1 // SPDX-License-Identifier: GPL-2.0 OR MIT
2 /*
3  * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
4  *
5  * This is based in part on Andrew Moon's poly1305-donna, which is in the
6  * public domain.
7  */
8 
9 #include <linux/kernel.h>
10 #include <asm/unaligned.h>
11 #include <crypto/internal/poly1305.h>
12 
poly1305_core_setkey(struct poly1305_core_key * key,const u8 raw_key[POLY1305_BLOCK_SIZE])13 void poly1305_core_setkey(struct poly1305_core_key *key,
14 			  const u8 raw_key[POLY1305_BLOCK_SIZE])
15 {
16 	/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
17 	key->key.r[0] = (get_unaligned_le32(&raw_key[0])) & 0x3ffffff;
18 	key->key.r[1] = (get_unaligned_le32(&raw_key[3]) >> 2) & 0x3ffff03;
19 	key->key.r[2] = (get_unaligned_le32(&raw_key[6]) >> 4) & 0x3ffc0ff;
20 	key->key.r[3] = (get_unaligned_le32(&raw_key[9]) >> 6) & 0x3f03fff;
21 	key->key.r[4] = (get_unaligned_le32(&raw_key[12]) >> 8) & 0x00fffff;
22 
23 	/* s = 5*r */
24 	key->precomputed_s.r[0] = key->key.r[1] * 5;
25 	key->precomputed_s.r[1] = key->key.r[2] * 5;
26 	key->precomputed_s.r[2] = key->key.r[3] * 5;
27 	key->precomputed_s.r[3] = key->key.r[4] * 5;
28 }
29 EXPORT_SYMBOL(poly1305_core_setkey);
30 
poly1305_core_blocks(struct poly1305_state * state,const struct poly1305_core_key * key,const void * src,unsigned int nblocks,u32 hibit)31 void poly1305_core_blocks(struct poly1305_state *state,
32 			  const struct poly1305_core_key *key, const void *src,
33 			  unsigned int nblocks, u32 hibit)
34 {
35 	const u8 *input = src;
36 	u32 r0, r1, r2, r3, r4;
37 	u32 s1, s2, s3, s4;
38 	u32 h0, h1, h2, h3, h4;
39 	u64 d0, d1, d2, d3, d4;
40 	u32 c;
41 
42 	if (!nblocks)
43 		return;
44 
45 	hibit <<= 24;
46 
47 	r0 = key->key.r[0];
48 	r1 = key->key.r[1];
49 	r2 = key->key.r[2];
50 	r3 = key->key.r[3];
51 	r4 = key->key.r[4];
52 
53 	s1 = key->precomputed_s.r[0];
54 	s2 = key->precomputed_s.r[1];
55 	s3 = key->precomputed_s.r[2];
56 	s4 = key->precomputed_s.r[3];
57 
58 	h0 = state->h[0];
59 	h1 = state->h[1];
60 	h2 = state->h[2];
61 	h3 = state->h[3];
62 	h4 = state->h[4];
63 
64 	do {
65 		/* h += m[i] */
66 		h0 += (get_unaligned_le32(&input[0])) & 0x3ffffff;
67 		h1 += (get_unaligned_le32(&input[3]) >> 2) & 0x3ffffff;
68 		h2 += (get_unaligned_le32(&input[6]) >> 4) & 0x3ffffff;
69 		h3 += (get_unaligned_le32(&input[9]) >> 6) & 0x3ffffff;
70 		h4 += (get_unaligned_le32(&input[12]) >> 8) | hibit;
71 
72 		/* h *= r */
73 		d0 = ((u64)h0 * r0) + ((u64)h1 * s4) +
74 		     ((u64)h2 * s3) + ((u64)h3 * s2) +
75 		     ((u64)h4 * s1);
76 		d1 = ((u64)h0 * r1) + ((u64)h1 * r0) +
77 		     ((u64)h2 * s4) + ((u64)h3 * s3) +
78 		     ((u64)h4 * s2);
79 		d2 = ((u64)h0 * r2) + ((u64)h1 * r1) +
80 		     ((u64)h2 * r0) + ((u64)h3 * s4) +
81 		     ((u64)h4 * s3);
82 		d3 = ((u64)h0 * r3) + ((u64)h1 * r2) +
83 		     ((u64)h2 * r1) + ((u64)h3 * r0) +
84 		     ((u64)h4 * s4);
85 		d4 = ((u64)h0 * r4) + ((u64)h1 * r3) +
