88 lines
2.1 KiB
Go
88 lines
2.1 KiB
Go
package utils
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import (
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"crypto/subtle"
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"encoding/base64"
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"errors"
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"fmt"
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"strings"
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"golang.org/x/crypto/argon2"
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)
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var (
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ErrInvalidHash = errors.New("the encoded hash is not in the correct format")
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ErrIncompatibleVersion = errors.New("incompatible version of argon2")
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)
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func Match(password string, email string) (bool, error) {
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user, err := GetUserByEmail(email)
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if err != nil {
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return false, err
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}
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check, err := comparePasswordAndHash(password, user.Password)
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if err != nil {
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return false, err
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}
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return check, nil
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}
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func comparePasswordAndHash(password, encodedHash string) (match bool, err error) {
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// Extract the parameters, salt and derived key from the encoded password
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// hash.
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p, salt, hash, err := decodeHash(encodedHash)
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if err != nil {
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return false, err
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}
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// Derive the key from the other password using the same parameters.
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otherHash := argon2.IDKey([]byte(password), salt, p.iterations, p.memory, p.parallelism, p.keyLength)
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// Check that the contents of the hashed passwords are identical. Note
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// that we are using the subtle.ConstantTimeCompare() function for this
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// to help prevent timing attacks.
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if subtle.ConstantTimeCompare(hash, otherHash) == 1 {
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return true, nil
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}
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return false, nil
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}
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func decodeHash(encodedHash string) (p *params, salt, hash []byte, err error) {
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vals := strings.Split(encodedHash, "$")
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if len(vals) != 6 {
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return nil, nil, nil, ErrInvalidHash
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}
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var version int
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_, err = fmt.Sscanf(vals[2], "v=%d", &version)
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if err != nil {
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return nil, nil, nil, err
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}
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if version != argon2.Version {
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return nil, nil, nil, ErrIncompatibleVersion
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}
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p = ¶ms{}
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_, err = fmt.Sscanf(vals[3], "m=%d,t=%d,p=%d", &p.memory, &p.iterations, &p.parallelism)
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if err != nil {
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return nil, nil, nil, err
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}
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salt, err = base64.RawStdEncoding.Strict().DecodeString(vals[4])
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if err != nil {
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return nil, nil, nil, err
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}
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p.saltLength = uint32(len(salt))
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hash, err = base64.RawStdEncoding.Strict().DecodeString(vals[5])
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if err != nil {
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return nil, nil, nil, err
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}
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p.keyLength = uint32(len(hash))
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return p, salt, hash, nil
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}
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