4 * \brief This file provides an API for Elliptic Curves over GF(P) (ECP).
6 * The use of ECP in cryptography and TLS is defined in
7 * <em>Standards for Efficient Cryptography Group (SECG): SEC1
8 * Elliptic Curve Cryptography</em> and
9 * <em>RFC-4492: Elliptic Curve Cryptography (ECC) Cipher Suites
10 * for Transport Layer Security (TLS)</em>.
12 * <em>RFC-2409: The Internet Key Exchange (IKE)</em> defines ECP
18 * Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved
19 * SPDX-License-Identifier: Apache-2.0
21 * Licensed under the Apache License, Version 2.0 (the "License"); you may
22 * not use this file except in compliance with the License.
23 * You may obtain a copy of the License at
25 * http://www.apache.org/licenses/LICENSE-2.0
27 * Unless required by applicable law or agreed to in writing, software
28 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
29 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
30 * See the License for the specific language governing permissions and
31 * limitations under the License.
33 * This file is part of Mbed TLS (https://tls.mbed.org)
39 #if !defined(MBEDTLS_CONFIG_FILE)
42 #include MBEDTLS_CONFIG_FILE
50 #define MBEDTLS_ERR_ECP_BAD_INPUT_DATA -0x4F80 /**< Bad input parameters to function. */
51 #define MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL -0x4F00 /**< The buffer is too small to write to. */
52 #define MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE -0x4E80 /**< The requested feature is not available, for example, the requested curve is not supported. */
53 #define MBEDTLS_ERR_ECP_VERIFY_FAILED -0x4E00 /**< The signature is not valid. */
54 #define MBEDTLS_ERR_ECP_ALLOC_FAILED -0x4D80 /**< Memory allocation failed. */
55 #define MBEDTLS_ERR_ECP_RANDOM_FAILED -0x4D00 /**< Generation of random value, such as ephemeral key, failed. */
56 #define MBEDTLS_ERR_ECP_INVALID_KEY -0x4C80 /**< Invalid private or public key. */
57 #define MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH -0x4C00 /**< The buffer contains a valid signature followed by more data. */
59 /* MBEDTLS_ERR_ECP_HW_ACCEL_FAILED is deprecated and should not be used. */
60 #define MBEDTLS_ERR_ECP_HW_ACCEL_FAILED -0x4B80 /**< The ECP hardware accelerator failed. */
62 #define MBEDTLS_ERR_ECP_IN_PROGRESS -0x4B00 /**< Operation in progress, call again with the same parameters to continue. */
69 * Domain-parameter identifiers: curve, subgroup, and generator.
71 * \note Only curves over prime fields are supported.
73 * \warning This library does not support validation of arbitrary domain
74 * parameters. Therefore, only standardized domain parameters from trusted
75 * sources should be used. See mbedtls_ecp_group_load().
79 MBEDTLS_ECP_DP_NONE = 0, /*!< Curve not defined. */
80 MBEDTLS_ECP_DP_SECP192R1, /*!< Domain parameters for the 192-bit curve defined by FIPS 186-4 and SEC1. */
81 MBEDTLS_ECP_DP_SECP224R1, /*!< Domain parameters for the 224-bit curve defined by FIPS 186-4 and SEC1. */
82 MBEDTLS_ECP_DP_SECP256R1, /*!< Domain parameters for the 256-bit curve defined by FIPS 186-4 and SEC1. */
83 MBEDTLS_ECP_DP_SECP384R1, /*!< Domain parameters for the 384-bit curve defined by FIPS 186-4 and SEC1. */
84 MBEDTLS_ECP_DP_SECP521R1, /*!< Domain parameters for the 521-bit curve defined by FIPS 186-4 and SEC1. */
85 MBEDTLS_ECP_DP_BP256R1, /*!< Domain parameters for 256-bit Brainpool curve. */
86 MBEDTLS_ECP_DP_BP384R1, /*!< Domain parameters for 384-bit Brainpool curve. */
87 MBEDTLS_ECP_DP_BP512R1, /*!< Domain parameters for 512-bit Brainpool curve. */
88 MBEDTLS_ECP_DP_CURVE25519, /*!< Domain parameters for Curve25519. */
89 MBEDTLS_ECP_DP_SECP192K1, /*!< Domain parameters for 192-bit "Koblitz" curve. */
90 MBEDTLS_ECP_DP_SECP224K1, /*!< Domain parameters for 224-bit "Koblitz" curve. */
91 MBEDTLS_ECP_DP_SECP256K1, /*!< Domain parameters for 256-bit "Koblitz" curve. */
92 MBEDTLS_ECP_DP_CURVE448, /*!< Domain parameters for Curve448. */
93 } mbedtls_ecp_group_id;
96 * The number of supported curves, plus one for #MBEDTLS_ECP_DP_NONE.
98 * \note Montgomery curves are currently excluded.
100 #define MBEDTLS_ECP_DP_MAX 12
107 MBEDTLS_ECP_TYPE_NONE = 0,
108 MBEDTLS_ECP_TYPE_SHORT_WEIERSTRASS, /* y^2 = x^3 + a x + b */
109 MBEDTLS_ECP_TYPE_MONTGOMERY, /* y^2 = x^3 + a x^2 + x */
110 } mbedtls_ecp_curve_type;
113 * Curve information, for use by other modules.
115 typedef struct mbedtls_ecp_curve_info
117 mbedtls_ecp_group_id grp_id; /*!< An internal identifier. */
118 uint16_t tls_id; /*!< The TLS NamedCurve identifier. */
119 uint16_t bit_size; /*!< The curve size in bits. */
120 const char *name; /*!< A human-friendly name. */
121 } mbedtls_ecp_curve_info;
124 * \brief The ECP point structure, in Jacobian coordinates.
