* Release 0.18.0-beta1 (03 Aug 2021)

New features:
* Support for EdDSA (Ed25519, Ed448) signature creation and verification.
* Support for Ed25519 and Ed448 in PKCS#8 and public key files.

New API:
* CurveEdTw class to represent the Twisted Edwards curve parameters.
* PointEdwards class to represent points on Twisted Edwards curve and
  provide point arithmetic on it.

* Release 0.17.0 (27 May 2021)

New API:
* Keys that use explicit curve parameters can now be read and written.
  Reading of explicit curves can be disabled by using the
  `valid_curve_encodings` keyword argument in `VerifyingKey.from_pem()`,
  `VerifyingKey.from_der()`, `SigningKey.from_pem()`, and
  `SigningKey.from_der()`.
* Keys can now be written with use of explicit curve parameters,
  use `curve_parameters_encoding` keyword argument of `VerifyingKey.to_pem()`,
  `VerifyingKey.to_der()`, `SigningKey.to_pem(), or `SigningKey.to_der()` to
  specify the format. By default `named_curve` will be used, unless the
  curve doesn't have an associated OID (as will be the case for an unsupported
  curve), then `explicit` encoding will be used.
* Allow specifying acceptable point formats when loading public keys
  (this also fixes a minor bug where python-ecdsa would accept raw
  encoding for points in PKCS#8 files). Set of accepted encodings is controlled
  by `valid_encodings` keyword argument in
  `ECDH.load_received_public_key_bytes()`, `VerifyingKey.from_string()`,
  `VerifyingKey.from_pem()`, VerifyingKey.from_der()`.
* `PointJacobi` and `Point` now inherit from `AbstractPoint` that implements
  the methods for parsing points. That added `from_bytes()` and
  `to_bytes()` methods to both of them.
* Curve parameters can now be read and written to PEM and DER files. The
  `Curve` class supports new `to_der()`, `from_der()`, `to_pem()`, and
  `from_pem()` methods.

Doc fix:
* Describe in detail which methods can raise `RSZeroError`, and that
  `SigningKey.sign_deterministic()` won't raise it.

Bug fix:
* Correctly truncate hash values larger than the curve order (only impacted
  custom curves and the curves added in this release).
* Correctly handle curves for which the order is larger than the prime
  (only impacted custom curves and the secp160r1 curve added in this release).
* Fix the handling of `==` and `!=` for `Public_key`, `Private_key`, `Point`,
  `PointJacobi`, `VerifyingKey`, and `SigningKey` so that it behaves
  consistently and in the expected way both in Python 2 and Python 3.
* Implement lock-less algorithm inside PointJacobi for keeping shared state
  so that when a calculation is aborted with KeyboardInterrupt, the state
  doesn't become corrupted (this fixes the occasional breakage of ecdsa in
  interactive shells).

New features:
* The `speed.py` script now provides performance for signature verification
  without the use of precomputation.
* New curves supported: secp112r1, secp112r2, secp128r1, secp160r1.

Performance:
* Use 2-ary Non-Adjacent Form for the combined multiply-add. This speeds up
  single-shot verify (i.e. without precomputation) by about 4 to 5%.
* Use native Python 3.8 support for calculating multiplicative inverses.

Maintenace:
* Include Python 3.9 in PyPI keywords.
* More realistic branch coverage counting (ignore Python version-specific
  branches).
* Additional test coverage to many parts of the library.
* Migrate to Github Actions for Continuous Testing.

* Release 0.16.1 (12 Nov 2020)

New API:
`VerifyingKey.precompute()` supports `lazy` argument to delay precomputation
to the first time the key is used to verify a signature.

Doc fixes:
Documentation for the `VerifyingKey.precompute()` method.

Bug fix:
Make created signatures correct when the hash used is bigger than the curve
order bit size and the curve order is not a multiple of 8 (this affects
only users of custom curves or hashes with output larger than 512 bits).

Performance:
Speed up library load time by calculating the generator point multiplication
tables the first time the points are used, not when they are initialised.

Maintenance:
Include Python 3.9 in CI testing.
Test coverage for the `VerifyingKey.precompute()` method.
Small speed-ups for the test suite.

* Release 0.16.0 (27 Aug 2020)

New features:
Support for reading and writing private keys in PKCS#8 format.

New API:
`to_pem` and `to_der` now accept new parameter, `format`, to specify
the format of the encoded files, either the default, legacy `ssleay`, or
the new `pkcs8` to use PKCS#8. Note that only unencrypted PKCS#8 files are
supported.
Add `allow_truncate` to `verify` in `VerifyingKey`, it defaults to True,
when specified as False, the use of large hashes smaller than curves will be
disallowed (as it was in 0.14.1 and earlier).

Bug fix:
Correctly calculate signatures for private keys equal to n-1.
Make `PointJacobi` and thus `SigningKey` and `VerifyingKey` pickleable.

