/**
* \file ecdsa.h
*
* \brief The Elliptic Curve Digital Signature Algorithm (ECDSA).
*
* ECDSA is defined in <em>Standards for Efficient Cryptography Group (SECG):
* SEC1 Elliptic Curve Cryptography</em>.
* The use of ECDSA for TLS is defined in <em>RFC-4492: Elliptic Curve
* Cryptography (ECC) Cipher Suites for Transport Layer Security (TLS)</em>.
*
*/
/*
* Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of Mbed TLS (https://tls.mbed.org)
*/
#ifndef MBEDTLS_ECDSA_H
#define MBEDTLS_ECDSA_H
#if !defined(MBEDTLS_CONFIG_FILE)
#include "config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#include "ecp.h"
#include "md.h"
/*
* RFC-4492 page 20:
*
* Ecdsa-Sig-Value ::= SEQUENCE {
* r INTEGER,
* s INTEGER
* }
*
* Size is at most
* 1 (tag) + 1 (len) + 1 (initial 0) + ECP_MAX_BYTES for each of r and s,
* twice that + 1 (tag) + 2 (len) for the sequence
* (assuming ECP_MAX_BYTES is less than 126 for r and s,
* and less than 124 (total len <= 255) for the sequence)
*/
#if MBEDTLS_ECP_MAX_BYTES > 124
#error "MBEDTLS_ECP_MAX_BYTES bigger than expected, please fix MBEDTLS_ECDSA_MAX_LEN"
#endif
/** The maximal size of an ECDSA signature in Bytes. */
#define MBEDTLS_ECDSA_MAX_LEN ( 3 + 2 * ( 3 + MBEDTLS_ECP_MAX_BYTES ) )
/**
* \brief The ECDSA context structure.
*/
typedef mbedtls_ecp_keypair mbedtls_ecdsa_context;
#ifdef __cplusplus
extern "C" {
#endif
/**
* \brief This function computes the ECDSA signature of a
* previously-hashed message.
*
* \note The deterministic version is usually preferred.
*
* \param grp The ECP group.
* \param r The first output integer.
* \param s The second output integer.
* \param d The private signing key.
* \param buf The message hash.
* \param blen The length of \p buf.
* \param f_rng The RNG function.
* \param p_rng The RNG parameter.
*
* \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 <em>Standards for Efficient Cryptography Group
* (SECG): SEC1 Elliptic Curve Cryptography</em>, section
* 4.1.3, step 5.
*
* \return \c 0 on success, or an \c MBEDTLS_ERR_ECP_XXX
* or \c MBEDTLS_MPI_XXX error code on failure.
*
* \see ecp.h
*/
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 );
#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
/**
* \brief This function computes the ECDSA signature of a
* previously-hashed message, deterministic version.
* For more information, see <em>RFC-6979: Deterministic
* Usage of the Digital Signature Algorithm (DSA) and Elliptic
* Curve Digital Signature Algorithm (ECDSA)</em>.
*
*
* \warning Since the output of the internal RNG is always the same for
* the same key and message, this limits the efficiency of
* blinding and leaks information through side channels. For
* secure behavior use mbedtls_ecdsa_sign_det_ext() instead.
*
* (Optimally the blinding is a random value that is different
* on every execution. In this case the blinding is still
* random from the attackers perspective, but is the same on
* each execution. This means that this blinding does not
* prevent attackers from recovering secrets by combining
* several measurement traces, but may prevent some attacks
* that exploit relationships between secret data.)
*
* \param grp The ECP group.
* \param r The first output integer.
* \param s The second output integer.
* \param d The private signing key.
* \param buf The message hash.
* \param blen The length of \p buf.
* \param md_alg The MD algorithm used to hash the 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 <em>Standards for Efficient Cryptography Group
* (SECG): SEC1 Elliptic Curve Cryptography</em>, section
* 4.1.3, step 5.
