1 /** 2 * \file nist_kw.h 3 * 4 * \brief This file provides an API for key wrapping (KW) and key wrapping with 5 * padding (KWP) as defined in NIST SP 800-38F. 6 * https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-38F.pdf 7 * 8 * Key wrapping specifies a deterministic authenticated-encryption mode 9 * of operation, according to <em>NIST SP 800-38F: Recommendation for 10 * Block Cipher Modes of Operation: Methods for Key Wrapping</em>. Its 11 * purpose is to protect cryptographic keys. 12 * 13 * Its equivalent is RFC 3394 for KW, and RFC 5649 for KWP. 14 * https://tools.ietf.org/html/rfc3394 15 * https://tools.ietf.org/html/rfc5649 16 * 17 */ 18 /* 19 * Copyright The Mbed TLS Contributors 20 * SPDX-License-Identifier: Apache-2.0 21 * 22 * Licensed under the Apache License, Version 2.0 (the "License"); you may 23 * not use this file except in compliance with the License. 24 * You may obtain a copy of the License at 25 * 26 * http://www.apache.org/licenses/LICENSE-2.0 27 * 28 * Unless required by applicable law or agreed to in writing, software 29 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 30 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 31 * See the License for the specific language governing permissions and 32 * limitations under the License. 33 */ 34 35 #ifndef MBEDTLS_NIST_KW_H 36 #define MBEDTLS_NIST_KW_H 37 38 #if !defined(MBEDTLS_CONFIG_FILE) 39 #include "mbedtls/config.h" 40 #else 41 #include MBEDTLS_CONFIG_FILE 42 #endif 43 44 #include "mbedtls/cipher.h" 45 46 #ifdef __cplusplus 47 extern "C" { 48 #endif 49 50 typedef enum 51 { 52 MBEDTLS_KW_MODE_KW = 0, 53 MBEDTLS_KW_MODE_KWP = 1 54 } mbedtls_nist_kw_mode_t; 55 56 #if !defined(MBEDTLS_NIST_KW_ALT) 57 // Regular implementation 58 // 59 60 /** 61 * \brief The key wrapping context-type definition. The key wrapping context is passed 62 * to the APIs called. 63 * 64 * \note The definition of this type may change in future library versions. 65 * Don't make any assumptions on this context! 66 */ 67 typedef struct { 68 mbedtls_cipher_context_t cipher_ctx; /*!< The cipher context used. */ 69 } mbedtls_nist_kw_context; 70 71 #else /* MBEDTLS_NIST_key wrapping_ALT */ 72 #include "nist_kw_alt.h" 73 #endif /* MBEDTLS_NIST_KW_ALT */ 74 75 /** 76 * \brief This function initializes the specified key wrapping context 77 * to make references valid and prepare the context 78 * for mbedtls_nist_kw_setkey() or mbedtls_nist_kw_free(). 79 * 80 * \param ctx The key wrapping context to initialize. 81 * 82 */ 83 void mbedtls_nist_kw_init( mbedtls_nist_kw_context *ctx ); 84 85 /** 86 * \brief This function initializes the key wrapping context set in the 87 * \p ctx parameter and sets the encryption key. 88 * 89 * \param ctx The key wrapping context. 90 * \param cipher The 128-bit block cipher to use. Only AES is supported. 91 * \param key The Key Encryption Key (KEK). 92 * \param keybits The KEK size in bits. This must be acceptable by the cipher. 93 * \param is_wrap Specify whether the operation within the context is wrapping or unwrapping 94 * 95 * \return \c 0 on success. 96 * \return \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for any invalid input. 97 * \return \c MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE for 128-bit block ciphers 98 * which are not supported. 99 * \return cipher-specific error code on failure of the underlying cipher. 100 */ 101 int mbedtls_nist_kw_setkey( mbedtls_nist_kw_context *ctx, 102 mbedtls_cipher_id_t cipher, 103 const unsigned char *key, 104 unsigned int keybits, 105 const int is_wrap ); 106 107 /** 108 * \brief This function releases and clears the specified key wrapping context 109 * and underlying cipher sub-context. 