126 * \note All functions expect and return points satisfying
127 * the following condition: <code>Z == 0</code> or
128 * <code>Z == 1</code>. Other values of \p Z are
129 * used only by internal functions.
130 * The point is zero, or "at infinity", if <code>Z == 0</code>.
131 * Otherwise, \p X and \p Y are its standard (affine)
134 typedef struct mbedtls_ecp_point
136 mbedtls_mpi X; /*!< The X coordinate of the ECP point. */
137 mbedtls_mpi Y; /*!< The Y coordinate of the ECP point. */
138 mbedtls_mpi Z; /*!< The Z coordinate of the ECP point. */
142 #if !defined(MBEDTLS_ECP_ALT)
144 * default mbed TLS elliptic curve arithmetic implementation
146 * (in case MBEDTLS_ECP_ALT is defined then the developer has to provide an
147 * alternative implementation for the whole module and it will replace this
152 * \brief The ECP group structure.
154 * We consider two types of curve equations:
155 * <ul><li>Short Weierstrass: <code>y^2 = x^3 + A x + B mod P</code>
156 * (SEC1 + RFC-4492)</li>
157 * <li>Montgomery: <code>y^2 = x^3 + A x^2 + x mod P</code> (Curve25519,
158 * Curve448)</li></ul>
159 * In both cases, the generator (\p G) for a prime-order subgroup is fixed.
161 * For Short Weierstrass, this subgroup is the whole curve, and its
162 * cardinality is denoted by \p N. Our code requires that \p N is an
163 * odd prime as mbedtls_ecp_mul() requires an odd number, and
164 * mbedtls_ecdsa_sign() requires that it is prime for blinding purposes.
166 * For Montgomery curves, we do not store \p A, but <code>(A + 2) / 4</code>,
167 * which is the quantity used in the formulas. Additionally, \p nbits is
168 * not the size of \p N but the required size for private keys.
170 * If \p modp is NULL, reduction modulo \p P is done using a generic algorithm.
171 * Otherwise, \p modp must point to a function that takes an \p mbedtls_mpi in the
172 * range of <code>0..2^(2*pbits)-1</code>, and transforms it in-place to an integer
173 * which is congruent mod \p P to the given MPI, and is close enough to \p pbits
174 * in size, so that it may be efficiently brought in the 0..P-1 range by a few
175 * additions or subtractions. Therefore, it is only an approximative modular
176 * reduction. It must return 0 on success and non-zero on failure.
178 * \note Alternative implementations must keep the group IDs distinct. If
179 * two group structures have the same ID, then they must be
183 typedef struct mbedtls_ecp_group
185 mbedtls_ecp_group_id id; /*!< An internal group identifier. */
186 mbedtls_mpi P; /*!< The prime modulus of the base field. */
187 mbedtls_mpi A; /*!< For Short Weierstrass: \p A in the equation. For
188 Montgomery curves: <code>(A + 2) / 4</code>. */
189 mbedtls_mpi B; /*!< For Short Weierstrass: \p B in the equation.
190 For Montgomery curves: unused. */
191 mbedtls_ecp_point G; /*!< The generator of the subgroup used. */
192 mbedtls_mpi N; /*!< The order of \p G. */
193 size_t pbits; /*!< The number of bits in \p P.*/
194 size_t nbits; /*!< For Short Weierstrass: The number of bits in \p P.
195 For Montgomery curves: the number of bits in the
197 unsigned int h; /*!< \internal 1 if the constants are static. */
198 int (*modp)(mbedtls_mpi *); /*!< The function for fast pseudo-reduction
199 mod \p P (see above).*/
200 int (*t_pre)(mbedtls_ecp_point *, void *); /*!< Unused. */
201 int (*t_post)(mbedtls_ecp_point *, void *); /*!< Unused. */
202 void *t_data; /*!< Unused. */
203 mbedtls_ecp_point *T; /*!< Pre-computed points for ecp_mul_comb(). */
204 size_t T_size; /*!< The number of pre-computed points. */
209 * \name SECTION: Module settings
211 * The configuration options you can set for this module are in this section.
212 * Either change them in config.h, or define them using the compiler command line.
216 #if !defined(MBEDTLS_ECP_MAX_BITS)
218 * The maximum size of the groups, that is, of \c N and \c P.
220 #define MBEDTLS_ECP_MAX_BITS 521 /**< The maximum size of groups, in bits. */
223 #define MBEDTLS_ECP_MAX_BYTES ( ( MBEDTLS_ECP_MAX_BITS + 7 ) / 8 )
224 #define MBEDTLS_ECP_MAX_PT_LEN ( 2 * MBEDTLS_ECP_MAX_BYTES + 1 )
226 #if !defined(MBEDTLS_ECP_WINDOW_SIZE)
228 * Maximum "window" size used for point multiplication.
230 * Minimum value: 2. Maximum value: 7.
232 * Result is an array of at most ( 1 << ( MBEDTLS_ECP_WINDOW_SIZE - 1 ) )
233 * points used for point multiplication. This value is directly tied to EC
234 * peak memory usage, so decreasing it by one should roughly cut memory usage
235 * by two (if large curves are in use).
237 * Reduction in size may reduce speed, but larger curves are impacted first.
238 * Sample performances (in ECDHE handshakes/s, with FIXED_POINT_OPTIM = 1):
240 * 521 145 141 135 120 97
241 * 384 214 209 198 177 146
242 * 256 320 320 303 262 226
243 * 224 475 475 453 398 342
244 * 192 640 640 633 587 476
246 #define MBEDTLS_ECP_WINDOW_SIZE 6 /**< The maximum window size used. */
247 #endif /* MBEDTLS_ECP_WINDOW_SIZE */
249 #if !defined(MBEDTLS_ECP_FIXED_POINT_OPTIM)
251 * Trade memory for speed on fixed-point multiplication.
