1 /* 2 * CDDL HEADER START 3 * 4 * This file and its contents are supplied under the terms of the 5 * Common Development and Distribution License ("CDDL"), version 1.0. 6 * You may only use this file in accordance with the terms of version 7 * 1.0 of the CDDL. 8 * 9 * A full copy of the text of the CDDL should have accompanied this 10 * source. A copy of the CDDL is also available via the Internet at 11 * http://www.illumos.org/license/CDDL. 12 * 13 * CDDL HEADER END 14 */ 15 16 /* 17 * Copyright (c) 2017, Datto, Inc. All rights reserved. 18 */ 19 20 #include <sys/crypto/api.h> 21 #include <sys/sha2.h> 22 #include <sys/hkdf.h> 23 24 static int 25 hkdf_sha512_extract(uint8_t *salt, uint_t salt_len, uint8_t *key_material, 26 uint_t km_len, uint8_t *out_buf) 27 { 28 int ret; 29 crypto_mechanism_t mech; 30 crypto_key_t key; 31 crypto_data_t input_cd, output_cd; 32 33 /* initialize HMAC mechanism */ 34 mech.cm_type = crypto_mech2id(SUN_CKM_SHA512_HMAC); 35 mech.cm_param = NULL; 36 mech.cm_param_len = 0; 37 38 /* initialize the salt as a crypto key */ 39 key.ck_format = CRYPTO_KEY_RAW; 40 key.ck_length = CRYPTO_BYTES2BITS(salt_len); 41 key.ck_data = salt; 42 43 /* initialize crypto data for the input and output data */ 44 input_cd.cd_format = CRYPTO_DATA_RAW; 45 input_cd.cd_offset = 0; 46 input_cd.cd_length = km_len; 47 input_cd.cd_raw.iov_base = (char *)key_material; 48 input_cd.cd_raw.iov_len = input_cd.cd_length; 49 50 output_cd.cd_format = CRYPTO_DATA_RAW; 51 output_cd.cd_offset = 0; 52 output_cd.cd_length = SHA512_DIGEST_LENGTH; 53 output_cd.cd_raw.iov_base = (char *)out_buf; 54 output_cd.cd_raw.iov_len = output_cd.cd_length; 55 56 ret = crypto_mac(&mech, &input_cd, &key, NULL, &output_cd, NULL); 57 if (ret != CRYPTO_SUCCESS) 58 return (SET_ERROR(EIO)); 59 60 return (0); 61 } 62 63 static int 64 hkdf_sha512_expand(uint8_t *extract_key, uint8_t *info, uint_t info_len, 65 uint8_t *out_buf, uint_t out_len) 66 { 67 int ret; 68 crypto_mechanism_t mech; 69 crypto_context_t ctx; 70 crypto_key_t key; 71 crypto_data_t T_cd, info_cd, c_cd; 72 uint_t i, T_len = 0, pos = 0; 73 uint8_t c; 74 uint_t N = (out_len + SHA512_DIGEST_LENGTH) / SHA512_DIGEST_LENGTH; 75 uint8_t T[SHA512_DIGEST_LENGTH]; 76 77 if (N > 255) 78 return (SET_ERROR(EINVAL)); 79 80 /* initialize HMAC mechanism */ 81 mech.cm_type = crypto_mech2id(SUN_CKM_SHA512_HMAC); 82 mech.cm_param = NULL; 83 mech.cm_param_len = 0; 84 85 /* initialize the salt as a crypto key */ 86 key.ck_format = CRYPTO_KEY_RAW; 87 key.ck_length = CRYPTO_BYTES2BITS(SHA512_DIGEST_LENGTH); 88 key.ck_data = extract_key; 89 90 /* initialize crypto data for the input and output data */ 91 T_cd.cd_format = CRYPTO_DATA_RAW; 92 T_cd.cd_offset = 0; 93 T_cd.cd_raw.iov_base = (char *)T; 94 95 c_cd.cd_format = CRYPTO_DATA_RAW; 96 c_cd.cd_offset = 0; 97 c_cd.cd_length = 1; 98 c_cd.cd_raw.iov_base = (char *)&c; 99 c_cd.cd_raw.iov_len = c_cd.cd_length; 100 101 info_cd.cd_format = CRYPTO_DATA_RAW; 102 info_cd.cd_offset = 0; 103 info_cd.cd_length = info_len; 104 info_cd.cd_raw.iov_base = (char *)info; 105 info_cd.cd_raw.iov_len = info_cd.cd_length; 106 107 for (i = 1; i <= N; i++) { 108 c = i; 109 110 T_cd.cd_length = T_len; 111 T_cd.cd_raw.iov_len = T_cd.cd_length; 112 113 ret = crypto_mac_init(&mech, &key, NULL, &ctx, NULL); 114 if (ret != CRYPTO_SUCCESS) 115 return (SET_ERROR(EIO)); 116 117 ret = crypto_mac_update(ctx, &T_cd, NULL); 118 if (ret != CRYPTO_SUCCESS) 119 return (SET_ERROR(EIO)); 120 121 ret = crypto_mac_update(ctx, &info_cd, NULL); 122 if (ret != CRYPTO_SUCCESS) 123 return (SET_ERROR(EIO)); 124 125 ret = crypto_mac_update(ctx, &c_cd, NULL); 126 if (ret != CRYPTO_SUCCESS) 127 return (SET_ERROR(EIO)); 128 129 T_len = SHA512_DIGEST_LENGTH; 130 T_cd.cd_length = T_len; 131 T_cd.cd_raw.iov_len = T_cd.cd_length; 132 133 ret = crypto_mac_final(ctx, &T_cd, NULL); 134 if (ret != CRYPTO_SUCCESS) 135 return (SET_ERROR(EIO)); 136 137 bcopy(T, out_buf + pos, 138 (i != N) ? SHA512_DIGEST_LENGTH : (out_len - pos)); 139 pos += SHA512_DIGEST_LENGTH; 140 } 141 142 return (0); 143 } 144 145 /* 146 * HKDF is designed to be a relatively fast function for deriving keys from a 147 * master key + a salt. We use this function to generate new encryption keys 148 * so as to avoid hitting the cryptographic limits of the underlying 149 * encryption modes. Note that, for the sake of deriving encryption keys, the 150 * info parameter is called the "salt" everywhere else in the code. 151 */ 152 int 153 hkdf_sha512(uint8_t *key_material, uint_t km_len, uint8_t *salt, 154 uint_t salt_len, uint8_t *info, uint_t info_len, uint8_t *output_key, 155 uint_t out_len) 156 { 157 int ret; 158 uint8_t extract_key[SHA512_DIGEST_LENGTH]; 159 160 ret = hkdf_sha512_extract(salt, salt_len, key_material, km_len, 161 extract_key); 162 if (ret != 0) 163 return (ret); 164 165 ret = hkdf_sha512_expand(extract_key, info, info_len, output_key, 166 out_len); 167 if (ret != 0) 168 return (ret); 169 170 return (0); 171 } 172