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ecdsa.h File Reference

This file contains ECDSA definitions and functions. More...

#include "ecp.h"
#include "md.h"
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Macros

#define MBEDTLS_ECDSA_MAX_LEN   ( 3 + 2 * ( 3 + MBEDTLS_ECP_MAX_BYTES ) )
 The maximal size of an ECDSA signature in Bytes. More...
 
#define MBEDTLS_DEPRECATED
 

Typedefs

typedef mbedtls_ecp_keypair mbedtls_ecdsa_context
 The ECDSA context structure. More...
 
typedef void mbedtls_ecdsa_restart_ctx
 

Functions

int mbedtls_ecdsa_sign (mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s, const mbedtls_mpi *d, const unsigned char *buf, size_t blen, int(*f_rng)(void *, unsigned char *, size_t), void *p_rng)
 This function computes the ECDSA signature of a previously-hashed message. More...
 
int mbedtls_ecdsa_sign_det (mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s, const mbedtls_mpi *d, const unsigned char *buf, size_t blen, mbedtls_md_type_t md_alg)
 This function computes the ECDSA signature of a previously-hashed message, deterministic version. More...
 
int mbedtls_ecdsa_verify (mbedtls_ecp_group *grp, const unsigned char *buf, size_t blen, const mbedtls_ecp_point *Q, const mbedtls_mpi *r, const mbedtls_mpi *s)
 This function verifies the ECDSA signature of a previously-hashed message. More...
 
int mbedtls_ecdsa_write_signature (mbedtls_ecdsa_context *ctx, mbedtls_md_type_t md_alg, const unsigned char *hash, size_t hlen, unsigned char *sig, size_t *slen, int(*f_rng)(void *, unsigned char *, size_t), void *p_rng)
 This function computes the ECDSA signature and writes it to a buffer, serialized as defined in RFC-4492: Elliptic Curve Cryptography (ECC) Cipher Suites for Transport Layer Security (TLS). More...
 
int mbedtls_ecdsa_write_signature_restartable (mbedtls_ecdsa_context *ctx, mbedtls_md_type_t md_alg, const unsigned char *hash, size_t hlen, unsigned char *sig, size_t *slen, int(*f_rng)(void *, unsigned char *, size_t), void *p_rng, mbedtls_ecdsa_restart_ctx *rs_ctx)
 This function computes the ECDSA signature and writes it to a buffer, in a restartable way. More...
 
int mbedtls_ecdsa_write_signature_det (mbedtls_ecdsa_context *ctx, const unsigned char *hash, size_t hlen, unsigned char *sig, size_t *slen, mbedtls_md_type_t md_alg) MBEDTLS_DEPRECATED
 This function computes an ECDSA signature and writes it to a buffer, serialized as defined in RFC-4492: Elliptic Curve Cryptography (ECC) Cipher Suites for Transport Layer Security (TLS). More...
 
int mbedtls_ecdsa_read_signature (mbedtls_ecdsa_context *ctx, const unsigned char *hash, size_t hlen, const unsigned char *sig, size_t slen)
 This function reads and verifies an ECDSA signature. More...
 
int mbedtls_ecdsa_read_signature_restartable (mbedtls_ecdsa_context *ctx, const unsigned char *hash, size_t hlen, const unsigned char *sig, size_t slen, mbedtls_ecdsa_restart_ctx *rs_ctx)
 This function reads and verifies an ECDSA signature, in a restartable way. More...
 
int mbedtls_ecdsa_genkey (mbedtls_ecdsa_context *ctx, mbedtls_ecp_group_id gid, int(*f_rng)(void *, unsigned char *, size_t), void *p_rng)
 This function generates an ECDSA keypair on the given curve. More...
 
int mbedtls_ecdsa_from_keypair (mbedtls_ecdsa_context *ctx, const mbedtls_ecp_keypair *key)
 This function sets up an ECDSA context from an EC key pair. More...
 
void mbedtls_ecdsa_init (mbedtls_ecdsa_context *ctx)
 This function initializes an ECDSA context. More...
 
void mbedtls_ecdsa_free (mbedtls_ecdsa_context *ctx)
 This function frees an ECDSA context. More...
 

