Amber: Nostr event signer for Android

Designed to have your keys on only one application

Current Features

• Offline
• Use nip-46 or make an addendum in nip-46
• Improve the ui (currently its showing a text with the raw json of the event)
• Check if we can use Amber to sign the events of web applications
• Change the sign button to just copy the signature of the event
• Use a service or another approach to not open the app always to get the signed event on android

Adding Amber support for your application

• Add a package querie in your AndroidManifest.xml

<queries>
    <package android:name="com.greenart7c3.nostrsigner"/>
</queries>

• Create the Nostr Event

val event = TextNoteEvent(id, pubKey, TimeUtils.now(), tags, message, signature = "")

• Convert the event to json

val json = event.toJson()

• Create the intent using the nostrsigner scheme

val intent = Intent(Intent.ACTION_VIEW, Uri.parse("nostrsigner:$json;name=Your Application name"))

• Set the package name of the signer app for the intent

intent.`package` = "com.greenart7c3.nostrsigner"

• Set the type eg (sign_event, nip04_encrypt, nip04_decrypt, nip44_encrypt, nip44_decrypt, get_public_key)

val signerType = when (type) {
    SignerType.SIGN_EVENT -> "sign_event"
    SignerType.NIP04_ENCRYPT -> "nip04_encrypt"
    SignerType.NIP04_DECRYPT -> "nip04_decrypt"
    SignerType.NIP44_ENCRYPT -> "nip44_encrypt"
    SignerType.NIP44_DECRYPT -> "nip44_decrypt"
    SignerType.GET_PUBLIC_KEY -> "get_public_key"
}
intent.putExtra("type", signerType)

• Set the pubkey if using nip04_decrypt

intent.putExtra("pubKey", pubKey)

• Start the signer Activity

context.startActivity(intent)

Support for Web Applications

• Create the Nostr Event

• Convert the event to json

const json = JSON.stringify(note)

• Create the intent

const intent = `nostrsigner:${json};name=Your Application name`

• Send the intent

window.location.href = intent;

Contributing

Issues and pull requests are very welcome.