feat(签章验签): 完善OFD加密、签章与验签能力，统一国密实现，优化界面文案与交互

ofdgo_crypto_editor.go

@@ -0,0 +1,84 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"bytes"
+	"io"
+)
+
+// SetEncryption 设置后续保存的加密策略，nil显式选择明文保存
+// 打开单用户口令或证书加密文档时默认继承原策略；多人口令和多层加密需显式选择输出策略
+// 新的加密密钥与初始向量在每次保存时独立生成，设置不改变文档内容或撤销历史
+// 入参: options 加密策略
+// 返回: error 错误信息
+func (e *Editor) SetEncryption(options *EncryptionOptions) error {
+	if options == nil {
+		e.encryption = nil
+		return nil
+	}
+	if err := validateEncryptionOptions(*options); err != nil {
+		return err
+	}
+	info := EncryptionInfo{Encrypted: true, Method: "1.1.1", Layers: 1}
+	if len(options.Password) != 0 {
+		name := options.UserName
+		if name == "" {
+			name = "User"
+		}
+		info.Users = []string{name}
+	} else {
+		info.Method = "1.1.2"
+		for _, recipient := range options.Recipients {
+			info.Users = append(info.Users, recipient.UserName)
+		}
+	}
+	e.encryption = &encryptionState{info: info, options: cloneEncryptionOptions(options)}
+	return nil
+}
+
+// writeEncrypted 在全部准备及加密成功后写出结果，取消不产生输出
+// 输出流自身写入失败时调用方仍需丢弃本次输出
+// 入参: writer 输出流
+// 返回: int64 写入字节数, error 错误信息
+func (e *Editor) writeEncrypted(writer io.Writer) (int64, error) {
+	if e.encryption.options == nil {
+		return 0, ErrEncryptionPolicyRequired
+	}
+	var plaintext bytes.Buffer
+	if _, err := e.writePlaintext(&plaintext); err != nil {
+		return 0, err
+	}
+	defer clear(plaintext.Bytes())
+	r, err := NewReader(bytes.NewReader(plaintext.Bytes()), int64(plaintext.Len()))
+	if err != nil {
+		return 0, err
+	}
+	defer r.Close()
+	parts, err := r.packageData()
+	if err != nil {
+		return 0, err
+	}
+	defer func() {
+		for _, data := range parts {
+			clear(data)
+		}
+	}()
+	data, err := encryptPackageParts(parts, *e.encryption.options, editorProgress(e.OnWriteProgress))
+	if err != nil {
+		return 0, err
+	}
+	return io.Copy(writer, bytes.NewReader(data))
+}