253 * This speeds up repeated multiplication of the generator (that is, the
254 * multiplication in ECDSA signatures, and half of the multiplications in
255 * ECDSA verification and ECDHE) by a factor roughly 3 to 4.
257 * The cost is increasing EC peak memory usage by a factor roughly 2.
259 * Change this value to 0 to reduce peak memory usage.
261 #define MBEDTLS_ECP_FIXED_POINT_OPTIM 1 /**< Enable fixed-point speed-up. */
262 #endif /* MBEDTLS_ECP_FIXED_POINT_OPTIM */
264 /* \} name SECTION: Module settings */
266 #else /* MBEDTLS_ECP_ALT */
268 #endif /* MBEDTLS_ECP_ALT */
270 #if defined(MBEDTLS_ECP_RESTARTABLE)
273 * \brief Internal restart context for multiplication
275 * \note Opaque struct
277 typedef struct mbedtls_ecp_restart_mul mbedtls_ecp_restart_mul_ctx;
280 * \brief Internal restart context for ecp_muladd()
282 * \note Opaque struct
284 typedef struct mbedtls_ecp_restart_muladd mbedtls_ecp_restart_muladd_ctx;
287 * \brief General context for resuming ECC operations
291 unsigned ops_done; /*!< current ops count */
292 unsigned depth; /*!< call depth (0 = top-level) */
293 mbedtls_ecp_restart_mul_ctx *rsm; /*!< ecp_mul_comb() sub-context */
294 mbedtls_ecp_restart_muladd_ctx *ma; /*!< ecp_muladd() sub-context */
295 } mbedtls_ecp_restart_ctx;
298 * Operation counts for restartable functions
300 #define MBEDTLS_ECP_OPS_CHK 3 /*!< basic ops count for ecp_check_pubkey() */
301 #define MBEDTLS_ECP_OPS_DBL 8 /*!< basic ops count for ecp_double_jac() */
302 #define MBEDTLS_ECP_OPS_ADD 11 /*!< basic ops count for see ecp_add_mixed() */
303 #define MBEDTLS_ECP_OPS_INV 120 /*!< empirical equivalent for mpi_mod_inv() */
306 * \brief Internal; for restartable functions in other modules.
307 * Check and update basic ops budget.
309 * \param grp Group structure
310 * \param rs_ctx Restart context
311 * \param ops Number of basic ops to do
313 * \return \c 0 if doing \p ops basic ops is still allowed,
314 * \return #MBEDTLS_ERR_ECP_IN_PROGRESS otherwise.
316 int mbedtls_ecp_check_budget( const mbedtls_ecp_group *grp,
317 mbedtls_ecp_restart_ctx *rs_ctx,
320 /* Utility macro for checking and updating ops budget */
321 #define MBEDTLS_ECP_BUDGET( ops ) \
322 MBEDTLS_MPI_CHK( mbedtls_ecp_check_budget( grp, rs_ctx, \
323 (unsigned) (ops) ) );
325 #else /* MBEDTLS_ECP_RESTARTABLE */
327 #define MBEDTLS_ECP_BUDGET( ops ) /* no-op; for compatibility */
329 /* We want to declare restartable versions of existing functions anyway */
330 typedef void mbedtls_ecp_restart_ctx;
332 #endif /* MBEDTLS_ECP_RESTARTABLE */
335 * \brief The ECP key-pair structure.
337 * A generic key-pair that may be used for ECDSA and fixed ECDH, for example.
339 * \note Members are deliberately in the same order as in the
340 * ::mbedtls_ecdsa_context structure.
342 typedef struct mbedtls_ecp_keypair
344 mbedtls_ecp_group grp; /*!< Elliptic curve and base point */
345 mbedtls_mpi d; /*!< our secret value */
346 mbedtls_ecp_point Q; /*!< our public value */
351 * Point formats, from RFC 4492's enum ECPointFormat
353 #define MBEDTLS_ECP_PF_UNCOMPRESSED 0 /**< Uncompressed point format. */
354 #define MBEDTLS_ECP_PF_COMPRESSED 1 /**< Compressed point format. */
357 * Some other constants from RFC 4492
359 #define MBEDTLS_ECP_TLS_NAMED_CURVE 3 /**< The named_curve of ECCurveType. */
361 #if defined(MBEDTLS_ECP_RESTARTABLE)
363 * \brief Set the maximum number of basic operations done in a row.
365 * If more operations are needed to complete a computation,
366 * #MBEDTLS_ERR_ECP_IN_PROGRESS will be returned by the
367 * function performing the computation. It is then the
368 * caller's responsibility to either call again with the same
369 * parameters until it returns 0 or an error code; or to free
370 * the restart context if the operation is to be aborted.
372 * It is strictly required that all input parameters and the
373 * restart context be the same on successive calls for the
374 * same operation, but output parameters need not be the
375 * same; they must not be used until the function finally
378 * This only applies to functions whose documentation
379 * mentions they may return #MBEDTLS_ERR_ECP_IN_PROGRESS (or
380 * #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS for functions in the
381 * SSL module). For functions that accept a "restart context"
382 * argument, passing NULL disables restart and makes the
383 * function equivalent to the function with the same name
384 * with \c _restartable removed. For functions in the ECDH
385 * module, restart is disabled unless the function accepts
386 * an "ECDH context" argument and
387 * mbedtls_ecdh_enable_restart() was previously called on
388 * that context. For function in the SSL module, restart is
389 * only enabled for specific sides and key exchanges
390 * (currently only for clients and ECDHE-ECDSA).
