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-Metadata-Version: 2.1
-Name: ecdsa
-Version: 0.16.1
-Summary: ECDSA cryptographic signature library (pure python)
-Home-page: http://github.com/warner/python-ecdsa
-Author: Brian Warner
-Author-email: [email protected]
-License: MIT
-Platform: UNKNOWN
-Classifier: Programming Language :: Python
-Classifier: Programming Language :: Python :: 2
-Classifier: Programming Language :: Python :: 2.6
-Classifier: Programming Language :: Python :: 2.7
-Classifier: Programming Language :: Python :: 3
-Classifier: Programming Language :: Python :: 3.3
-Classifier: Programming Language :: Python :: 3.4
-Classifier: Programming Language :: Python :: 3.5
-Classifier: Programming Language :: Python :: 3.6
-Classifier: Programming Language :: Python :: 3.7
-Classifier: Programming Language :: Python :: 3.8
-Requires-Python: >=2.6, !=3.0.*, !=3.1.*, !=3.2.*
-Description-Content-Type: text/markdown
-Requires-Dist: six (>=1.9.0)
-Provides-Extra: gmpy
-Requires-Dist: gmpy ; extra == 'gmpy'
-Provides-Extra: gmpy2
-Requires-Dist: gmpy2 ; extra == 'gmpy2'
-
-# Pure-Python ECDSA
-
-[![build status](https://travis-ci.org/warner/python-ecdsa.png)](http://travis-ci.org/warner/python-ecdsa)
-[![Coverage Status](https://coveralls.io/repos/warner/python-ecdsa/badge.svg)](https://coveralls.io/r/warner/python-ecdsa)
-[![condition coverage](https://img.shields.io/badge/condition%20coverage-81%25-yellow)](https://travis-ci.org/warner/python-ecdsa/jobs/626479178#L776)
-[![Latest Version](https://img.shields.io/pypi/v/ecdsa.svg?style=flat)](https://pypi.python.org/pypi/ecdsa/)
-![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg?style=flat)
-
-
-This is an easy-to-use implementation of ECDSA cryptography (Elliptic Curve
-Digital Signature Algorithm), implemented purely in Python, released under
-the MIT license. With this library, you can quickly create keypairs (signing
-key and verifying key), sign messages, and verify the signatures. The keys
-and signatures are very short, making them easy to handle and incorporate
-into other protocols.
-
-## Features
-
-This library provides key generation, signing, and verifying, for five
-popular NIST "Suite B" GF(p) (_prime field_) curves, with key lengths of 192,
-224, 256, 384, and 521 bits. The "short names" for these curves, as known by
-the OpenSSL tool (`openssl ecparam -list_curves`), are: `prime192v1`,
-`secp224r1`, `prime256v1`, `secp384r1`, and `secp521r1`. It includes the
-256-bit curve `secp256k1` used by Bitcoin. There is also support for the
-regular (non-twisted) variants of Brainpool curves from 160 to 512 bits. The
-"short names" of those curves are: `brainpoolP160r1`, `brainpoolP192r1`,
-`brainpoolP224r1`, `brainpoolP256r1`, `brainpoolP320r1`, `brainpoolP384r1`,
-`brainpoolP512r1`.
-No other curves are included, but it is not too hard to add support for more
-curves over prime fields.
-
-## Dependencies
-
-This library uses only Python and the 'six' package. It is compatible with
-Python 2.6, 2.7 and 3.3+. It also supports execution on the alternative
-implementations like pypy and pypy3.
-
-If `gmpy2` or `gmpy` is installed, they will be used for faster arithmetic.
-Either of them can be installed after this library is installed,
-`python-ecdsa` will detect their presence on start-up and use them
-automatically.
-
-To run the OpenSSL compatibility tests, the 'openssl' tool must be in your
-`PATH`. This release has been tested successfully against OpenSSL 0.9.8o,
-1.0.0a, 1.0.2f and 1.1.1d (among others).
