Add signer

2024-08-07 11:09:40 -07:00
parent 28daebabee
commit bb7a370fba
12 changed files with 507 additions and 0 deletions
@@ -0,0 +1,77 @@
+import {UnwrappedEvent, SignedEvent, HashedEvent, EventTemplate, WRAP, SEAL} from '@welshman/util'
+import {own, hash, decrypt, ISigner} from './util'
+
+// Wrapper
+
+export type WrapperParams = {
+  author?: string
+  wrap?: {
+    author: string
+    recipient: string
+    tags?: string[][]
+  }
+}
+
+export class Wrapper {
+  seen = new Map<string, UnwrappedEvent | Error>()
+
+  constructor(readonly userSigner: ISigner, readonly wrapSigner: ISigner) {}
+
+  now = (drift = 0) =>
+    Math.round(Date.now() / 1000 - Math.random() * Math.pow(10, drift))
+
+  getSeal = async (pk: string, rumor: HashedEvent) =>
+    this.userSigner.sign(hash({
+      kind: SEAL,
+      pubkey: await this.userSigner.getPubkey(),
+      content: await this.userSigner.nip44.encrypt(pk, JSON.stringify(rumor)),
+      created_at: this.now(5),
+      tags: [],
+    }))
+
+  getWrap = async (pk: string, seal: SignedEvent) =>
+    this.wrapSigner.sign(hash({
+      kind: WRAP,
+      pubkey: await this.wrapSigner.getPubkey(),
+      content: await this.wrapSigner.nip44.encrypt(pk, JSON.stringify(seal)),
+      created_at: this.now(5),
+      tags: [["p", pk]],
+    }))
+
+  wrap = async (pk: string, template: EventTemplate) => {
+    const pubkey = await this.userSigner.getPubkey()
+    const rumor = hash(own(pubkey, template))
+    const seal = await this.getSeal(pk, rumor)
+    const wrap = await this.getWrap(pk, seal)
+
+    return wrap
+  }
+
+  unwrap = async (wrap: SignedEvent) => {
+    // Avoid decrypting the same event multiple times
+    if (this.seen.has(wrap.id)) {
+      const rumorOrError = this.seen.get(wrap.id)
+
+      if (rumorOrError instanceof Error) {
+        throw rumorOrError
+      } else {
+        return rumorOrError
+      }
+    }
+
+    try {
+      const seal = JSON.parse(await decrypt(this.wrapSigner, wrap.pubkey, wrap.content))
+      const rumor = JSON.parse(await decrypt(this.wrapSigner, seal.pubkey, seal.content))
+
+      if (seal.pubkey !== rumor.pubkey) throw new Error("Seal pubkey does not match rumor pubkey")
+
+      this.seen.set(wrap.id, rumor)
+
+      return rumor
+    } catch (error) {
+      this.seen.set(wrap.id, error as Error)
+
+      throw error
+    }
+  }
+}