69 lines
1.5 KiB
Go
69 lines
1.5 KiB
Go
package chat
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import (
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"encoding/hex"
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"fmt"
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"sync"
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"golang.org/x/crypto/argon2"
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)
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// UserID uniquely identifies an individual user who has posted a message in a
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// Room.
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type UserID struct {
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// Name will be the user's chosen display name.
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Name string `json:"name"`
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// Hash will be a hex string generated from a secret only the user knows.
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Hash string `json:"id"`
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}
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// UserIDCalculator is used to calculate UserIDs.
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type UserIDCalculator struct {
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// Secret is used when calculating UserID Hash salts.
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Secret []byte
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// TimeCost, MemoryCost, and Threads are used as inputs to the Argon2id
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// algorithm which is used to generate the Hash.
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TimeCost, MemoryCost uint32
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Threads uint8
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// HashLen specifies the number of bytes the Hash should be.
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HashLen uint32
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// Lock, if set, forces concurrent Calculate calls to occur sequentially.
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Lock *sync.Mutex
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}
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// NewUserIDCalculator returns a UserIDCalculator with sane defaults.
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func NewUserIDCalculator(secret []byte) *UserIDCalculator {
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return &UserIDCalculator{
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Secret: secret,
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TimeCost: 15,
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MemoryCost: 128 * 1024,
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Threads: 2,
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HashLen: 16,
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Lock: new(sync.Mutex),
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}
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}
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// Calculate accepts a name and password and returns the calculated UserID.
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func (c *UserIDCalculator) Calculate(name, password string) UserID {
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input := fmt.Sprintf("%q:%q", name, password)
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hashB := argon2.IDKey(
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[]byte(input),
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c.Secret, // salt
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c.TimeCost, c.MemoryCost, c.Threads,
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c.HashLen,
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)
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return UserID{
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Name: name,
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Hash: hex.EncodeToString(hashB),
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}
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}
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