-
-
-## Installation
-
-This library is available on PyPI, it's recommended to install it using `pip`:
-
-```
-pip install ecdsa
-```
-
-In case higher performance is wanted and using native code is not a problem,
-it's possible to specify installation together with `gmpy2`:
-
-```
-pip install ecdsa[gmpy2]
-```
-
-or (slower, legacy option):
-```
-pip install ecdsa[gmpy]
-```
-
-## Speed
-
-The following table shows how long this library takes to generate keypairs
-(`keygen`), to sign data (`sign`), and to verify those signatures (`verify`).
-All those values are in seconds.
-For convenience, the inverses of those values are also provided:
-how many keys per second can be generated (`keygen/s`), how many signatures
-can be made per second (`sign/s`) and how many signatures can be verified
-per second (`verify/s`). The size of raw signature (generally the smallest
-way a signature can be encoded) is also provided in the `siglen` column.
-Use `tox -e speed` to generate this table on your own computer.
-On an Intel Core i7 4790K @ 4.0GHz I'm getting the following performance:
-
-```
-                  siglen    keygen   keygen/s      sign     sign/s    verify   verify/s
-        NIST192p:     48   0.00035s   2893.02   0.00038s   2620.53   0.00069s   1458.92
-        NIST224p:     56   0.00043s   2307.11   0.00048s   2092.00   0.00088s   1131.33
-        NIST256p:     64   0.00056s   1793.70   0.00061s   1639.87   0.00113s    883.79
-        NIST384p:     96   0.00116s    864.33   0.00124s    806.29   0.00233s    429.87
-        NIST521p:    132   0.00221s    452.16   0.00234s    427.31   0.00460s    217.19
-       SECP256k1:     64   0.00056s   1772.65   0.00061s   1628.73   0.00110s    912.13
- BRAINPOOLP160r1:     40   0.00026s   3801.86   0.00029s   3401.11   0.00052s   1930.47
- BRAINPOOLP192r1:     48   0.00034s   2925.73   0.00038s   2634.34   0.00070s   1438.06
- BRAINPOOLP224r1:     56   0.00044s   2287.98   0.00048s   2083.87   0.00088s   1137.52
- BRAINPOOLP256r1:     64   0.00056s   1774.11   0.00061s   1628.25   0.00112s    890.71
- BRAINPOOLP320r1:     80   0.00081s   1238.18   0.00087s   1146.71   0.00151s    661.95
- BRAINPOOLP384r1:     96   0.00117s    855.47   0.00124s    804.56   0.00241s    414.83
- BRAINPOOLP512r1:    128   0.00223s    447.99   0.00234s    427.49   0.00437s    229.09
-
-                       ecdh     ecdh/s
-        NIST192p:   0.00110s    910.70
-        NIST224p:   0.00143s    701.17
-        NIST256p:   0.00178s    560.44
-        NIST384p:   0.00383s    261.03
-        NIST521p:   0.00745s    134.23
-       SECP256k1:   0.00168s    596.23
- BRAINPOOLP160r1:   0.00085s   1174.02
- BRAINPOOLP192r1:   0.00113s    883.47
- BRAINPOOLP224r1:   0.00145s    687.82
- BRAINPOOLP256r1:   0.00195s    514.03
- BRAINPOOLP320r1:   0.00277s    360.80
- BRAINPOOLP384r1:   0.00412s    242.58
- BRAINPOOLP512r1:   0.00787s    127.12
-```
-
-To test performance with `gmpy2` loaded, use `tox -e speedgmpy2`.
