bitcoin/contrib/lax_der_parsing.h
Pieter Wuille bdca9bcb6c Squashed 'src/secp256k1/' changes from 3967d96bf1..efad3506a8
efad3506a8 Merge #906: Use modified divsteps with initial delta=1/2 for constant-time
cc2c09e3a7 Merge #918: Clean up configuration in gen_context
07067967ee add ECMULT_GEN_PREC_BITS to basic_config.h
a3aa2628c7 gen_context: Don't include basic-config.h
be0609fd54 Add unit tests for edge cases with delta=1/2 variant of divsteps
cd393ce228 Optimization: only do 59 hddivsteps per iteration instead of 62
277b224b6a Use modified divsteps with initial delta=1/2 for constant-time
376ca366db Fix typo in explanation
1e5d50fa93 Merge #889: fix uninitialized read in tests
c083cc6e52 Merge #903: Make argument of fe_normalizes_to_zero{_var} const
6e898534ff Merge #907: changed import to use brackets <> for openssl
4504472269 changed import to use brackets <> for openssl as they are not local to the project
26de4dfeb1 Merge #831: Safegcd inverses, drop Jacobi symbols, remove libgmp
23c3fb629b Make argument of fe_normalizes_to_zero{_var} const
24ad04fc06 Make scalar_inverse{,_var} benchmark scale with SECP256K1_BENCH_ITERS
ebc1af700f Optimization: track f,g limb count and pass to new variable-time update_fg_var
b306935ac1 Optimization: use formulas instead of lookup tables for cancelling g bits
9164a1b658 Optimization: special-case zero modulus limbs in modinv64
1f233b3fa0 Remove num/gmp support
20448b8d09 Remove unused Jacobi symbol support
5437e7bdfb Remove unused scalar_sqr
aa9cc52180 Improve field/scalar inverse tests
1e0e885c8a Make field/scalar code use the new modinv modules for inverses
436281afdc Move secp256k1_fe_inverse{_var} to per-impl files
aa404d53be Move secp256k1_scalar_{inverse{_var},is_even} to per-impl files
08d54964e5 Improve bounds checks in modinv modules
151aac00d3 Add tests for modinv modules
d8a92fcc4c Add extensive comments on the safegcd algorithm and implementation
8e415acba2 Add safegcd based modular inverse modules
de0a643c3d Add secp256k1_ctz{32,64}_var functions
4c3ba88c3a Merge #901: ci: Switch all Linux builds to Debian and more improvements
9361f360bb ci: Select number of parallel make jobs depending on CI environment
28eccdf806 ci: Split output of logs into multiple sections
c7f754fe4d ci: Run PRs on merge result instead of on the source branch
b994a8be3c ci: Print information about binaries using "file"
f24e122d13 ci: Switch all Linux builds to Debian
ebdba03cb5 Merge #891: build: Add workaround for automake 1.13 and older
3a8b47bc6d Merge #894: ctime_test: move context randomization test to the end
7d3497cdc4 ctime_test: move context randomization test to the end
99a1cfec17 print warnings for conditional-uninitialized
3d2cf6c5bd initialize variable in tests
f329bba244 build: Add workaround for automake 1.13 and older
24d1656c32 Merge #882: Use bit ops instead of int mult for constant-time logic in gej_add_ge
e491d06b98 Use bit ops instead of int mult for constant-time logic in gej_add_ge
f8c0b57e6b Merge #864: Add support for Cirrus CI
cc2a5451dc ci: Refactor Nix shell files
2480e55c8f ci: Remove support for Travis CI
2b359f1c1d ci: Enable simple cache for brewing valgrind on macOS
8c02e465c5 ci: Add support for Cirrus CI
659d0d4798 Merge #880: Add parens around ROUND_TO_ALIGN's parameter.
b6f649889a Add parens around ROUND_TO_ALIGN's parameter. This makes the macro robust against a hypothetical ROUND_TO_ALIGN(foo ? sizeA : size B) invocation.
a4abaab793 Merge #877: Add missing secp256k1_ge_set_gej_var decl.
5671e5f3fd Merge #874: Remove underscores from header defs.
db726782fa Merge #878: Remove unused secp256k1_fe_inv_all_var
b732701faa Merge #875: Avoid casting (void**) values.
75d2ae149e Remove unused secp256k1_fe_inv_all_var
482e4a9cfc Add missing secp256k1_ge_set_gej_var decl.
2730618604 Avoid casting (void**) values. Replaced with an expression that only casts (void*) values.
fb390c5299 Remove underscores from header defs. This makes them consistent with other files and avoids reserved identifiers.
f2d9aeae6d Merge #862: Autoconf improvements
328aaef22a Merge #845: Extract the secret key from a keypair
3c15130709 Improve CC_FOR_BUILD detection
47802a4762 Restructure and tidy configure.ac
252c19dfc6 Ask brew for valgrind include path
8c727b9087 Merge #860: fixed trivial typo
b7bc3a4aaa fixed typo
33cb3c2b1f Add secret key extraction from keypair to constant time tests
36d9dc1e8e Add seckey extraction from keypair to the extrakeys tests
fc96aa73f5 Add a function to extract the secretkey from a keypair
98dac87839 Merge #858: Fix insecure links
07aa4c70ff Fix insecure links
b61f9da54e Merge #857: docs: fix simple typo, dependecy -> dependency
18aadf9d28 docs: fix simple typo, dependecy -> dependency
2d9e7175c6 Merge #852: Add sage script for generating scalar_split_lambda constants
dc6e5c3a5c Merge #854: Rename msg32 to msghash32 in ecdsa_sign/verify and add explanation
6e85d675aa Rename tweak to tweak32 in public API
f587f04e35 Rename msg32 to msghash32 in ecdsa_sign/verify and add explanation
329a2e0a3f sage: Add script for generating scalar_split_lambda constants
8f0c6f1545 Merge #851: make test count iteration configurable by environment variable
f4fa8d226a forbid a test iteration of 0 or less
f554dfc708 sage: Reorganize files
3a106966aa Merge #849: Convert Sage code to Python 3 (as used by Sage >= 9)
13c88efed0 Convert Sage code to Python 3 (as used by Sage >= 9)
0ce4554881 make test count iteration configurable by environment variable
9e5939d284 Merge #835: Don't use reserved identifiers memczero and benchmark_verify_t
d0a83f7328 Merge #839: Prevent arithmetic on NULL pointer if the scratch space is too small
903b16aa6c Merge #840: Return NULL early in context_preallocated_create if flags invalid
1f4dd03838 Typedef (u)int128_t only when they're not provided by the compiler
ebfa2058e9 Return NULL early in context_preallocated_create if flags invalid
29a299e373 Run the undefined behaviour sanitizer on Travis
7506e064d7 Prevent arithmetic on NULL pointer if the scratch space is too small
e89278f211 Don't use reserved identifiers memczero and benchmark_verify_t