*
* \return \c 0 on success,
* or an \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX
* error code on failure.
*
* \see ecp.h
*/
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 );
/**
* \brief This function computes the ECDSA signature of a
* previously-hashed message, deterministic version.
*
* For more information, see <em>RFC-6979: Deterministic
* Usage of the Digital Signature Algorithm (DSA) and Elliptic
* Curve Digital Signature Algorithm (ECDSA)</em>.
*
* \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 <em>Standards for Efficient Cryptography Group
* (SECG): SEC1 Elliptic Curve Cryptography</em>, section
* 4.1.3, step 5.
*
* \see ecp.h
*
* \param grp The context for the elliptic curve to use.
* This must be initialized and have group parameters
* set, for example through mbedtls_ecp_group_load().
* \param r The MPI context in which to store the first part
* the signature. This must be initialized.
* \param s The MPI context in which to store the second part
* the signature. This must be initialized.
* \param d The private signing key. This must be initialized
* and setup, for example through mbedtls_ecp_gen_privkey().
* \param buf The hashed content to be signed. This must be a readable
* buffer of length \p blen Bytes. It may be \c NULL if
* \p blen is zero.
* \param blen The length of \p buf in Bytes.
* \param md_alg The hash algorithm used to hash the original data.
* \param f_rng_blind The RNG function used for blinding. This must not be
* \c NULL.
* \param p_rng_blind The RNG context to be passed to \p f_rng. This may be
* \c NULL if \p f_rng doesn't need a context parameter.
*
* \return \c 0 on success.
* \return An \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX
* error code on failure.
*/
int mbedtls_ecdsa_sign_det_ext( 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,
int (*f_rng_blind)(void *, unsigned char *,
size_t),
void *p_rng_blind );
#endif /* MBEDTLS_ECDSA_DETERMINISTIC */
/**
* \brief This function verifies the ECDSA signature of a
* previously-hashed message.
*
* \param grp The ECP group.
* \param buf The message hash.
* \param blen The length of \p buf.
* \param Q The public key to use for verification.
* \param r The first integer of the signature.
* \param s The second integer of the 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 <em>Standards for Efficient Cryptography Group
* (SECG): SEC1 Elliptic Curve Cryptography</em>, section
* 4.1.4, step 3.
*
* \return \c 0 on success,
* #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if signature is invalid,
* or an \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX
* error code on failure for any other reason.
*
* \see ecp.h
*/
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);
/**
* \brief This function computes the ECDSA signature and writes it
* to a buffer, serialized as defined in <em>RFC-4492:
* Elliptic Curve Cryptography (ECC) Cipher Suites for
* Transport Layer Security (TLS)</em>.
*
* \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 <em>RFC-6979: Deterministic Usage
* of the Digital Signature Algorithm (DSA) and Elliptic
* Curve Digital Signature Algorithm (ECDSA)</em>.
*
* \param ctx The ECDSA context.
* \param md_alg The message digest that was used to hash the message.
* \param hash The message hash.
* \param hlen The length of the hash.
* \param sig The buffer that holds the signature.
* \param slen The length of the signature written.
* \param f_rng The RNG function.
* \param p_rng The RNG parameter.
*
* \note The \p sig buffer must be 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.
*
* \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 <em>Standards for Efficient Cryptography Group
* (SECG): SEC1 Elliptic Curve Cryptography</em>, section
* 4.1.3, step 5.
*
* \return \c 0 on success,
* or an \c MBEDTLS_ERR_ECP_XXX, \c MBEDTLS_ERR_MPI_XXX or
* \c MBEDTLS_ERR_ASN1_XXX error code on failure.
