1 /*
2 * Copyright 2015-2016 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10 #include <openssl/evp.h>
11
12 #include <assert.h>
13
14 #include <openssl/err.h>
15 #include <openssl/mem.h>
16
17 #include "../internal.h"
18
19
20 // This file implements scrypt, described in RFC 7914.
21 //
22 // Note scrypt refers to both "blocks" and a "block size" parameter, r. These
23 // are two different notions of blocks. A Salsa20 block is 64 bytes long,
24 // represented in this implementation by 16 |uint32_t|s. |r| determines the
25 // number of 64-byte Salsa20 blocks in a scryptBlockMix block, which is 2 * |r|
26 // Salsa20 blocks. This implementation refers to them as Salsa20 blocks and
27 // scrypt blocks, respectively.
28
29 // A block_t is a Salsa20 block.
30 typedef struct { uint32_t words[16]; } block_t;
31
32 static_assert(sizeof(block_t) == 64, "block_t has padding");
33
34 // salsa208_word_specification implements the Salsa20/8 core function, also
35 // described in RFC 7914, section 3. It modifies the block at |inout|
36 // in-place.
salsa208_word_specification(block_t * inout)37 static void salsa208_word_specification(block_t *inout) {
38 block_t x;
39 OPENSSL_memcpy(&x, inout, sizeof(x));
40
41 for (int i = 8; i > 0; i -= 2) {
42 x.words[4] ^= CRYPTO_rotl_u32(x.words[0] + x.words[12], 7);
43 x.words[8] ^= CRYPTO_rotl_u32(x.words[4] + x.words[0], 9);
44 x.words[12] ^= CRYPTO_rotl_u32(x.words[8] + x.words[4], 13);
45 x.words[0] ^= CRYPTO_rotl_u32(x.words[12] + x.words[8], 18);
46 x.words[9] ^= CRYPTO_rotl_u32(x.words[5] + x.words[1], 7);
47 x.words[13] ^= CRYPTO_rotl_u32(x.words[9] + x.words[5], 9);
48 x.words[1] ^= CRYPTO_rotl_u32(x.words[13] + x.words[9], 13);
49 x.words[5] ^= CRYPTO_rotl_u32(x.words[1] + x.words[13], 18);
50 x.words[14] ^= CRYPTO_rotl_u32(x.words[10] + x.words[6], 7);
51 x.words[2] ^= CRYPTO_rotl_u32(x.words[14] + x.words[10], 9);
52 x.words[6] ^= CRYPTO_rotl_u32(x.words[2] + x.words[14], 13);
53 x.words[10] ^= CRYPTO_rotl_u32(x.words[6] + x.words[2], 18);
54 x.words[3] ^= CRYPTO_rotl_u32(x.words[15] + x.words[11], 7);
55 x.words[7] ^= CRYPTO_rotl_u32(x.words[3] + x.words[15], 9);
56 x.words[11] ^= CRYPTO_rotl_u32(x.words[7] + x.words[3], 13);
57 x.words[15] ^= CRYPTO_rotl_u32(x.words[11] + x.words[7], 18);
58 x.words[1] ^= CRYPTO_rotl_u32(x.words[0] + x.words[3], 7);
59 x.words[2] ^= CRYPTO_rotl_u32(x.words[1] + x.words[0], 9);
60 x.words[3] ^= CRYPTO_rotl_u32(x.words[2] + x.words[1], 13);
61 x.words[0] ^= CRYPTO_rotl_u32(x.words[3] + x.words[2], 18);
62 x.words[6] ^= CRYPTO_rotl_u32(x.words[5] + x.words[4], 7);
63 x.words[7] ^= CRYPTO_rotl_u32(x.words[6] + x.words[5], 9);
64 x.words[4] ^= CRYPTO_rotl_u32(x.words[7] + x.words[6], 13);
65 x.words[5] ^= CRYPTO_rotl_u32(x.words[4] + x.words[7], 18);
66 x.words[11] ^= CRYPTO_rotl_u32(x.words[10] + x.words[9], 7);
67 x.words[8] ^= CRYPTO_rotl_u32(x.words[11] + x.words[10], 9);
68 x.words[9] ^= CRYPTO_rotl_u32(x.words[8] + x.words[11], 13);
69 x.words[10] ^= CRYPTO_rotl_u32(x.words[9] + x.words[8], 18);
70 x.words[12] ^= CRYPTO_rotl_u32(x.words[15] + x.words[14], 7);
71 x.words[13] ^= CRYPTO_rotl_u32(x.words[12] + x.words[15], 9);
72 x.words[14] ^= CRYPTO_rotl_u32(x.words[13] + x.words[12], 13);
73 x.words[15] ^= CRYPTO_rotl_u32(x.words[14] + x.words[13], 18);
74 }
75
76 for (int i = 0; i < 16; ++i) {
77 inout->words[i] += x.words[i];
78 }
79 }
80
81 // xor_block sets |*out| to be |*a| XOR |*b|.
