libsodium: Needed for Dnscrypto-proxy Release 1.3.0
[tomato.git] / release / src / router / libsodium / src / libsodium / crypto_scalarmult / curve25519 / ref / smult_curve25519_ref.c
blobba20195510d96315ce96ac540ee4a3afdbfac899
1 /*
2 version 20081011
3 Matthew Dempsky
4 Public domain.
5 Derived from public domain code by D. J. Bernstein.
6 */
8 #include "api.h"
10 #ifndef HAVE_TI_MODE
12 static void add(unsigned int out[32],const unsigned int a[32],const unsigned int b[32])
14 unsigned int j;
15 unsigned int u;
16 u = 0;
17 for (j = 0;j < 31;++j) { u += a[j] + b[j]; out[j] = u & 255; u >>= 8; }
18 u += a[31] + b[31]; out[31] = u;
21 static void sub(unsigned int out[32],const unsigned int a[32],const unsigned int b[32])
23 unsigned int j;
24 unsigned int u;
25 u = 218;
26 for (j = 0;j < 31;++j) {
27 u += a[j] + 65280 - b[j];
28 out[j] = u & 255;
29 u >>= 8;
31 u += a[31] - b[31];
32 out[31] = u;
35 static void squeeze(unsigned int a[32])
37 unsigned int j;
38 unsigned int u;
39 u = 0;
40 for (j = 0;j < 31;++j) { u += a[j]; a[j] = u & 255; u >>= 8; }
41 u += a[31]; a[31] = u & 127;
42 u = 19 * (u >> 7);
43 for (j = 0;j < 31;++j) { u += a[j]; a[j] = u & 255; u >>= 8; }
44 u += a[31]; a[31] = u;
47 static const unsigned int minusp[32] = {
48 19, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 128
49 } ;
51 static void freeze(unsigned int a[32])
53 unsigned int aorig[32];
54 unsigned int j;
55 unsigned int negative;
57 for (j = 0;j < 32;++j) aorig[j] = a[j];
58 add(a,a,minusp);
59 negative = -((a[31] >> 7) & 1);
60 for (j = 0;j < 32;++j) a[j] ^= negative & (aorig[j] ^ a[j]);
63 static void mult(unsigned int out[32],const unsigned int a[32],const unsigned int b[32])
65 unsigned int i;
66 unsigned int j;
67 unsigned int u;
69 for (i = 0;i < 32;++i) {
70 u = 0;
71 for (j = 0;j <= i;++j) u += a[j] * b[i - j];
72 for (j = i + 1;j < 32;++j) u += 38 * a[j] * b[i + 32 - j];
73 out[i] = u;
75 squeeze(out);
78 static void mult121665(unsigned int out[32],const unsigned int a[32])
80 unsigned int j;
81 unsigned int u;
83 u = 0;
84 for (j = 0;j < 31;++j) { u += 121665 * a[j]; out[j] = u & 255; u >>= 8; }
85 u += 121665 * a[31]; out[31] = u & 127;
86 u = 19 * (u >> 7);
87 for (j = 0;j < 31;++j) { u += out[j]; out[j] = u & 255; u >>= 8; }
88 u += out[j]; out[j] = u;
91 static void square(unsigned int out[32],const unsigned int a[32])
93 unsigned int i;
94 unsigned int j;
95 unsigned int u;
97 for (i = 0;i < 32;++i) {
98 u = 0;
99 for (j = 0;j < i - j;++j) u += a[j] * a[i - j];
100 for (j = i + 1;j < i + 32 - j;++j) u += 38 * a[j] * a[i + 32 - j];
101 u *= 2;
102 if ((i & 1) == 0) {
103 u += a[i / 2] * a[i / 2];
104 u += 38 * a[i / 2 + 16] * a[i / 2 + 16];
106 out[i] = u;
108 squeeze(out);
111 static void select(unsigned int p[64],unsigned int q[64],const unsigned int r[64],const unsigned int s[64],unsigned int b)
113 unsigned int j;
114 unsigned int t;
115 unsigned int bminus1;
117 bminus1 = b - 1;
118 for (j = 0;j < 64;++j) {
119 t = bminus1 & (r[j] ^ s[j]);
120 p[j] = s[j] ^ t;
121 q[j] = r[j] ^ t;
125 static void mainloop(unsigned int work[64],const unsigned char e[32])
127 unsigned int xzm1[64];
128 unsigned int xzm[64];
129 unsigned int xzmb[64];
130 unsigned int xzm1b[64];
131 unsigned int xznb[64];
132 unsigned int xzn1b[64];
133 unsigned int a0[64];
134 unsigned int a1[64];
135 unsigned int b0[64];
136 unsigned int b1[64];
137 unsigned int c1[64];
138 unsigned int r[32];
139 unsigned int s[32];
140 unsigned int t[32];
141 unsigned int u[32];
142 unsigned int j;
143 unsigned int b;
144 int pos;
