//! Key type wrappers of various kinds used in onion services.

//!

//! (We define wrappers here as a safety net against confusing one kind of

//! key for another: without a system like this, it can get pretty hard making

//! sure that each key is used only in the right way.)

use std::fmt::{self, Debug, Display};

use std::str::FromStr;

use digest::Digest;

use itertools::{chain, Itertools};

use thiserror::Error;

use tor_basic_utils::{impl_debug_hex, StrExt as _};

use tor_key_forge::ToEncodableKey;

use tor_llcrypto::d::Sha3_256;

use tor_llcrypto::pk::ed25519::{Ed25519PublicKey, Ed25519SigningKey};

use tor_llcrypto::pk::{curve25519, ed25519, keymanip};

use tor_llcrypto::util::ct::CtByteArray;

use crate::macros::{define_bytes, define_pk_keypair};

use crate::time::TimePeriod;

#[allow(deprecated)]

pub use hs_client_intro_auth::{HsClientIntroAuthKey, HsClientIntroAuthKeypair};

define_bytes! {

/// The identity of a v3 onion service. (KP_hs_id)

///

/// This is the decoded and validated ed25519 public key that is encoded as a

/// `${base32}.onion` address.  When expanded, it is a public key whose

/// corresponding secret key is controlled by the onion service.

///

/// `HsId`'s `Display` and `FromStr` representation is the domain name

/// `"${base32}.onion"`.  (Without any subdomains.)

///

/// Note: This is a separate type from [`HsIdKey`] because it is about 6x

/// smaller.

#[derive(Copy, Clone, Eq, PartialEq, Hash)]

pub struct HsId([u8; 32]);

}

impl fmt::LowerHex for HsId {

        }

}

impl Debug for HsId {

}

define_pk_keypair! {

/// The identity of a v3 onion service, expanded into a public key. (KP_hs_id)

///

/// This is the decoded and validated ed25519 public key that is encoded as

/// a `${base32}.onion` address.

///

/// This key is not used to sign or validate anything on its own; instead, it is

/// used to derive a [`HsBlindIdKey`].

///

/// Note: This is a separate type from [`HsId`] because it is about 6x

/// larger.  It is an expanded form, used for doing actual cryptography.

//

// NOTE: This is called the "master" key in rend-spec-v3, but we're deprecating

// that vocabulary generally.

pub struct HsIdKey(ed25519::PublicKey) /

    ///

    /// This is stored as an expanded secret key, for compatibility with the C

    /// tor implementation, and in order to support custom-generated addresses.

    ///

    /// (About custom generated addresses: When making a vanity onion address,

    /// it is inefficient to search for a compact secret key `s` and compute

    /// `SHA512(s)=(a,r)` and `A=aB` until you find an `s` that produces an `A`

    /// that you like.  Instead, most folks use the algorithm of

    /// rend-spec-v3.txt appendix C, wherein you search for a good `a` directly

    /// by repeatedly adding `8B` to A until you find an `A` you like.  The only

    /// major drawback is that once you have found a good `a`, you can't get an

    /// `s` for it, since you presumably can't find SHA512 preimages.  And that

    /// is why we store the private key in (a,r) form.)

    HsIdKeypair(ed25519::ExpandedKeypair);

}

impl HsIdKey {

    /// Return a representation of this key as an [`HsId`].

    ///

    /// ([`HsId`] is much smaller, and easier to store.)

}

impl TryFrom<HsId> for HsIdKey {

    type Error = signature::Error;

}

impl From<HsIdKey> for HsId {

}

impl From<&HsIdKeypair> for HsIdKey {

}

impl From<HsIdKeypair> for HsIdKey {

}

/// VERSION from rend-spec-v3 s.6 \[ONIONADDRESS]

const HSID_ONION_VERSION: u8 = 0x03;

/// The fixed string `.onion`

pub const HSID_ONION_SUFFIX: &str = ".onion";

impl Display for HsId {

}

impl safelog::Redactable for HsId {

    // We here display some of the end.  We don't want to display the

    // *start* because vanity domains, which would perhaps suffer from

    // reduced deniability.

