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# `hashlib` — Secure hashes and message digests

Código-fonte: Lib/hashlib.py

This module implements a common interface to many different secure hash and message digest algorithms. Included are the FIPS secure hash algorithms SHA1, SHA224, SHA256, SHA384, and SHA512 (defined in FIPS 180-2) as well as RSA’s MD5 algorithm (defined in Internet RFC 1321). The terms “secure hash” and “message digest” are interchangeable. Older algorithms were called message digests. The modern term is secure hash.

Nota

Se você quiser as funções de hash adler32 ou crc32, elas estão disponíveis no módulo `zlib`.

Aviso

Some algorithms have known hash collision weaknesses, refer to the “See also” section at the end.

## Algoritmos de hash

There is one constructor method named for each type of hash. All return a hash object with the same simple interface. For example: use `sha256()` to create a SHA-256 hash object. You can now feed this object with bytes-like objects (normally `bytes`) using the `update()` method. At any point you can ask it for the digest of the concatenation of the data fed to it so far using the `digest()` or `hexdigest()` methods.

Nota

For better multithreading performance, the Python GIL is released for data larger than 2047 bytes at object creation or on update.

Nota

Feeding string objects into `update()` is not supported, as hashes work on bytes, not on characters.

Constructors for hash algorithms that are always present in this module are `sha1()`, `sha224()`, `sha256()`, `sha384()`, `sha512()`, `blake2b()`, and `blake2s()`. `md5()` is normally available as well, though it may be missing or blocked if you are using a rare “FIPS compliant” build of Python. Additional algorithms may also be available depending upon the OpenSSL library that Python uses on your platform. On most platforms the `sha3_224()`, `sha3_256()`, `sha3_384()`, `sha3_512()`, `shake_128()`, `shake_256()` are also available.

Novo na versão 3.6: SHA3 (Keccak) and SHAKE constructors `sha3_224()`, `sha3_256()`, `sha3_384()`, `sha3_512()`, `shake_128()`, `shake_256()`.

Novo na versão 3.6: `blake2b()` and `blake2s()` were added.

Alterado na versão 3.9: Todos os construtores de hashlib aceitam um argumento somente-nomeado usedforsecurity com o valor padrão `True`. Um valor falso permite o uso de algoritmos de hash inseguros e bloqueados em ambientes restritos. `False` indica que o algoritmo de hash não é usado em um contexto de segurança, por exemplo, como uma função de compressão unidirecional não criptográfica.

Hashlib now uses SHA3 and SHAKE from OpenSSL 1.1.1 and newer.

For example, to obtain the digest of the byte string `b'Nobody inspects the spammish repetition'`:

    >>> import hashlib
    >>> m = hashlib.sha256()
    >>> m.update(b"Nobody inspects")
    >>> m.update(b" the spammish repetition")
    >>> m.digest()
    b'\x03\x1e\xdd}Ae\x15\x93\xc5\xfe\\\x00o\xa5u+7\xfd\xdf\xf7\xbcN\x84:\xa6\xaf\x0c\x95\x0fK\x94\x06'
    >>> m.digest_size
    32
    >>> m.block_size
    64

Mais condensado:

    >>> hashlib.sha224(b"Nobody inspects the spammish repetition").hexdigest()
    'a4337bc45a8fc544c03f52dc550cd6e1e87021bc896588bd79e901e2'

`hashlib.``new`(name, [data, ]*, usedforsecurity=True)

  Is a generic constructor that takes the string name of the desired algorithm as its first parameter. It also exists to allow access to the above listed hashes as well as any other algorithms that your OpenSSL library may offer. The named constructors are much faster than `new()` and should be preferred.

Using `new()` with an algorithm provided by OpenSSL:

    >>> h = hashlib.new('sha256')
    >>> h.update(b"Nobody inspects the spammish repetition")
    >>> h.hexdigest()
    '031edd7d41651593c5fe5c006fa5752b37fddff7bc4e843aa6af0c950f4b9406'

Hashlib provides the following constant attributes:

`hashlib.``algorithms_guaranteed`

  Um conjunto contendo os nomes dos algoritmos de hash com suporte garantido por este módulo em todas as plataformas. Observe que “md5” está nesta lista, apesar de alguns fornecedores originais oferecerem uma estranha construção Python “compatível com FIPS” que o exclui.

  Novo na versão 3.2.