-On the same machine I'm getting the following performance with `gmpy2`:
-```
-                  siglen    keygen   keygen/s      sign     sign/s    verify   verify/s
-        NIST192p:     48   0.00017s   5945.50   0.00018s   5544.66   0.00033s   3002.54
-        NIST224p:     56   0.00021s   4742.14   0.00022s   4463.52   0.00044s   2248.59
-        NIST256p:     64   0.00024s   4155.73   0.00025s   3994.28   0.00047s   2105.34
-        NIST384p:     96   0.00041s   2415.06   0.00043s   2316.41   0.00085s   1177.18
-        NIST521p:    132   0.00072s   1391.14   0.00074s   1359.63   0.00140s    716.31
-       SECP256k1:     64   0.00024s   4216.50   0.00025s   3994.52   0.00047s   2120.57
- BRAINPOOLP160r1:     40   0.00014s   7038.99   0.00015s   6501.55   0.00029s   3397.79
- BRAINPOOLP192r1:     48   0.00017s   5983.18   0.00018s   5626.08   0.00035s   2843.62
- BRAINPOOLP224r1:     56   0.00021s   4727.54   0.00022s   4464.86   0.00043s   2326.84
- BRAINPOOLP256r1:     64   0.00024s   4221.00   0.00025s   4010.26   0.00049s   2046.40
- BRAINPOOLP320r1:     80   0.00032s   3142.14   0.00033s   3009.15   0.00061s   1652.88
- BRAINPOOLP384r1:     96   0.00041s   2415.98   0.00043s   2340.35   0.00083s   1198.77
- BRAINPOOLP512r1:    128   0.00064s   1567.27   0.00066s   1526.33   0.00127s    788.51
-
-                       ecdh     ecdh/s
-        NIST192p:   0.00051s   1960.26
-        NIST224p:   0.00067s   1502.97
-        NIST256p:   0.00073s   1376.12
-        NIST384p:   0.00132s    758.68
-        NIST521p:   0.00231s    433.23
-       SECP256k1:   0.00072s   1387.18
- BRAINPOOLP160r1:   0.00042s   2366.60
- BRAINPOOLP192r1:   0.00049s   2026.80
- BRAINPOOLP224r1:   0.00067s   1486.52
- BRAINPOOLP256r1:   0.00076s   1310.31
- BRAINPOOLP320r1:   0.00101s    986.16
- BRAINPOOLP384r1:   0.00131s    761.35
- BRAINPOOLP512r1:   0.00211s    473.30
-```
-
-(there's also `gmpy` version, execute it using `tox -e speedgmpy`)
-
-For comparison, a highly optimised implementation (including curve-specific
-assembly for some curves), like the one in OpenSSL 1.1.1d, provides following
-performance numbers on the same machine.
-Run `openssl speed ecdsa` and `openssl speed ecdh` to reproduce it:
-```
-                              sign    verify    sign/s verify/s
- 192 bits ecdsa (nistp192)   0.0002s   0.0002s   4785.6   5380.7
- 224 bits ecdsa (nistp224)   0.0000s   0.0001s  22475.6   9822.0
- 256 bits ecdsa (nistp256)   0.0000s   0.0001s  45069.6  14166.6
- 384 bits ecdsa (nistp384)   0.0008s   0.0006s   1265.6   1648.1
- 521 bits ecdsa (nistp521)   0.0003s   0.0005s   3753.1   1819.5
- 256 bits ecdsa (brainpoolP256r1)   0.0003s   0.0003s   2983.5   3333.2
- 384 bits ecdsa (brainpoolP384r1)   0.0008s   0.0007s   1258.8   1528.1
- 512 bits ecdsa (brainpoolP512r1)   0.0015s   0.0012s    675.1    860.1
-
-                               op      op/s
- 192 bits ecdh (nistp192)   0.0002s   4853.4
- 224 bits ecdh (nistp224)   0.0001s  15252.1
- 256 bits ecdh (nistp256)   0.0001s  18436.3
- 384 bits ecdh (nistp384)   0.0008s   1292.7
- 521 bits ecdh (nistp521)   0.0003s   2884.7
- 256 bits ecdh (brainpoolP256r1)   0.0003s   3066.5
- 384 bits ecdh (brainpoolP384r1)   0.0008s   1298.0
- 512 bits ecdh (brainpoolP512r1)   0.0014s    694.8
-```
-
-Keys and signature can be serialized in different ways (see Usage, below).