        /// Length of the base32 data part of the address

        const DATA: usize = 56;

        // We show this part of the domain:

        //     e     n     l     5     s     i     d     .onion

        //   KKKKK KKKKK KCCCC CCCCC CCCCC CCVVV VVVVV

        //                           ^^^^^^^^^^^^^^^^^ ^^^^^^^^^

        // This contains 3 characters of base32, which is 15 bits.

        // 8 of those bits are the version, which is currently always 0x03.

        // So we are showing 7 bits derived from the site key.

}

impl FromStr for HsId {

    type Err = HsIdParseError;

        use HsIdParseError as PE;

        // Ideally we'd have code here that would provide a clear error message if

        // we encounter an address with the wrong version.  But that is very complicated

        // because the encoding format does not make that at all convenient.

        // So instead our errors tell you what aspect of the parsing went wrong.

}

/// Error that can occur parsing an `HsId` from a v3 `.onion` domain name

#[derive(Error, Clone, Debug)]

#[non_exhaustive]

pub enum HsIdParseError {

    /// Supplied domain name string does not end in `.onion`

    #[error("Domain name does not end in .onion")]

    NotOnionDomain,

    /// Base32 decoding failed

    ///

    /// `position` is indeed the (byte) position in the input string

    #[error("Invalid base32 in .onion address")]

    InvalidBase32(#[from] data_encoding::DecodeError),

    /// Encoded binary data is invalid

    #[error("Invalid encoded binary data in .onion address")]

    InvalidData(#[from] tor_bytes::Error),

    /// Unsupported `.onion` address version

    #[error("Unsupported .onion address version, v{0}")]

    UnsupportedVersion(u8),

    /// Checksum failed

    #[error("Checksum failed, .onion address corrupted")]

    WrongChecksum,

    /// If you try to parse a domain with subdomains as an `HsId`

    #[error("`.onion` address with subdomain passed where not expected")]

    HsIdContainsSubdomain,

}

impl HsId {

    /// Calculates CHECKSUM rend-spec-v3 s.6 \[ONIONADDRESS]

}

impl HsIdKey {

    /// Derive the blinded key and subcredential for this identity during `cur_period`.

    /// Given a time period and a blinded public key, compute the subcredential.

    /// Compute the 32-byte "blinding factor" used to compute blinded public

    /// (and secret) keys.

    ///

    /// Returns the value `h = H(...)`, from rend-spec-v3 A.2., before clamping.

        // rend-spec-v3 appendix A.2

        // We generate our key blinding factor as

        //    h = H(BLIND_STRING | A | s | B | N)

        // Where:

        //    H is SHA3-256.

        //    A is this public key.

        //    BLIND_STRING = "Derive temporary signing key" | INT_1(0)

        //    s is an optional secret (not implemented here.)

        //    B is the ed25519 basepoint.

        //    N = "key-blind" || INT_8(period_num) || INT_8(period_length).

        /// String used as part of input to blinding hash.

        const BLIND_STRING: &[u8] = b"Derive temporary signing key\0";

        /// String representation of our Ed25519 basepoint.

        const ED25519_BASEPOINT: &[u8] =

            b"(15112221349535400772501151409588531511454012693041857206046113283949847762202, \

               46316835694926478169428394003475163141307993866256225615783033603165251855960)";

}

impl HsIdKeypair {

    /// Derive the blinded key and subcredential for this identity during `cur_period`.

        // Note: This implementation is somewhat inefficient, as it recomputes

        // the PublicKey, and computes our blinding factor twice.  But we

        // only do this on an onion service once per time period: the

        // performance does not matter.

}

define_pk_keypair! {

/// The "blinded" identity of a v3 onion service. (`KP_hs_blind_id`)

///

/// This key is derived via a one-way transformation from an

/// `HsIdKey` and the current time period.

///

/// It is used for two purposes: first, to compute an index into the HSDir

/// ring, and second, to sign a `DescSigningKey`.

///

/// Note: This is a separate type from [`HsBlindId`] because it is about 6x

/// larger.  It is an expanded form, used for doing actual cryptography.

pub struct HsBlindIdKey(ed25519::PublicKey) / HsBlindIdKeypair(ed25519::ExpandedKeypair);

}

impl From<HsBlindIdKeypair> for HsBlindIdKey {

}

define_bytes! {

/// A blinded onion service identity, represented in a compact format. (`KP_hs_blind_id`)

///

/// Note: This is a separate type from [`HsBlindIdKey`] because it is about

/// 6x smaller.