`hashlib.``algorithms_available`

  Um conjunto contendo os nomes dos algoritmos de hash disponíveis no interpretador Python em execução. Esses nomes serão reconhecidos quando passados para `new()`. `algorithms_guaranteed` sempre será um subconjunto. O mesmo algoritmo pode aparecer várias vezes neste conjunto com nomes diferentes (graças ao OpenSSL).

  Novo na versão 3.2.

Os seguintes valores são fornecidos como atributos constantes dos objetos hash retornados pelos construtores:

`hash.``digest_size`

  O tamanho do hash resultante em bytes.

`hash.``block_size`

  O tamanho do bloco interna do algoritmo de hash em bytes.

Um objeto hash tem os seguintes atributos:

`hash.``name`

  O nome canônico deste hash, sempre em minúsculas e sempre adequado como parâmetro para `new()` para criar outro hash deste tipo.

  Alterado na versão 3.4: O atributo name está presente no CPython desde o seu início, mas até o Python 3.4 não era especificado formalmente, então pode não existir em algumas plataformas.

Um objeto hash tem os seguintes métodos:

`hash.``update`(data)

  Atualiza o objeto hash com o objeto bytes ou similar. Chamadas repetidas são equivalentes a uma única chamada com a concatenação de todos os argumentos: `m.update(a); m.update(b)` é equivalente a `m.update(a+b)`.

  Alterado na versão 3.1: The Python GIL is released to allow other threads to run while hash updates on data larger than 2047 bytes is taking place when using hash algorithms supplied by OpenSSL.

`hash.``digest`()

  Retorna o resumo dos dados passados ao método `update()` até o momento. Este é um objeto bytes de tamanho `digest_size` que pode conter bytes em todo o intervalo de 0 a 255.

`hash.``hexdigest`()

  Similar a `digest()`, exceto que o resumo é retornado como um objeto string de comprimento duplo, contendo apenas dígitos hexadecimais. Isso pode ser usado para trocar o valor com segurança em e-mails ou outros ambientes não binários.

`hash.``copy`()

  Retorna uma cópia (“clone”) do objeto hash. Isso pode ser usado para calcular com eficiência os resumos de dados que compartilham uma substring inicial comum.

## Resumos de comprimento variável de SHAKE

Os algoritmos `shake_128()` e `shake_256()` fornecem resumos de comprimento variável com length_in_bits//2 de até 128 ou 256 bits de segurança. Portanto, seus métodos de resumo exigem um comprimento. O comprimento máximo não é limitado pelo algoritmo SHAKE.

`shake.``digest`(length)

  Return the digest of the data passed to the `update()` method so far. This is a bytes object of size length which may contain bytes in the whole range from 0 to 255.

`shake.``hexdigest`(length)

  Similar a `digest()`, exceto que o resumo é retornado como um objeto string de comprimento duplo, contendo apenas dígitos hexadecimais. Isso pode ser usado para trocar o valor com segurança em e-mails ou outros ambientes não binários.

## Derivação de chave

Algoritmos de alongamento de chave e derivação de chave são projetados para criar hashes de senhas seguros. Algoritmos ingênuos como `sha1(password)` não são resistentes a ataques de força bruta. Uma boa função de hashing de senhas deve ser ajustável, lenta e incluir um salt.

`hashlib.``pbkdf2_hmac`(hash_name, password, salt, iterations, dklen=None)

  A função fornece a função 2 de derivação de chave baseada em senha PKCS#5. Ela usa HMAC como função pseudoaleatória.

  A string hash_name é o nome desejado do algoritmo de resumo de hash para HMAC, por exemplo, ‘sha1’ ou ‘sha256’. password e salt são interpretados como buffers de bytes. Aplicações e bibliotecas devem limitar password a um comprimento razoável (por exemplo, 1024). salt deve ter cerca de 16 bytes ou mais de uma fonte adequada, por exemplo, `os.urandom()`.

  The number of iterations should be chosen based on the hash algorithm and computing power. As of 2013, at least 100,000 iterations of SHA-256 are suggested.

  dklen is the length of the derived key. If dklen is `None` then the digest size of the hash algorithm hash_name is used, e.g. 64 for SHA-512.

      >>> import hashlib
      >>> dk = hashlib.pbkdf2_hmac('sha256', b'password', b'salt', 100000)
      >>> dk.hex()
      '0394a2ede332c9a13eb82e9b24631604c31df978b4e2f0fbd2c549944f9d79a5'

  Novo na versão 3.4.

