ecdh.c File Reference

#include "mbedtls/config.h"
#include "mbedtls/ecdh.h"
#include <string.h>

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Functions
int	mbedtls_ecdh_gen_public (mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp_point *Q, int(*f_rng)(void *, unsigned char *, size_t), void *p_rng)
	Generate a public key. Raw function that only does the core computation. More...
int	mbedtls_ecdh_compute_shared (mbedtls_ecp_group *grp, mbedtls_mpi *z, const mbedtls_ecp_point *Q, const mbedtls_mpi *d, int(*f_rng)(void *, unsigned char *, size_t), void *p_rng)
	Compute shared secret Raw function that only does the core computation. More...
void	mbedtls_ecdh_init (mbedtls_ecdh_context *ctx)
	Initialize context. More...
void	mbedtls_ecdh_free (mbedtls_ecdh_context *ctx)
	Free context. More...
int	mbedtls_ecdh_make_params (mbedtls_ecdh_context *ctx, size_t *olen, unsigned char *buf, size_t blen, int(*f_rng)(void *, unsigned char *, size_t), void *p_rng)
	Generate a public key and a TLS ServerKeyExchange payload. (First function used by a TLS server for ECDHE.) More...
int	mbedtls_ecdh_read_params (mbedtls_ecdh_context *ctx, const unsigned char **buf, const unsigned char *end)
	Parse and procress a TLS ServerKeyExhange payload. (First function used by a TLS client for ECDHE.) More...
int	mbedtls_ecdh_get_params (mbedtls_ecdh_context *ctx, const mbedtls_ecp_keypair *key, mbedtls_ecdh_side side)
	Setup an ECDH context from an EC key. (Used by clients and servers in place of the ServerKeyEchange for static ECDH: import ECDH parameters from a certificate's EC key information.) More...
int	mbedtls_ecdh_make_public (mbedtls_ecdh_context *ctx, size_t *olen, unsigned char *buf, size_t blen, int(*f_rng)(void *, unsigned char *, size_t), void *p_rng)
	Generate a public key and a TLS ClientKeyExchange payload. (Second function used by a TLS client for ECDH(E).) More...
int	mbedtls_ecdh_read_public (mbedtls_ecdh_context *ctx, const unsigned char *buf, size_t blen)
	Parse and process a TLS ClientKeyExchange payload. (Second function used by a TLS server for ECDH(E).) More...
int	mbedtls_ecdh_calc_secret (mbedtls_ecdh_context *ctx, size_t *olen, unsigned char *buf, size_t blen, int(*f_rng)(void *, unsigned char *, size_t), void *p_rng)
	Derive and export the shared secret. (Last function used by both TLS client en servers.) More...

Function Documentation

mbedtls_ecdh_calc_secret()

int mbedtls_ecdh_calc_secret	(	mbedtls_ecdh_context *	ctx,
		size_t *	olen,
		unsigned char *	buf,
		size_t	blen,
		int(*)(void *, unsigned char *, size_t)	f_rng,
		void *	p_rng
	)

Derive and export the shared secret. (Last function used by both TLS client en servers.)

Parameters

ctx	ECDH context
olen	number of bytes written
buf	destination buffer
blen	buffer length
f_rng	RNG function, see notes for mbedtls_ecdh_compute_shared()
p_rng	RNG parameter

Returns

0 if successful, or an MBEDTLS_ERR_ECP_XXX error code

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mbedtls_ecdh_compute_shared()

int mbedtls_ecdh_compute_shared	(	mbedtls_ecp_group *	grp,
		mbedtls_mpi *	z,
		const mbedtls_ecp_point *	Q,
		const mbedtls_mpi *	d,
		int(*)(void *, unsigned char *, size_t)	f_rng,
		void *	p_rng
	)

Compute shared secret Raw function that only does the core computation.

Parameters

grp	ECP group
z	Destination MPI (shared secret)
Q	Public key from other party
d	Our secret exponent (private key)
f_rng	RNG function (see notes)
p_rng	RNG parameter

Returns

0 if successful, or a MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code

Note

If f_rng is not NULL, it is used to implement countermeasures against potential elaborate timing attacks, see mbedtls_ecp_mul() for details.