#[derive(Copy, Clone, Eq, PartialEq, Hash)]

pub struct HsBlindId([u8; 32]);

}

impl_debug_hex! { HsBlindId .0 }

impl HsBlindIdKey {

    /// Return a representation of this key as a [`HsBlindId`].

    ///

    /// ([`HsBlindId`] is much smaller, and easier to store.)

}

impl TryFrom<HsBlindId> for HsBlindIdKey {

    type Error = signature::Error;

}

impl From<&HsBlindIdKeypair> for HsBlindIdKey {

}

impl From<HsBlindIdKey> for HsBlindId {

}

impl From<ed25519::Ed25519Identity> for HsBlindId {

}

impl Ed25519SigningKey for HsBlindIdKeypair {

}

impl Ed25519PublicKey for HsBlindIdKeypair {

}

define_pk_keypair! {

/// A key used to sign onion service descriptors. (`KP_desc_sign`)

///

/// It is authenticated with a [`HsBlindIdKey`] to prove that it belongs to

/// the right onion service, and is used in turn to sign the descriptor that

/// tells clients what they need to know about contacting an onion service.

///

/// Onion services create a new `DescSigningKey` every time the

/// `HsBlindIdKey` rotates, to prevent descriptors made in one time period

/// from being linkable to those made in another.

///

/// Note: we use a separate signing key here, rather than using the

/// `HsBlindIdKey` directly, so that the [`HsBlindIdKeypair`]

/// can be kept offline.

pub struct HsDescSigningKey(ed25519::PublicKey) / HsDescSigningKeypair(ed25519::Keypair);

}

define_pk_keypair! {

/// A key used to identify and authenticate an onion service at a single

/// introduction point. (`KP_hs_ipt_sid`)

///

/// This key is included in the onion service's descriptor; a different one is

/// used at each introduction point.  Introduction points don't know the

/// relation of this key to the onion service: they only recognize the same key

/// when they see it again.

pub struct HsIntroPtSessionIdKey(ed25519::PublicKey) / HsIntroPtSessionIdKeypair(ed25519::Keypair);

}

define_pk_keypair! {

/// A key used in the HsNtor handshake between the client and the onion service.

/// (`KP_hss_ntor`)

///

/// The onion service chooses a different one of these to use with each

/// introduction point, though it does not need to tell the introduction points

/// about these keys.

pub struct HsSvcNtorKey(curve25519::PublicKey) / HsSvcNtorSecretKey(curve25519::StaticSecret);

curve25519_pair as HsSvcNtorKeypair;

}

mod hs_client_intro_auth {

    #![allow(deprecated)]

    //! Key type wrappers for the deprecated `HsClientIntroKey`/`HsClientIntroKeypair` types.

    use tor_llcrypto::pk::ed25519;

    use crate::macros::define_pk_keypair;

    define_pk_keypair! {

    /// First type of client authorization key, used for the introduction protocol.

    /// (`KP_hsc_intro_auth`)

    ///

    /// This is used to sign a nonce included in an extension in the encrypted

    /// portion of an introduce cell.

    #[deprecated(note = "This key type is not used in the protocol implemented today.")]

    pub struct HsClientIntroAuthKey(ed25519::PublicKey) /

    #[deprecated(note = "This key type is not used in the protocol implemented today.")]

    HsClientIntroAuthKeypair(ed25519::Keypair);

    }

}

define_pk_keypair! {

/// Client service discovery key, used for onion descriptor

/// decryption. (`KP_hsc_desc_enc`)

///

/// Any client who knows the secret key corresponding to this key can decrypt

/// the inner layer of the onion service descriptor.

///

/// The [`Display`] and [`FromStr`] representation of keys of this type is

/// `descriptor:x25519:<base32-encoded-x25519-public-key>`.

/// Note: the base32 encoding of the key is unpadded and case-insensitive,

/// for compatibility with the format accepted by C Tor.

/// See also `CLIENT AUTHORIZATION` in `tor(1)`.