  Nota

  A fast implementation of pbkdf2_hmac is available with OpenSSL. The Python implementation uses an inline version of `hmac`. It is about three times slower and doesn’t release the GIL.

`hashlib.``scrypt`(password, *, salt, n, r, p, maxmem=0, dklen=64)

  A função fornece a função de derivação de chave baseada em senha scrypt, conforme definido em RFC 7914.

  password e salt devem ser objetos bytes ou similares. Aplicações e bibliotecas devem limitar password a um tamanho razoável (por exemplo, 1024). salt deve ter cerca de 16 bytes ou mais de uma fonte adequada, por exemplo, `os.urandom()`.

  n is the CPU/Memory cost factor, r the block size, p parallelization factor and maxmem limits memory (OpenSSL 1.1.0 defaults to 32 MiB). dklen is the length of the derived key.

  Availability: OpenSSL 1.1+.

  Novo na versão 3.6.

## BLAKE2

BLAKE2 é uma função hash criptográfica definida em RFC 7693 que vem em dois sabores:

- BLAKE2b, otimizado para plataformas de 64 bits e produz resumos de qualquer tamanho entre 1 e 64 bytes,

- BLAKE2s, otimizado para plataformas de 8 a 32 bits e produz resumos de qualquer tamanho entre 1 e 32 bytes.

BLAKE2 supports keyed mode (a faster and simpler replacement for HMAC), salted hashing, personalization, and tree hashing.

Os objetos hash deste módulo seguem a API dos objetos `hashlib` da biblioteca padrão.

### Criando objetos hash

Novos objetos hash são criados chamando funções construtoras:

`hashlib.``blake2b`(data=b'', *, digest_size=64, key=b'', salt=b'', person=b'', fanout=1, depth=1, leaf_size=0, node_offset=0, node_depth=0, inner_size=0, last_node=False, usedforsecurity=True)

`hashlib.``blake2s`(data=b'', *, digest_size=32, key=b'', salt=b'', person=b'', fanout=1, depth=1, leaf_size=0, node_offset=0, node_depth=0, inner_size=0, last_node=False, usedforsecurity=True)

Essas funções retornam os objetos hash correspondentes para calcular BLAKE2b ou BLAKE2s. Opcionalmente, elas aceitam estes parâmetros gerais:

- data: pedaço inicial de dados para hash, que deve ser objeto bytes ou similar. Pode ser passado apenas como argumento posicional.

- digest_size: tamanho do resumo de saída em bytes.

- key: chave para hash com chave (até 64 bytes para BLAKE2b, até 32 bytes para BLAKE2s).

- salt: sal para hash aleatório (até 16 bytes para BLAKE2b, até 8 bytes para BLAKE2s).

- person: string de personalização (até 16 bytes para BLAKE2b, até 8 bytes para BLAKE2s).

A tabela a seguir mostra os limites para parâmetros gerais (em bytes):

Hash | digest_size | len(key) | len(salt) | len(person)
--- | --- | --- | --- | ---
BLAKE2b | 64 | 64 | 16 | 16
BLAKE2s | 32 | 32 | 8 | 8

Nota

BLAKE2 specification defines constant lengths for salt and personalization parameters, however, for convenience, this implementation accepts byte strings of any size up to the specified length. If the length of the parameter is less than specified, it is padded with zeros, thus, for example, `b'salt'` and `b'salt\x00'` is the same value. (This is not the case for key.)

These sizes are available as module constants described below.

Constructor functions also accept the following tree hashing parameters:

- fanout: fanout (0 to 255, 0 if unlimited, 1 in sequential mode).

- depth: maximal depth of tree (1 to 255, 255 if unlimited, 1 in sequential mode).

- leaf_size: maximal byte length of leaf (0 to `2**32-1`, 0 if unlimited or in sequential mode).

- node_offset: node offset (0 to `2**64-1` for BLAKE2b, 0 to `2**48-1` for BLAKE2s, 0 for the first, leftmost, leaf, or in sequential mode).

- node_depth: node depth (0 to 255, 0 for leaves, or in sequential mode).

- inner_size: inner digest size (0 to 64 for BLAKE2b, 0 to 32 for BLAKE2s, 0 in sequential mode).

- last_node: boolean indicating whether the processed node is the last one (False for sequential mode).

See section 2.10 in BLAKE2 specification for comprehensive review of tree hashing.

