Libgourou

Libgourou Commit Details

Date:2022-09-04 09:25:06 (1 year 19 days ago)
Author:Grégory Soutadé
Branch:master
Commit:6e3958f09e6eee9128c60e54ab81f2e834cd6ff8
Parents: 2dbd4cc343529568c3cf05d3f3c9f54501e56435
Message:Compute over encrypted key also for PDF files
Changes:
Minclude/libgourou.h (1 diff)
Msrc/libgourou.cpp (5 diffs)

File differences

include/libgourou.h
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␉void buildSignInRequest(pugi::xml_document& signInRequest, const std::string& adobeID, const std::string& adobePassword, const std::string& authenticationCertificate);␊
␉void fetchLicenseServiceCertificate(const std::string& licenseURL,␊
␉␉␉␉␉ const std::string& operatorURL);␊
␉std::string encryptedKeyFirstPass(pugi::xml_document& rightsDoc, const std::string& encryptedKey, const std::string& keyType);␊
␉std::string encryptedKeyFirstPass(pugi::xml_document& rightsDoc, const std::string& encryptedKey, const std::string& keyType, ITEM_TYPE type);␊
␉void decryptADEPTKey(const std::string& encryptedKey, unsigned char* decryptedKey);␊
␉void removeEPubDRM(const std::string& filenameIn, const std::string& filenameOut, const unsigned char* encryptionKey, unsigned encryptionKeySize);␊
␉void generatePDFObjectKey(int version,␊
src/libgourou.cpp
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␊
/**␊
* RSA Key can be over encrypted with AES128-CBC if keyType attribute is set␊
* Key = SHA256(keyType)[14:22] || SHA256(keyType)[7:13]␊
* For EPUB, Key = SHA256(keyType)[14:22] || SHA256(keyType)[7:13]␊
* For PDF, Key = SHA256(keyType)[6:19] || SHA256(keyType)[3:6]␊
* IV = DeviceID ^ FulfillmentId ^ VoucherId␊
*␊
* @return Base64 encoded decrypted key␊
*/␊
std::string DRMProcessor::encryptedKeyFirstPass(pugi::xml_document& rightsDoc, const std::string& encryptedKey, const std::string& keyType)␊
std::string DRMProcessor::encryptedKeyFirstPass(pugi::xml_document& rightsDoc, const std::string& encryptedKey, const std::string& keyType, ITEM_TYPE type)␊
{␊
␉unsigned char digest[32], key[16], iv[16];␊
␉unsigned int dataOutLength;␊
␉std::string id;␊
␉␉␊
␉client->digest("SHA256", (unsigned char*)keyType.c_str(), keyType.size(), digest);␊
␉memcpy(key, &digest[14], 9);␊
␉memcpy(&key[9], &digest[7], 7);␊
␊
␉dumpBuffer(gourou::LG_LOG_DEBUG, "SHA of KeyType : ", digest, sizeof(digest));␊
␊
␉switch(type)␊
␉{␊
␉case EPUB:␊
␉ memcpy(key, &digest[14], 9);␊
␉ memcpy(&key[9], &digest[7], 7);␊
␉ break;␊
␉case PDF:␊
␉ memcpy(key, &digest[6], 13);␊
␉ memcpy(&key[13], &digest[3], 3);␊
␉ break;␊
␉}␊
␊
␉id = extractTextElem(rightsDoc, "/adept:rights/licenseToken/device");␊
␉if (id == "")␊
␉ std::string keyType = extractTextAttribute(rightsDoc, "/adept:rights/licenseToken/encryptedKey", "keyType", false);␊
␊
␉ if (keyType != "")␊
␉␉encryptedKey = encryptedKeyFirstPass(rightsDoc, encryptedKey, keyType);␊
␉␉encryptedKey = encryptedKeyFirstPass(rightsDoc, encryptedKey, keyType, EPUB);␊
␉ ␊
␉ decryptADEPTKey(encryptedKey, decryptedKey);␊
␊
␉␉std::string encryptedKey = extractTextElem(rightsDoc, "/adept:rights/licenseToken/encryptedKey");␊
␊
␉␉if (!encryptionKey)␊
␉␉{␊
␉␉ std::string keyType = extractTextAttribute(rightsDoc, "/adept:rights/licenseToken/encryptedKey", "keyType", false);␊
␊
␉␉ if (keyType != "")␊
␉␉␉encryptedKey = encryptedKeyFirstPass(rightsDoc, encryptedKey, keyType, PDF);␊
␉␉ ␊
␉␉ decryptADEPTKey(encryptedKey, decryptedKey);␊
␊
␉␉ dumpBuffer(gourou::LG_LOG_DEBUG, "Decrypted : ", decryptedKey, RSA_KEY_SIZE);␊
␊
␉␉ if (decryptedKey[0] != 0x00 || decryptedKey[1] != 0x02 ||␊
␉␉␉decryptedKey[RSA_KEY_SIZE-16-1] != 0x00)␊
␉␉␉EXCEPTION(DRM_ERR_ENCRYPTION_KEY, "Unable to retrieve encryption key");␊
␉␉}␊
␉␉else␊
␉␉{␊
␉␉ GOUROU_LOG(DEBUG, "Use provided encryption key");␊
␉␉ GOUROU_LOG(DEBUG, "Decrypt string " << dictIt->first << " " << dataLength);␊
␊
␉␉ client->decrypt(CryptoInterface::ALGO_RC4, CryptoInterface::CHAIN_ECB,␊
␉␉␉␉ tmpKey, 16, /* Key */␊
␉␉␉␉ tmpKey, sizeof(tmpKey), /* Key */␊
␉␉␉␉ NULL, 0, /* IV */␊
␉␉␉␉ encryptedData, dataLength,␊
␉␉␉␉ clearData, &dataOutLength);␊
␉␉GOUROU_LOG(DEBUG, "Decrypt stream id " << object->objectId() << ", size " << stream->dataLength());␊
␊
␉␉client->decrypt(CryptoInterface::ALGO_RC4, CryptoInterface::CHAIN_ECB,␊
␉␉␉␉tmpKey, 16, /* Key */␊
␉␉␉␉tmpKey, sizeof(tmpKey), /* Key */␊
␉␉␉␉NULL, 0, /* IV */␊
␉␉␉␉encryptedData, dataLength,␊
␉␉␉␉clearData, &dataOutLength);␊

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