392 * \param max_ops Maximum number of basic operations done in a row.
393 * Default: 0 (unlimited).
394 * Lower (non-zero) values mean ECC functions will block for
395 * a lesser maximum amount of time.
397 * \note A "basic operation" is defined as a rough equivalent of a
398 * multiplication in GF(p) for the NIST P-256 curve.
399 * As an indication, with default settings, a scalar
400 * multiplication (full run of \c mbedtls_ecp_mul()) is:
401 * - about 3300 basic operations for P-256
402 * - about 9400 basic operations for P-384
404 * \note Very low values are not always respected: sometimes
405 * functions need to block for a minimum number of
406 * operations, and will do so even if max_ops is set to a
407 * lower value. That minimum depends on the curve size, and
408 * can be made lower by decreasing the value of
409 * \c MBEDTLS_ECP_WINDOW_SIZE. As an indication, here is the
410 * lowest effective value for various curves and values of
411 * that parameter (w for short):
412 * w=6 w=5 w=4 w=3 w=2
413 * P-256 208 208 160 136 124
414 * P-384 682 416 320 272 248
415 * P-521 1364 832 640 544 496
417 * \note This setting is currently ignored by Curve25519.
419 void mbedtls_ecp_set_max_ops( unsigned max_ops );
422 * \brief Check if restart is enabled (max_ops != 0)
424 * \return \c 0 if \c max_ops == 0 (restart disabled)
425 * \return \c 1 otherwise (restart enabled)
427 int mbedtls_ecp_restart_is_enabled( void );
428 #endif /* MBEDTLS_ECP_RESTARTABLE */
431 * Get the type of a curve
433 mbedtls_ecp_curve_type mbedtls_ecp_get_type( const mbedtls_ecp_group *grp );
436 * \brief This function retrieves the information defined in
437 * mbedtls_ecp_curve_info() for all supported curves in order
440 * \return A statically allocated array. The last entry is 0.
442 const mbedtls_ecp_curve_info *mbedtls_ecp_curve_list( void );
445 * \brief This function retrieves the list of internal group
446 * identifiers of all supported curves in the order of
449 * \return A statically allocated array,
450 * terminated with MBEDTLS_ECP_DP_NONE.
452 const mbedtls_ecp_group_id *mbedtls_ecp_grp_id_list( void );
455 * \brief This function retrieves curve information from an internal
458 * \param grp_id An \c MBEDTLS_ECP_DP_XXX value.
460 * \return The associated curve information on success.
461 * \return NULL on failure.
463 const mbedtls_ecp_curve_info *mbedtls_ecp_curve_info_from_grp_id( mbedtls_ecp_group_id grp_id );
466 * \brief This function retrieves curve information from a TLS
469 * \param tls_id An \c MBEDTLS_ECP_DP_XXX value.
471 * \return The associated curve information on success.
472 * \return NULL on failure.
474 const mbedtls_ecp_curve_info *mbedtls_ecp_curve_info_from_tls_id( uint16_t tls_id );
477 * \brief This function retrieves curve information from a
478 * human-readable name.
480 * \param name The human-readable name.
482 * \return The associated curve information on success.
483 * \return NULL on failure.
485 const mbedtls_ecp_curve_info *mbedtls_ecp_curve_info_from_name( const char *name );
488 * \brief This function initializes a point as zero.
490 * \param pt The point to initialize.
492 void mbedtls_ecp_point_init( mbedtls_ecp_point *pt );
495 * \brief This function initializes an ECP group context
496 * without loading any domain parameters.
498 * \note After this function is called, domain parameters
499 * for various ECP groups can be loaded through the
500 * mbedtls_ecp_group_load() or mbedtls_ecp_tls_read_group()
503 void mbedtls_ecp_group_init( mbedtls_ecp_group *grp );
506 * \brief This function initializes a key pair as an invalid one.
508 * \param key The key pair to initialize.
510 void mbedtls_ecp_keypair_init( mbedtls_ecp_keypair *key );
513 * \brief This function frees the components of a point.
515 * \param pt The point to free.
517 void mbedtls_ecp_point_free( mbedtls_ecp_point *pt );
520 * \brief This function frees the components of an ECP group.
522 * \param grp The group to free. This may be \c NULL, in which
523 * case this function returns immediately. If it is not
524 * \c NULL, it must point to an initialized ECP group.
526 void mbedtls_ecp_group_free( mbedtls_ecp_group *grp );
529 * \brief This function frees the components of a key pair.
531 * \param key The key pair to free. This may be \c NULL, in which
532 * case this function returns immediately. If it is not
533 * \c NULL, it must point to an initialized ECP key pair.
535 void mbedtls_ecp_keypair_free( mbedtls_ecp_keypair *key );
537 #if defined(MBEDTLS_ECP_RESTARTABLE)
539 * \brief Initialize a restart context.
541 * \param ctx The restart context to initialize. This must
544 void mbedtls_ecp_restart_init( mbedtls_ecp_restart_ctx *ctx );
547 * \brief Free the components of a restart context.
549 * \param ctx The restart context to free. This may be \c NULL, in which
550 * case this function returns immediately. If it is not
551 * \c NULL, it must point to an initialized restart context.
553 void mbedtls_ecp_restart_free( mbedtls_ecp_restart_ctx *ctx );
554 #endif /* MBEDTLS_ECP_RESTARTABLE */
557 * \brief This function copies the contents of point \p Q into
560 * \param P The destination point. This must be initialized.
561 * \param Q The source point. This must be initialized.
563 * \return \c 0 on success.
564 * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
565 * \return Another negative error code for other kinds of failure.