xor_block(block_t * out,const block_t * a,const block_t * b)82 static void xor_block(block_t *out, const block_t *a, const block_t *b) {
83 for (size_t i = 0; i < 16; i++) {
84 out->words[i] = a->words[i] ^ b->words[i];
85 }
86 }
87
88 // scryptBlockMix implements the function described in RFC 7914, section 4. B'
89 // is written to |out|. |out| and |B| may not alias and must be each one scrypt
90 // block (2 * |r| Salsa20 blocks) long.
scryptBlockMix(block_t * out,const block_t * B,uint64_t r)91 static void scryptBlockMix(block_t *out, const block_t *B, uint64_t r) {
92 assert(out != B);
93
94 block_t X;
95 OPENSSL_memcpy(&X, &B[r * 2 - 1], sizeof(X));
96 for (uint64_t i = 0; i < r * 2; i++) {
97 xor_block(&X, &X, &B[i]);
98 salsa208_word_specification(&X);
99
100 // This implements the permutation in step 3.
101 OPENSSL_memcpy(&out[i / 2 + (i & 1) * r], &X, sizeof(X));
102 }
103 }
104
105 // scryptROMix implements the function described in RFC 7914, section 5. |B| is
106 // an scrypt block (2 * |r| Salsa20 blocks) and is modified in-place. |T| and
107 // |V| are scratch space allocated by the caller. |T| must have space for one
108 // scrypt block (2 * |r| Salsa20 blocks). |V| must have space for |N| scrypt
109 // blocks (2 * |r| * |N| Salsa20 blocks).
scryptROMix(block_t * B,uint64_t r,uint64_t N,block_t * T,block_t * V)110 static void scryptROMix(block_t *B, uint64_t r, uint64_t N, block_t *T,
111 block_t *V) {
112 // Steps 1 and 2.
113 OPENSSL_memcpy(V, B, 2 * r * sizeof(block_t));
114 for (uint64_t i = 1; i < N; i++) {
115 scryptBlockMix(&V[2 * r * i /* scrypt block i */],
116 &V[2 * r * (i - 1) /* scrypt block i-1 */], r);
117 }
118 scryptBlockMix(B, &V[2 * r * (N - 1) /* scrypt block N-1 */], r);
119
120 // Step 3.
121 for (uint64_t i = 0; i < N; i++) {
122 // Note this assumes |N| <= 2^32 and is a power of 2.
