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 OR GPL-2.0-or-later 21 */ 22 23 #ifndef MBEDTLS_NIST_KW_H 24 #define MBEDTLS_NIST_KW_H 25 #include "mbedtls/private_access.h" 26 27 #include "mbedtls/build_info.h" 28 29 #include "mbedtls/cipher.h" 30 31 #ifdef __cplusplus 32 extern "C" { 33 #endif 34 35 typedef enum { 36 MBEDTLS_KW_MODE_KW = 0, 37 MBEDTLS_KW_MODE_KWP = 1 38 } mbedtls_nist_kw_mode_t; 39 40 #if !defined(MBEDTLS_NIST_KW_ALT) 41 // Regular implementation 42 // 43 44 /** 45 * \brief The key wrapping context-type definition. The key wrapping context is passed 46 * to the APIs called. 47 * 48 * \note The definition of this type may change in future library versions. 49 * Don't make any assumptions on this context! 50 */ 51 typedef struct { 52 mbedtls_cipher_context_t MBEDTLS_PRIVATE(cipher_ctx); /*!< The cipher context used. */ 53 } mbedtls_nist_kw_context; 54 55 #else /* MBEDTLS_NIST_key wrapping_ALT */ 56 #include "nist_kw_alt.h" 57 #endif /* MBEDTLS_NIST_KW_ALT */ 58 59 /** 60 * \brief This function initializes the specified key wrapping context 61 * to make references valid and prepare the context 62 * for mbedtls_nist_kw_setkey() or mbedtls_nist_kw_free(). 63 * 64 * \param ctx The key wrapping context to initialize. 65 * 66 */ 67 void mbedtls_nist_kw_init(mbedtls_nist_kw_context *ctx); 68 69 /** 70 * \brief This function initializes the key wrapping context set in the 71 * \p ctx parameter and sets the encryption key. 72 * 73 * \param ctx The key wrapping context. 74 * \param cipher The 128-bit block cipher to use. Only AES is supported. 75 * \param key The Key Encryption Key (KEK). 76 * \param keybits The KEK size in bits. This must be acceptable by the cipher. 77 * \param is_wrap Specify whether the operation within the context is wrapping or unwrapping 78 * 79 * \return \c 0 on success. 80 * \return \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for any invalid input. 81 * \return \c MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE for 128-bit block ciphers 82 * which are not supported. 83 * \return cipher-specific error code on failure of the underlying cipher. 84 */ 85 int mbedtls_nist_kw_setkey(mbedtls_nist_kw_context *ctx, 86 mbedtls_cipher_id_t cipher, 87 const unsigned char *key, 88 unsigned int keybits, 89 const int is_wrap); 90 91 /** 92 * \brief This function releases and clears the specified key wrapping context 93 * and underlying cipher sub-context. 94 * 95 * \param ctx The key wrapping context to clear. 96 */ 97 void mbedtls_nist_kw_free(mbedtls_nist_kw_context *ctx); 98 99 /** 100 * \brief This function encrypts a buffer using key wrapping. 101 * 102 * \param ctx The key wrapping context to use for encryption. 103 * \param mode The key wrapping mode to use (MBEDTLS_KW_MODE_KW or MBEDTLS_KW_MODE_KWP) 104 * \param input The buffer holding the input data. 105 * \param in_len The length of the input data in Bytes. 106 * The input uses units of 8 Bytes called semiblocks. 107 * <ul><li>For KW mode: a multiple of 8 bytes between 16 and 2^57-8 inclusive. </li> 108 * <li>For KWP mode: any length between 1 and 2^32-1 inclusive.</li></ul> 109 * \param[out] output The buffer holding the output data. 110 * <ul><li>For KW mode: Must be at least 8 bytes larger than \p in_len.</li> 111 * <li>For KWP mode: Must be at least 8 bytes larger rounded up to a multiple of 112 * 8 bytes for KWP (15 bytes at most).</li></ul> 113 * \param[out] out_len The number of bytes written to the output buffer. \c 0 on failure. 114 * \param[in] out_size The capacity of the output buffer. 115 * 116 * \return \c 0 on success. 117 * \return \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for invalid input length. 118 * \return cipher-specific error code on failure of the underlying cipher. 119 */ 120 int mbedtls_nist_kw_wrap(mbedtls_nist_kw_context *ctx, mbedtls_nist_kw_mode_t mode, 121 const unsigned char *input, size_t in_len, 122 unsigned char *output, size_t *out_len, size_t out_size); 123 124 /** 125 * \brief This function decrypts a buffer using key wrapping. 126 * 127 * \param ctx The key wrapping context to use for decryption. 128 * \param mode The key wrapping mode to use (MBEDTLS_KW_MODE_KW or MBEDTLS_KW_MODE_KWP) 129 * \param input The buffer holding the input data. 130 * \param in_len The length of the input data in Bytes. 131 * The input uses units of 8 Bytes called semiblocks. 132 * The input must be a multiple of semiblocks. 133 * <ul><li>For KW mode: a multiple of 8 bytes between 24 and 2^57 inclusive. </li> 134 * <li>For KWP mode: a multiple of 8 bytes between 16 and 2^32 inclusive.</li></ul> 135 * \param[out] output The buffer holding the output data. 136 * The output buffer's minimal length is 8 bytes shorter than \p in_len. 137 * \param[out] out_len The number of bytes written to the output buffer. \c 0 on failure. 138 * For KWP mode, the length could be up to 15 bytes shorter than \p in_len, 139 * depending on how much padding was added to the data. 140 * \param[in] out_size The capacity of the output buffer. 141 * 142 * \return \c 0 on success. 143 * \return \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for invalid input length. 144 * \return \c MBEDTLS_ERR_CIPHER_AUTH_FAILED for verification failure of the ciphertext. 145 * \return cipher-specific error code on failure of the underlying cipher. 146 */ 147 int mbedtls_nist_kw_unwrap(mbedtls_nist_kw_context *ctx, mbedtls_nist_kw_mode_t mode, 148 const unsigned char *input, size_t in_len, 149 unsigned char *output, size_t *out_len, size_t out_size); 150 151 152 #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C) 153 /** 154 * \brief The key wrapping checkup routine. 155 * 156 * \return \c 0 on success. 157 * \return \c 1 on failure. 158 */ 159 int mbedtls_nist_kw_self_test(int verbose); 160 #endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */ 161 162 #ifdef __cplusplus 163 } 164 #endif 165 166 #endif /* MBEDTLS_NIST_KW_H */ 167
