+
+// Panics if `unblinded_tlvs` length is less than `unblinded_pks` length
+pub(super) fn construct_blinded_hops<'a, T, I1, I2>(
+ secp_ctx: &Secp256k1<T>, unblinded_pks: I1, mut unblinded_tlvs: I2, session_priv: &SecretKey
+) -> Result<Vec<BlindedHop>, secp256k1::Error>
+where
+ T: secp256k1::Signing + secp256k1::Verification,
+ I1: Iterator<Item=&'a PublicKey>,
+ I2: Iterator,
+ I2::Item: Writeable
+{
+ let mut blinded_hops = Vec::with_capacity(unblinded_pks.size_hint().0);
+ construct_keys_callback(
+ secp_ctx, unblinded_pks, None, session_priv,
+ |blinded_node_id, _, _, encrypted_payload_rho, _, _| {
+ blinded_hops.push(BlindedHop {
+ blinded_node_id,
+ encrypted_payload: encrypt_payload(unblinded_tlvs.next().unwrap(), encrypted_payload_rho),
+ });
+ })?;
+ Ok(blinded_hops)
+}
+
+/// Encrypt TLV payload to be used as a [`crate::blinded_path::BlindedHop::encrypted_payload`].
+fn encrypt_payload<P: Writeable>(payload: P, encrypted_tlvs_rho: [u8; 32]) -> Vec<u8> {
+ let write_adapter = ChaChaPolyWriteAdapter::new(encrypted_tlvs_rho, &payload);
+ write_adapter.encode()
+}
+
+/// Blinded path encrypted payloads may be padded to ensure they are equal length.
+///
+/// Reads padding to the end, ignoring what's read.
+pub(crate) struct Padding {}
+impl Readable for Padding {
+ #[inline]
+ fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+ loop {
+ let mut buf = [0; 8192];
+ if reader.read(&mut buf[..])? == 0 { break; }
+ }
+ Ok(Self {})
+ }
+}