### Constantes

`blake2b.``SALT_SIZE`

`blake2s.``SALT_SIZE`

Salt length (maximum length accepted by constructors).

`blake2b.``PERSON_SIZE`

`blake2s.``PERSON_SIZE`

Personalization string length (maximum length accepted by constructors).

`blake2b.``MAX_KEY_SIZE`

`blake2s.``MAX_KEY_SIZE`

Maximum key size.

`blake2b.``MAX_DIGEST_SIZE`

`blake2s.``MAX_DIGEST_SIZE`

Maximum digest size that the hash function can output.

### Exemplos

#### Simple hashing

To calculate hash of some data, you should first construct a hash object by calling the appropriate constructor function (`blake2b()` or `blake2s()`), then update it with the data by calling `update()` on the object, and, finally, get the digest out of the object by calling `digest()` (or `hexdigest()` for hex-encoded string).

    >>> from hashlib import blake2b
    >>> h = blake2b()
    >>> h.update(b'Hello world')
    >>> h.hexdigest()
    '6ff843ba685842aa82031d3f53c48b66326df7639a63d128974c5c14f31a0f33343a8c65551134ed1ae0f2b0dd2bb495dc81039e3eeb0aa1bb0388bbeac29183'

As a shortcut, you can pass the first chunk of data to update directly to the constructor as the positional argument:

    >>> from hashlib import blake2b
    >>> blake2b(b'Hello world').hexdigest()
    '6ff843ba685842aa82031d3f53c48b66326df7639a63d128974c5c14f31a0f33343a8c65551134ed1ae0f2b0dd2bb495dc81039e3eeb0aa1bb0388bbeac29183'

You can call `hash.update()` as many times as you need to iteratively update the hash:

    >>> from hashlib import blake2b
    >>> items = [b'Hello', b' ', b'world']
    >>> h = blake2b()
    >>> for item in items:
    ...     h.update(item)
    >>> h.hexdigest()
    '6ff843ba685842aa82031d3f53c48b66326df7639a63d128974c5c14f31a0f33343a8c65551134ed1ae0f2b0dd2bb495dc81039e3eeb0aa1bb0388bbeac29183'

#### Using different digest sizes

BLAKE2 has configurable size of digests up to 64 bytes for BLAKE2b and up to 32 bytes for BLAKE2s. For example, to replace SHA-1 with BLAKE2b without changing the size of output, we can tell BLAKE2b to produce 20-byte digests:

    >>> from hashlib import blake2b
    >>> h = blake2b(digest_size=20)
    >>> h.update(b'Replacing SHA1 with the more secure function')
    >>> h.hexdigest()
    'd24f26cf8de66472d58d4e1b1774b4c9158b1f4c'
    >>> h.digest_size
    20
    >>> len(h.digest())
    20

Hash objects with different digest sizes have completely different outputs (shorter hashes are not prefixes of longer hashes); BLAKE2b and BLAKE2s produce different outputs even if the output length is the same:

    >>> from hashlib import blake2b, blake2s
    >>> blake2b(digest_size=10).hexdigest()
    '6fa1d8fcfd719046d762'
    >>> blake2b(digest_size=11).hexdigest()
    'eb6ec15daf9546254f0809'
    >>> blake2s(digest_size=10).hexdigest()
    '1bf21a98c78a1c376ae9'
    >>> blake2s(digest_size=11).hexdigest()
    '567004bf96e4a25773ebf4'

#### Keyed hashing

Keyed hashing can be used for authentication as a faster and simpler replacement for Hash-based message authentication code (HMAC). BLAKE2 can be securely used in prefix-MAC mode thanks to the indifferentiability property inherited from BLAKE.

This example shows how to get a (hex-encoded) 128-bit authentication code for message `b'message data'` with key `b'pseudorandom key'`:

    >>> from hashlib import blake2b
    >>> h = blake2b(key=b'pseudorandom key', digest_size=16)
    >>> h.update(b'message data')
    >>> h.hexdigest()
    '3d363ff7401e02026f4a4687d4863ced'

As a practical example, a web application can symmetrically sign cookies sent to users and later verify them to make sure they weren’t tampered with:

    >>> from hashlib import blake2b
    >>> from hmac import compare_digest
    >>>
    >>> SECRET_KEY = b'pseudorandomly generated server secret key'
    >>> AUTH_SIZE = 16
    >>>
    >>> def sign(cookie):
    ...     h = blake2b(digest_size=AUTH_SIZE, key=SECRET_KEY)
    ...     h.update(cookie)
    ...     return h.hexdigest().encode('utf-8')
    >>>
    >>> def verify(cookie, sig):
    ...     good_sig = sign(cookie)
    ...     return compare_digest(good_sig, sig)
    >>>
    >>> cookie = b'user-alice'
    >>> sig = sign(cookie)
    >>> print("{0},{1}".format(cookie.decode('utf-8'), sig))
    user-alice,b'43b3c982cf697e0c5ab22172d1ca7421'
    >>> verify(cookie, sig)
    True
    >>> verify(b'user-bob', sig)
    False
    >>> verify(cookie, b'0102030405060708090a0b0c0d0e0f00')
    False

Even though there’s a native keyed hashing mode, BLAKE2 can, of course, be used in HMAC construction with `hmac` module:

    >>> import hmac, hashlib
    >>> m = hmac.new(b'secret key', digestmod=hashlib.blake2s)
    >>> m.update(b'message')
    >>> m.hexdigest()
    'e3c8102868d28b5ff85fc35dda07329970d1a01e273c37481326fe0c861c8142'

#### Randomized hashing

By setting salt parameter users can introduce randomization to the hash function. Randomized hashing is useful for protecting against collision attacks on the hash function used in digital signatures.

> Randomized hashing is designed for situations where one party, the message preparer, generates all or part of a message to be signed by a second party, the message signer. If the message preparer is able to find cryptographic hash function collisions (i.e., two messages producing the same hash value), then they might prepare meaningful versions of the message that would produce the same hash value and digital signature, but with different results (e.g., transferring $1,000,000 to an account, rather than $10). Cryptographic hash functions have been designed with collision resistance as a major goal, but the current concentration on attacking cryptographic hash functions may result in a given cryptographic hash function providing less collision resistance than expected. Randomized hashing offers the signer additional protection by reducing the likelihood that a preparer can generate two or more messages that ultimately yield the same hash value during the digital signature generation process — even if it is practical to find collisions for the hash function. However, the use of randomized hashing may reduce the amount of security provided by a digital signature when all portions of the message are prepared by the signer.

> (NIST SP-800-106 “Randomized Hashing for Digital Signatures”)

In BLAKE2 the salt is processed as a one-time input to the hash function during initialization, rather than as an input to each compression function.

Aviso

Salted hashing (or just hashing) with BLAKE2 or any other general-purpose cryptographic hash function, such as SHA-256, is not suitable for hashing passwords. See BLAKE2 FAQ for more information.

    >>> import os
    >>> from hashlib import blake2b
    >>> msg = b'some message'
    >>> # Calculate the first hash with a random salt.
    >>> salt1 = os.urandom(blake2b.SALT_SIZE)
    >>> h1 = blake2b(salt=salt1)
    >>> h1.update(msg)
    >>> # Calculate the second hash with a different random salt.
    >>> salt2 = os.urandom(blake2b.SALT_SIZE)
    >>> h2 = blake2b(salt=salt2)
    >>> h2.update(msg)
    >>> # The digests are different.
    >>> h1.digest() != h2.digest()
    True

#### Personalization

Sometimes it is useful to force hash function to produce different digests for the same input for different purposes. Quoting the authors of the Skein hash function:

> We recommend that all application designers seriously consider doing this; we have seen many protocols where a hash that is computed in one part of the protocol can be used in an entirely different part because two hash computations were done on similar or related data, and the attacker can force the application to make the hash inputs the same. Personalizing each hash function used in the protocol summarily stops this type of attack.

> (The Skein Hash Function Family, p. 21)

BLAKE2 can be personalized by passing bytes to the person argument:

    >>> from hashlib import blake2b
    >>> FILES_HASH_PERSON = b'MyApp Files Hash'
    >>> BLOCK_HASH_PERSON = b'MyApp Block Hash'
    >>> h = blake2b(digest_size=32, person=FILES_HASH_PERSON)
    >>> h.update(b'the same content')
    >>> h.hexdigest()
    '20d9cd024d4fb086aae819a1432dd2466de12947831b75c5a30cf2676095d3b4'
    >>> h = blake2b(digest_size=32, person=BLOCK_HASH_PERSON)
    >>> h.update(b'the same content')
    >>> h.hexdigest()
    'cf68fb5761b9c44e7878bfb2c4c9aea52264a80b75005e65619778de59f383a3'

Personalization together with the keyed mode can also be used to derive different keys from a single one.