86 		     ((u64)h2 * r2) + ((u64)h3 * r1) +
87 		     ((u64)h4 * r0);
88 
89 		/* (partial) h %= p */
90 		c = (u32)(d0 >> 26);
91 		h0 = (u32)d0 & 0x3ffffff;
92 		d1 += c;
93 		c = (u32)(d1 >> 26);
94 		h1 = (u32)d1 & 0x3ffffff;
95 		d2 += c;
96 		c = (u32)(d2 >> 26);
97 		h2 = (u32)d2 & 0x3ffffff;
98 		d3 += c;
99 		c = (u32)(d3 >> 26);
100 		h3 = (u32)d3 & 0x3ffffff;
101 		d4 += c;
102 		c = (u32)(d4 >> 26);
103 		h4 = (u32)d4 & 0x3ffffff;
104 		h0 += c * 5;
105 		c = (h0 >> 26);
106 		h0 = h0 & 0x3ffffff;
107 		h1 += c;
108 
109 		input += POLY1305_BLOCK_SIZE;
110 	} while (--nblocks);
111 
112 	state->h[0] = h0;
113 	state->h[1] = h1;
114 	state->h[2] = h2;
115 	state->h[3] = h3;
116 	state->h[4] = h4;
117 }
118 EXPORT_SYMBOL(poly1305_core_blocks);
119 
poly1305_core_emit(const struct poly1305_state * state,const u32 nonce[4],void * dst)120 void poly1305_core_emit(const struct poly1305_state *state, const u32 nonce[4],
121 			void *dst)
122 {
123 	u8 *mac = dst;
124 	u32 h0, h1, h2, h3, h4, c;
125 	u32 g0, g1, g2, g3, g4;
126 	u64 f;
127 	u32 mask;
128 
129 	/* fully carry h */
130 	h0 = state->h[0];
131 	h1 = state->h[1];
132 	h2 = state->h[2];
133 	h3 = state->h[3];
134 	h4 = state->h[4];
135 
136 	c = h1 >> 26;
137 	h1 = h1 & 0x3ffffff;
138 	h2 += c;
139 	c = h2 >> 26;
140 	h2 = h2 & 0x3ffffff;
141 	h3 += c;
142 	c = h3 >> 26;
143 	h3 = h3 & 0x3ffffff;
144 	h4 += c;
145 	c = h4 >> 26;
146 	h4 = h4 & 0x3ffffff;
147 	h0 += c * 5;
148 	c = h0 >> 26;
149 	h0 = h0 & 0x3ffffff;
150 	h1 += c;
151 
152 	/* compute h + -p */
153 	g0 = h0 + 5;
154 	c = g0 >> 26;
155 	g0 &= 0x3ffffff;
156 	g1 = h1 + c;
157 	c = g1 >> 26;
158 	g1 &= 0x3ffffff;
159 	g2 = h2 + c;
160 	c = g2 >> 26;
161 	g2 &= 0x3ffffff;
162 	g3 = h3 + c;
163 	c = g3 >> 26;
164 	g3 &= 0x3ffffff;
165 	g4 = h4 + c - (1UL << 26);
166 
167 	/* select h if h < p, or h + -p if h >= p */
168 	mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1;
169 	g0 &= mask;
170 	g1 &= mask;
171 	g2 &= mask;
172 	g3 &= mask;
173 	g4 &= mask;
174 	mask = ~mask;
175 
176 	h0 = (h0 & mask) | g0;
177 	h1 = (h1 & mask) | g1;
178 	h2 = (h2 & mask) | g2;
179 	h3 = (h3 & mask) | g3;
180 	h4 = (h4 & mask) | g4;
181 
182 	/* h = h % (2^128) */
183 	h0 = ((h0) | (h1 << 26)) & 0xffffffff;
184 	h1 = ((h1 >> 6) | (h2 << 20)) & 0xffffffff;
185 	h2 = ((h2 >> 12) | (h3 << 14)) & 0xffffffff;
186 	h3 = ((h3 >> 18) | (h4 << 8)) & 0xffffffff;
187 
188 	if (likely(nonce)) {
189 		/* mac = (h + nonce) % (2^128) */
190 		f = (u64)h0 + nonce[0];
191 		h0 = (u32)f;
192 		f = (u64)h1 + nonce[1] + (f >> 32);
193 		h1 = (u32)f;
194 		f = (u64)h2 + nonce[2] + (f >> 32);
195 		h2 = (u32)f;
196 		f = (u64)h3 + nonce[3] + (f >> 32);
197 		h3 = (u32)f;
198 	}
199 
200 	put_unaligned_le32(h0, &mac[0]);
201 	put_unaligned_le32(h1, &mac[4]);
202 	put_unaligned_le32(h2, &mac[8]);
203 	put_unaligned_le32(h3, &mac[12]);
204 }
205 EXPORT_SYMBOL(poly1305_core_emit);
206