Doc fixes:
`to_pem` functions return `bytes` not `str`, document them as such.
`from_pem` and `from_pem` in `SigningKey` returns `SigningKey`, document them
as such.

Maintenance:
Ensure that version checks will work with Python 4.
Format the source with black.
Fix uses of `assert_` in the test suite.
Use newer Ubuntu in Travis to test against OpenSSL 1.1.1 (and thus
test the interoperability of ECDH code in Travis).

* Release 0.15 (02 Jan 2020)

Bug fixes:
`from curves import *` will now correctly import `BRAINPOOLP256r1` and
`BRAINPOOLP320r1` curves.

New features:
ECDH operations have a public explicit API.
Large hashes are now supported with small curves (e.g. SHA-256 can be used
with NIST192p).
`VerifyingKey` now supports the `precompute()` method to further speed up
signature verification with the given instance of the key.

New API:
`VerifyingKey`, `SigningKey`, `Public_key`, `Private_key` and
`CurveFp` now have `__eq__` methods.
`ecdsa.ecdh` module and `ECDH` class.
`PointJacobi` added.
`VerifyingKey.verify_digest`, `SigningKey.sign_digest` and
`SigningKey.sign_digest_deterministic` methods now accept the `allow_truncate`
argument to enable the use of hashes larger than the curve order.
`VerifyingKey` `from_pem` and `from_der` now accept `hashfunc` parameter
like other `from*` methods.
`VerifyingKey` has the `precompute` method now.
`VerifyingKey.from_public_point` may now not perform validation of public
point when `validate_point=False` argument is passed to the method.
`CurveFp` constructor now accepts the `h` parameter - the cofactor of the
elliptic curve, it's used for the selection of algorithm of public point
verification.

Performance:
`randrange` now will perform much fewer calls to the system random number
generator.
`PointJacobi` introduced and used as the underlying implementation; speeds up
the library by a factor of about 20.
The library has now optional dependencies on `gmpy` and `gmpy2`. When they are
available, the elliptic curve calculations will be about 3 times faster.

Maintenance:
expected minimum version of `six` module (1.9.0) is now specified explicitly
in `setup.py` and tested against.
Significantly faster test suite execution.

* Release 0.14.1 (06 Nov 2019)

Remove the obsolete `six.py` file from wheel

* Release 0.14 (06 Nov 2019)

Bug fixes:
Strict checking of DER requirements when parsing SEQUENCE, INTEGER,
OBJECT IDENTIFIER and BITSTRING objects.
DER parsers now consistently raise `UnexpectedDER` exception on malformed DER
encoded byte strings.
Make sure that both malformed and invalid signatures raise `BadSignatureError`.
Ensure that all `SigningKey` and `VerifyingKey` methods that should accept
bytes-like objects actually do accept them (also avoid copying input strings).
Make `SigningKey.sign_digest_deterministic` use default object hashfunc when
none was provided.
`encode_integer` now works for large integers.
Make `encode_oid` and `remove_object` correctly handle OBJECT IDENTIFIERs
with large second sub-identifier and padding in encoded sub-identifiers.

New features:
Deterministic signature methods now accept the `extra_entropy` parameter to
further randomise the selection of `k` (the nonce) for signature, as specified
in RFC6979.
Recovery of the public key from signature is now supported.
Support for SEC1/X9.62 formatted keys, all three encodings are supported:
"uncompressed", "compressed" and "hybrid". Both string, and PEM/DER will
automatically accept them, if the size of the key matches the curve.
Benchmarking application now provides performance numbers that are easier to
compare against OpenSSL.
Support for all Brainpool curves (non-twisted).

New API:
`CurveFp`: `__str__` is now supported.
`SigningKey.sign_deterministic`, `SigningKey.sign_digest_deterministic` and
`generate_k`: extra_entropy parameter was added
`Signature.recover_public_keys` was added
`VerifyingKey.from_public_key_recovery` and
`VerifyingKey.from_public_key_recovery_with_digest` were added
`VerifyingKey.to_string`: `encoding` parameter was added
`VerifyingKey.to_der` and `SigningKey.to_der`: `point_encoding` parameter was
added.
`encode_bitstring`: `unused` parameter was added
`remove_bitstring`: `expect_unused` parameter was added
`SECP256k1` is now part of `curves` `*` import
`Curves`: `__repr__` is now supported
`VerifyingKey`: `__repr__` is now supported