-For a NIST192p key, the three basic representations require strings of the
-following lengths (in bytes):
-
-    to_string:  signkey= 24, verifykey= 48, signature=48
-    compressed: signkey=n/a, verifykey= 25, signature=n/a
-    DER:        signkey=106, verifykey= 80, signature=55
-    PEM:        signkey=278, verifykey=162, (no support for PEM signatures)
-
-## History
-
-In 2006, Peter Pearson announced his pure-python implementation of ECDSA in a
-[message to sci.crypt][1], available from his [download site][2]. In 2010,
-Brian Warner wrote a wrapper around this code, to make it a bit easier and
-safer to use. Hubert Kario then included an implementation of elliptic curve
-cryptography that uses Jacobian coordinates internally, improving performance
-about 20-fold. You are looking at the README for this wrapper.
-
-[1]: http://www.derkeiler.com/Newsgroups/sci.crypt/2006-01/msg00651.html
-[2]: http://webpages.charter.net/curryfans/peter/downloads.html
-
-## Testing
-
-To run the full test suite, do this:
-
-    tox -e coverage
-
-On an Intel Core i7 4790K @ 4.0GHz, the tests take about 16 seconds to execute.
-The test suite uses
-[`hypothesis`](https://github.com/HypothesisWorks/hypothesis) so there is some
-inherent variability in the test suite execution time.
-
-One part of `test_pyecdsa.py` checks compatibility with OpenSSL, by
-running the "openssl" CLI tool, make sure it's in your `PATH` if you want
-to test compatibility with it.
-
-## Security
-
-This library was not designed with security in mind. If you are processing
-data that needs to be protected we suggest you use a quality wrapper around
-OpenSSL. [pyca/cryptography](https://cryptography.io) is one example of such
-a wrapper. The primary use-case of this library is as a portable library for
-interoperability testing and as a teaching tool.
-
-**This library does not protect against side channel attacks.**
-
-Do not allow attackers to measure how long it takes you to generate a keypair
-or sign a message. Do not allow attackers to run code on the same physical
-machine when keypair generation or signing is taking place (this includes
-virtual machines). Do not allow attackers to measure how much power your
-computer uses while generating the keypair or signing a message. Do not allow
-attackers to measure RF interference coming from your computer while generating
-a keypair or signing a message. Note: just loading the private key will cause
-keypair generation. Other operations or attack vectors may also be
-vulnerable to attacks. **For a sophisticated attacker observing just one
-operation with a private key will be sufficient to completely
-reconstruct the private key**.
-
-Please also note that any Pure-python cryptographic library will be vulnerable
-to the same side channel attacks. This is because Python does not provide
-side-channel secure primitives (with the exception of
-[`hmac.compare_digest()`][3]), making side-channel secure programming
-impossible.
-
-This library depends upon a strong source of random numbers. Do not use it on
-a system where `os.urandom()` does not provide cryptographically secure
-random numbers.
-
-[3]: https://docs.python.org/3/library/hmac.html#hmac.compare_digest
-
-## Usage
-
-You start by creating a `SigningKey`. You can use this to sign data, by passing
-in data as a byte string and getting back the signature (also a byte string).
-You can also ask a `SigningKey` to give you the corresponding `VerifyingKey`.
-The `VerifyingKey` can be used to verify a signature, by passing it both the
-data string and the signature byte string: it either returns True or raises
-`BadSignatureError`.
-
-```python
-from ecdsa import SigningKey
-sk = SigningKey.generate() # uses NIST192p
-vk = sk.verifying_key
-signature = sk.sign(b"message")
-assert vk.verify(signature, b"message")
-```
-
-Each `SigningKey`/`VerifyingKey` is associated with a specific curve, like
-NIST192p (the default one). Longer curves are more secure, but take longer to
-use, and result in longer keys and signatures.
-
-```python
-from ecdsa import SigningKey, NIST384p
-sk = SigningKey.generate(curve=NIST384p)
-vk = sk.verifying_key
-signature = sk.sign(b"message")
-assert vk.verify(signature, b"message")
-```
-
-The `SigningKey` can be serialized into several different formats: the shortest
-is to call `s=sk.to_string()`, and then re-create it with
-`SigningKey.from_string(s, curve)` . This short form does not record the
-curve, so you must be sure to pass to `from_string()` the same curve you used
-for the original key. The short form of a NIST192p-based signing key is just 24
-bytes long. If a point encoding is invalid or it does not lie on the specified
-curve, `from_string()` will raise `MalformedPointError`.
