drm是數字版權保護的一種方式，前一段時間在做四川文軒數字圖書館項目的時候用到了相關的知識，感覺這東西對於一些在線閱讀和視頻播放還是有很大用處的。
對於其工作原理我也很好奇，先摘抄度娘的內容如下，當然你也可以直接訪問度娘:http://baike.baidu.com/view/47310.htm?fr=aladdin
DRM技術的工作原理是，首先建立數字節目授權中心。編碼壓縮后的數字節目內容，可以利用
密鑰（Key）進行加密保護（lock），加密的數字節目頭部存放着KeyID和節目授權中心的URL。用戶在點播時，根據節目頭部的KeyID和URL信息，就可以通過數字節目
授權中心的驗證授權后送出相關的
密鑰解密（unlock），節目方可播放。
需要保護的節目被加密，即使被用戶下載保存，沒有得到數字節目授權中心的驗證授權也無法播放，從而嚴密地保護了節目的版權。
密鑰一般有兩把，一把
公鑰（public key），一把
私鑰（private key）。
公鑰用於加密節目內容本身，
私鑰用於解密節目，私鑰還可以防止當節目頭部有被改動或破壞的情況，利用
密鑰就可以判斷出來，從而阻止節目被非法使用。 上述這種加密的方法，有一個明顯的缺陷，就是當解密的
密鑰在發送給用戶時，一旦被
黑客獲得密鑰，即可方便解密節目，從而不能真正確保節目內容提供商的實際版權利益。另一種更加安全的加密方法是使用三把
密鑰，即把密鑰分成兩把，一把存放在用戶的Pc機上，另一把放在驗證站（access ticket）。要解密數字節目，必須同時具備這兩把
密鑰，方能解開數字節目。
毫無疑問，加密保護技術在開發
電子商務系統中正起着重要的防盜版作用。比如，在互聯網上傳輸音樂或視頻節目等內容，這些內容很容易被拷貝復制。為了避免這些風險，節目內容在互聯網上傳輸過程中一般都要經過加密保護。也就是說，收到加密的數字節目的人必須有一把
密鑰（key）才能打開數字節目並播放收看。因此，傳送
密鑰的工作必須緊跟在加密節目傳輸之后。
市場上比較多應用的是
微軟的 DRM 技術。
系統原理
系統會將
密鑰標識和許可證頒發機構地址寫入打包加密后的內容的頭部，並且使用另一對密鑰。
通過橢圓曲線
加密算法對頭部信息進行簽名，防止頭部信息被非法修改。
這個
密鑰散列的前12字節將用作生成加密過程中使用的密鑰。
這12個字節將作為一個
密鑰，通過RC4算法加密一個全零的64字節串，得到一個64字節的加密結果。
具體運算過程是，32位數據與6個32位字的的
密鑰的第一節字節相乘，然后除以4294967296，取其余數，並交換結果的高16位和低16位，然后再與6個32位字的的密鑰的第二節字節相乘，然后除以4294967296取其余數，並交換結果的高16位和低16位，然后再與6個32位字的的密鑰的第三節字節相乘，然后除以4294967296取其余數，並交換結果的高16位和低16位，然后再與6個字節的密鑰的第四節字節相乘，然后除以4294967296取其余數，並交換結果的高16位和低16位，然后再與6個32位字的的密鑰的第一節字節相乘，然后除以4294967296取其余數，並交換結果的高16位和低16位，然后再加上6個32位字的密鑰，然后除以4294967296取其余數，上述過程定義為函數f(x)，設一個64位狀態值，並設初值為零。
說了太多的廢話，這玩意兒到底怎么用還沒說，下面來點干貨，上代碼
1 /** 2 * 文件名 BaseFoac.java 3 * 包含類名列表 com.issmobile.numlibrary.tool 4 * 版本信息 版本號 5 * 創建日期 2014年7月15日 6 * 版權聲明 7 */ 8 9 package com.issmobile.numlibrary.tool; 10 11 import java.io.BufferedReader; 12 import java.io.InputStreamReader; 13 import java.net.InetAddress; 14 15 import org.apache.http.HttpEntity; 16 import org.apache.http.HttpResponse; 17 import org.apache.http.client.CookieStore; 18 import org.apache.http.client.methods.HttpPost; 19 import org.apache.http.entity.StringEntity; 20 import org.apache.http.impl.client.AbstractHttpClient; 21 import org.apache.http.impl.client.DefaultHttpClient; 22 import org.apache.http.params.CoreConnectionPNames; 23 24 import android.util.Log; 25 26 import com.foxit.general.BufferFileRead; 27 import com.foxit.general.DrmNative; 28 import com.foxit.general.PdfBaseDef; 29 import com.foxit.general.PdfDocNative; 30 import com.foxit.general.PdfDrmNative; 31 import com.foxit.general.ObjectRef; 32 import com.foxit.general.PdfSecurityNative; 33 import com.foxit.general.RsaKey; 34 import com.foxit.general.RtBaseDef; 35 import com.foxit.general.RtNative; 36 37 /** 38 * 類名 39 * @author 王洪賀<br/> 40 * 實現的主要功能。 