add sth.

1 files changed, 60 insertions, 0 deletions

diff --git a/internal/security/password.go b/internal/security/password.go
new file mode 100644
index 0000000..5d805ca
--- /dev/null
+++ b/internal/security/password.go
@@ -0,0 +1,60 @@
+package security
+
+import (
+	"crypto/pbkdf2"
+	"crypto/rand"
+	"crypto/sha256"
+	"crypto/subtle"
+	"errors"
+	"unicode"
+)
+
+const (
+	PasswordSaltBytes  = 16
+	PasswordHashBytes  = 32
+	PasswordIterations = 600_000
+)
+
+var ErrWeakPassword = errors.New("password must be 12-128 characters and contain letters and numbers")
+
+func ValidatePassword(password string) error {
+	runes := []rune(password)
+	if len(runes) < 12 || len(runes) > 128 {
+		return ErrWeakPassword
+	}
+	var letter, number bool
+	for _, value := range runes {
+		letter = letter || unicode.IsLetter(value)
+		number = number || unicode.IsNumber(value)
+	}
+	if !letter || !number {
+		return ErrWeakPassword
+	}
+	return nil
+}
+
+func HashPassword(password string) (hash, salt []byte, iterations int, err error) {
+	if err := ValidatePassword(password); err != nil {
+		return nil, nil, 0, err
+	}
+	salt = make([]byte, PasswordSaltBytes)
+	if _, err := rand.Read(salt); err != nil {
+		return nil, nil, 0, err
+	}
+	hash, err = pbkdf2.Key(sha256.New, password, salt, PasswordIterations, PasswordHashBytes)
+	if err != nil {
+		return nil, nil, 0, err
+	}
+	return hash, salt, PasswordIterations, nil
+}
+
+func VerifyPassword(password string, expectedHash, salt []byte, iterations int) bool {
+	if len(expectedHash) != PasswordHashBytes || len(salt) != PasswordSaltBytes || iterations < 100_000 || iterations > 10_000_000 || len([]rune(password)) > 128 {
+		return false
+	}
+	actual, err := pbkdf2.Key(sha256.New, password, salt, iterations, len(expectedHash))
+	if err != nil {
+		return false
+	}
+	return subtle.ConstantTimeCompare(actual, expectedHash) == 1
+}