Detailed Description

This file contains ECDSA definitions and functions.

The Elliptic Curve Digital Signature Algorithm (ECDSA) is defined in Standards for Efficient Cryptography Group (SECG): SEC1 Elliptic Curve Cryptography. The use of ECDSA for TLS is defined in RFC-4492: Elliptic Curve Cryptography (ECC) Cipher Suites for Transport Layer Security (TLS).

Definition in file ecdsa.h.

Macro Definition Documentation

#define MBEDTLS_DEPRECATED

Definition at line 342 of file ecdsa.h.

#define MBEDTLS_ECDSA_MAX_LEN   ( 3 + 2 * ( 3 + MBEDTLS_ECP_MAX_BYTES ) )

The maximal size of an ECDSA signature in Bytes.

Definition at line 56 of file ecdsa.h.

Typedef Documentation

The ECDSA context structure.

Warning
Performing multiple operations concurrently on the same ECDSA context is not supported; objects of this type should not be shared between multiple threads.

Definition at line 69 of file ecdsa.h.

Definition at line 113 of file ecdsa.h.

Function Documentation

void mbedtls_ecdsa_free ( mbedtls_ecdsa_context ctx)

This function frees an ECDSA context.

Parameters
ctxThe ECDSA context to free. This may be NULL, in which case this function does nothing. If it is not NULL, it must be initialized.
int mbedtls_ecdsa_from_keypair ( mbedtls_ecdsa_context ctx,
const mbedtls_ecp_keypair key 
)

This function sets up an ECDSA context from an EC key pair.

See also
ecp.h
Parameters
ctxThe ECDSA context to setup. This must be initialized.
keyThe EC key to use. This must be initialized and hold a private-public key pair or a public key. In the former case, the ECDSA context may be used for signature creation and verification after this call. In the latter case, it may be used for signature verification.
Returns
0 on success.
An MBEDTLS_ERR_ECP_XXX code on failure.
int mbedtls_ecdsa_genkey ( mbedtls_ecdsa_context ctx,
mbedtls_ecp_group_id  gid,
int(*)(void *, unsigned char *, size_t)  f_rng,
void *  p_rng 
)

This function generates an ECDSA keypair on the given curve.

See also
ecp.h
Parameters
ctxThe ECDSA context to store the keypair in. This must be initialized.
gidThe elliptic curve to use. One of the various MBEDTLS_ECP_DP_XXX macros depending on configuration.
f_rngThe RNG function to use. This must not be NULL.
p_rngThe RNG context to be passed to f_rng. This may be NULL if f_rng doesn't need a context argument.
Returns
0 on success.
An MBEDTLS_ERR_ECP_XXX code on failure.
void mbedtls_ecdsa_init ( mbedtls_ecdsa_context ctx)

This function initializes an ECDSA context.

Parameters
ctxThe ECDSA context to initialize. This must not be NULL.
int mbedtls_ecdsa_read_signature ( mbedtls_ecdsa_context ctx,
const unsigned char *  hash,
size_t  hlen,
const unsigned char *  sig,
size_t  slen 
)

This function reads and verifies an ECDSA signature.

Note
If the bitlength of the message hash is larger than the bitlength of the group order, then the hash is truncated as defined in Standards for Efficient Cryptography Group (SECG): SEC1 Elliptic Curve Cryptography, section 4.1.4, step 3.
See also
ecp.h
Parameters
ctxThe ECDSA context to use. This must be initialized and have a group and public key bound to it.
hashThe message hash that was signed. This must be a readable buffer of length size Bytes.
hlenThe size of the hash hash.
sigThe signature to read and verify. This must be a readable buffer of length slen Bytes.
slenThe size of sig in Bytes.
Returns
0 on success.
MBEDTLS_ERR_ECP_BAD_INPUT_DATA if signature is invalid.
MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH if there is a valid signature in sig, but its length is less than siglen.
An MBEDTLS_ERR_ECP_XXX or MBEDTLS_ERR_MPI_XXX error code on failure for any other reason.
int mbedtls_ecdsa_read_signature_restartable ( mbedtls_ecdsa_context ctx,
const unsigned char *  hash,
size_t  hlen,
const unsigned char *  sig,
size_t  slen,
mbedtls_ecdsa_restart_ctx rs_ctx 
)