41 * 創建日期 2014年7月15日 42 */ 43 44 public class BaseFoac { 45 46 protected ObjectRef m_encryptParams = null; 47 private CookieStore m_cookieStore = null; 48 private byte[] m_decoderPubKey = null; 49 50 /**用戶名*/ 51 private String mUserName; 52 /**密碼*/ 53 private String mPassword; 54 /**密碼*/ 55 private String mDevSN; 56 57 private String m_host = null; 58 private String m_port = null; 59 private String m_object = null; 60 private ObjectRef security = null; 61 private RsaKey m_rsaKey = null; 62 /**文件本地地址*/ 63 private String drmfile = null; 64 private DefaultHttpClient httpClient = null;//new DefaultHttpClient(); 65 private String m_sessionID = null; 66 67 /** 68 * 獲取信封的時候初始化，需要用戶名密碼 69 * */ 70 public BaseFoac(String mUserName, String mPassword, String drmfile) { 71 this.mUserName = "ElibUser." + mUserName; 72 this.mPassword = mPassword; 73 this.mDevSN = mPassword; 74 this.drmfile = drmfile; 75 } 76 77 /** 78 * 解密文件的時候初始化 79 * */ 80 public BaseFoac() { 81 } 82 83 public void setDRMFileName(String filename) { 84 drmfile = filename; 85 } 86 87 public boolean isDocWrapper(ObjectRef document) { 88 if (!PdfDrmNative.isDocWrapper(document)) 89 return false; 90 return true; 91 } 92 93 public boolean isFoxitDRM(ObjectRef document) { 94 if (!PdfDrmNative.isDocWrapper(document)) 95 return false; 96 97 m_encryptParams = PdfDrmNative.getEncryptParams(document); 98 99 if (m_encryptParams == null) 100 return false; 101 102 return true; 103 } 104 105 protected String getServiceURL() { 106 //TODO 獲取到書籍中驗證drm的網址，由於目前服務器不可用，返回默認地址，正式版修改回來 107 // return PdfDrmNative.getEncryptParamsItemString(m_encryptParams, 108 // PdfBaseDef.ENCRYPTPARAMS_SERVICEURL); 109 return URLConstants.licenseURL; 110 } 111 112 /** 113 * 解析網址 114 */ 115 protected void parseURL(String serviceUrl) { 116 if (serviceUrl == null) 117 return; 118 int hostIndex = serviceUrl.indexOf("://"); 119 String tmp = serviceUrl.substring(hostIndex + 3); 120 int objIndex = tmp.indexOf("/"); 121 int portIndex = tmp.indexOf(":"); 122 if (portIndex < 0) { 123 m_port = "80"; 124 m_host = tmp.substring(0, objIndex); 125 } else { 126 m_port = tmp.substring(portIndex + 1, objIndex); 127 m_host = tmp.substring(0, portIndex); 128 } 129 m_object = tmp.substring(objIndex + 1); 130 } 131 132 /** 133 * 獲取開始的請求信息 134 */ 135 protected String getSessionBeginRequest(String sessionID) { 136 ObjectRef foac = DrmNative.createFoac(true); 137 if (foac == null) 138 return null; 139 140 DrmNative.setFoacSessionID(foac, sessionID); 141 142 ObjectRef category = DrmNative.getFoacDataCategory(foac); 143 if (category == null) { 144 DrmNative.deleteFoac(foac); 145 return null; 146 } 147 148 DrmNative.setFoacRequestID(foac, "SessionBegin"); 149 150 ObjectRef subCategory = DrmNative.addSubCategory(category, "FlowCode", true); 151 String flowCode = PdfDrmNative.getEncryptParamsItemString(m_encryptParams, 152 PdfBaseDef.ENCRYPTPARAMS_FLOWCODE); 153 DrmNative.setCategoryAttribute(subCategory, "Value", flowCode); 154 155 String request = DrmNative.saveFoac(foac); 156 DrmNative.deleteFoac(foac); 157 return "XmlContent=" + request; 158 } 159 