-
-```python
-from ecdsa import SigningKey, NIST384p
-sk = SigningKey.generate(curve=NIST384p)
-sk_string = sk.to_string()
-sk2 = SigningKey.from_string(sk_string, curve=NIST384p)
-print(sk_string.hex())
-print(sk2.to_string().hex())
-```
-
-Note: while the methods are called `to_string()` the type they return is
-actually `bytes`, the "string" part is leftover from Python 2.
-
-`sk.to_pem()` and `sk.to_der()` will serialize the signing key into the same
-formats that OpenSSL uses. The PEM file looks like the familiar ASCII-armored
-`"-----BEGIN EC PRIVATE KEY-----"` base64-encoded format, and the DER format
-is a shorter binary form of the same data.
-`SigningKey.from_pem()/.from_der()` will undo this serialization. These
-formats include the curve name, so you do not need to pass in a curve
-identifier to the deserializer. In case the file is malformed `from_der()`
-and `from_pem()` will raise `UnexpectedDER` or` MalformedPointError`.
-
-```python
-from ecdsa import SigningKey, NIST384p
-sk = SigningKey.generate(curve=NIST384p)
-sk_pem = sk.to_pem()
-sk2 = SigningKey.from_pem(sk_pem)
-# sk and sk2 are the same key
-```
-
-Likewise, the `VerifyingKey` can be serialized in the same way:
-`vk.to_string()/VerifyingKey.from_string()`, `to_pem()/from_pem()`, and
-`to_der()/from_der()`. The same `curve=` argument is needed for
-`VerifyingKey.from_string()`.
-
-```python
-from ecdsa import SigningKey, VerifyingKey, NIST384p
-sk = SigningKey.generate(curve=NIST384p)
-vk = sk.verifying_key
-vk_string = vk.to_string()
-vk2 = VerifyingKey.from_string(vk_string, curve=NIST384p)
-# vk and vk2 are the same key
-
-from ecdsa import SigningKey, VerifyingKey, NIST384p
-sk = SigningKey.generate(curve=NIST384p)
-vk = sk.verifying_key
-vk_pem = vk.to_pem()
-vk2 = VerifyingKey.from_pem(vk_pem)
-# vk and vk2 are the same key
-```
-
-There are a couple of different ways to compute a signature. Fundamentally,
-ECDSA takes a number that represents the data being signed, and returns a
-pair of numbers that represent the signature. The `hashfunc=` argument to
-`sk.sign()` and `vk.verify()` is used to turn an arbitrary string into
-fixed-length digest, which is then turned into a number that ECDSA can sign,
-and both sign and verify must use the same approach. The default value is
-`hashlib.sha1`, but if you use NIST256p or a longer curve, you can use
-`hashlib.sha256` instead.
-
-There are also multiple ways to represent a signature. The default
-`sk.sign()` and `vk.verify()` methods present it as a short string, for
-simplicity and minimal overhead. To use a different scheme, use the
-`sk.sign(sigencode=)` and `vk.verify(sigdecode=)` arguments. There are helper
-functions in the `ecdsa.util` module that can be useful here.
-
-It is also possible to create a `SigningKey` from a "seed", which is
-deterministic. This can be used in protocols where you want to derive
-consistent signing keys from some other secret, for example when you want
-three separate keys and only want to store a single master secret. You should
-start with a uniformly-distributed unguessable seed with about `curve.baselen`
-bytes of entropy, and then use one of the helper functions in `ecdsa.util` to
-convert it into an integer in the correct range, and then finally pass it
-into `SigningKey.from_secret_exponent()`, like this:
-
-```python
-import os
-from ecdsa import NIST384p, SigningKey
-from ecdsa.util import randrange_from_seed__trytryagain
-
-def make_key(seed):
-  secexp = randrange_from_seed__trytryagain(seed, NIST384p.order)
-  return SigningKey.from_secret_exponent(secexp, curve=NIST384p)
-
-seed = os.urandom(NIST384p.baselen) # or other starting point
-sk1a = make_key(seed)
-sk1b = make_key(seed)
-# note: sk1a and sk1b are the same key
-assert sk1a.to_string() == sk1b.to_string()
-sk2 = make_key(b"2-"+seed)  # different key
-assert sk1a.to_string() != sk2.to_string()
-```
-
-In case the application will verify a lot of signatures made with a single
-key, it's possible to precompute some of the internal values to make
-signature verification significantly faster. The break-even point occurs at
-about 100 signatures verified.