567 int mbedtls_ecp_copy( mbedtls_ecp_point *P, const mbedtls_ecp_point *Q );
570 * \brief This function copies the contents of group \p src into
573 * \param dst The destination group. This must be initialized.
574 * \param src The source group. This must be initialized.
576 * \return \c 0 on success.
577 * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
578 * \return Another negative error code on other kinds of failure.
580 int mbedtls_ecp_group_copy( mbedtls_ecp_group *dst,
581 const mbedtls_ecp_group *src );
584 * \brief This function sets a point to the point at infinity.
586 * \param pt The point to set. This must be initialized.
588 * \return \c 0 on success.
589 * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
590 * \return Another negative error code on other kinds of failure.
592 int mbedtls_ecp_set_zero( mbedtls_ecp_point *pt );
595 * \brief This function checks if a point is the point at infinity.
597 * \param pt The point to test. This must be initialized.
599 * \return \c 1 if the point is zero.
600 * \return \c 0 if the point is non-zero.
601 * \return A negative error code on failure.
603 int mbedtls_ecp_is_zero( mbedtls_ecp_point *pt );
606 * \brief This function compares two points.
608 * \note This assumes that the points are normalized. Otherwise,
609 * they may compare as "not equal" even if they are.
611 * \param P The first point to compare. This must be initialized.
612 * \param Q The second point to compare. This must be initialized.
614 * \return \c 0 if the points are equal.
615 * \return #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if the points are not equal.
617 int mbedtls_ecp_point_cmp( const mbedtls_ecp_point *P,
618 const mbedtls_ecp_point *Q );
621 * \brief This function imports a non-zero point from two ASCII
624 * \param P The destination point. This must be initialized.
625 * \param radix The numeric base of the input.
626 * \param x The first affine coordinate, as a null-terminated string.
627 * \param y The second affine coordinate, as a null-terminated string.
629 * \return \c 0 on success.
630 * \return An \c MBEDTLS_ERR_MPI_XXX error code on failure.
632 int mbedtls_ecp_point_read_string( mbedtls_ecp_point *P, int radix,
633 const char *x, const char *y );
636 * \brief This function exports a point into unsigned binary data.
638 * \param grp The group to which the point should belong.
639 * This must be initialized and have group parameters
640 * set, for example through mbedtls_ecp_group_load().
641 * \param P The point to export. This must be initialized.
642 * \param format The point format. This must be either
643 * #MBEDTLS_ECP_PF_COMPRESSED or #MBEDTLS_ECP_PF_UNCOMPRESSED.
644 * (For groups without these formats, this parameter is
645 * ignored. But it still has to be either of the above
647 * \param olen The address at which to store the length of
648 * the output in Bytes. This must not be \c NULL.
649 * \param buf The output buffer. This must be a writable buffer
650 * of length \p buflen Bytes.
651 * \param buflen The length of the output buffer \p buf in Bytes.
653 * \return \c 0 on success.
654 * \return #MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL if the output buffer
655 * is too small to hold the point.
656 * \return #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if the point format
657 * or the export for the given group is not implemented.
658 * \return Another negative error code on other kinds of failure.
660 int mbedtls_ecp_point_write_binary( const mbedtls_ecp_group *grp,
661 const mbedtls_ecp_point *P,
662 int format, size_t *olen,
663 unsigned char *buf, size_t buflen );
666 * \brief This function imports a point from unsigned binary data.
668 * \note This function does not check that the point actually
669 * belongs to the given group, see mbedtls_ecp_check_pubkey()
672 * \param grp The group to which the point should belong.
673 * This must be initialized and have group parameters
674 * set, for example through mbedtls_ecp_group_load().
675 * \param P The destination context to import the point to.
676 * This must be initialized.
677 * \param buf The input buffer. This must be a readable buffer
678 * of length \p ilen Bytes.
679 * \param ilen The length of the input buffer \p buf in Bytes.
681 * \return \c 0 on success.
682 * \return #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if the input is invalid.
683 * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
684 * \return #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if the import for the
685 * given group is not implemented.
687 int mbedtls_ecp_point_read_binary( const mbedtls_ecp_group *grp,
688 mbedtls_ecp_point *P,
689 const unsigned char *buf, size_t ilen );
692 * \brief This function imports a point from a TLS ECPoint record.
694 * \note On function return, \p *buf is updated to point immediately
695 * after the ECPoint record.
697 * \param grp The ECP group to use.
698 * This must be initialized and have group parameters
699 * set, for example through mbedtls_ecp_group_load().
700 * \param pt The destination point.
701 * \param buf The address of the pointer to the start of the input buffer.
702 * \param len The length of the buffer.
704 * \return \c 0 on success.
705 * \return An \c MBEDTLS_ERR_MPI_XXX error code on initialization
707 * \return #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if input is invalid.
709 int mbedtls_ecp_tls_read_point( const mbedtls_ecp_group *grp,
710 mbedtls_ecp_point *pt,
711 const unsigned char **buf, size_t len );
714 * \brief This function exports a point as a TLS ECPoint record
715 * defined in RFC 4492, Section 5.4.
717 * \param grp The ECP group to use.
718 * This must be initialized and have group parameters
719 * set, for example through mbedtls_ecp_group_load().
720 * \param pt The point to be exported. This must be initialized.
721 * \param format The point format to use. This must be either
722 * #MBEDTLS_ECP_PF_COMPRESSED or #MBEDTLS_ECP_PF_UNCOMPRESSED.
723 * \param olen The address at which to store the length in Bytes
724 * of the data written.
725 * \param buf The target buffer. This must be a writable buffer of
726 * length \p blen Bytes.
727 * \param blen The length of the target buffer \p buf in Bytes.
