How to implement DRM coming from other lib

[paulocoutinhox]

Hi,

Im coming from other ePub reader library and try migrate to Readium.

That library implemented ePub drm/encryption using ePub specs (https://www.w3.org/TR/epub-33/#sec-container-metainf-encryption.xml).

We have a decrypt method that receive the encrypted data and return decrypted data:

import XyzReader
import Foundation

class MyEncryptionMethod: EncryptionMethod {
    var name: String = "http://site.com/2020/algorithmDrm"

    func decrypt(data: Data, resourceMetadata: XyzReader.ResourceMetadata, xmlEncryptionEntry _: XyzReader.XmlEncryptionEntry, completion: @escaping (Result<Data, Error>) -> Void) {
        UBLogger.d("[UBEncryptionMethod : decrypt] Start decrypt: ${resourceMetadata.url}")

        let publicKey = ReaderData.shared.drmKey

        do {
            if publicKey.isEmpty {
                UBLogger.e("[MyEncryptionMethod : decrypt] DRM key is empty")
                completion(.failure(NSError(domain: "DRM key is empty", code: 0, userInfo: nil)))
            } else {
                let decryptedData = MyHelperSecurityHelper.decryptEpubData(data, compressed: true, publicKey: publicKey)
                UBLogger.d("[MyEncryptionMethod : decrypt] Decrypted file with success: \(resourceMetadata.path)/\(resourceMetadata)")

                if decryptedData.isEmpty {
                    UBLogger.e("[MyEncryptionMethod : decrypt] Decrypted data is empty for file: \(resourceMetadata.path)/\(resourceMetadata)")
                    completion(.failure(NSError(domain: "Decrypted data is empty for file: \(resourceMetadata.path)/\(resourceMetadata)", code: 0, userInfo: nil)))
                } else {
                    completion(.success(decryptedData))
                }
            }
        } catch {
            UBLogger.e("[MyEncryptionMethod : decrypt] Fail to decrypt file: ${resourceMetadata.url}. Message: ${e.message}")
            completion(.failure(error))
        }
    }
}

Since my ePub is using default ePub specs for encryption (https://www.w3.org/TR/epub-33/#sec-container-metainf-encryption.xml), how i can implement DRM decryption using Readium?

Thanks.

[mickael-menu]

You can take a look at this documentation on Content Protection. Some Streamer APIs changed but the overall concepts are the same: https://readium.org/architecture/proposals/006-content-protection.html

There's a concrete example in the ReadiumLCP module: https://github.com/readium/swift-toolkit/blob/develop/Sources/LCP/Content%20Protection/LCPContentProtection.swift

[paulocoutinhox]

Solved, thanks.