langchain屏蔽解析器和转换器是一个用于屏蔽和重新水合字符串的可扩展模块。

屏蔽

实验掩蔽解析器和转换器是一个可扩展的模块，用于掩蔽和重新水合字符串。该模块的主要用例之一是在调用llm之前，从字符串中编辑PII（个人标识信息）。

真实世界场景​

客户支持系统接收包含敏感客户信息的消息。系统必须解析这些消息，屏蔽任何PII（如姓名、电子邮件地址和电话号码），并在遵守隐私法规的同时将其记录下来进行分析。在记录转录本之前，将使用llm生成摘要。
开始​

基本示例​

使用RegexMaskingTransformer为电子邮件和电话创建一个简单的掩码。

TIP

See this section for general instructions on installing integration packages.

• npm
• Yarn
• pnpm

npm install @langchain/openai

import {
  MaskingParser,
  RegexMaskingTransformer,
} from "langchain/experimental/masking";

// Define masking strategy
const emailMask = () => `[email-${Math.random().toString(16).slice(2)}]`;
const phoneMask = () => `[phone-${Math.random().toString(16).slice(2)}]`;

// Configure pii transformer
const piiMaskingTransformer = new RegexMaskingTransformer({
  email: { regex: /\S+@\S+\.\S+/g, mask: emailMask },
  phone: { regex: /\d{3}-\d{3}-\d{4}/g, mask: phoneMask },
});

const maskingParser = new MaskingParser({
  transformers: [piiMaskingTransformer],
});
maskingParser.addTransformer(piiMaskingTransformer);

const input =
  "Contact me at jane.doe@email.com or 555-123-4567. Also reach me at john.smith@email.com";
const masked = await maskingParser.mask(input);

console.log(masked);
// Contact me at [email-a31e486e324f6] or [phone-da8fc1584f224]. Also reach me at [email-d5b6237633d95]

const rehydrated = await maskingParser.rehydrate(masked);
console.log(rehydrated);
// Contact me at jane.doe@email.com or 555-123-4567. Also reach me at john.smith@email.com

API Reference:

• MaskingParser from langchain/experimental/masking
• RegexMaskingTransformer from langchain/experimental/masking

NOTE

如果计划存储掩蔽状态以异步重新水合原始值，请确保遵循最佳安全实践。在大多数情况下，您将希望定义一个自定义哈希和盐析策略。

Next.js stream​

示例nextjs聊天端点利用RegexMaskingTransformer。每次使用聊天负载调用api时，都会屏蔽当前聊天消息和聊天消息历史记录。

// app/api/chat

import {
  MaskingParser,
  RegexMaskingTransformer,
} from "langchain/experimental/masking";
import { ChatOpenAI } from "@langchain/openai";
import { PromptTemplate } from "@langchain/core/prompts";
import { BytesOutputParser } from "@langchain/core/output_parsers";

export const runtime = "edge";

// Function to format chat messages for consistency
const formatMessage = (message: any) => `${message.role}: ${message.content}`;

const CUSTOMER_SUPPORT = `You are a customer support summarizer agent. Always include masked PII in your response.
  Current conversation:
  {chat_history}
  User: {input}
  AI:`;

// Configure Masking Parser
const maskingParser = new MaskingParser();
// Define transformations for masking emails and phone numbers using regular expressions
const piiMaskingTransformer = new RegexMaskingTransformer({
  email: { regex: /\S+@\S+\.\S+/g }, // If a regex is provided without a mask we fallback to a simple default hashing function
  phone: { regex: /\d{3}-\d{3}-\d{4}/g },
});

maskingParser.addTransformer(piiMaskingTransformer);

export async function POST(req: Request) {
  try {
    const body = await req.json();
    const messages = body.messages ?? [];
    const formattedPreviousMessages = messages.slice(0, -1).map(formatMessage);
    const currentMessageContent = messages[messages.length - 1].content; // Extract the content of the last message
    // Mask sensitive information in the current message
    const guardedMessageContent = await maskingParser.mask(
      currentMessageContent
    );
    // Mask sensitive information in the chat history
    const guardedHistory = await maskingParser.mask(
      formattedPreviousMessages.join("\n")
    );

    const prompt = PromptTemplate.fromTemplate(CUSTOMER_SUPPORT);
    const model = new ChatOpenAI({ temperature: 0.8 });
    // Initialize an output parser that handles serialization and byte-encoding for streaming
    const outputParser = new BytesOutputParser();
    const chain = prompt.pipe(model).pipe(outputParser); // Chain the prompt, model, and output parser together

    console.log("[GUARDED INPUT]", guardedMessageContent); // Contact me at -1157967895 or -1626926859.
    console.log("[GUARDED HISTORY]", guardedHistory); // user: Contact me at -1157967895 or -1626926859. assistant: Thank you for providing your contact information.
    console.log("[STATE]", maskingParser.getState()); // { '-1157967895' => 'jane.doe@email.com', '-1626926859' => '555-123-4567'}

