---
title: "init(recipientKey:ciphersuite:info:presharedKey:presharedKeyIdentifier:)"
framework: cryptokit
role: symbol
role_heading: Initializer
path: "cryptokit/hpke/sender/init(recipientkey:ciphersuite:info:presharedkey:presharedkeyidentifier:)"
---

# init(recipientKey:ciphersuite:info:presharedKey:presharedKeyIdentifier:)

Creates a sender in preshared key (PSK) mode.

## Declaration

```swift
init<PK>(recipientKey: PK, ciphersuite: HPKE.Ciphersuite, info: Data, presharedKey psk: SymmetricKey, presharedKeyIdentifier pskID: Data) throws where PK : HPKEDiffieHellmanPublicKey
```

## Parameters

- `recipientKey`: The recipient’s public key for encrypting the messages.
- `ciphersuite`: The cipher suite that defines the cryptographic algorithms to use.
- `info`: Data that the key derivation function uses to compute the symmetric key material. The sender and the recipient need to use the same info data.
- `psk`: A preshared key (PSK) that the sender and the recipient both hold.
- `pskID`: An identifier for the PSK.

## Discussion

Discussion The Sender encrypts messages in PSK mode using a symmetric encryption key that the sender and recipient both know in advance, in combination with a key it derives using a key derivation function (KDF) and the key schedule data in info. The Sender encapsulates the derived key using the recipient’s public key. You access the encapsulated key using encapsulatedKey. note: The system throws errors from HPKE.Errors when it encounters them.