160 /** 161 * 發送請求信息並返回接受到的數據，需訪問網絡 162 */ 163 protected String sendAndReceive(String bsSend) { 164 String result = null; 165 try { 166 httpClient = new DefaultHttpClient(); 167 String temp = bsSend.replace("&", "%26"); 168 temp = temp.replace("+", "%2B"); 169 InetAddress addr = InetAddress.getByName(m_host); 170 171 String url; 172 if (addr.toString().substring(1).indexOf("/") != -1) 173 url = "http://" + m_host + ":" + m_port + "/" + m_object; 174 else 175 url = "http://" + m_host + ":" + m_port + "/" + m_object; 176 HttpPost httpPost = new HttpPost(url); 177 HttpEntity entity = new StringEntity(temp); 178 httpPost.setEntity(entity); 179 180 httpPost.addHeader("Content-Type", "application/x-www-form-urlencoded; charset=utf-8"); 181 182 // if (m_cookieStore != null) 183 httpClient.setCookieStore(m_cookieStore); 184 185 httpClient.getParams().setIntParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 300000); 186 httpClient.getParams().setIntParameter(CoreConnectionPNames.SO_TIMEOUT, 300000); 187 188 HttpResponse httpResponse = httpClient.execute(httpPost); 189 int status = httpResponse.getStatusLine().getStatusCode(); 190 long len = httpResponse.getEntity().getContentLength(); 191 192 StringBuilder builder = new StringBuilder(); 193 BufferedReader reader = new BufferedReader(new InputStreamReader(httpResponse 194 .getEntity().getContent())); 195 for (String s = reader.readLine(); s != null; s = reader.readLine()) { 196 builder.append(s); 197 } 198 result = builder.toString(); 199 m_cookieStore = ((AbstractHttpClient) httpClient).getCookieStore(); 200 201 if (result.indexOf("xml") == -1) 202 return null; 203 204 } catch (Exception e) { 205 e.printStackTrace(); 206 } 207 return result; 208 } 209 210 /** 211 * 解析收到的信息 212 */ 213 protected void parseSessionBeginRecieve(String receive) { 214 ObjectRef foac = DrmNative.loadFoac(receive.getBytes()); 215 if (foac == null) 216 return; 217 218 String state = DrmNative.getFoacAnswerState(foac); 219 if (state.indexOf("1") > -1) { 220 ObjectRef category = DrmNative.getFoacDataCategory(foac); 221 222 //Pubkey 223 int iCount = DrmNative.countSubCategories(category, "ServerPubKey"); 224 if (iCount == 0) { 225 DrmNative.deleteFoac(foac); 226 return; 227 } 228 ObjectRef subCategory = DrmNative.getSubCategory(category, "ServerPubKey", 0); 229 String bsPubKey = DrmNative.getCategoryAttributeValue(subCategory, "Value"); 230 231 ObjectRef sessionID = DrmNative.getSubCategory(category, "SessionID", 0); 232 m_sessionID = DrmNative.getCategoryAttributeValue(sessionID, "Value"); 233 234 // m_decoderPubKey = Base64.decode(bsPubKey, Base64.DEFAULT); 235 m_decoderPubKey = RtNative.base64Decode(bsPubKey.getBytes(), 0, bsPubKey.length()); 236 } 237 DrmNative.deleteFoac(foac); 238 } 239 240 /** 241 * 加密字符串 242 */ 243 protected String EncryptString(String str) { 