    >>> from hashlib import blake2s
    >>> from base64 import b64decode, b64encode
    >>> orig_key = b64decode(b'Rm5EPJai72qcK3RGBpW3vPNfZy5OZothY+kHY6h21KM=')
    >>> enc_key = blake2s(key=orig_key, person=b'kEncrypt').digest()
    >>> mac_key = blake2s(key=orig_key, person=b'kMAC').digest()
    >>> print(b64encode(enc_key).decode('utf-8'))
    rbPb15S/Z9t+agffno5wuhB77VbRi6F9Iv2qIxU7WHw=
    >>> print(b64encode(mac_key).decode('utf-8'))
    G9GtHFE1YluXY1zWPlYk1e/nWfu0WSEb0KRcjhDeP/o=

#### Modo árvore

Here’s an example of hashing a minimal tree with two leaf nodes:

      10
     /  \
    00  01

This example uses 64-byte internal digests, and returns the 32-byte final digest:

    >>> from hashlib import blake2b
    >>>
    >>> FANOUT = 2
    >>> DEPTH = 2
    >>> LEAF_SIZE = 4096
    >>> INNER_SIZE = 64
    >>>
    >>> buf = bytearray(6000)
    >>>
    >>> # Left leaf
    ... h00 = blake2b(buf[0:LEAF_SIZE], fanout=FANOUT, depth=DEPTH,
    ...               leaf_size=LEAF_SIZE, inner_size=INNER_SIZE,
    ...               node_offset=0, node_depth=0, last_node=False)
    >>> # Right leaf
    ... h01 = blake2b(buf[LEAF_SIZE:], fanout=FANOUT, depth=DEPTH,
    ...               leaf_size=LEAF_SIZE, inner_size=INNER_SIZE,
    ...               node_offset=1, node_depth=0, last_node=True)
    >>> # Root node
    ... h10 = blake2b(digest_size=32, fanout=FANOUT, depth=DEPTH,
    ...               leaf_size=LEAF_SIZE, inner_size=INNER_SIZE,
    ...               node_offset=0, node_depth=1, last_node=True)
    >>> h10.update(h00.digest())
    >>> h10.update(h01.digest())
    >>> h10.hexdigest()
    '3ad2a9b37c6070e374c7a8c508fe20ca86b6ed54e286e93a0318e95e881db5aa'

### Credits

BLAKE2 was designed by Jean-Philippe Aumasson, Samuel Neves, Zooko Wilcox-O’Hearn, and Christian Winnerlein based on SHA-3 finalist BLAKE created by Jean-Philippe Aumasson, Luca Henzen, Willi Meier, and Raphael C.-W. Phan.

It uses core algorithm from ChaCha cipher designed by Daniel J. Bernstein.

The stdlib implementation is based on pyblake2 module. It was written by Dmitry Chestnykh based on C implementation written by Samuel Neves. The documentation was copied from pyblake2 and written by Dmitry Chestnykh.

The C code was partly rewritten for Python by Christian Heimes.

The following public domain dedication applies for both C hash function implementation, extension code, and this documentation:

> To the extent possible under law, the author(s) have dedicated all copyright and related and neighboring rights to this software to the public domain worldwide. This software is distributed without any warranty.

> You should have received a copy of the CC0 Public Domain Dedication along with this software. If not, see https://creativecommons.org/publicdomain/zero/1.0/.

The following people have helped with development or contributed their changes to the project and the public domain according to the Creative Commons Public Domain Dedication 1.0 Universal:

- Alexandr Sokolovskiy

Ver também

Module `hmac`

  A module to generate message authentication codes using hashes.

Módulo `base64`

  Another way to encode binary hashes for non-binary environments.

https://blake2.net

  Official BLAKE2 website.

https://csrc.nist.gov/csrc/media/publications/fips/180/2/archive/2002-08-01/documents/fips180-2.pdf

  The FIPS 180-2 publication on Secure Hash Algorithms.

https://en.wikipedia.org/wiki/Cryptographic_hash_function#Cryptographic_hash_algorithms

  Wikipedia article with information on which algorithms have known issues and what that means regarding their use.

https://www.ietf.org/rfc/rfc2898.txt

  PKCS #5: Password-Based Cryptography Specification Version 2.0