fe_frombytes.c (2412B)
1 #include "fe.h" 2 #include "crypto_int64.h" 3 #include "crypto_uint64.h" 4 5 static crypto_uint64 load_3(const unsigned char *in) 6 { 7 crypto_uint64 result; 8 result = (crypto_uint64) in[0]; 9 result |= ((crypto_uint64) in[1]) << 8; 10 result |= ((crypto_uint64) in[2]) << 16; 11 return result; 12 } 13 14 static crypto_uint64 load_4(const unsigned char *in) 15 { 16 crypto_uint64 result; 17 result = (crypto_uint64) in[0]; 18 result |= ((crypto_uint64) in[1]) << 8; 19 result |= ((crypto_uint64) in[2]) << 16; 20 result |= ((crypto_uint64) in[3]) << 24; 21 return result; 22 } 23 24 /* 25 Ignores top bit of h. 26 */ 27 28 void fe_frombytes(fe h,const unsigned char *s) 29 { 30 crypto_int64 h0 = load_4(s); 31 crypto_int64 h1 = load_3(s + 4) << 6; 32 crypto_int64 h2 = load_3(s + 7) << 5; 33 crypto_int64 h3 = load_3(s + 10) << 3; 34 crypto_int64 h4 = load_3(s + 13) << 2; 35 crypto_int64 h5 = load_4(s + 16); 36 crypto_int64 h6 = load_3(s + 20) << 7; 37 crypto_int64 h7 = load_3(s + 23) << 5; 38 crypto_int64 h8 = load_3(s + 26) << 4; 39 crypto_int64 h9 = (load_3(s + 29) & 8388607) << 2; 40 crypto_int64 carry0; 41 crypto_int64 carry1; 42 crypto_int64 carry2; 43 crypto_int64 carry3; 44 crypto_int64 carry4; 45 crypto_int64 carry5; 46 crypto_int64 carry6; 47 crypto_int64 carry7; 48 crypto_int64 carry8; 49 crypto_int64 carry9; 50 51 carry9 = (h9 + (crypto_int64) (1<<24)) >> 25; h0 += carry9 * 19; h9 -= SHL64(carry9,25); 52 carry1 = (h1 + (crypto_int64) (1<<24)) >> 25; h2 += carry1; h1 -= SHL64(carry1,25); 53 carry3 = (h3 + (crypto_int64) (1<<24)) >> 25; h4 += carry3; h3 -= SHL64(carry3,25); 54 carry5 = (h5 + (crypto_int64) (1<<24)) >> 25; h6 += carry5; h5 -= SHL64(carry5,25); 55 carry7 = (h7 + (crypto_int64) (1<<24)) >> 25; h8 += carry7; h7 -= SHL64(carry7,25); 56 57 carry0 = (h0 + (crypto_int64) (1<<25)) >> 26; h1 += carry0; h0 -= SHL64(carry0,26); 58 carry2 = (h2 + (crypto_int64) (1<<25)) >> 26; h3 += carry2; h2 -= SHL64(carry2,26); 59 carry4 = (h4 + (crypto_int64) (1<<25)) >> 26; h5 += carry4; h4 -= SHL64(carry4,26); 60 carry6 = (h6 + (crypto_int64) (1<<25)) >> 26; h7 += carry6; h6 -= SHL64(carry6,26); 61 carry8 = (h8 + (crypto_int64) (1<<25)) >> 26; h9 += carry8; h8 -= SHL64(carry8,26); 62 63 h[0] = (crypto_int32) h0; 64 h[1] = (crypto_int32) h1; 65 h[2] = (crypto_int32) h2; 66 h[3] = (crypto_int32) h3; 67 h[4] = (crypto_int32) h4; 68 h[5] = (crypto_int32) h5; 69 h[6] = (crypto_int32) h6; 70 h[7] = (crypto_int32) h7; 71 h[8] = (crypto_int32) h8; 72 h[9] = (crypto_int32) h9; 73 }