git-subtree-dir: src/secp256k1
git-subtree-split: efad3506a8937162e8010f5839fdf3771dfcf516
2021-04-23 11:35:15 -07:00

91 lines
3.9 KiB
C

/***********************************************************************
* Copyright (c) 2015 Pieter Wuille *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or https://www.opensource.org/licenses/mit-license.php.*
***********************************************************************/
/****
* Please do not link this file directly. It is not part of the libsecp256k1
* project and does not promise any stability in its API, functionality or
* presence. Projects which use this code should instead copy this header
* and its accompanying .c file directly into their codebase.
****/
/* This file defines a function that parses DER with various errors and
* violations. This is not a part of the library itself, because the allowed
* violations are chosen arbitrarily and do not follow or establish any
* standard.
*
* In many places it matters that different implementations do not only accept
* the same set of valid signatures, but also reject the same set of signatures.
* The only means to accomplish that is by strictly obeying a standard, and not
* accepting anything else.
*
* Nonetheless, sometimes there is a need for compatibility with systems that
* use signatures which do not strictly obey DER. The snippet below shows how
* certain violations are easily supported. You may need to adapt it.
*
* Do not use this for new systems. Use well-defined DER or compact signatures
* instead if you have the choice (see secp256k1_ecdsa_signature_parse_der and
* secp256k1_ecdsa_signature_parse_compact).
*
* The supported violations are:
* - All numbers are parsed as nonnegative integers, even though X.609-0207
* section 8.3.3 specifies that integers are always encoded as two's
* complement.
* - Integers can have length 0, even though section 8.3.1 says they can't.
* - Integers with overly long padding are accepted, violation section
* 8.3.2.
* - 127-byte long length descriptors are accepted, even though section
* 8.1.3.5.c says that they are not.
* - Trailing garbage data inside or after the signature is ignored.
* - The length descriptor of the sequence is ignored.
*
* Compared to for example OpenSSL, many violations are NOT supported:
* - Using overly long tag descriptors for the sequence or integers inside,
* violating section 8.1.2.2.
* - Encoding primitive integers as constructed values, violating section
* 8.3.1.
*/
#ifndef SECP256K1_CONTRIB_LAX_DER_PARSING_H
#define SECP256K1_CONTRIB_LAX_DER_PARSING_H
#include <secp256k1.h>
#ifdef __cplusplus
extern "C" {
#endif
/** Parse a signature in "lax DER" format
*
* Returns: 1 when the signature could be parsed, 0 otherwise.
* Args: ctx: a secp256k1 context object
* Out: sig: a pointer to a signature object
* In: input: a pointer to the signature to be parsed
* inputlen: the length of the array pointed to be input
*
* This function will accept any valid DER encoded signature, even if the
* encoded numbers are out of range. In addition, it will accept signatures
* which violate the DER spec in various ways. Its purpose is to allow
* validation of the Bitcoin blockchain, which includes non-DER signatures
* from before the network rules were updated to enforce DER. Note that
* the set of supported violations is a strict subset of what OpenSSL will
* accept.
*
* After the call, sig will always be initialized. If parsing failed or the
* encoded numbers are out of range, signature validation with it is
* guaranteed to fail for every message and public key.
*/
int ecdsa_signature_parse_der_lax(
const secp256k1_context* ctx,
secp256k1_ecdsa_signature* sig,
const unsigned char *input,
size_t inputlen
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
#ifdef __cplusplus
}
#endif
#endif /* SECP256K1_CONTRIB_LAX_DER_PARSING_H */