*
* \see ecp.h
*/
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 );
#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
#if ! defined(MBEDTLS_DEPRECATED_REMOVED)
#if defined(MBEDTLS_DEPRECATED_WARNING)
#define MBEDTLS_DEPRECATED __attribute__((deprecated))
#else
#define MBEDTLS_DEPRECATED
#endif
/**
* \brief This function computes an ECDSA signature and writes it to a buffer,
* serialized as defined in <em>RFC-4492: Elliptic Curve Cryptography
* (ECC) Cipher Suites for Transport Layer Security (TLS)</em>.
*
* The deterministic version is defined in <em>RFC-6979:
* Deterministic Usage of the Digital Signature Algorithm (DSA) and
* Elliptic Curve Digital Signature Algorithm (ECDSA)</em>.
*
* \warning It is not thread-safe to use the same context in
* multiple threads.
*
* \deprecated Superseded by mbedtls_ecdsa_write_signature() in 2.0.0
*
* \param ctx The ECDSA context.
* \param hash The Message hash.
* \param hlen The length of the hash.
* \param sig The buffer that holds the signature.
* \param slen The length of the signature written.
* \param md_alg The MD algorithm used to hash the message.
*
* \note The \p sig buffer must be 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.
*
* \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 <em>Standards for Efficient Cryptography Group
* (SECG): SEC1 Elliptic Curve Cryptography</em>, section
* 4.1.3, step 5.
*
* \return \c 0 on success,
* or an \c MBEDTLS_ERR_ECP_XXX, \c MBEDTLS_ERR_MPI_XXX or
* \c MBEDTLS_ERR_ASN1_XXX error code on failure.
*
* \see ecp.h
*/
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;
#undef MBEDTLS_DEPRECATED
#endif /* MBEDTLS_DEPRECATED_REMOVED */
#endif /* MBEDTLS_ECDSA_DETERMINISTIC */
/**
* \brief This function reads and verifies an ECDSA signature.
*
* \param ctx The ECDSA context.
* \param hash The message hash.
* \param hlen The size of the hash.
* \param sig The signature to read and verify.
* \param slen The size of \p sig.
*
* \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 <em>Standards for Efficient Cryptography Group
* (SECG): SEC1 Elliptic Curve Cryptography</em>, section
* 4.1.4, step 3.
*
* \return \c 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 \p siglen,
* or an \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_ERR_MPI_XXX
* error code on failure for any other reason.
*
* \see ecp.h
*/
int mbedtls_ecdsa_read_signature( mbedtls_ecdsa_context *ctx,
const unsigned char *hash, size_t hlen,
const unsigned char *sig, size_t slen );
/**
* \brief This function generates an ECDSA keypair on the given curve.
*
* \param ctx The ECDSA context to store the keypair in.
* \param gid The elliptic curve to use. One of the various
* \c MBEDTLS_ECP_DP_XXX macros depending on configuration.
* \param f_rng The RNG function.
* \param p_rng The RNG parameter.
*
* \return \c 0 on success, or an \c MBEDTLS_ERR_ECP_XXX code on
* failure.
*
* \see ecp.h
*/
int mbedtls_ecdsa_genkey( mbedtls_ecdsa_context *ctx, mbedtls_ecp_group_id gid,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
/**
* \brief This function sets an ECDSA context from an EC key pair.
*
* \param ctx The ECDSA context to set.
* \param key The EC key to use.
*
* \return \c 0 on success, or an \c MBEDTLS_ERR_ECP_XXX code on
* failure.
*
* \see ecp.h
*/
int mbedtls_ecdsa_from_keypair( mbedtls_ecdsa_context *ctx, const mbedtls_ecp_keypair *key );
/**
* \brief This function initializes an ECDSA context.
*
* \param ctx The ECDSA context to initialize.
*/
void mbedtls_ecdsa_init( mbedtls_ecdsa_context *ctx );
/**
* \brief This function frees an ECDSA context.
*
* \param ctx The ECDSA context to free.
*/
void mbedtls_ecdsa_free( mbedtls_ecdsa_context *ctx );
#ifdef __cplusplus
}
#endif
#endif /* ecdsa.h */