Deprecations:
Python 2.5 is not supported anymore - dead code removal.
`from ecdsa.keys import *` will now import only objects defined in that module.
Trying to decode a malformed point using `VerifyingKey.from_string`
will rise now the `MalformedPointError` exception (that inherits from
`AssertionError` but is not it).
Multiple functions in `numbertheory` are considered deprecated: `phi`,
`carmichael`, `carmichael_of_factorized`, `carmichael_of_ppower`,
`order_mod`, `largest_factor_relatively_prime`, `kinda_order_mod`. They will
now emit `DeprecationWarning` when used. Run the application or test suite
with `-Wd` option or with `PYTHONWARNINGS=default` environment variable to
verify if those methods are not used. They will be removed completely in a
future release.
`encode_bitstring` and `decode_bitstring` expect the number of unused
bits to be passed as an argument now. They will emit `DeprecationWarning`
if they are used in the deprecated way.
modular_exp: will emit `DeprecationWarning`

Hardening:
Deterministic signatures now verify that the signature won't leak private
key through a very unlikely selection of `k` value (the nonce).
Nonce bit size hiding was added (hardening against Minerva attack). Please
note that it DOES NOT make the library secure against side-channel attacks
(timing attacks).

Performance:
The public key in key generation is not verified twice now, making key
generation and private key reading about 33% faster.
Microoptimisation to `inverse_mod` function, increasing performance by about
40% for all operations.

Maintenance:
Extended test coverage to newer python versions.
Fixes to examples in README.md: correct commands, more correct code (now works
on Python 3).
Stopped bundling `six`
Moved sources into `src` subdirectory
Made benchmarking script standalone (runnable either with `tox -e speed`, or
after installation, with `python speed.py`)
Now test coverage reported to coveralls is branch coverage, not line coverage
Autodetection of curves supported by OpenSSL (test suite compatibility with
Fedora OpenSSL package).
More readable error messages (exceptions) in `der` module.
Documentation to `VerifyingKey`, `SigningKey` and signature encoder/decoder
functions added.
Added measuring and verifying condition coverage to Continuous Integration.
Big clean-up of the test suite, use pytest parametrisation and hypothesis
for better test coverage and more precise failure reporting.
Use platform-provided `math.gcd`, when provided.

* Release 0.13.3 (07 Oct 2019)

Fix CVE-2019-14853 - possible DoS caused by malformed signature decoding and
signature malleability.

Also harden key decoding from string and DER encodings.

* Release 0.13.2 (17 Apr 2019)

Restore compatibility of setup.py with Python 2.6 and 2.7.

* Release 0.13.1 (17 Apr 2019)

Fix the PyPI wheel - the old version included .pyc files.

* Release 0.13 (07 Feb 2015)

Fix the argument order for Curve constructor (put openssl_name= at the end,
with a default value) to unbreak compatibility with external callers who used
the 0.11 convention.

* Release 0.12 (06 Feb 2015)

Switch to Versioneer for version-string management (fixing the broken
`ecdsa.__version__` attribute). Add Curve.openssl_name property. Mention
secp256k1 in README, test against OpenSSL. Produce "wheel" distributions. Add
py3.4 and pypy3 compatibility testing. Other minor fixes.

* Release 0.11 (10 Mar 2014)

Add signature-encoding functions "sigencode_{strings,string,der}_canonize"
which canonicalize the S value (using the smaller of the two possible
values). Add "validate_point=" argument to VerifyingKey.from_string()
constructor (defaults to True) which can be used to disable time-consuming
point validation when importing a pre-validated verifying key. Drop python2.5
support (untested but not explicitly broken yet), update trove classifiers.

* Release 0.10 (23 Oct 2013)

Make the secp256k1 available in __init__.py too (thanks to Scott Bannert).

* Release 0.9 (01 Oct 2013)

Add secp256k1 curve (thanks to Benjamin Dauvergne). Add deterministic (no
entropy needed) signatures (thanks to slush). Added py3.2/py3.3 compatibility
(thanks to Elizabeth Myers).

* Release 0.8 (04 Oct 2011)

Small API addition: accept a hashfunc= argument in the constructors for
SigningKey and VerifyingKey. This makes it easier to write wrappers that e.g.
use NIST256p and SHA256 without their obligating callers to pass
hashfunc=sha256 in each time they call sign() or verify().

* Release 0.7 (28 Nov 2010)

Fix test failure against OpenSSL-1.0.0 (previous versions only worked against
openssl-0.9.8 or earlier). Increase python requirement to py2.5 or later
(still no py3 compatibility, but work is underway). Replace the use of obsolete
'sha' library with modern 'hashlib'. Clean up unit test runner (stop using
subprocesses).

* Release 0.6 (15 Oct 2010)

Small packaging changes: extract the version number from git, add
'setup.py test' command, set exit code correctly on test failure. Fix pyflakes
warnings.

* Release 0.5 (27 Apr 2010)

Initial release. EC-DSA signature for five NIST "Suite B" GF(p) curves:
prime192v1, secp224r1, prime256v1, secp384r1, and secp521r1. DER/PEM
input/output functions, seed-to-randrange helper functions.
