87 lines
3.2 KiB
Go
87 lines
3.2 KiB
Go
package common
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import (
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"crypto/rand"
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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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"os"
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"strings"
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"unicode/utf8"
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"golang.org/x/crypto/argon2"
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)
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const (
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MinAccountPasswordLength = 8
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MaxAccountPasswordLength = 128
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accountPasswordMemory = 19 * 1024
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accountPasswordTime = 2
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accountPasswordSaltBytes = 16
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accountPasswordKeyBytes = 32
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)
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var (
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ErrAccountPasswordLength = errors.New("Password must contain between 8 and 128 characters.")
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ErrAccountPasswordSame = errors.New("New password must be different from current password")
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ErrPasswordLegacyLimit = errors.New("Long passwords are unavailable until the password storage upgrade is complete.")
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)
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// ValidateNewAccountPassword applies only when a user chooses a new password.
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// Authentication must continue to accept historical passwords without applying
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// the new policy. Do not normalize passwords, including surrounding whitespace.
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func ValidateNewAccountPassword(password string) error {
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if !utf8.ValidString(password) || utf8.RuneCountInString(password) < MinAccountPasswordLength || utf8.RuneCountInString(password) > MaxAccountPasswordLength {
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return ErrAccountPasswordLength
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}
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return nil
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}
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// HashAccountPassword is for account passwords, not MFA backup codes. The
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// temporary bcrypt mode permits rolling out dual-format readers to all nodes
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// before enabling Argon2id writes. Existing hashes are never rewritten in bulk.
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func HashAccountPassword(password string) (string, error) {
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if err := ValidateNewAccountPassword(password); err != nil {
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return "", err
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}
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switch os.Getenv("ACCOUNT_PASSWORD_HASH_ALGORITHM") {
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case "bcrypt":
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if len(password) > 72 {
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return "", ErrPasswordLegacyLimit
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}
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return Password2Hash(password)
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case "", "argon2id":
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default:
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return "", errors.New("Unsupported account password hashing configuration.")
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}
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salt := make([]byte, accountPasswordSaltBytes)
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if _, err := rand.Read(salt); err != nil {
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return "", fmt.Errorf("generate account password salt: %w", err)
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}
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key := argon2.IDKey([]byte(password), salt, accountPasswordTime, accountPasswordMemory, 1, accountPasswordKeyBytes)
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return fmt.Sprintf("$argon2id$v=19$m=19456,t=2,p=1$%s$%s", base64.RawStdEncoding.EncodeToString(salt), base64.RawStdEncoding.EncodeToString(key)), nil
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}
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func validateArgon2AccountPassword(password, encoded string) bool {
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// Bound both plaintext and parameters before invoking a memory-hard KDF.
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// Only the version/parameters emitted by this application are accepted.
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if len(password) > MaxAccountPasswordLength*utf8.UTFMax || len(encoded) > 256 {
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return false
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}
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parts := strings.Split(encoded, "$")
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if len(parts) != 6 || parts[0] != "" || parts[1] != "argon2id" || parts[2] != "v=19" || parts[3] != "m=19456,t=2,p=1" {
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return false
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}
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salt, err := base64.RawStdEncoding.Strict().DecodeString(parts[4])
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if err != nil || len(salt) != accountPasswordSaltBytes {
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return false
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}
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expected, err := base64.RawStdEncoding.Strict().DecodeString(parts[5])
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if err != nil || len(expected) != accountPasswordKeyBytes {
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return false
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}
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actual := argon2.IDKey([]byte(password), salt, accountPasswordTime, accountPasswordMemory, 1, accountPasswordKeyBytes)
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return subtle.ConstantTimeCompare(actual, expected) == 1
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}
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