Certificates and on-device signers
Feather, ESign, Scarlet, device registration, P12 trust, revocation, and the no-computer trade-off.
On-device signers accept a P12 identity and provisioning profile, modify and sign an IPA locally, then initiate installation. Feather is open source. ESign and Scarlet are also widely used, but their provenance, distribution, and exact trust model differ.
The real product is the signing pair
The app is only the interface. Capability comes from the certificate and private key, P12 password, matching profile, App ID, entitlements, registered UDID, and current Apple trust. Changing signers cannot repair a revoked certificate or a profile that excludes your device.
Provider questions that matter
- What Apple program and profile type are used?
- Do I receive the original P12 and profile?
- Is the profile explicit or wildcard, and which entitlements are present?
- What is the actual certificate and profile expiry?
- What happens after revocation?
- How many replacements are included?
- How are UDIDs and private keys stored?
- Can I use another signer?
- What happens when device inventory is full?
Signer choice
- Feather: open-source certificate-pair management, sources, signing controls, and several installation modes.
- ESign: common on-device file manager and signer. It is closed source with no single canonical upstream repository, so clones and repackaged builds are widespread and there is no public tracker to check behavior against. Verify the exact distributor, keep the P12, profile, and password backed up outside the app, and keep the Feather path working as a fallback.
- Scarlet: direct, computer, custom-certificate, developer-login, and TrollStore modes. Each has a different trust and expiry model (Scarlet).
Revocation and DNS
Apple can revoke a certificate before expiry. A replacement window is a commercial promise, not a certificate property. DNS filtering may affect verification or a signer's local hostname, but it cannot cryptographically restore a revoked certificate.
Avoid calling every shared direct-install certificate “free.” Someone controls the identity, and publicly reused certificates can disappear quickly.