244 byte[] data = DrmNative.pkiRsaEncrypt(str, m_decoderPubKey); 245 //return Base64.encodeToString(data, Base64.DEFAULT); 246 return RtNative.base64EncodeToString(data, 0, data.length); 247 } 248 249 /** 250 * 獲取檢查賬戶的請求信息 251 */ 252 protected String GetCheckAccountRequest(String sessionID) { 253 String fileID = PdfDrmNative.getEncryptParamsItemString(m_encryptParams, 254 PdfBaseDef.ENCRYPTPARAMS_FILEID); 255 String strFileID = EncryptString(fileID); 256 257 String order = PdfDrmNative.getEncryptParamsItemString(m_encryptParams, 258 PdfBaseDef.ENCRYPTPARAMS_ORDER); 259 String strOrder = EncryptString(order); 260 261 String account = EncryptString(mUserName); 262 String password = EncryptString(mPassword); 263 264 ObjectRef foac = DrmNative.createFoac(true); 265 DrmNative.setFoacSessionID(foac, sessionID); 266 267 DrmNative.setFoacRequestID(foac, "AuthAccount"); 268 269 ObjectRef category = DrmNative.getFoacDataCategory(foac); 270 if (category == null) { 271 DrmNative.deleteFoac(foac); 272 return null; 273 } 274 275 ObjectRef subCategory = DrmNative.addSubCategory(category, "EncryptAccount", true); 276 DrmNative.setCategoryAttribute(subCategory, "Value", account); 277 278 subCategory = DrmNative.addSubCategory(category, "EncryptPassword", true); 279 DrmNative.setCategoryAttribute(subCategory, "Value", password); 280 281 subCategory = DrmNative.addSubCategory(category, "EncryptOrderID", true); 282 DrmNative.setCategoryAttribute(subCategory, "Value", strOrder); 283 284 subCategory = DrmNative.addSubCategory(category, "EncryptFileID", true); 285 DrmNative.setCategoryAttribute(subCategory, "Value", strFileID); 286 287 String request = DrmNative.saveFoac(foac); 288 289 DrmNative.deleteFoac(foac); 290 291 return "XmlContent=" + request; 292 } 293 294 /** 295 * 解析收到賬戶認證的信息 296 */ 297 protected boolean ParseCheckAccountRequest(String receive) { 298 ObjectRef foac = DrmNative.loadFoac(receive.getBytes()); 299 if (foac == null) 300 return false; 301 302 boolean bRet = false; 303 304 ///foac verify 305 String bsState = DrmNative.getFoacAnswerState(foac); 306 if (bsState.equals("1")) { 307 ObjectRef category = DrmNative.getFoacDataCategory(foac); 308 309 int iCount = DrmNative.countSubCategories(category, "Result"); 310 if (iCount == 0) { 311 DrmNative.deleteFoac(foac); 312 return false; 313 } 314 ObjectRef subCategory = DrmNative.getSubCategory(category, "Result", 0); 315 String result = DrmNative.getCategoryAttributeValue(subCategory, "Value"); 316 bRet = result.equals("1"); 317 } 318 DrmNative.deleteFoac(foac); 319 return bRet; 320 } 321 322 /** 323 * 獲取信封請求信息 324 */ 325 public String GetEnvelopRequest(String sessionID) { 326 String fileID = PdfDrmNative.getEncryptParamsItemString(m_encryptParams, 327 PdfBaseDef.ENCRYPTPARAMS_FILEID); 328 String strFileID = EncryptString(fileID); 329 330 String order = PdfDrmNative.getEncryptParamsItemString(m_encryptParams, 331 PdfBaseDef.ENCRYPTPARAMS_ORDER); 332 String strOrder = order;//EncryptString(order); 333 334 String userName = mUserName;//EncryptString(m_userName); 335 String password = EncryptString(mPassword); 336 String devSn = EncryptString(mDevSN); 337 338 byte[] seed = { 339 'F', 'o', 'x', 'i', 't', 'A', 'n', 'd', 'r', 'o', 'i', 'd' 340 }; 341 342 m_rsaKey = DrmNative.createRsaKey(1024, seed, null); 343 344 if (m_rsaKey == null) 345 return null; 346 347 String strClientPubKey = RtNative.base64EncodeToString(m_rsaKey.publicKey, 0, 348 m_rsaKey.publicKey.length); 349 // String strClientPubKey = Base64.encodeToString(clientPubKey, Base64.DEFAULT); 350 351 ObjectRef foac = DrmNative.createFoac(true); 352 DrmNative.setFoacSessionID(foac, sessionID); 353 354 DrmNative.setFoacRequestID(foac, "GetEnvelop"); 355 356 ObjectRef category = DrmNative.getFoacDataCategory(foac); 357 if (category == null) { 358 DrmNative.deleteFoac(foac); 359 return null; 360 } 361 362 ObjectRef subCategory = DrmNative.addSubCategory(category, "OrderID", true); 363 DrmNative.setCategoryAttribute(subCategory, "Value", strOrder); 364 365 subCategory = DrmNative.addSubCategory(category, "EncryptFileID", true); 366 DrmNative.setCategoryAttribute(subCategory, "Value", strFileID); 367 368 subCategory = DrmNative.addSubCategory(category, "ClientPubKey", true); 369 DrmNative.setCategoryAttribute(subCategory, "Value", strClientPubKey); 370 371 subCategory = DrmNative.addSubCategory(category, "Usermail", true); 372 DrmNative.setCategoryAttribute(subCategory, "Value", userName); 373 374 subCategory = DrmNative.addSubCategory(category, "EncryptPassword", true); 375 DrmNative.setCategoryAttribute(subCategory, "Value", password); 376 377 subCategory = DrmNative.addSubCategory(category, "EncryptDeviceSN", true); 378 DrmNative.setCategoryAttribute(subCategory, "Value", devSn); 379 380 String request = DrmNative.saveFoac(foac); 381 382 DrmNative.deleteFoac(foac); 383 384 return "XmlContent=" + request; 385 } 386 387 /** 388 * 解析收到的信封信息 389 */ 390 public boolean parseEnvelopRequest(ObjectRef document, String receive) { 391 392 BufferFileRead bufReader = new BufferFileRead(receive.getBytes(), 0); 393 ObjectRef envelope = DrmNative.loadEnvelope(bufReader); 394 byte[] key = DrmNative.getEnvelopeKey(envelope); 395 396 String algorithm = DrmNative.getEnvelopeAlgorithm(envelope); 397 byte[] deKey = DrmNative.pkiRsaDecrypt(key, m_rsaKey.privateKey); 398 399 security = new ObjectRef(); 400 String filter = "FoxitSTD"; 401 int ret = PdfSecurityNative.createFoxitDRMSecurity(filter, 402 algorithm.equals("FOXIT_ENCRYPT2") ? RtBaseDef.CIPHER_AES : RtBaseDef.CIPHER_RC4, 403 deKey, security); 404 if (ret != RtBaseDef.ERR_SUCCESS) 405 return false; 406 407 int offset = PdfDrmNative.getDocWrapperOffset(document); 