leif-ibsen / swifthpke

Hybrid Public Key Encryption (HPKE) in Swift

SwiftHPKE

SwiftHPKE implements the Hybrid Public Key Encryption standard as defined in RFC 9180 including all four modes of operation:

• Base mode
• Preshared key mode
• Authenticated mode
• Authenticated, preshared key mode

SwiftHPKE requires Swift 5.0. It also requires that the Int and UInt types be 64 bit types.

Its documentation is build with the DocC plugin and published on GitHub Pages at this location:

https://leif-ibsen.github.io/SwiftHPKE/documentation/swifthpke

The documentation is also available in the SwiftHPKE.doccarchive file.

swifthpke's Issues

PublicKey constructor failure

In the PublicKey constructor init(kem:bytes:) bytes represents either
an uncompressed curve point or a compressed curve point.

The constructor fails if bytes is a compressed curve point.

To be corrected in a coming release.

Algorithm not compatible with newest apple version

I was testing the repository to check compatibility with the new apple implementation of HPKE but seems is not compatible.
When running this MVE

func letsTest() {
     let cypher = HPKE.Ciphersuite(
        kem: .P384_HKDF_SHA384,
        kdf: .HKDF_SHA384,
        aead: .AES_GCM_256
    )
    let cypherLegacy = SwiftHPKE.CipherSuite(
        kem: .P384,
        kdf: .KDF384,
        aead: .AESGCM256
    )
    let privateKey = P384.KeyAgreement.PrivateKey(compactRepresentable: false)
    let bePrivateKey = P384.KeyAgreement.PrivateKey(compactRepresentable: false)
    let privateKeyLegacy = try! PrivateKey(der: Bytes(privateKey.derRepresentation))
    let publicKeyLegacy = try! PublicKey(der: Bytes(privateKey.publicKey.derRepresentation))
    let bePrivateKeyLegacy = try! PrivateKey(der: Bytes(bePrivateKey.derRepresentation))
    let bePublicKeyLegacy = try! PublicKey(der: Bytes(bePrivateKey.publicKey.derRepresentation))

    let message = "Hello World"
    var sender = try! HPKE.Sender(
        recipientKey: privateKey.publicKey,
        ciphersuite: cypher,
        info: "info".data(using: .utf8)!,
        authenticatedBy: bePrivateKey
    )
    let encryptedMessage = try! sender.seal(
        message.data(using: .utf8)!,
        authenticating: "auth".data(using: .utf8)!
    )
    let decrypted = try! cypherLegacy.open(
        privateKey: privateKeyLegacy,
        info: Bytes("info".data(using: .utf8)!),
        authentication: bePublicKeyLegacy,
        ct: Bytes(encryptedMessage),
        aad: Bytes("auth".data(using: .utf8)!),
        encap: Bytes(sender.encapsulatedKey)
    )
    print(String(bytes: decrypted, encoding: .utf8)!)
}

In this example I've created two pair of keys, converted them fo use this library following the documentation and tried to encrypt a simple message with the new Apple API.
When decoding it using this library, an error is thrown
Thread 1: Fatal error: 'try!' expression unexpectedly raised an error: CryptoKit.CryptoKitError.authenticationFailure