2 * Copyright (C) 2010 The Android Open Source Project
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 /* This structure starts 16,384 bytes before the end of a hardware
18 * partition that is encrypted, or in a separate partition. It's location
19 * is specified by a property set in init.<device>.rc.
20 * The structure allocates 48 bytes for a key, but the real key size is
21 * specified in the struct. Currently, the code is hardcoded to use 128
23 * The fields after salt are only valid in rev 1.1 and later stuctures.
24 * Obviously, the filesystem does not include the last 16 kbytes
25 * of the partition if the crypt_mnt_ftr lives at the end of the
29 #include <cutils/properties.h>
31 /* The current cryptfs version */
32 #define CURRENT_MAJOR_VERSION 1
33 #define CURRENT_MINOR_VERSION 2
35 #define CRYPT_FOOTER_OFFSET 0x4000
36 #define CRYPT_FOOTER_TO_PERSIST_OFFSET 0x1000
37 #define CRYPT_PERSIST_DATA_SIZE 0x1000
39 #define MAX_CRYPTO_TYPE_NAME_LEN 64
41 #define MAX_KEY_LEN 48
44 /* definitions of flags in the structure below */
45 #define CRYPT_MNT_KEY_UNENCRYPTED 0x1 /* The key for the partition is not encrypted. */
46 #define CRYPT_ENCRYPTION_IN_PROGRESS 0x2 /* Set when starting encryption,
47 * clear when done before rebooting */
49 #define CRYPT_MNT_MAGIC 0xD0B5B1C4
50 #define PERSIST_DATA_MAGIC 0xE950CD44
52 #define SCRYPT_PROP "ro.crypto.scrypt_params"
53 #define SCRYPT_DEFAULTS { 15, 3, 1 }
55 /* Key Derivation Function algorithms */
59 #define __le32 unsigned int
60 #define __le16 unsigned short int
61 #define __le8 unsigned char
63 struct crypt_mnt_ftr {
64 __le32 magic; /* See above */
67 __le32 ftr_size; /* in bytes, not including key following */
68 __le32 flags; /* See above */
69 __le32 keysize; /* in bytes */
70 __le32 spare1; /* ignored */
71 __le64 fs_size; /* Size of the encrypted fs, in 512 byte sectors */
72 __le32 failed_decrypt_count; /* count of # of failed attempts to decrypt and
73 mount, set to 0 on successful mount */
74 unsigned char crypto_type_name[MAX_CRYPTO_TYPE_NAME_LEN]; /* The type of encryption
75 needed to decrypt this
76 partition, null terminated */
77 __le32 spare2; /* ignored */
78 unsigned char master_key[MAX_KEY_LEN]; /* The encrypted key for decrypting the filesystem */
79 unsigned char salt[SALT_LEN]; /* The salt used for this encryption */
80 __le64 persist_data_offset[2]; /* Absolute offset to both copies of crypt_persist_data
81 * on device with that info, either the footer of the
82 * real_blkdevice or the metadata partition. */
84 __le32 persist_data_size; /* The number of bytes allocated to each copy of the
85 * persistent data table*/
87 __le8 kdf_type; /* The key derivation function used. */
89 /* scrypt parameters. See www.tarsnap.com/scrypt/scrypt.pdf */
90 __le8 N_factor; /* (1 << N) */
91 __le8 r_factor; /* (1 << r) */
92 __le8 p_factor; /* (1 << p) */
95 /* Persistant data that should be available before decryption.
96 * Things like airplane mode, locale and timezone are kept
97 * here and can be retrieved by the CryptKeeper UI to properly
98 * configure the phone before asking for the password
99 * This is only valid if the major and minor version above
100 * is set to 1.1 or higher.
102 * This is a 4K structure. There are 2 copies, and the code alternates
103 * writing one and then clearing the previous one. The reading
104 * code reads the first valid copy it finds, based on the magic number.
105 * The absolute offset to the first of the two copies is kept in rev 1.1
106 * and higher crypt_mnt_ftr structures.
108 struct crypt_persist_entry {
109 char key[PROPERTY_KEY_MAX];
110 char val[PROPERTY_VALUE_MAX];
113 /* Should be exactly 4K in size */
114 struct crypt_persist_data {
115 __le32 persist_magic;
116 __le32 persist_valid_entries;
117 __le32 persist_spare[30];
118 struct crypt_persist_entry persist_entry[0];
124 struct crypt_mnt_ftr crypt_ftr;
127 char crypto_blkdev[256];
130 #define VOL_NONREMOVABLE 0x1
131 #define VOL_ENCRYPTABLE 0x2
137 typedef void (*kdf_func)(char *passwd, unsigned char *salt, unsigned char *ikey, void *params);
139 int cryptfs_crypto_complete(void);
140 int cryptfs_check_passwd(char *pw);
141 int cryptfs_verify_passwd(char *newpw);
142 int cryptfs_restart(void);
143 int cryptfs_enable(char *flag, char *passwd);
144 int cryptfs_changepw(char *newpw);
145 int cryptfs_setup_volume(const char *label, int major, int minor,
146 char *crypto_dev_path, unsigned int max_pathlen,
147 int *new_major, int *new_minor);
148 int cryptfs_revert_volume(const char *label);
149 int cryptfs_getfield(char *fieldname, char *value, int len);
150 int cryptfs_setfield(char *fieldname, char *value);