1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * DES & Triple DES EDE key verification helpers
4 */
5
6 #ifndef __CRYPTO_INTERNAL_DES_H
7 #define __CRYPTO_INTERNAL_DES_H
8
9 #include <linux/crypto.h>
10 #include <linux/fips.h>
11 #include <crypto/des.h>
12 #include <crypto/aead.h>
13 #include <crypto/skcipher.h>
14
15 /**
16 * crypto_des_verify_key - Check whether a DES key is weak
17 * @tfm: the crypto algo
18 * @key: the key buffer
19 *
20 * Returns -EINVAL if the key is weak and the crypto TFM does not permit weak
21 * keys. Otherwise, 0 is returned.
22 *
23 * It is the job of the caller to ensure that the size of the key equals
24 * DES_KEY_SIZE.
25 */
26 static inline int crypto_des_verify_key(struct crypto_tfm *tfm, const u8 *key)
27 {
28 struct des_ctx tmp;
29 int err;
30
31 err = des_expand_key(&tmp, key, DES_KEY_SIZE);
32 if (err == -ENOKEY) {
33 if (crypto_tfm_get_flags(tfm) & CRYPTO_TFM_REQ_FORBID_WEAK_KEYS)
34 err = -EINVAL;
35 else
36 err = 0;
37 }
38 memzero_explicit(&tmp, sizeof(tmp));
39 return err;
40 }
41
42 /*
43 * RFC2451:
44 *
45 * For DES-EDE3, there is no known need to reject weak or
46 * complementation keys. Any weakness is obviated by the use of
47 * multiple keys.
48 *
49 * However, if the first two or last two independent 64-bit keys are
50 * equal (k1 == k2 or k2 == k3), then the DES3 operation is simply the
51 * same as DES. Implementers MUST reject keys that exhibit this
52 * property.
53 *
54 */
55 static inline int des3_ede_verify_key(const u8 *key, unsigned int key_len,
56 bool check_weak)
57 {
58 int ret = fips_enabled ? -EINVAL : -ENOKEY;
59 u32 K[6];
60
61 memcpy(K, key, DES3_EDE_KEY_SIZE);
62
63 if ((!((K[0] ^ K[2]) | (K[1] ^ K[3])) ||
64 !((K[2] ^ K[4]) | (K[3] ^ K[5]))) &&
65 (fips_enabled || check_weak))
66 goto bad;
67
68 if ((!((K[0] ^ K[4]) | (K[1] ^ K[5]))) && fips_enabled)
69 goto bad;
70
71 ret = 0;
72 bad:
73 memzero_explicit(K, DES3_EDE_KEY_SIZE);
74
75 return ret;
76 }
77
78 /**
79 * crypto_des3_ede_verify_key - Check whether a DES3-EDE key is weak
80 * @tfm: the crypto algo
81 * @key: the key buffer
82 *
83 * Returns -EINVAL if the key is weak and the crypto TFM does not permit weak
84 * keys or when running in FIPS mode. Otherwise, 0 is returned. Note that some
85 * keys are rejected in FIPS mode even if weak keys are permitted by the TFM
86 * flags.
87 *
88 * It is the job of the caller to ensure that the size of the key equals
89 * DES3_EDE_KEY_SIZE.
90 */
91 static inline int crypto_des3_ede_verify_key(struct crypto_tfm *tfm,
92 const u8 *key)
93 {
94 return des3_ede_verify_key(key, DES3_EDE_KEY_SIZE,
95 crypto_tfm_get_flags(tfm) &
96 CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
97 }
98
99 static inline int verify_skcipher_des_key(struct crypto_skcipher *tfm,
100 const u8 *key)
101 {
102 return crypto_des_verify_key(crypto_skcipher_tfm(tfm), key);
103 }
104
105 static inline int verify_skcipher_des3_key(struct crypto_skcipher *tfm,
106 const u8 *key)
107 {
108 return crypto_des3_ede_verify_key(crypto_skcipher_tfm(tfm), key);
109 }
110
111 static inline int verify_aead_des_key(struct crypto_aead *tfm, const u8 *key,
112 int keylen)
113 {
114 if (keylen != DES_KEY_SIZE)
115 return -EINVAL;
116 return crypto_des_verify_key(crypto_aead_tfm(tfm), key);
117 }
118
119 static inline int verify_aead_des3_key(struct crypto_aead *tfm, const u8 *key,
120 int keylen)
121 {
122 if (keylen != DES3_EDE_KEY_SIZE)
123 return -EINVAL;
124 return crypto_des3_ede_verify_key(crypto_aead_tfm(tfm), key);
125 }
126
127 #endif /* __CRYPTO_INTERNAL_DES_H */
128
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