408 boolean flag = PdfSecurityNative.verifyFoxitDRMSecurity(security); 409 410 ret = PdfDocNative.closeDoc(document); 411 if (ret != RtBaseDef.ERR_SUCCESS) 412 return false; 413 414 ret = PdfDocNative.loadDoc(drmfile, 0, offset, document); 415 if (ret != RtBaseDef.ERR_SUCCESS) 416 return false; 417 418 return true; 419 } 420 421 /** 422 * 解密文件 423 */ 424 public boolean decrypt(ObjectRef document) { 425 if (document == null) 426 return false; 427 428 String serviceUrl = getServiceURL(); 429 if (serviceUrl == null) 430 return false; 431 parseURL(serviceUrl); 432 System.out.println("URL ==" + serviceUrl); 433 434 String sessionID = "6F9629FF-8A86-D011-B42D-00C04FC964FF"; 435 String send = getSessionBeginRequest(sessionID); 436 if (send == null) 437 return false; 438 String receive = sendAndReceive(send); 439 if (receive == null) 440 return false; 441 parseSessionBeginRecieve(receive); 442 443 String checkAccount = GetCheckAccountRequest(sessionID); 444 if (checkAccount == null) 445 return false; 446 receive = sendAndReceive(checkAccount); 447 if (receive == null) 448 return false; 449 if (!ParseCheckAccountRequest(receive)) 450 return false; 451 452 String envelope = GetEnvelopRequest(sessionID); 453 if (envelope == null) 454 return false; 455 receive = sendAndReceive(envelope); 456 if (receive == null) 457 return false; 458 459 return parseEnvelopRequest(document, receive); 460 } 461 462 /** 463 * 獲取信封 464 * @author honghe 465 */ 466 public String getEnvelop(ObjectRef document) { 467 if (document == null) 468 return null; 469 470 String serviceUrl = getServiceURL(); 471 if (serviceUrl == null) 472 return null; 473 parseURL(serviceUrl); 474 System.out.println("URL ==" + serviceUrl); 475 476 String sessionID = "6F9629FF-8A86-D011-B42D-00C04FC964FF"; 477 String send = getSessionBeginRequest(sessionID); 478 if (send == null) 479 return null; 480 String receive = sendAndReceive(send); 481 if (receive == null) 482 return null; 483 parseSessionBeginRecieve(receive); 484 485 String checkAccount = GetCheckAccountRequest(sessionID); 486 if (checkAccount == null) 487 return null; 488 receive = sendAndReceive(checkAccount); 489 if (receive == null) 490 return null; 491 if (!ParseCheckAccountRequest(receive)) 492 return null; 493 494 String envelope = GetEnvelopRequest(sessionID); 495 if (envelope == null) 496 return null; 497 receive = sendAndReceive(envelope); 498 if (receive == null) 499 return null; 500 501 return receive; 502 } 503 504 /** 505 * 根據信封信息解密文檔 506 * @author honghe 507 */ 508 public boolean decryptDoc(ObjectRef document, String receive) { 509 BufferFileRead bufReader = new BufferFileRead(receive.getBytes(), 0); 510 ObjectRef envelope = DrmNative.loadEnvelope(bufReader); 511 byte[] key = DrmNative.getEnvelopeKey(envelope); 512 String algorithm = DrmNative.getEnvelopeAlgorithm(envelope); 