729 * \return \c 0 on success.
730 * \return #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if the input is invalid.
731 * \return #MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL if the target buffer
732 * is too small to hold the exported point.
733 * \return Another negative error code on other kinds of failure.
735 int mbedtls_ecp_tls_write_point( const mbedtls_ecp_group *grp,
736 const mbedtls_ecp_point *pt,
737 int format, size_t *olen,
738 unsigned char *buf, size_t blen );
741 * \brief This function sets up an ECP group context
742 * from a standardized set of domain parameters.
744 * \note The index should be a value of the NamedCurve enum,
745 * as defined in <em>RFC-4492: Elliptic Curve Cryptography
746 * (ECC) Cipher Suites for Transport Layer Security (TLS)</em>,
747 * usually in the form of an \c MBEDTLS_ECP_DP_XXX macro.
749 * \param grp The group context to setup. This must be initialized.
750 * \param id The identifier of the domain parameter set to load.
752 * \return \c 0 on success.
753 * \return #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if \p id doesn't
754 * correspond to a known group.
755 * \return Another negative error code on other kinds of failure.
757 int mbedtls_ecp_group_load( mbedtls_ecp_group *grp, mbedtls_ecp_group_id id );
760 * \brief This function sets up an ECP group context from a TLS
761 * ECParameters record as defined in RFC 4492, Section 5.4.
763 * \note The read pointer \p buf is updated to point right after
764 * the ECParameters record on exit.
766 * \param grp The group context to setup. This must be initialized.
767 * \param buf The address of the pointer to the start of the input buffer.
768 * \param len The length of the input buffer \c *buf in Bytes.
770 * \return \c 0 on success.
771 * \return #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if input is invalid.
772 * \return #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if the group is not
774 * \return Another negative error code on other kinds of failure.
776 int mbedtls_ecp_tls_read_group( mbedtls_ecp_group *grp,
777 const unsigned char **buf, size_t len );
780 * \brief This function extracts an elliptic curve group ID from a
781 * TLS ECParameters record as defined in RFC 4492, Section 5.4.
783 * \note The read pointer \p buf is updated to point right after
784 * the ECParameters record on exit.
786 * \param grp The address at which to store the group id.
787 * This must not be \c NULL.
788 * \param buf The address of the pointer to the start of the input buffer.
789 * \param len The length of the input buffer \c *buf in Bytes.
791 * \return \c 0 on success.
792 * \return #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if input is invalid.
793 * \return #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if the group is not
795 * \return Another negative error code on other kinds of failure.
797 int mbedtls_ecp_tls_read_group_id( mbedtls_ecp_group_id *grp,
798 const unsigned char **buf,
801 * \brief This function exports an elliptic curve as a TLS
802 * ECParameters record as defined in RFC 4492, Section 5.4.
804 * \param grp The ECP group to be exported.
805 * This must be initialized and have group parameters
806 * set, for example through mbedtls_ecp_group_load().
807 * \param olen The address at which to store the number of Bytes written.
808 * This must not be \c NULL.
809 * \param buf The buffer to write to. This must be a writable buffer
810 * of length \p blen Bytes.
811 * \param blen The length of the output buffer \p buf in Bytes.
813 * \return \c 0 on success.
814 * \return #MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL if the output
815 * buffer is too small to hold the exported group.
816 * \return Another negative error code on other kinds of failure.
818 int mbedtls_ecp_tls_write_group( const mbedtls_ecp_group *grp,
820 unsigned char *buf, size_t blen );
823 * \brief This function performs a scalar multiplication of a point
824 * by an integer: \p R = \p m * \p P.
826 * It is not thread-safe to use same group in multiple threads.
828 * \note To prevent timing attacks, this function
829 * executes the exact same sequence of base-field
830 * operations for any valid \p m. It avoids any if-branch or
831 * array index depending on the value of \p m.
833 * \note If \p f_rng is not NULL, it is used to randomize
834 * intermediate results to prevent potential timing attacks
835 * targeting these results. We recommend always providing
836 * a non-NULL \p f_rng. The overhead is negligible.
838 * \param grp The ECP group to use.
839 * This must be initialized and have group parameters
840 * set, for example through mbedtls_ecp_group_load().
841 * \param R The point in which to store the result of the calculation.
842 * This must be initialized.
843 * \param m The integer by which to multiply. This must be initialized.
844 * \param P The point to multiply. This must be initialized.
845 * \param f_rng The RNG function. This may be \c NULL if randomization
846 * of intermediate results isn't desired (discouraged).
847 * \param p_rng The RNG context to be passed to \p p_rng.
849 * \return \c 0 on success.
850 * \return #MBEDTLS_ERR_ECP_INVALID_KEY if \p m is not a valid private
851 * key, or \p P is not a valid public key.
852 * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
853 * \return Another negative error code on other kinds of failure.
855 int mbedtls_ecp_mul( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
856 const mbedtls_mpi *m, const mbedtls_ecp_point *P,
857 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
860 * \brief This function performs multiplication of a point by
861 * an integer: \p R = \p m * \p P in a restartable way.
863 * \see mbedtls_ecp_mul()
865 * \note This function does the same as \c mbedtls_ecp_mul(), but
866 * it can return early and restart according to the limit set
867 * with \c mbedtls_ecp_set_max_ops() to reduce blocking.
869 * \param grp The ECP group to use.
870 * This must be initialized and have group parameters
871 * set, for example through mbedtls_ecp_group_load().
872 * \param R The point in which to store the result of the calculation.
873 * This must be initialized.
874 * \param m The integer by which to multiply. This must be initialized.
875 * \param P The point to multiply. This must be initialized.