123 uint32_t j = B[2 * r - 1].words[0] & (N - 1);
124 for (size_t k = 0; k < 2 * r; k++) {
125 xor_block(&T[k], &B[k], &V[2 * r * j + k]);
126 }
127 scryptBlockMix(B, T, r);
128 }
129 }
130
131 // SCRYPT_PR_MAX is the maximum value of p * r. This is equivalent to the
132 // bounds on p in section 6:
133 //
134 // p <= ((2^32-1) * hLen) / MFLen iff
135 // p <= ((2^32-1) * 32) / (128 * r) iff
136 // p * r <= (2^30-1)
137 #define SCRYPT_PR_MAX ((1 << 30) - 1)
138
139 // SCRYPT_MAX_MEM is the default maximum memory that may be allocated by
140 // |EVP_PBE_scrypt|.
141 #define SCRYPT_MAX_MEM (1024 * 1024 * 32)
142
EVP_PBE_scrypt(const char * password,size_t password_len,const uint8_t * salt,size_t salt_len,uint64_t N,uint64_t r,uint64_t p,size_t max_mem,uint8_t * out_key,size_t key_len)143 int EVP_PBE_scrypt(const char *password, size_t password_len,
144 const uint8_t *salt, size_t salt_len, uint64_t N, uint64_t r,
145 uint64_t p, size_t max_mem, uint8_t *out_key,
146 size_t key_len) {
147 if (r == 0 || p == 0 || p > SCRYPT_PR_MAX / r ||
148 // |N| must be a power of two.
149 N < 2 || (N & (N - 1)) ||
150 // We only support |N| <= 2^32 in |scryptROMix|.
151 N > UINT64_C(1) << 32 ||
152 // Check that |N| < 2^(128×r / 8).
153 (16 * r <= 63 && N >= UINT64_C(1) << (16 * r))) {
154 OPENSSL_PUT_ERROR(EVP, EVP_R_INVALID_PARAMETERS);
155 return 0;
156 }
157
158 // Determine the amount of memory needed. B, T, and V are |p|, 1, and |N|
159 // scrypt blocks, respectively. Each scrypt block is 2*|r| |block_t|s.
160 if (max_mem == 0) {
161 max_mem = SCRYPT_MAX_MEM;
162 }
163
164 size_t max_scrypt_blocks = max_mem / (2 * r * sizeof(block_t));
165 if (max_scrypt_blocks < p + 1 ||
166 max_scrypt_blocks - p - 1 < N) {
167 OPENSSL_PUT_ERROR(EVP, EVP_R_MEMORY_LIMIT_EXCEEDED);
168 return 0;
169 }
170
171 // Allocate and divide up the scratch space. |max_mem| fits in a size_t, which
172 // is no bigger than uint64_t, so none of these operations may overflow.
173 static_assert(UINT64_MAX >= SIZE_MAX, "size_t exceeds uint64_t");
174 size_t B_blocks = p * 2 * r;
175 size_t B_bytes = B_blocks * sizeof(block_t);
176 size_t T_blocks = 2 * r;
177 size_t V_blocks = N * 2 * r;
178 block_t *B = OPENSSL_calloc(B_blocks + T_blocks + V_blocks, sizeof(block_t));
179 if (B == NULL) {
180 return 0;
181 }
182
183 int ret = 0;
184 block_t *T = B + B_blocks;
185 block_t *V = T + T_blocks;
186
187 // NOTE: PKCS5_PBKDF2_HMAC can only fail due to allocation failure
188 // or |iterations| of 0 (we pass 1 here). This is consistent with
189 // the documented failure conditions of EVP_PBE_scrypt.
190 if (!PKCS5_PBKDF2_HMAC(password, password_len, salt, salt_len, 1,
191 EVP_sha256(), B_bytes, (uint8_t *)B)) {
192 goto err;
193 }
194
195 for (uint64_t i = 0; i < p; i++) {
196 scryptROMix(B + 2 * r * i, r, N, T, V);
197 }
198
199 if (!PKCS5_PBKDF2_HMAC(password, password_len, (const uint8_t *)B, B_bytes, 1,
200 EVP_sha256(), key_len, out_key)) {
201 goto err;
202 }
203
204 ret = 1;
205
206 err:
207 OPENSSL_free(B);
208 return ret;
209 }
210