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ts/mail/delivery/classes.emailsignjob.ts

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+import * as plugins from '../../plugins.ts';
+import type { UnifiedEmailServer } from '../routing/classes.unified.email.server.ts';
+
+interface Headers {
+  [key: string]: string;
+}
+
+interface IEmailSignJobOptions {
+  domain: string;
+  selector: string;
+  headers: Headers;
+  body: string;
+}
+
+export class EmailSignJob {
+  emailServerRef: UnifiedEmailServer;
+  jobOptions: IEmailSignJobOptions;
+
+  constructor(emailServerRef: UnifiedEmailServer, options: IEmailSignJobOptions) {
+    this.emailServerRef = emailServerRef;
+    this.jobOptions = options;
+  }
+
+  async loadPrivateKey(): Promise<string> {
+    const keyInfo = await this.emailServerRef.dkimCreator.readDKIMKeys(this.jobOptions.domain);
+    return keyInfo.privateKey;
+  }
+
+  public async getSignatureHeader(emailMessage: string): Promise<string> {
+    const signResult = await plugins.dkimSign(emailMessage, {
+      // Optional, default canonicalization, default is "relaxed/relaxed"
+      canonicalization: 'relaxed/relaxed', // c=
+
+      // Optional, default signing and hashing algorithm
+      // Mostly useful when you want to use rsa-sha1, otherwise no need to set
+      algorithm: 'rsa-sha256',
+
+      // Optional, default is current time
+      signTime: new Date(), // t=
+
+      // Keys for one or more signatures
+      // Different signatures can use different algorithms (mostly useful when
+      // you want to sign a message both with RSA and Ed25519)
+      signatureData: [
+        {
+          signingDomain: this.jobOptions.domain, // d=
+          selector: this.jobOptions.selector, // s=
+          // supported key types: RSA, Ed25519
+          privateKey: await this.loadPrivateKey(), // k=
+
+          // Optional algorithm, default is derived from the key.
+          // Overrides whatever was set in parent object
+          algorithm: 'rsa-sha256',
+
+          // Optional signature specifc canonicalization, overrides whatever was set in parent object
+          canonicalization: 'relaxed/relaxed', // c=
+
+          // Maximum number of canonicalized body bytes to sign (eg. the "l=" tag).
+          // Do not use though. This is available only for compatibility testing.
+          // maxBodyLength: 12345
+        },
+      ],
+    });
+    const signature = signResult.signatures;
+    return signature;
+  }
+}