876 * \param f_rng The RNG function. This may be \c NULL if randomization
877 * of intermediate results isn't desired (discouraged).
878 * \param p_rng The RNG context to be passed to \p p_rng.
879 * \param rs_ctx The restart context (NULL disables restart).
881 * \return \c 0 on success.
882 * \return #MBEDTLS_ERR_ECP_INVALID_KEY if \p m is not a valid private
883 * key, or \p P is not a valid public key.
884 * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
885 * \return #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
886 * operations was reached: see \c mbedtls_ecp_set_max_ops().
887 * \return Another negative error code on other kinds of failure.
889 int mbedtls_ecp_mul_restartable( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
890 const mbedtls_mpi *m, const mbedtls_ecp_point *P,
891 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
892 mbedtls_ecp_restart_ctx *rs_ctx );
895 * \brief This function performs multiplication and addition of two
896 * points by integers: \p R = \p m * \p P + \p n * \p Q
898 * It is not thread-safe to use same group in multiple threads.
900 * \note In contrast to mbedtls_ecp_mul(), this function does not
901 * guarantee a constant execution flow and timing.
903 * \param grp The ECP group to use.
904 * This must be initialized and have group parameters
905 * set, for example through mbedtls_ecp_group_load().
906 * \param R The point in which to store the result of the calculation.
907 * This must be initialized.
908 * \param m The integer by which to multiply \p P.
909 * This must be initialized.
910 * \param P The point to multiply by \p m. This must be initialized.
911 * \param n The integer by which to multiply \p Q.
912 * This must be initialized.
913 * \param Q The point to be multiplied by \p n.
914 * This must be initialized.
916 * \return \c 0 on success.
917 * \return #MBEDTLS_ERR_ECP_INVALID_KEY if \p m or \p n are not
918 * valid private keys, or \p P or \p Q are not valid public
920 * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
921 * \return Another negative error code on other kinds of failure.
923 int mbedtls_ecp_muladd( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
924 const mbedtls_mpi *m, const mbedtls_ecp_point *P,
925 const mbedtls_mpi *n, const mbedtls_ecp_point *Q );
928 * \brief This function performs multiplication and addition of two
929 * points by integers: \p R = \p m * \p P + \p n * \p Q in a
932 * \see \c mbedtls_ecp_muladd()
934 * \note This function works the same as \c mbedtls_ecp_muladd(),
935 * but it can return early and restart according to the limit
936 * set with \c mbedtls_ecp_set_max_ops() to reduce blocking.
938 * \param grp The ECP group to use.
939 * This must be initialized and have group parameters
940 * set, for example through mbedtls_ecp_group_load().
941 * \param R The point in which to store the result of the calculation.
942 * This must be initialized.
943 * \param m The integer by which to multiply \p P.
944 * This must be initialized.
945 * \param P The point to multiply by \p m. This must be initialized.
946 * \param n The integer by which to multiply \p Q.
947 * This must be initialized.
948 * \param Q The point to be multiplied by \p n.
949 * This must be initialized.
950 * \param rs_ctx The restart context (NULL disables restart).
952 * \return \c 0 on success.
953 * \return #MBEDTLS_ERR_ECP_INVALID_KEY if \p m or \p n are not
954 * valid private keys, or \p P or \p Q are not valid public
956 * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
957 * \return #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
958 * operations was reached: see \c mbedtls_ecp_set_max_ops().
959 * \return Another negative error code on other kinds of failure.
961 int mbedtls_ecp_muladd_restartable(
962 mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
963 const mbedtls_mpi *m, const mbedtls_ecp_point *P,
964 const mbedtls_mpi *n, const mbedtls_ecp_point *Q,
965 mbedtls_ecp_restart_ctx *rs_ctx );
968 * \brief This function checks that a point is a valid public key
971 * It only checks that the point is non-zero, has
972 * valid coordinates and lies on the curve. It does not verify
973 * that it is indeed a multiple of \p G. This additional
974 * check is computationally more expensive, is not required
975 * by standards, and should not be necessary if the group
976 * used has a small cofactor. In particular, it is useless for
977 * the NIST groups which all have a cofactor of 1.
979 * \note This function uses bare components rather than an
980 * ::mbedtls_ecp_keypair structure, to ease use with other
981 * structures, such as ::mbedtls_ecdh_context or
982 * ::mbedtls_ecdsa_context.
984 * \param grp The ECP group the point should belong to.
985 * This must be initialized and have group parameters
986 * set, for example through mbedtls_ecp_group_load().
987 * \param pt The point to check. This must be initialized.
989 * \return \c 0 if the point is a valid public key.
990 * \return #MBEDTLS_ERR_ECP_INVALID_KEY if the point is not
991 * a valid public key for the given curve.
992 * \return Another negative error code on other kinds of failure.
994 int mbedtls_ecp_check_pubkey( const mbedtls_ecp_group *grp,
995 const mbedtls_ecp_point *pt );
998 * \brief This function checks that an \p mbedtls_mpi is a
999 * valid private key for this curve.
1001 * \note This function uses bare components rather than an
1002 * ::mbedtls_ecp_keypair structure to ease use with other
1003 * structures, such as ::mbedtls_ecdh_context or
1004 * ::mbedtls_ecdsa_context.
1006 * \param grp The ECP group the private key should belong to.
1007 * This must be initialized and have group parameters
1008 * set, for example through mbedtls_ecp_group_load().
1009 * \param d The integer to check. This must be initialized.
1011 * \return \c 0 if the point is a valid private key.
1012 * \return #MBEDTLS_ERR_ECP_INVALID_KEY if the point is not a valid
1013 * private key for the given curve.
1014 * \return Another negative error code on other kinds of failure.