///

/// # Example

///

/// ```rust

/// # use tor_hscrypto::pk::HsClientDescEncKey;

/// # use std::str::FromStr;

/// // A client service discovery key for connecting

/// // to a service running in restricted discovery mode,

/// // with an uppercase base32 encoding for the key material.

/// const CLIENT_KEY1: &str = "descriptor:x25519:ZPRRMIV6DV6SJFL7SFBSVLJ5VUNPGCDFEVZ7M23LTLVTCCXJQBKA";

/// // An identical key using lowercase base32 encoding for the key material.

/// const CLIENT_KEY2: &str = "descriptor:x25519:zprrmiv6dv6sjfl7sfbsvlj5vunpgcdfevz7m23ltlvtccxjqbka";

///

/// // Both key encodings parse successfully

/// let key1 = HsClientDescEncKey::from_str(CLIENT_KEY1).unwrap();

/// let key2 = HsClientDescEncKey::from_str(CLIENT_KEY2).unwrap();

/// // The keys are identical

/// assert_eq!(key1, key2);

/// ```

pub struct HsClientDescEncKey(curve25519::PublicKey) / HsClientDescEncSecretKey(curve25519::StaticSecret);

curve25519_pair as HsClientDescEncKeypair;

}

impl PartialEq for HsClientDescEncKey {

}

impl Eq for HsClientDescEncKey {}

impl Display for HsClientDescEncKey {

}

impl FromStr for HsClientDescEncKey {

    type Err = HsClientDescEncKeyParseError;

}

/// Error that can occur parsing an `HsClientDescEncKey` from C Tor format.

#[derive(Error, Clone, Debug, PartialEq)]

#[non_exhaustive]

pub enum HsClientDescEncKeyParseError {

    /// The auth type is not "descriptor".

    #[error("Invalid auth type {0}")]

    InvalidAuthType(String),

    /// The key type is not "x25519".

    #[error("Invalid key type {0}")]

    InvalidKeyType(String),

    /// The key is not in the `<auth-type>:x25519:<base32-encoded-public-key>` format.

    #[error("Invalid key format")]

    InvalidFormat,

    /// The encoded key material is invalid.

    #[error("Invalid key material")]

    InvalidKeyMaterial,

    /// Base32 decoding failed.

    #[error("Invalid base32 in client key")]

    InvalidBase32(#[from] data_encoding::DecodeError),

}

define_pk_keypair! {

/// Server key, used for diffie hellman during onion descriptor decryption.

/// (`KP_hss_desc_enc`)

///

/// This key is created for a single descriptor, and then thrown away.

pub struct HsSvcDescEncKey(curve25519::PublicKey) / HsSvcDescEncSecretKey(curve25519::StaticSecret);

}

impl From<&HsClientDescEncSecretKey> for HsClientDescEncKey {

}

impl From<&HsClientDescEncKeypair> for HsClientDescEncKey {

}

/// An ephemeral x25519 keypair, generated by an onion service

/// and used to for onion service encryption.

#[allow(clippy::exhaustive_structs)]

#[derive(Debug)]

pub struct HsSvcDescEncKeypair {

    /// The public part of the key.

    pub public: HsSvcDescEncKey,

    /// The secret part of the key.

    pub secret: HsSvcDescEncSecretKey,

}

// TODO: let the define_ed25519_keypair/define_curve25519_keypair macros

// auto-generate these impls.

//

// For some of the keys here, this currently cannot be done

// because the macro doesn't support generating expanded ed25519 keys.

impl ToEncodableKey for HsClientDescEncKeypair {

    type Key = curve25519::StaticKeypair;

    type KeyPair = HsClientDescEncKeypair;

}

impl ToEncodableKey for HsBlindIdKeypair {

    type Key = ed25519::ExpandedKeypair;

    type KeyPair = HsBlindIdKeypair;

}

impl ToEncodableKey for HsBlindIdKey {

    type Key = ed25519::PublicKey;

    type KeyPair = HsBlindIdKeypair;

}

impl ToEncodableKey for HsIdKeypair {

    type Key = ed25519::ExpandedKeypair;

    type KeyPair = HsIdKeypair;