513 byte[] seed = { 514 'F', 'o', 'x', 'i', 't', 'A', 'n', 'd', 'r', 'o', 'i', 'd' 515 }; 516 m_rsaKey = DrmNative.createRsaKey(1024, seed, null); 517 byte[] deKey = DrmNative.pkiRsaDecrypt(key, m_rsaKey.privateKey); 518 519 security = new ObjectRef(); 520 String filter = "FoxitSTD"; 521 int ret = PdfSecurityNative.createFoxitDRMSecurity(filter, 522 algorithm.equals("FOXIT_ENCRYPT2") ? RtBaseDef.CIPHER_AES : RtBaseDef.CIPHER_RC4, 523 deKey, security); 524 if (ret != RtBaseDef.ERR_SUCCESS) 525 return false; 526 527 int offset = PdfDrmNative.getDocWrapperOffset(document); 528 boolean flag = PdfSecurityNative.verifyFoxitDRMSecurity(security); 529 530 ret = PdfDocNative.closeDoc(document); 531 if (ret != RtBaseDef.ERR_SUCCESS) 532 return false; 533 534 ret = PdfDocNative.loadDoc(drmfile, 0, offset, document); 535 if (ret != RtBaseDef.ERR_SUCCESS) 536 return false; 537 538 return true; 539 } 540 541 public void destroy() { 542 int ret = RtBaseDef.ERR_ERROR; 543 if (m_encryptParams != null) 544 ret = PdfDrmNative.releaseEncryptParams(m_encryptParams); 545 if (security != null) 546 ret = PdfSecurityNative.destroySecurity(security); 547 548 } 549 550 }
簡單的說一下調用的過程：
1.首先用客戶端下載一本經過drm加密的書籍（加密的過程是文軒那邊已經加密好的了）
2.下載完后根據書籍中的drm地址和加密信息以及用戶的用戶名和密碼獲取信封(按照福昕提供的api是在閱讀的時候在線聯網解密的，但客戶要求可以離線閱讀，因此下載書的時候要先取得解密用的信封)
獲取信封的調用方法
1 if(finished) { 2 FoxitRAMManager.getInstance(); 3 ObjectRef document = new ObjectRef(); 4 int result = PdfDocNative.loadDoc(book.loc, null, document); 5 if (result != RtBaseDef.ERR_SUCCESS) { 6 throw new Exception("load drm fail!"); 7 } 8 User user = AppContext.getInstance().getUserModel().user; 9 BaseFoac baseFoac = new BaseFoac(user.uName, user.pwd, book.loc); 10 if (baseFoac.isFoxitDRM(document)) { 11 baseFoac.setDRMFileName(book.loc); 12 String envelop = baseFoac.getEnvelop(document); 13 if (envelop != null) { 14 book.receive = envelop; 15 } 16 else { 17 throw new Exception("get envelop fail!"); 18 } 19 } 20 // baseFoac.destroy(); 21 PdfDocNative.closeDoc(document); 22 }
3.將獲取的信封根據書籍對應的信息保存到數據庫中，一本書一個用來解密的信封。
4.用戶打開書籍的時候獲取該書籍存儲於數據庫中的信封，用信封對書籍進行解密，用戶就可以看到該書籍了。
1 FoxitRAMManager.getInstance(); 2 document = new ObjectRef(); 3 int result = PdfDocNative.loadDoc(filePath, null, document); 4 if (result != RtBaseDef.ERR_SUCCESS) 5 return false; 6 // 根據得到的信封解密書籍 7 mBaseFoac = new BaseFoac(); 8 if (mBaseFoac.isDocWrapper(document)) { 9 mBaseFoac.setDRMFileName(filePath); 10 if (!mBaseFoac.decryptDoc(document, receive)) { 11 return false; 12 } 13 } else { 14 return false; 15 }
這樣做的好處是該用戶下載的書籍用其他的閱讀器是無法打開的，而且解密的信封也是跟用戶和服務器相關的，其他人或者是不聯網驗證也是無法查看傳送的書籍的，有效的保護了數字版權。
代碼已上傳github。
地址為：https://github.com/dongweiq/study/tree/master/pdf_drm
代碼中appid和password已刪除，此外你只有加入jar包和so文件才可以運行。
我的github地址：https://github.com/dongweiq/study
歡迎關注，歡迎star o(∩_∩)o 。有什么問題請郵箱聯系 dongweiqmail@gmail.com qq714094450