Example implementations relate to attestation. For example, in an implementation, a target device attestation request is transmitted to a target device, where the target device attestation request includes an identity-based encryption (IBE) ciphertext and a retrieval index. The ciphertext is a nonce encrypted using a trusted platform module (TPM) public key together with an IBE public key. The TPM public key is retrieved from a TPM of the target device, and the IBE public key is an expected value presumed to be stored at the TPM.