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50 lines
1.9 KiB
Go
50 lines
1.9 KiB
Go
// cryptopasta - basic cryptography examples
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//
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// Written in 2015 by George Tankersley <george.tankersley@gmail.com>
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//
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// To the extent possible under law, the author(s) have dedicated all copyright
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// and related and neighboring rights to this software to the public domain
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// worldwide. This software is distributed without any warranty.
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//
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// You should have received a copy of the CC0 Public Domain Dedication along
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// with this software. If not, see // <http://creativecommons.org/publicdomain/zero/1.0/>.
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// Provides a recommended hashing algorithm.
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//
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// The hash function is HMAC-SHA512/256 where SHA512/256 is as described in
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// FIPS 180-4. This construction avoids length-extension attacks while
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// maintaining a widely compatible digest size with better performance on
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// 64-bit systems.
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//
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// Password hashing uses bcrypt with a work factor of 14.
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package cryptopasta
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import (
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"crypto/hmac"
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"crypto/sha512"
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"golang.org/x/crypto/bcrypt"
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)
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// Hash generates a hash of data using HMAC-SHA-512/256. The tag is intended to
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// be a natural-language string describing the purpose of the hash, such as
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// "hash file for lookup key" or "master secret to client secret". It serves
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// as an HMAC "key" and ensures that different purposes will have different
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// hash output. This function is NOT suitable for hashing passwords.
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func Hash(tag string, data []byte) []byte {
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h := hmac.New(sha512.New512_256, []byte(tag))
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h.Write(data)
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return h.Sum(nil)
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}
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// HashPassword generates a bcrypt hash of the password using work factor 10
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func HashPassword(password []byte) ([]byte, error) {
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return bcrypt.GenerateFromPassword(password, 10)
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}
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// CheckPassword securely compares a bcrypt hashed password with its possible
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// plaintext equivalent. Returns nil on success, or an error on failure.
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func CheckPasswordHash(hash, password []byte) error {
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return bcrypt.CompareHashAndPassword(hash, password)
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}
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