This function reads and verifies an ECDSA signature, in a restartable way.

See also
mbedtls_ecdsa_read_signature()
Note
This function is like mbedtls_ecdsa_read_signature() but it can return early and restart according to the limit set with mbedtls_ecp_set_max_ops() to reduce blocking.
Parameters
ctxThe ECDSA context to use. This must be initialized and have a group and public key bound to it.
hashThe message hash that was signed. This must be a readable buffer of length size Bytes.
hlenThe size of the hash hash.
sigThe signature to read and verify. This must be a readable buffer of length slen Bytes.
slenThe size of sig in Bytes.
rs_ctxThe restart context to use. This may be NULL to disable restarting. If it is not NULL, it must point to an initialized restart context.
Returns
0 on success.
MBEDTLS_ERR_ECP_BAD_INPUT_DATA if signature is invalid.
MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH if there is a valid signature in sig, but its length is less than siglen.
MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of operations was reached: see mbedtls_ecp_set_max_ops().
Another MBEDTLS_ERR_ECP_XXX or MBEDTLS_ERR_MPI_XXX error code on failure for any other reason.
int mbedtls_ecdsa_sign ( mbedtls_ecp_group grp,
mbedtls_mpi r,
mbedtls_mpi s,
const mbedtls_mpi d,
const unsigned char *  buf,
size_t  blen,
int(*)(void *, unsigned char *, size_t)  f_rng,
void *  p_rng 
)

This function computes the ECDSA signature of a previously-hashed message.

Note
The deterministic version implemented in mbedtls_ecdsa_sign_det() is usually preferred.
If the bitlength of the message hash is larger than the bitlength of the group order, then the hash is truncated as defined in Standards for Efficient Cryptography Group (SECG): SEC1 Elliptic Curve Cryptography, section 4.1.3, step 5.
See also
ecp.h
Parameters
grpThe context for the elliptic curve to use. This must be initialized and have group parameters set, for example through mbedtls_ecp_group_load().
rThe MPI context in which to store the first part the signature. This must be initialized.
sThe MPI context in which to store the second part the signature. This must be initialized.
dThe private signing key. This must be initialized.
bufThe content to be signed. This is usually the hash of the original data to be signed. This must be a readable buffer of length blen Bytes. It may be NULL if blen is zero.
blenThe length of buf in Bytes.
f_rngThe RNG function. This must not be NULL.
p_rngThe RNG context to be passed to f_rng. This may be NULL if f_rng doesn't need a context parameter.
Returns
0 on success.
An MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code on failure.
int mbedtls_ecdsa_sign_det ( mbedtls_ecp_group grp,
mbedtls_mpi r,
mbedtls_mpi s,
const mbedtls_mpi d,
const unsigned char *  buf,
size_t  blen,
mbedtls_md_type_t  md_alg 
)

This function computes the ECDSA signature of a previously-hashed message, deterministic version.

For more information, see RFC-6979: Deterministic Usage of the Digital Signature Algorithm (DSA) and Elliptic Curve Digital Signature Algorithm (ECDSA).