-
-To perform precomputation, you can call the `precompute()` method
-on `VerifyingKey` instance:
-```python
-from ecdsa import SigningKey, NIST384p
-sk = SigningKey.generate(curve=NIST384p)
-vk = sk.verifying_key
-vk.precompute()
-signature = sk.sign(b"message")
-assert vk.verify(signature, b"message")
-```
-
-Once `precompute()` was called, all signature verifications with this key will
-be faster to execute.
-
-## OpenSSL Compatibility
-
-To produce signatures that can be verified by OpenSSL tools, or to verify
-signatures that were produced by those tools, use:
-
-```python
-# openssl ecparam -name prime256v1 -genkey -out sk.pem
-# openssl ec -in sk.pem -pubout -out vk.pem
-# echo "data for signing" > data
-# openssl dgst -sha256 -sign sk.pem -out data.sig data
-# openssl dgst -sha256 -verify vk.pem -signature data.sig data
-# openssl dgst -sha256 -prverify sk.pem -signature data.sig data
-
-import hashlib
-from ecdsa import SigningKey, VerifyingKey
-from ecdsa.util import sigencode_der, sigdecode_der
-
-with open("vk.pem") as f:
-   vk = VerifyingKey.from_pem(f.read())
-
-with open("data", "rb") as f:
-   data = f.read()
-
-with open("data.sig", "rb") as f:
-   signature = f.read()
-
-assert vk.verify(signature, data, hashlib.sha256, sigdecode=sigdecode_der)
-
-with open("sk.pem") as f:
-   sk = SigningKey.from_pem(f.read(), hashlib.sha256)
-
-new_signature = sk.sign_deterministic(data, sigencode=sigencode_der)
-
-with open("data.sig2", "wb") as f:
-   f.write(new_signature)
-
-# openssl dgst -sha256 -verify vk.pem -signature data.sig2 data
-```
-
-Note: if compatibility with OpenSSL 1.0.0 or earlier is necessary, the
-`sigencode_string` and `sigdecode_string` from `ecdsa.util` can be used for
-respectively writing and reading the signatures.
-
-The keys also can be written in format that openssl can handle:
-
-```python
-from ecdsa import SigningKey, VerifyingKey
-
-with open("sk.pem") as f:
-    sk = SigningKey.from_pem(f.read())
-with open("sk.pem", "wb") as f:
-    f.write(sk.to_pem())
-
-with open("vk.pem") as f:
-    vk = VerifyingKey.from_pem(f.read())
-with open("vk.pem", "wb") as f:
-    f.write(vk.to_pem())
-```
-
-## Entropy
-
-Creating a signing key with `SigningKey.generate()` requires some form of
-entropy (as opposed to
-`from_secret_exponent`/`from_string`/`from_der`/`from_pem`,
-which are deterministic and do not require an entropy source). The default
-source is `os.urandom()`, but you can pass any other function that behaves
-like `os.urandom` as the `entropy=` argument to do something different. This
-may be useful in unit tests, where you want to achieve repeatable results. The
-`ecdsa.util.PRNG` utility is handy here: it takes a seed and produces a strong
-pseudo-random stream from it:
-
-```python
-from ecdsa.util import PRNG
-from ecdsa import SigningKey
-rng1 = PRNG(b"seed")
-sk1 = SigningKey.generate(entropy=rng1)
-rng2 = PRNG(b"seed")
-sk2 = SigningKey.generate(entropy=rng2)
-# sk1 and sk2 are the same key
-```
-
-Likewise, ECDSA signature generation requires a random number, and each
-signature must use a different one (using the same number twice will
-immediately reveal the private signing key). The `sk.sign()` method takes an
-`entropy=` argument which behaves the same as `SigningKey.generate(entropy=)`.
