first

backend/internal/platform/security/password.go

@@ -0,0 +1,82 @@
+// Package security provides password hashing and JWT issuing/verification
+// shared across auth modules.
+package security
+
+import (
+	"crypto/rand"
+	"crypto/subtle"
+	"encoding/base64"
+	"fmt"
+	"strings"
+
+	"golang.org/x/crypto/argon2"
+)
+
+const (
+	argon2Time    = 3
+	argon2Memory  = 64 * 1024 // 64 MB
+	argon2Threads = 2
+	argon2SaltLen = 16
+	argon2KeyLen  = 32
+)
+
+// HashPassword hashes a plaintext password using argon2id and returns the
+// PHC-formatted string ($argon2id$v=19$m=...,t=...,p=...$salt$hash).
+func HashPassword(password string) (string, error) {
+	salt := make([]byte, argon2SaltLen)
+	if _, err := rand.Read(salt); err != nil {
+		return "", fmt.Errorf("generate salt: %w", err)
+	}
+
+	hash := argon2.IDKey([]byte(password), salt, argon2Time, argon2Memory, argon2Threads, argon2KeyLen)
+
+	encoded := fmt.Sprintf(
+		"$argon2id$v=%d$m=%d,t=%d,p=%d$%s$%s",
+		argon2.Version,
+		argon2Memory,
+		argon2Time,
+		argon2Threads,
+		base64.RawStdEncoding.EncodeToString(salt),
+		base64.RawStdEncoding.EncodeToString(hash),
+	)
+	return encoded, nil
+}
+
+// VerifyPassword checks a plaintext password against a PHC-formatted argon2id hash.
+func VerifyPassword(encodedHash, password string) (bool, error) {
+	parts := strings.Split(encodedHash, "$")
+	if len(parts) != 6 || parts[1] != "argon2id" {
+		return false, fmt.Errorf("invalid hash format")
+	}
+
+	var version int
+	if _, err := fmt.Sscanf(parts[2], "v=%d", &version); err != nil {
+		return false, fmt.Errorf("invalid hash version segment: %w", err)
+	}
+	if version != argon2.Version {
+		return false, fmt.Errorf("unsupported argon2 version: %d", version)
+	}
+
+	var memory uint32
+	var time uint32
+	var threads uint8
+	if _, err := fmt.Sscanf(parts[3], "m=%d,t=%d,p=%d", &memory, &time, &threads); err != nil {
+		return false, fmt.Errorf("invalid hash params segment: %w", err)
+	}
+
+	salt, err := base64.RawStdEncoding.DecodeString(parts[4])
+	if err != nil {
+		return false, fmt.Errorf("decode salt: %w", err)
+	}
+	wantHash, err := base64.RawStdEncoding.DecodeString(parts[5])
+	if err != nil {
+		return false, fmt.Errorf("decode hash: %w", err)
+	}
+
+	gotHash := argon2.IDKey([]byte(password), salt, time, memory, threads, uint32(len(wantHash)))
+
+	if subtle.ConstantTimeCompare(gotHash, wantHash) == 1 {
+		return true, nil
+	}
+	return false, nil
+}