哈希函数——示例

In this section we shall provide a few examples about calculating cryptographic hash functions in Python.

在本节中，我们将提供一些有关在 Python 中使用加密哈希函数计算的示例。

在 Python 中使用加密哈希函数计算

We shall use the standard Python library hashlib. The input data for hashing should be given as bytes sequence (bytes object), so we need to encode the input string using some text encoding, e.g. utf8. The produced output data is also a bytes sequence, which can be printed as hex digits using binascii.hexlify() as shown below:

我们将使用标准的 Python 库 hashlib。用于哈希的输入数据应该以字节序列（bytes 对象）的形式给出，因此我们需要使用一些文本编码例如 utf8 对输入字符串进行编码。产生的输出数据也是一个字节序列，可以使用 binascii.hexlify() 打印为十六进制数字，如下所示:

import hashlib, binascii

text = 'hello'
data = text.encode("utf8")

sha256hash = hashlib.sha256(data).digest()
print("SHA-256:   ", binascii.hexlify(sha256hash))

sha3_256 = hashlib.sha3_256(data).digest()
print("SHA3-256:  ", binascii.hexlify(sha3_256))

blake2s = hashlib.new('blake2s', data).digest()
print("BLAKE2s:   ", binascii.hexlify(blake2s))

ripemd160 = hashlib.new('ripemd160', data).digest()
print("RIPEMD-160:", binascii.hexlify(ripemd160))

Run the above code example: https://repl.it/@nakov/Hashes-SHA2-SHA3-BLAKE2-RIPEMD-in-Python.

可在此链接中运行该示例代码：https://repl.it/@nakov/Hashes-SHA2-SHA3-BLAKE2-RIPEMD-in-Python。

The expected output from the above example looks like this:

上述示例的预期输出如下：

SHA-256:    b'2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824'
SHA3-256:   b'3338be694f50c5f338814986cdf0686453a888b84f424d792af4b9202398f392'
BLAKE2s:    b'19213bacc58dee6dbde3ceb9a47cbb330b3d86f8cca8997eb00be456f140ca25'
RIPEMD-160: b'108f07b8382412612c048d07d13f814118445acd'

Calculating Keccak-256 hashes (the hash function used in the Ethereum blockchain) requires non-standard Python functions. In the below example we use the pycryptodome package available from PyPI: https://pypi.org/project/pycryptodome.

计算 Keccak-256 哈希（以太坊区块链中使用的哈希函数）需要非标准的 Python 函数。在以下示例中，我们使用可从 PyPI 获得的 pycryptodome 软件包：https://pypi.org/project/pycryptodome。

First install "pycryptodome" (https://www.pycryptodome.org)

首先安装 pycryptodome 软件包（https://www.pycryptodome.org）。

pip install pycryptodome

Now write some Python code to calculate a Keccak-256 hash:

现在编写一些 Python 代码来计算一个 Keccak-256 的哈希值：

from Crypto.Hash import keccak
import binascii

keccak256 = keccak.new(data=b'hello', digest_bits=256).digest()
print("Keccak256:", binascii.hexlify(keccak256))

Run the above code example: https://repl.it/@nakov/Keccak256-in-Python.

可在此链接中运行该示例代码：https://repl.it/@nakov/Keccak256-in-Python。

The output from the above examples is:

上述示例的预期输出为：

Keccak256: b'1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8'