-
-## Deterministic Signatures
-
-If you call `SigningKey.sign_deterministic(data)` instead of `.sign(data)`,
-the code will generate a deterministic signature instead of a random one.
-This uses the algorithm from RFC6979 to safely generate a unique `k` value,
-derived from the private key and the message being signed. Each time you sign
-the same message with the same key, you will get the same signature (using
-the same `k`).
-
-This may become the default in a future version, as it is not vulnerable to
-failures of the entropy source.
-
-## Examples
-
-Create a NIST192p keypair and immediately save both to disk:
-
-```python
-from ecdsa import SigningKey
-sk = SigningKey.generate()
-vk = sk.verifying_key
-with open("private.pem", "wb") as f:
-    f.write(sk.to_pem())
-with open("public.pem", "wb") as f:
-    f.write(vk.to_pem())
-```
-
-Load a signing key from disk, use it to sign a message (using SHA-1), and write
-the signature to disk:
-
-```python
-from ecdsa import SigningKey
-with open("private.pem") as f:
-    sk = SigningKey.from_pem(f.read())
-with open("message", "rb") as f:
-    message = f.read()
-sig = sk.sign(message)
-with open("signature", "wb") as f:
-    f.write(sig)
-```
-
-Load the verifying key, message, and signature from disk, and verify the
-signature (assume SHA-1 hash):
-
-```python
-from ecdsa import VerifyingKey, BadSignatureError
-vk = VerifyingKey.from_pem(open("public.pem").read())
-with open("message", "rb") as f:
-    message = f.read()
-with open("signature", "rb") as f:
-    sig = f.read()
-try:
-    vk.verify(sig, message)
-    print "good signature"
-except BadSignatureError:
-    print "BAD SIGNATURE"
-```
-
-Create a NIST521p keypair:
-
-```python
-from ecdsa import SigningKey, NIST521p
-sk = SigningKey.generate(curve=NIST521p)
-vk = sk.verifying_key
-```
-
-Create three independent signing keys from a master seed:
-
-```python
-from ecdsa import NIST192p, SigningKey
-from ecdsa.util import randrange_from_seed__trytryagain
-
-def make_key_from_seed(seed, curve=NIST192p):
-    secexp = randrange_from_seed__trytryagain(seed, curve.order)
-    return SigningKey.from_secret_exponent(secexp, curve)
-
-sk1 = make_key_from_seed("1:%s" % seed)
-sk2 = make_key_from_seed("2:%s" % seed)
-sk3 = make_key_from_seed("3:%s" % seed)
-```
-
-Load a verifying key from disk and print it using hex encoding in
-uncompressed and compressed format (defined in X9.62 and SEC1 standards):
-
-```python
-from ecdsa import VerifyingKey
-
-with open("public.pem") as f:
-    vk = VerifyingKey.from_pem(f.read())
-
-print("uncompressed: {0}".format(vk.to_string("uncompressed").hex()))
-print("compressed: {0}".format(vk.to_string("compressed").hex()))
-```
-
-Load a verifying key from a hex string from compressed format, output
-uncompressed:
-
-```python
-from ecdsa import VerifyingKey, NIST256p
-
-comp_str = '022799c0d0ee09772fdd337d4f28dc155581951d07082fb19a38aa396b67e77759'
-vk = VerifyingKey.from_string(bytearray.fromhex(comp_str), curve=NIST256p)
-print(vk.to_string("uncompressed").hex())
-```
-
-ECDH key exchange with remote party
-
-```python
-from ecdsa import ECDH, NIST256p
-
-ecdh = ECDH(curve=NIST256p)
-ecdh.generate_private_key()
-local_public_key = ecdh.get_public_key()
-#send `local_public_key` to remote party and receive `remote_public_key` from remote party
-with open("remote_public_key.pem") as e:
-    remote_public_key = e.read()
-ecdh.load_received_public_key_pem(remote_public_key)
-secret = ecdh.generate_sharedsecret_bytes()
-```
-
-