146 for (j = 0;j < 32;++j) xzm1[j] = work[j];
147 xzm1[32] = 1;
148 for (j = 33;j < 64;++j) xzm1[j] = 0;
150 xzm[0] = 1;
151 for (j = 1;j < 64;++j) xzm[j] = 0;
153 for (pos = 254;pos >= 0;--pos) {
154 b = e[pos / 8] >> (pos & 7);
155 b &= 1;
156 select(xzmb,xzm1b,xzm,xzm1,b);
157 add(a0,xzmb,xzmb + 32);
158 sub(a0 + 32,xzmb,xzmb + 32);
159 add(a1,xzm1b,xzm1b + 32);
160 sub(a1 + 32,xzm1b,xzm1b + 32);
161 square(b0,a0);
162 square(b0 + 32,a0 + 32);
163 mult(b1,a1,a0 + 32);
164 mult(b1 + 32,a1 + 32,a0);
165 add(c1,b1,b1 + 32);
166 sub(c1 + 32,b1,b1 + 32);
167 square(r,c1 + 32);
168 sub(s,b0,b0 + 32);
169 mult121665(t,s);
170 add(u,t,b0);
171 mult(xznb,b0,b0 + 32);
172 mult(xznb + 32,s,u);
173 square(xzn1b,c1);
174 mult(xzn1b + 32,r,work);
175 select(xzm,xzm1,xznb,xzn1b,b);
178 for (j = 0;j < 64;++j) work[j] = xzm[j];
181 static void recip(unsigned int out[32],const unsigned int z[32])
183 unsigned int z2[32];
184 unsigned int z9[32];
185 unsigned int z11[32];
186 unsigned int z2_5_0[32];
187 unsigned int z2_10_0[32];
188 unsigned int z2_20_0[32];
189 unsigned int z2_50_0[32];
190 unsigned int z2_100_0[32];
191 unsigned int t0[32];
192 unsigned int t1[32];
193 int i;
195 /* 2 */ square(z2,z);
196 /* 4 */ square(t1,z2);
197 /* 8 */ square(t0,t1);
198 /* 9 */ mult(z9,t0,z);
199 /* 11 */ mult(z11,z9,z2);
200 /* 22 */ square(t0,z11);
201 /* 2^5 - 2^0 = 31 */ mult(z2_5_0,t0,z9);
203 /* 2^6 - 2^1 */ square(t0,z2_5_0);
204 /* 2^7 - 2^2 */ square(t1,t0);
205 /* 2^8 - 2^3 */ square(t0,t1);
206 /* 2^9 - 2^4 */ square(t1,t0);
207 /* 2^10 - 2^5 */ square(t0,t1);
208 /* 2^10 - 2^0 */ mult(z2_10_0,t0,z2_5_0);
210 /* 2^11 - 2^1 */ square(t0,z2_10_0);
211 /* 2^12 - 2^2 */ square(t1,t0);
212 /* 2^20 - 2^10 */ for (i = 2;i < 10;i += 2) { square(t0,t1); square(t1,t0); }
213 /* 2^20 - 2^0 */ mult(z2_20_0,t1,z2_10_0);
215 /* 2^21 - 2^1 */ square(t0,z2_20_0);
216 /* 2^22 - 2^2 */ square(t1,t0);
217 /* 2^40 - 2^20 */ for (i = 2;i < 20;i += 2) { square(t0,t1); square(t1,t0); }
218 /* 2^40 - 2^0 */ mult(t0,t1,z2_20_0);
220 /* 2^41 - 2^1 */ square(t1,t0);
221 /* 2^42 - 2^2 */ square(t0,t1);
222 /* 2^50 - 2^10 */ for (i = 2;i < 10;i += 2) { square(t1,t0); square(t0,t1); }
223 /* 2^50 - 2^0 */ mult(z2_50_0,t0,z2_10_0);
225 /* 2^51 - 2^1 */ square(t0,z2_50_0);
226 /* 2^52 - 2^2 */ square(t1,t0);
227 /* 2^100 - 2^50 */ for (i = 2;i < 50;i += 2) { square(t0,t1); square(t1,t0); }
228 /* 2^100 - 2^0 */ mult(z2_100_0,t1,z2_50_0);
230 /* 2^101 - 2^1 */ square(t1,z2_100_0);
231 /* 2^102 - 2^2 */ square(t0,t1);
232 /* 2^200 - 2^100 */ for (i = 2;i < 100;i += 2) { square(t1,t0); square(t0,t1); }
233 /* 2^200 - 2^0 */ mult(t1,t0,z2_100_0);
235 /* 2^201 - 2^1 */ square(t0,t1);
236 /* 2^202 - 2^2 */ square(t1,t0);
237 /* 2^250 - 2^50 */ for (i = 2;i < 50;i += 2) { square(t0,t1); square(t1,t0); }
238 /* 2^250 - 2^0 */ mult(t0,t1,z2_50_0);
240 /* 2^251 - 2^1 */ square(t1,t0);
241 /* 2^252 - 2^2 */ square(t0,t1);
242 /* 2^253 - 2^3 */ square(t1,t0);
243 /* 2^254 - 2^4 */ square(t0,t1);
244 /* 2^255 - 2^5 */ square(t1,t0);
245 /* 2^255 - 21 */ mult(out,t1,z11);
248 int crypto_scalarmult(unsigned char *q,
249 const unsigned char *n,
250 const unsigned char *p)
252 unsigned int work[96];
253 unsigned char e[32];
254 unsigned int i;
255 for (i = 0;i < 32;++i) e[i] = n[i];
256 e[0] &= 248;
257 e[31] &= 127;
258 e[31] |= 64;
259 for (i = 0;i < 32;++i) work[i] = p[i];
260 mainloop(work,e);
261 recip(work + 32,work + 32);
262 mult(work + 64,work,work + 32);
263 freeze(work + 64);
264 for (i = 0;i < 32;++i) q[i] = work[64 + i];
265 return 0;
268 #endif