NIST Key Wrapping

Data Structures
struct	mbedtls_nist_kw_context
	The key wrapping context-type definition. More...

Functions
void	mbedtls_nist_kw_init (mbedtls_nist_kw_context *ctx)
	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(). More...
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)
	This function initializes the key wrapping context set in the ctx parameter and sets the encryption key. More...
void	mbedtls_nist_kw_free (mbedtls_nist_kw_context *ctx)
	This function releases and clears the specified key wrapping context and underlying cipher sub-context. More...
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)
	This function encrypts a buffer using key wrapping. More...
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)
	This function decrypts a buffer using key wrapping. More...

Detailed Description

Function Documentation

mbedtls_nist_kw_init()

void mbedtls_nist_kw_init

(

mbedtls_nist_kw_context *

ctx

)

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().

Parameters

ctx	The key wrapping context to initialize.

mbedtls_nist_kw_setkey()

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
	)

This function initializes the key wrapping context set in the ctx parameter and sets the encryption key.

Parameters

ctx	The key wrapping context.
cipher	The 128-bit block cipher to use. Only AES is supported.
key	The Key Encryption Key (KEK).
keybits	The KEK size in bits. This must be acceptable by the cipher.
is_wrap	Specify whether the operation within the context is wrapping or unwrapping

Returns

0 on success.

MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for any invalid input.

MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE for 128-bit block ciphers which are not supported.

cipher-specific error code on failure of the underlying cipher.

mbedtls_nist_kw_free()

void mbedtls_nist_kw_free

(

mbedtls_nist_kw_context *

ctx

)

This function releases and clears the specified key wrapping context and underlying cipher sub-context.

Parameters

ctx	The key wrapping context to clear.

mbedtls_nist_kw_wrap()

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
	)

This function encrypts a buffer using key wrapping.

Parameters

	ctx	The key wrapping context to use for encryption.
	mode	The key wrapping mode to use (MBEDTLS_KW_MODE_KW or MBEDTLS_KW_MODE_KWP)
	input	The buffer holding the input data.
	in_len	The length of the input data in Bytes. The input uses units of 8 Bytes called semiblocks. For KW mode: a multiple of 8 bytes between 16 and 2^57-8 inclusive. For KWP mode: any length between 1 and 2^32-1 inclusive.
[out]	output	The buffer holding the output data. For KW mode: Must be at least 8 bytes larger than in_len. For KWP mode: Must be at least 8 bytes larger rounded up to a multiple of 8 bytes for KWP (15 bytes at most).
[out]	out_len	The number of bytes written to the output buffer. 0 on failure.
[in]	out_size	The capacity of the output buffer.

Returns

0 on success.

MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for invalid input length.

cipher-specific error code on failure of the underlying cipher.

mbedtls_nist_kw_unwrap()

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
	)

This function decrypts a buffer using key wrapping.

Parameters

	ctx	The key wrapping context to use for decryption.
	mode	The key wrapping mode to use (MBEDTLS_KW_MODE_KW or MBEDTLS_KW_MODE_KWP)
	input	The buffer holding the input data.
	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. For KW mode: a multiple of 8 bytes between 24 and 2^57 inclusive. For KWP mode: a multiple of 8 bytes between 16 and 2^32 inclusive.
[out]	output	The buffer holding the output data. The output buffer's minimal length is 8 bytes shorter than in_len.
[out]	out_len	The number of bytes written to the output buffer. 0 on failure. For KWP mode, the length could be up to 15 bytes shorter than in_len, depending on how much padding was added to the data.
[in]	out_size	The capacity of the output buffer.

Returns

0 on success.

MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for invalid input length.

MBEDTLS_ERR_CIPHER_AUTH_FAILED for verification failure of the ciphertext.

cipher-specific error code on failure of the underlying cipher.