Note
If the bitlength of the message hash is larger than the bitlength of the group order, then the hash is truncated as defined in Standards for Efficient Cryptography Group (SECG): SEC1 Elliptic Curve Cryptography, section 4.1.3, step 5.
See also
ecp.h
Parameters
grpThe context for the elliptic curve to use. This must be initialized and have group parameters set, for example through mbedtls_ecp_group_load().
rThe MPI context in which to store the first part the signature. This must be initialized.
sThe MPI context in which to store the second part the signature. This must be initialized.
dThe private signing key. This must be initialized and setup, for example through mbedtls_ecp_gen_privkey().
bufThe hashed content to be signed. This must be a readable buffer of length blen Bytes. It may be NULL if blen is zero.
blenThe length of buf in Bytes.
md_algThe hash algorithm used to hash the original data.
Returns
0 on success.
An MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code on failure.
int mbedtls_ecdsa_verify ( mbedtls_ecp_group grp,
const unsigned char *  buf,
size_t  blen,
const mbedtls_ecp_point Q,
const mbedtls_mpi r,
const mbedtls_mpi s 
)

This function verifies the ECDSA signature of a previously-hashed message.

Note
If the bitlength of the message hash is larger than the bitlength of the group order, then the hash is truncated as defined in Standards for Efficient Cryptography Group (SECG): SEC1 Elliptic Curve Cryptography, section 4.1.4, step 3.
See also
ecp.h
Parameters
grpThe ECP group to use. This must be initialized and have group parameters set, for example through mbedtls_ecp_group_load().
bufThe hashed content that was signed. This must be a readable buffer of length blen Bytes. It may be NULL if blen is zero.
blenThe length of buf in Bytes.
QThe public key to use for verification. This must be initialized and setup.
rThe first integer of the signature. This must be initialized.
sThe second integer of the signature. This must be initialized.
Returns
0 on success.
MBEDTLS_ERR_ECP_BAD_INPUT_DATA if the signature is invalid.
An MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code on failure for any other reason.
int mbedtls_ecdsa_write_signature ( mbedtls_ecdsa_context ctx,
mbedtls_md_type_t  md_alg,
const unsigned char *  hash,
size_t  hlen,
unsigned char *  sig,
size_t *  slen,
int(*)(void *, unsigned char *, size_t)  f_rng,
void *  p_rng 
)

This function computes the ECDSA signature and writes it to a buffer, serialized as defined in RFC-4492: Elliptic Curve Cryptography (ECC) Cipher Suites for Transport Layer Security (TLS).

Warning
It is not thread-safe to use the same context in multiple threads.
Note
The deterministic version is used if MBEDTLS_ECDSA_DETERMINISTIC is defined. For more information, see RFC-6979: Deterministic Usage of the Digital Signature Algorithm (DSA) and Elliptic Curve Digital Signature Algorithm (ECDSA).
If the bitlength of the message hash is larger than the bitlength of the group order, then the hash is truncated as defined in Standards for Efficient Cryptography Group (SECG): SEC1 Elliptic Curve Cryptography, section 4.1.3, step 5.
See also
ecp.h
Parameters
ctxThe ECDSA context to use. This must be initialized and have a group and private key bound to it, for example via mbedtls_ecdsa_genkey() or mbedtls_ecdsa_from_keypair().
md_algThe message digest that was used to hash the message.
hashThe message hash to be signed. This must be a readable buffer of length blen Bytes.
hlenThe length of the hash hash in Bytes.
sigThe buffer to which to write the signature. This must be a writable buffer of length at least twice as large as the size of the curve used, plus 9. For example, 73 Bytes if a 256-bit curve is used. A buffer length of MBEDTLS_ECDSA_MAX_LEN is always safe.
slenThe address at which to store the actual length of the signature written. Must not be NULL.
f_rngThe RNG function. This must not be NULL if MBEDTLS_ECDSA_DETERMINISTIC is unset. Otherwise, it is unused and may be set to NULL.
p_rngThe RNG context to be passed to f_rng. This may be NULL if f_rng is NULL or doesn't use a context.
Returns
0 on success.
An MBEDTLS_ERR_ECP_XXX, MBEDTLS_ERR_MPI_XXX or MBEDTLS_ERR_ASN1_XXX error code on failure.
int mbedtls_ecdsa_write_signature_det ( mbedtls_ecdsa_context ctx,
const unsigned char *  hash,
size_t  hlen,
unsigned char *  sig,
size_t *  slen,
mbedtls_md_type_t  md_alg 
)

This function computes an ECDSA signature and writes it to a buffer, serialized as defined in RFC-4492: Elliptic Curve Cryptography (ECC) Cipher Suites for Transport Layer Security (TLS).

