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/**
* \file nist_kw.h
*
* \brief This file provides an API for key wrapping (KW) and key wrapping with
* padding (KWP) as defined in NIST SP 800-38F.
* https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-38F.pdf
*
* Key wrapping specifies a deterministic authenticated-encryption mode
* of operation, according to <em>NIST SP 800-38F: Recommendation for
* Block Cipher Modes of Operation: Methods for Key Wrapping</em>. Its
* purpose is to protect cryptographic keys.
*
* Its equivalent is RFC 3394 for KW, and RFC 5649 for KWP.
* https://tools.ietf.org/html/rfc3394
* https://tools.ietf.org/html/rfc5649
*
*/
/*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#ifndef MBEDTLS_NIST_KW_H
#define MBEDTLS_NIST_KW_H
#include "mbedtls/private_access.h"
#include "mbedtls/build_info.h"
#include "mbedtls/cipher.h"
#ifdef __cplusplus
extern "C" {
#endif
typedef enum {
MBEDTLS_KW_MODE_KW = 0,
MBEDTLS_KW_MODE_KWP = 1
} mbedtls_nist_kw_mode_t;
#if !defined(MBEDTLS_NIST_KW_ALT)
// Regular implementation
//
/**
* \brief The key wrapping context-type definition. The key wrapping context is passed
* to the APIs called.
*
* \note The definition of this type may change in future library versions.
* Don't make any assumptions on this context!
*/
typedef struct {
mbedtls_cipher_context_t MBEDTLS_PRIVATE(cipher_ctx); /*!< The cipher context used. */
} mbedtls_nist_kw_context;
#else /* MBEDTLS_NIST_key wrapping_ALT */
#include "nist_kw_alt.h"
#endif /* MBEDTLS_NIST_KW_ALT */
/**
* \brief This function initializes the specified key wrapping context
* to make references valid and prepare the context
* for mbedtls_nist_kw_setkey() or mbedtls_nist_kw_free().
*
* \param ctx The key wrapping context to initialize.
*
*/
void mbedtls_nist_kw_init(mbedtls_nist_kw_context *ctx);
/**
* \brief This function initializes the key wrapping context set in the
* \p ctx parameter and sets the encryption key.
*
* \param ctx The key wrapping context.
* \param cipher The 128-bit block cipher to use. Only AES is supported.
* \param key The Key Encryption Key (KEK).
* \param keybits The KEK size in bits. This must be acceptable by the cipher.
* \param is_wrap Specify whether the operation within the context is wrapping or unwrapping
*
* \return \c 0 on success.
* \return \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for any invalid input.
* \return \c MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE for 128-bit block ciphers
* which are not supported.
* \return cipher-specific error code on failure of the underlying cipher.
*/
int mbedtls_nist_kw_setkey(mbedtls_nist_kw_context *ctx,
mbedtls_cipher_id_t cipher,
const unsigned char *key,
unsigned int keybits,
const int is_wrap);
/**
* \brief This function releases and clears the specified key wrapping context
* and underlying cipher sub-context.
*
* \param ctx The key wrapping context to clear.
*/
void mbedtls_nist_kw_free(mbedtls_nist_kw_context *ctx);
/**
* \brief This function encrypts a buffer using key wrapping.
*
* \param ctx The key wrapping context to use for encryption.
* \param mode The key wrapping mode to use (MBEDTLS_KW_MODE_KW or MBEDTLS_KW_MODE_KWP)
* \param input The buffer holding the input data.
* \param in_len The length of the input data in Bytes.
* The input uses units of 8 Bytes called semiblocks.
* <ul><li>For KW mode: a multiple of 8 bytes between 16 and 2^57-8 inclusive. </li>
* <li>For KWP mode: any length between 1 and 2^32-1 inclusive.</li></ul>
* \param[out] output The buffer holding the output data.
* <ul><li>For KW mode: Must be at least 8 bytes larger than \p in_len.</li>
* <li>For KWP mode: Must be at least 8 bytes larger rounded up to a multiple of
* 8 bytes for KWP (15 bytes at most).</li></ul>
* \param[out] out_len The number of bytes written to the output buffer. \c 0 on failure.
* \param[in] out_size The capacity of the output buffer.
*
* \return \c 0 on success.
* \return \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for invalid input length.
* \return cipher-specific error code on failure of the underlying cipher.
*/
int mbedtls_nist_kw_wrap(mbedtls_nist_kw_context *ctx, mbedtls_nist_kw_mode_t mode,
const unsigned char *input, size_t in_len,
unsigned char *output, size_t *out_len, size_t out_size);
/**
* \brief This function decrypts a buffer using key wrapping.
*
* \param ctx The key wrapping context to use for decryption.
* \param mode The key wrapping mode to use (MBEDTLS_KW_MODE_KW or MBEDTLS_KW_MODE_KWP)
* \param input The buffer holding the input data.
* \param in_len The length of the input data in Bytes.
* The input uses units of 8 Bytes called semiblocks.
* The input must be a multiple of semiblocks.
* <ul><li>For KW mode: a multiple of 8 bytes between 24 and 2^57 inclusive. </li>
* <li>For KWP mode: a multiple of 8 bytes between 16 and 2^32 inclusive.</li></ul>
* \param[out] output The buffer holding the output data.
* The output buffer's minimal length is 8 bytes shorter than \p in_len.
* \param[out] out_len The number of bytes written to the output buffer. \c 0 on failure.
* For KWP mode, the length could be up to 15 bytes shorter than \p in_len,
* depending on how much padding was added to the data.
* \param[in] out_size The capacity of the output buffer.
*
* \return \c 0 on success.
* \return \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for invalid input length.
* \return \c MBEDTLS_ERR_CIPHER_AUTH_FAILED for verification failure of the ciphertext.
* \return cipher-specific error code on failure of the underlying cipher.
*/
int mbedtls_nist_kw_unwrap(mbedtls_nist_kw_context *ctx, mbedtls_nist_kw_mode_t mode,
const unsigned char *input, size_t in_len,
unsigned char *output, size_t *out_len, size_t out_size);
#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
/**
* \brief The key wrapping checkup routine.
*
* \return \c 0 on success.
* \return \c 1 on failure.
*/
int mbedtls_nist_kw_self_test(int verbose);
#endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */
#ifdef __cplusplus
}
#endif
#endif /* MBEDTLS_NIST_KW_H */
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