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Use SSE-C

Last reviewed: 3 months ago

The following tutorial shows some snippets for how to use Server-Side Encryption with Customer-Provided Keys (SSE-C) on R2.

Before you begin

  • When using SSE-C, make sure you store your encryption key(s) in a safe place. In the event you misplace them, Cloudflare will be unable to recover the body of any objects encrypted using those keys.
  • While SSE-C does provide MD5 hashes, this hash can be used for identification of keys only. The MD5 hash is not used in the encryption process itself.

Workers

interface Environment {
  R2: R2Bucket
  /**
   * In this example, your SSE-C is stored as a hexadecimal string (preferably a secret).
   * The R2 API also supports providing an ArrayBuffer directly, if you want to generate/
   * store your keys dynamically.
  */
  SSEC_KEY: string
}
export default {
  async fetch(req: Request, env: Env) {
    const { SSEC_KEY, R2 } = env;
    const { pathname: filename } = new URL(req.url);
    switch(req.method) {
      case "GET": {
        const maybeObj = await env.BUCKET.get(filename, {
          onlyIf: req.headers,
          ssecKey: SSEC_KEY,
        });
        if(!maybeObj) {
          return new Response("Not Found", {
            status: 404
          });
        }
        const headers = new Headers();
        maybeObj.writeHttpMetadata(headers);
        return new Response(body, {
          headers
        });
      }
      case 'POST': {
        const multipartUpload = await env.BUCKET.createMultipartUpload(filename, {
          httpMetadata: req.headers,
          ssecKey: SSEC_KEY,
        });
        /**
         * This example only provides a single-part "multipart" upload.
         * For multiple parts, the process is the same(the key must be provided)
         * for every part.
        */
        const partOne = await multipartUpload.uploadPart(1, req.body, ssecKey);
        const obj = await multipartUpload.complete([partOne]);
        const headers = new Headers();
        obj.writeHttpMetadata(headers);
        return new Response(null, {
          headers,
          status: 201
        });
      }
      case 'PUT': {
        const obj = await env.BUCKET.put(filename, req.body, {
          httpMetadata: req.headers,
          ssecKey: SSEC_KEY,
        });
        const headers = new Headers();
        maybeObj.writeHttpMetadata(headers);
        return new Response(null, {
          headers,
          status: 201
        });
      }
      default: {
        return new Response("Method not allowed", {
          status: 405
        });
      }
    }
  }
}

S3-API

import {
  UploadPartCommand,
  PutObjectCommand, S3Client,
  CompleteMultipartUploadCommand,
  CreateMultipartUploadCommand,
  type UploadPartCommandOutput
} from "@aws-sdk/client-s3";


const s3 = new S3Client({
  endpoint: process.env.R2_ENDPOINT,
  credentials: {
    accessKeyId: process.env.R2_ACCESS_KEY_ID,
    secretAccessKey: process.env.R2_SECRET_ACCESS_KEY,
  },
});


const SSECustomerAlgorithm = "AES256";
const SSECustomerKey = process.env.R2_SSEC_KEY;
const SSECustomerKeyMD5 = process.env.R2_SSEC_KEY_MD5;


await s3.send(
  new PutObjectCommand({
    Bucket: "your-bucket",
    Key: "single-part",
    Body: "BeepBoop",
    SSECustomerAlgorithm,
    SSECustomerKey,
    SSECustomerKeyMD5,
  }),
);


const multi = await s3.send(
  new CreateMultipartUploadCommand({
    Bucket: "your-bucket",
    Key: "multi-part",
    SSECustomerAlgorithm,
    SSECustomerKey,
    SSECustomerKeyMD5,
  }),
);
const UploadId = multi.UploadId;


const parts: UploadPartCommandOutput[] = [];


parts.push(
  await s3.send(
    new UploadPartCommand({
      Bucket: "your-bucket",
      Key: "multi-part",
      UploadId,
      //   filledBuf()` generates some random data.
      // Replace with a function/body of your choice.
      Body: filledBuf(),
      PartNumber: 1,
      SSECustomerAlgorithm,
      SSECustomerKey,
      SSECustomerKeyMD5,
    }),
  ),
);
parts.push(
  await s3.send(
    new UploadPartCommand({
      Bucket: "your-bucket",
      Key: "multi-part",
      UploadId,
      //   filledBuf()` generates some random data.
      // Replace with a function/body of your choice.
      Body: filledBuf(),
      PartNumber: 2,
      SSECustomerAlgorithm,
      SSECustomerKey,
      SSECustomerKeyMD5,
    }),
  ),
);
await s3.send(
  new CompleteMultipartUploadCommand({
    Bucket: "your-bucket",
    Key: "multi-part",
    UploadId,
    MultipartUpload: {
      Parts: parts.map(({ ETag }, PartNumber) => ({
        ETag,
        PartNumber: PartNumber + 1,
      })),
    },
    SSECustomerAlgorithm,
    SSECustomerKey,
    SSECustomerKeyMD5,
  }),
);


const HeadObjectOutput = await s3.send(
  new HeadObjectCommand({
    Bucket: "your-bucket",
    Key: "multi-part",
    SSECustomerAlgorithm,
    SSECustomerKey,
    SSECustomerKeyMD5,
  }),
);


const GetObjectOutput = await s3.send(
  new GetObjectCommand({
    Bucket: "your-bucket",
    Key: "single-part",
    SSECustomerAlgorithm,
    SSECustomerKey,
    SSECustomerKeyMD5,
  }),
);
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