1016 int mbedtls_ecp_check_privkey( const mbedtls_ecp_group *grp,
1017 const mbedtls_mpi *d );
1020 * \brief This function generates a private key.
1022 * \param grp The ECP group to generate a private key for.
1023 * This must be initialized and have group parameters
1024 * set, for example through mbedtls_ecp_group_load().
1025 * \param d The destination MPI (secret part). This must be initialized.
1026 * \param f_rng The RNG function. This must not be \c NULL.
1027 * \param p_rng The RNG parameter to be passed to \p f_rng. This may be
1028 * \c NULL if \p f_rng doesn't need a context argument.
1030 * \return \c 0 on success.
1031 * \return An \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX error code
1034 int mbedtls_ecp_gen_privkey( const mbedtls_ecp_group *grp,
1036 int (*f_rng)(void *, unsigned char *, size_t),
1040 * \brief This function generates a keypair with a configurable base
1043 * \note This function uses bare components rather than an
1044 * ::mbedtls_ecp_keypair structure to ease use with other
1045 * structures, such as ::mbedtls_ecdh_context or
1046 * ::mbedtls_ecdsa_context.
1048 * \param grp The ECP group to generate a key pair for.
1049 * This must be initialized and have group parameters
1050 * set, for example through mbedtls_ecp_group_load().
1051 * \param G The base point to use. This must be initialized
1052 * and belong to \p grp. It replaces the default base
1053 * point \c grp->G used by mbedtls_ecp_gen_keypair().
1054 * \param d The destination MPI (secret part).
1055 * This must be initialized.
1056 * \param Q The destination point (public part).
1057 * This must be initialized.
1058 * \param f_rng The RNG function. This must not be \c NULL.
1059 * \param p_rng The RNG context to be passed to \p f_rng. This may
1060 * be \c NULL if \p f_rng doesn't need a context argument.
1062 * \return \c 0 on success.
1063 * \return An \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX error code
1066 int mbedtls_ecp_gen_keypair_base( mbedtls_ecp_group *grp,
1067 const mbedtls_ecp_point *G,
1068 mbedtls_mpi *d, mbedtls_ecp_point *Q,
1069 int (*f_rng)(void *, unsigned char *, size_t),
1073 * \brief This function generates an ECP keypair.
1075 * \note This function uses bare components rather than an
1076 * ::mbedtls_ecp_keypair structure to ease use with other
1077 * structures, such as ::mbedtls_ecdh_context or
1078 * ::mbedtls_ecdsa_context.
1080 * \param grp The ECP group to generate a key pair for.
1081 * This must be initialized and have group parameters
1082 * set, for example through mbedtls_ecp_group_load().
1083 * \param d The destination MPI (secret part).
1084 * This must be initialized.
1085 * \param Q The destination point (public part).
1086 * This must be initialized.
1087 * \param f_rng The RNG function. This must not be \c NULL.
1088 * \param p_rng The RNG context to be passed to \p f_rng. This may
1089 * be \c NULL if \p f_rng doesn't need a context argument.
1091 * \return \c 0 on success.
1092 * \return An \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX error code
1095 int mbedtls_ecp_gen_keypair( mbedtls_ecp_group *grp, mbedtls_mpi *d,
1096 mbedtls_ecp_point *Q,
1097 int (*f_rng)(void *, unsigned char *, size_t),
1101 * \brief This function generates an ECP key.
1103 * \param grp_id The ECP group identifier.
1104 * \param key The destination key. This must be initialized.
1105 * \param f_rng The RNG function to use. This must not be \c NULL.
1106 * \param p_rng The RNG context to be passed to \p f_rng. This may
1107 * be \c NULL if \p f_rng doesn't need a context argument.
1109 * \return \c 0 on success.
1110 * \return An \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX error code
1113 int mbedtls_ecp_gen_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
1114 int (*f_rng)(void *, unsigned char *, size_t),
1118 * \brief This function reads an elliptic curve private key.
1120 * \param grp_id The ECP group identifier.
1121 * \param key The destination key.
1122 * \param buf The the buffer containing the binary representation of the
1123 * key. (Big endian integer for Weierstrass curves, byte
1124 * string for Montgomery curves.)
1125 * \param buflen The length of the buffer in bytes.
1127 * \return \c 0 on success.
1128 * \return #MBEDTLS_ERR_ECP_INVALID_KEY error if the key is
1130 * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed.
1131 * \return #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if the operation for
1132 * the group is not implemented.
1133 * \return Another negative error code on different kinds of failure.
1135 int mbedtls_ecp_read_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
1136 const unsigned char *buf, size_t buflen );
1138 * \brief This function checks that the keypair objects
1139 * \p pub and \p prv have the same group and the
1140 * same public point, and that the private key in
1141 * \p prv is consistent with the public key.
1143 * \param pub The keypair structure holding the public key. This
1144 * must be initialized. If it contains a private key, that
1146 * \param prv The keypair structure holding the full keypair.
1147 * This must be initialized.
1149 * \return \c 0 on success, meaning that the keys are valid and match.
1150 * \return #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if the keys are invalid or do not match.
1151 * \return An \c MBEDTLS_ERR_ECP_XXX or an \c MBEDTLS_ERR_MPI_XXX
1152 * error code on calculation failure.
1154 int mbedtls_ecp_check_pub_priv( const mbedtls_ecp_keypair *pub,
1155 const mbedtls_ecp_keypair *prv );
1157 #if defined(MBEDTLS_SELF_TEST)
1160 * \brief The ECP checkup routine.
1162 * \return \c 0 on success.
1163 * \return \c 1 on failure.
1165 int mbedtls_ecp_self_test( int verbose );
1167 #endif /* MBEDTLS_SELF_TEST */