The deterministic version is defined in RFC-6979: Deterministic Usage of the Digital Signature Algorithm (DSA) and Elliptic Curve Digital Signature Algorithm (ECDSA).

Warning
It is not thread-safe to use the same context in multiple threads.
Note
If the bitlength of the message hash is larger than the bitlength of the group order, then the hash is truncated as defined in Standards for Efficient Cryptography Group (SECG): SEC1 Elliptic Curve Cryptography, section 4.1.3, step 5.
See also
ecp.h
Deprecated:
Superseded by mbedtls_ecdsa_write_signature() in Mbed TLS version 2.0 and later.
Parameters
ctxThe ECDSA context to use. This must be initialized and have a group and private key bound to it, for example via mbedtls_ecdsa_genkey() or mbedtls_ecdsa_from_keypair().
hashThe message hash to be signed. This must be a readable buffer of length blen Bytes.
hlenThe length of the hash hash in Bytes.
sigThe buffer to which to write the signature. This must be a writable buffer of length at least twice as large as the size of the curve used, plus 9. For example, 73 Bytes if a 256-bit curve is used. A buffer length of MBEDTLS_ECDSA_MAX_LEN is always safe.
slenThe address at which to store the actual length of the signature written. Must not be NULL.
md_algThe message digest that was used to hash the message.
Returns
0 on success.
An MBEDTLS_ERR_ECP_XXX, MBEDTLS_ERR_MPI_XXX or MBEDTLS_ERR_ASN1_XXX error code on failure.
int mbedtls_ecdsa_write_signature_restartable ( mbedtls_ecdsa_context ctx,
mbedtls_md_type_t  md_alg,
const unsigned char *  hash,
size_t  hlen,
unsigned char *  sig,
size_t *  slen,
int(*)(void *, unsigned char *, size_t)  f_rng,
void *  p_rng,
mbedtls_ecdsa_restart_ctx rs_ctx 
)

This function computes the ECDSA signature and writes it to a buffer, in a restartable way.

See also
mbedtls_ecdsa_write_signature()
Note
This function is like mbedtls_ecdsa_write_signature() but it can return early and restart according to the limit set with mbedtls_ecp_set_max_ops() to reduce blocking.
Parameters
ctxThe ECDSA context to use. This must be initialized and have a group and private key bound to it, for example via mbedtls_ecdsa_genkey() or mbedtls_ecdsa_from_keypair().
md_algThe message digest that was used to hash the message.
hashThe message hash to be signed. This must be a readable buffer of length blen Bytes.
hlenThe length of the hash hash in Bytes.
sigThe buffer to which to write the signature. This must be a writable buffer of length at least twice as large as the size of the curve used, plus 9. For example, 73 Bytes if a 256-bit curve is used. A buffer length of MBEDTLS_ECDSA_MAX_LEN is always safe.
slenThe address at which to store the actual length of the signature written. Must not be NULL.
f_rngThe RNG function. This must not be NULL if MBEDTLS_ECDSA_DETERMINISTIC is unset. Otherwise, it is unused and may be set to NULL.
p_rngThe RNG context to be passed to f_rng. This may be NULL if f_rng is NULL or doesn't use a context.
rs_ctxThe restart context to use. This may be NULL to disable restarting. If it is not NULL, it must point to an initialized restart context.
Returns
0 on success.
MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of operations was reached: see mbedtls_ecp_set_max_ops().
Another MBEDTLS_ERR_ECP_XXX, MBEDTLS_ERR_MPI_XXX or MBEDTLS_ERR_ASN1_XXX error code on failure.