110 * 111 * \param ctx The key wrapping context to clear. 112 */ 113 void mbedtls_nist_kw_free( mbedtls_nist_kw_context *ctx ); 114 115 /** 116 * \brief This function encrypts a buffer using key wrapping. 117 * 118 * \param ctx The key wrapping context to use for encryption. 119 * \param mode The key wrapping mode to use (MBEDTLS_KW_MODE_KW or MBEDTLS_KW_MODE_KWP) 120 * \param input The buffer holding the input data. 121 * \param in_len The length of the input data in Bytes. 122 * The input uses units of 8 Bytes called semiblocks. 123 * <ul><li>For KW mode: a multiple of 8 bytes between 16 and 2^57-8 inclusive. </li> 124 * <li>For KWP mode: any length between 1 and 2^32-1 inclusive.</li></ul> 125 * \param[out] output The buffer holding the output data. 126 * <ul><li>For KW mode: Must be at least 8 bytes larger than \p in_len.</li> 127 * <li>For KWP mode: Must be at least 8 bytes larger rounded up to a multiple of 128 * 8 bytes for KWP (15 bytes at most).</li></ul> 129 * \param[out] out_len The number of bytes written to the output buffer. \c 0 on failure. 130 * \param[in] out_size The capacity of the output buffer. 131 * 132 * \return \c 0 on success. 133 * \return \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for invalid input length. 134 * \return cipher-specific error code on failure of the underlying cipher. 135 */ 136 int mbedtls_nist_kw_wrap( mbedtls_nist_kw_context *ctx, mbedtls_nist_kw_mode_t mode, 137 const unsigned char *input, size_t in_len, 138 unsigned char *output, size_t* out_len, size_t out_size ); 139 140 /** 141 * \brief This function decrypts a buffer using key wrapping. 142 * 143 * \param ctx The key wrapping context to use for decryption. 144 * \param mode The key wrapping mode to use (MBEDTLS_KW_MODE_KW or MBEDTLS_KW_MODE_KWP) 145 * \param input The buffer holding the input data. 146 * \param in_len The length of the input data in Bytes. 147 * The input uses units of 8 Bytes called semiblocks. 148 * The input must be a multiple of semiblocks. 149 * <ul><li>For KW mode: a multiple of 8 bytes between 24 and 2^57 inclusive. </li> 150 * <li>For KWP mode: a multiple of 8 bytes between 16 and 2^32 inclusive.</li></ul> 151 * \param[out] output The buffer holding the output data. 152 * The output buffer's minimal length is 8 bytes shorter than \p in_len. 153 * \param[out] out_len The number of bytes written to the output buffer. \c 0 on failure. 154 * For KWP mode, the length could be up to 15 bytes shorter than \p in_len, 155 * depending on how much padding was added to the data. 156 * \param[in] out_size The capacity of the output buffer. 157 * 158 * \return \c 0 on success. 159 * \return \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for invalid input length. 160 * \return \c MBEDTLS_ERR_CIPHER_AUTH_FAILED for verification failure of the ciphertext. 161 * \return cipher-specific error code on failure of the underlying cipher. 162 */ 163 int mbedtls_nist_kw_unwrap( mbedtls_nist_kw_context *ctx, mbedtls_nist_kw_mode_t mode, 164 const unsigned char *input, size_t in_len, 165 unsigned char *output, size_t* out_len, size_t out_size); 166 167 168 #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C) 169 /** 170 * \brief The key wrapping checkup routine. 171 * 172 * \return \c 0 on success. 173 * \return \c 1 on failure. 174 */ 175 int mbedtls_nist_kw_self_test( int verbose ); 176 #endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */ 177 178 #ifdef __cplusplus 179 } 180 #endif 181 182 #endif /* MBEDTLS_NIST_KW_H */ 183