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mbedtls_ecdh_free()

void mbedtls_ecdh_free

(

mbedtls_ecdh_context *

ctx

)

Free context.

Parameters

ctx	Context to free

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mbedtls_ecdh_gen_public()

int mbedtls_ecdh_gen_public	(	mbedtls_ecp_group *	grp,
		mbedtls_mpi *	d,
		mbedtls_ecp_point *	Q,
		int(*)(void *, unsigned char *, size_t)	f_rng,
		void *	p_rng
	)

Generate a public key. Raw function that only does the core computation.

Parameters

grp	ECP group
d	Destination MPI (secret exponent, aka private key)
Q	Destination point (public key)
f_rng	RNG function
p_rng	RNG parameter

Returns

0 if successful, or a MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code

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mbedtls_ecdh_get_params()

int mbedtls_ecdh_get_params	(	mbedtls_ecdh_context *	ctx,
		const mbedtls_ecp_keypair *	key,
		mbedtls_ecdh_side	side
	)

Setup an ECDH context from an EC key. (Used by clients and servers in place of the ServerKeyEchange for static ECDH: import ECDH parameters from a certificate's EC key information.)

Parameters

ctx	ECDH constext to set
key	EC key to use
side	Is it our key (1) or the peer's key (0) ?

Returns

0 if successful, or an MBEDTLS_ERR_ECP_XXX error code

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mbedtls_ecdh_init()

void mbedtls_ecdh_init

(

mbedtls_ecdh_context *

ctx

)

Initialize context.

Parameters

ctx	Context to initialize

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mbedtls_ecdh_make_params()

int mbedtls_ecdh_make_params	(	mbedtls_ecdh_context *	ctx,
		size_t *	olen,
		unsigned char *	buf,
		size_t	blen,
		int(*)(void *, unsigned char *, size_t)	f_rng,
		void *	p_rng
	)

Generate a public key and a TLS ServerKeyExchange payload. (First function used by a TLS server for ECDHE.)

Parameters

ctx	ECDH context
olen	number of chars written
buf	destination buffer
blen	length of buffer
f_rng	RNG function
p_rng	RNG parameter

Note

This function assumes that ctx->grp has already been properly set (for example using mbedtls_ecp_group_load).

Returns

0 if successful, or an MBEDTLS_ERR_ECP_XXX error code

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mbedtls_ecdh_make_public()

int mbedtls_ecdh_make_public	(	mbedtls_ecdh_context *	ctx,
		size_t *	olen,
		unsigned char *	buf,
		size_t	blen,
		int(*)(void *, unsigned char *, size_t)	f_rng,
		void *	p_rng
	)

Generate a public key and a TLS ClientKeyExchange payload. (Second function used by a TLS client for ECDH(E).)

Parameters

ctx	ECDH context
olen	number of bytes actually written
buf	destination buffer
blen	size of destination buffer
f_rng	RNG function
p_rng	RNG parameter

Returns

0 if successful, or an MBEDTLS_ERR_ECP_XXX error code

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mbedtls_ecdh_read_params()

int mbedtls_ecdh_read_params	(	mbedtls_ecdh_context *	ctx,
		const unsigned char **	buf,
		const unsigned char *	end
	)

Parse and procress a TLS ServerKeyExhange payload. (First function used by a TLS client for ECDHE.)

Parameters

ctx	ECDH context
buf	pointer to start of input buffer
end	one past end of buffer

Returns

0 if successful, or an MBEDTLS_ERR_ECP_XXX error code

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mbedtls_ecdh_read_public()

int mbedtls_ecdh_read_public	(	mbedtls_ecdh_context *	ctx,
		const unsigned char *	buf,
		size_t	blen
	)

Parse and process a TLS ClientKeyExchange payload. (Second function used by a TLS server for ECDH(E).)

Parameters

ctx	ECDH context
buf	start of input buffer
blen	length of input buffer

Returns

0 if successful, or an MBEDTLS_ERR_ECP_XXX error code

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