    // Stream the AI response based on the masked chat history and current message
    const stream = await chain.stream({
      chat_history: guardedHistory,
      input: guardedMessageContent,
    });

    return new Response(stream, {
      headers: { "content-type": "text/plain; charset=utf-8" },
    });
  } catch (e: any) {
    return new Response(JSON.stringify({ error: e.message }), {
      status: 500,
      headers: {
        "content-type": "application/json",
      },
    });
  }
}

API Reference:

• MaskingParser from langchain/experimental/masking
• RegexMaskingTransformer from langchain/experimental/masking
• ChatOpenAI from @langchain/openai
• PromptTemplate from @langchain/core/prompts
• BytesOutputParser from @langchain/core/output_parsers

Kitchen sink​

import {
  MaskingParser,
  RegexMaskingTransformer,
} from "langchain/experimental/masking";

// A simple hash function for demonstration purposes
function simpleHash(input: string): string {
  let hash = 0;
  for (let i = 0; i < input.length; i += 1) {
    const char = input.charCodeAt(i);
    hash = (hash << 5) - hash + char;
    hash |= 0; // Convert to 32bit integer
  }
  return hash.toString(16);
}

const emailMask = (match: string) => `[email-${simpleHash(match)}]`;
const phoneMask = (match: string) => `[phone-${simpleHash(match)}]`;
const nameMask = (match: string) => `[name-${simpleHash(match)}]`;
const ssnMask = (match: string) => `[ssn-${simpleHash(match)}]`;
const creditCardMask = (match: string) => `[creditcard-${simpleHash(match)}]`;
const passportMask = (match: string) => `[passport-${simpleHash(match)}]`;
const licenseMask = (match: string) => `[license-${simpleHash(match)}]`;
const addressMask = (match: string) => `[address-${simpleHash(match)}]`;
const dobMask = (match: string) => `[dob-${simpleHash(match)}]`;
const bankAccountMask = (match: string) => `[bankaccount-${simpleHash(match)}]`;

// Regular expressions for different types of PII
const patterns = {
  email: { regex: /\S+@\S+\.\S+/g, mask: emailMask },
  phone: { regex: /\b\d{3}-\d{3}-\d{4}\b/g, mask: phoneMask },
  name: { regex: /\b[A-Z][a-z]+ [A-Z][a-z]+\b/g, mask: nameMask },
  ssn: { regex: /\b\d{3}-\d{2}-\d{4}\b/g, mask: ssnMask },
  creditCard: { regex: /\b(?:\d{4}[ -]?){3}\d{4}\b/g, mask: creditCardMask },
  passport: { regex: /(?i)\b[A-Z]{1,2}\d{6,9}\b/g, mask: passportMask },
  license: { regex: /(?i)\b[A-Z]{1,2}\d{6,8}\b/g, mask: licenseMask },
  address: {
    regex: /\b\d{1,5}\s[A-Z][a-z]+(?:\s[A-Z][a-z]+)\*\b/g,
    mask: addressMask,
  },
  dob: { regex: /\b\d{4}-\d{2}-\d{2}\b/g, mask: dobMask },
  bankAccount: { regex: /\b\d{8,17}\b/g, mask: bankAccountMask },
};

// Create a RegexMaskingTransformer with multiple patterns
const piiMaskingTransformer = new RegexMaskingTransformer(patterns);

// Hooks for different stages of masking and rehydrating
const onMaskingStart = (message: string) =>
  console.log(`Starting to mask message: ${message}`);
const onMaskingEnd = (maskedMessage: string) =>
  console.log(`Masked message: ${maskedMessage}`);
const onRehydratingStart = (message: string) =>
  console.log(`Starting to rehydrate message: ${message}`);
const onRehydratingEnd = (rehydratedMessage: string) =>
  console.log(`Rehydrated message: ${rehydratedMessage}`);

// Initialize MaskingParser with the transformer and hooks
const maskingParser = new MaskingParser({
  transformers: [piiMaskingTransformer],
  onMaskingStart,
  onMaskingEnd,
  onRehydratingStart,
  onRehydratingEnd,
});

// Example message containing multiple types of PII
const message =
  "Contact Jane Doe at jane.doe@email.com or 555-123-4567. Her SSN is 123-45-6789 and her credit card number is 1234-5678-9012-3456. Passport number: AB1234567, Driver's License: X1234567, Address: 123 Main St, Date of Birth: 1990-01-01, Bank Account: 12345678901234567.";

// Mask and rehydrate the message
maskingParser
  .mask(message)
  .then((maskedMessage: string) => {
    console.log(`Masked message: ${maskedMessage}`);
    return maskingParser.rehydrate(maskedMessage);
  })
  .then((rehydratedMessage: string) => {
    console.log(`Final rehydrated message: ${rehydratedMessage}`);
  });

API Reference:

• MaskingParser from langchain/experimental/masking
• RegexMaskingTransformer from langchain/experimental/masking