*
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Public domain by Andrew M. <liquidsun@gmail.com>
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*/
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/*
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Arithmetic modulo the group order n = 2^252 + 27742317777372353535851937790883648493 = 7237005577332262213973186563042994240857116359379907606001950938285454250989
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k = 32
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b = 1 << 8 = 256
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m = 2^252 + 27742317777372353535851937790883648493 = 0x1000000000000000000000000000000014def9dea2f79cd65812631a5cf5d3ed
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mu = floor( b^(k*2) / m ) = 0xfffffffffffffffffffffffffffffffeb2106215d086329a7ed9ce5a30a2c131b
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*/
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#define bignum256modm_bits_per_limb 30
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#define bignum256modm_limb_size 9
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typedef uint32_t bignum256modm_element_t;
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typedef bignum256modm_element_t bignum256modm[9];
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/* see HAC, Alg. 14.42 Step 4 */
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void reduce256_modm(bignum256modm r);
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/*
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Barrett reduction, see HAC, Alg. 14.42
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Instead of passing in x, pre-process in to q1 and r1 for efficiency
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*/
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void barrett_reduce256_modm(bignum256modm r, const bignum256modm q1, const bignum256modm r1);
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/* addition modulo m */
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void add256_modm(bignum256modm r, const bignum256modm x, const bignum256modm y);
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/* -x modulo m */
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void neg256_modm(bignum256modm r, const bignum256modm x);
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/* subtraction x-y modulo m */
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void sub256_modm(bignum256modm r, const bignum256modm x, const bignum256modm y);
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/* multiplication modulo m */
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void mul256_modm(bignum256modm r, const bignum256modm x, const bignum256modm y);
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void expand256_modm(bignum256modm out, const unsigned char *in, size_t len);
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void expand_raw256_modm(bignum256modm out, const unsigned char in[32]);
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void contract256_modm(unsigned char out[32], const bignum256modm in);
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void contract256_window4_modm(signed char r[64], const bignum256modm in);
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void contract256_slidingwindow_modm(signed char r[256], const bignum256modm s, int windowsize);
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