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35 lines
1.3 KiB
Go
35 lines
1.3 KiB
Go
// Copyright (c) 2018 Shivaram Lingamneni
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// released under the MIT license
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package passwd
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import "golang.org/x/crypto/bcrypt"
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import "golang.org/x/crypto/sha3"
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const (
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MinCost = bcrypt.MinCost
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DefaultCost = 12 // ballpark: 250 msec on a modern Intel CPU
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)
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// implements Dropbox's strategy of applying an initial pass of a "normal"
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// (i.e., fast) cryptographically secure hash with 512 bits of output before
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// applying bcrypt. This allows the use of, e.g., Diceware/XKCD-style passphrases
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// that may be longer than the 80-character bcrypt limit.
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// https://blogs.dropbox.com/tech/2016/09/how-dropbox-securely-stores-your-passwords/
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// we are only using this for user-generated passwords, as opposed to the server
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// and operator passwords that are hashed by `oragono genpasswd` and then
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// hard-coded by the server admins into the config file, to avoid breaking
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// backwards compatibility (since we can't upgrade the config file on the fly
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// the way we can with the database).
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func GenerateFromPassword(password []byte, cost int) (result []byte, err error) {
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sum := sha3.Sum512(password)
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return bcrypt.GenerateFromPassword(sum[:], cost)
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}
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func CompareHashAndPassword(hashedPassword, password []byte) error {
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sum := sha3.Sum512(password)
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return bcrypt.CompareHashAndPassword(hashedPassword, sum[:])
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}
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