}

impl ToEncodableKey for HsIdKey {

    type Key = ed25519::PublicKey;

    type KeyPair = HsIdKeypair;

}

impl ToEncodableKey for HsDescSigningKeypair {

    type Key = ed25519::Keypair;

    type KeyPair = HsDescSigningKeypair;

}

impl ToEncodableKey for HsIntroPtSessionIdKeypair {

    type Key = ed25519::Keypair;

    type KeyPair = HsIntroPtSessionIdKeypair;

}

impl ToEncodableKey for HsSvcNtorKeypair {

    type Key = curve25519::StaticKeypair;

    type KeyPair = HsSvcNtorKeypair;

}

#[cfg(test)]

mod test {

    // @@ begin test lint list maintained by maint/add_warning @@

    #![allow(clippy::bool_assert_comparison)]

    #![allow(clippy::clone_on_copy)]

    #![allow(clippy::dbg_macro)]

    #![allow(clippy::mixed_attributes_style)]

    #![allow(clippy::print_stderr)]

    #![allow(clippy::print_stdout)]

    #![allow(clippy::single_char_pattern)]

    #![allow(clippy::unwrap_used)]

    #![allow(clippy::unchecked_duration_subtraction)]

    #![allow(clippy::useless_vec)]

    #![allow(clippy::needless_pass_by_value)]

    //! <!-- @@ end test lint list maintained by maint/add_warning @@ -->

    use hex_literal::hex;

    use itertools::izip;

    use safelog::Redactable;

    use std::time::{Duration, SystemTime};

    use tor_basic_utils::test_rng::testing_rng;

    use super::*;

    #[test]

    fn hsid_strings() {

        use HsIdParseError as PE;

        // From C Tor src/test/test_hs_common.c test_build_address

        let hex = "d75a980182b10ab7d54bfed3c964073a0ee172f3daa62325af021a68f707511a";

        let b32 = "25njqamcweflpvkl73j4szahhihoc4xt3ktcgjnpaingr5yhkenl5sid";

        let hsid: [u8; 32] = hex::decode(hex).unwrap().try_into().unwrap();

        let hsid = HsId::from(hsid);

        let onion = format!("{}.onion", b32);

        assert_eq!(onion.parse::<HsId>().unwrap(), hsid);

        assert_eq!(hsid.to_string(), onion);

        let weird_case: String = izip!(onion.chars(), [false, true].iter().cloned().cycle(),)

            .map(|(c, swap)| if swap { c.to_ascii_uppercase() } else { c })

            .collect();

        dbg!(&weird_case);

        assert_eq!(weird_case.parse::<HsId>().unwrap(), hsid);

        macro_rules! chk_err { { $s:expr, $($pat:tt)* } => {

            let e = $s.parse::<HsId>();

            assert!(matches!(e, Err($($pat)*)), "{:?}", &e);

        } }

        let edited = |i, c| {

            let mut s = b32.to_owned().into_bytes();

            s[i] = c;

            format!("{}.onion", String::from_utf8(s).unwrap())

        };

        chk_err!("wrong", PE::NotOnionDomain);

        chk_err!("@.onion", PE::InvalidBase32(..));

        chk_err!("aaaaaaaa.onion", PE::InvalidData(..));

        chk_err!(edited(55, b'E'), PE::UnsupportedVersion(4));

        chk_err!(edited(53, b'X'), PE::WrongChecksum);

        chk_err!(&format!("www.{}", &onion), PE::HsIdContainsSubdomain);

        assert_eq!(format!("{:x}", &hsid), format!("HsId(0x{})", hex));

        assert_eq!(format!("{:?}", &hsid), format!("HsId({})", onion));

        assert_eq!(format!("{}", hsid.redacted()), "???sid.onion");

    }

    #[test]

    fn key_blinding_blackbox() {

        let mut rng = testing_rng();

        let offset = Duration::new(12 * 60 * 60, 0);

        let when = TimePeriod::new(Duration::from_secs(3600), SystemTime::now(), offset).unwrap();

        let keypair = ed25519::Keypair::generate(&mut rng);

        let id_pub = HsIdKey::from(keypair.verifying_key());

        let id_keypair = HsIdKeypair::from(ed25519::ExpandedKeypair::from(&keypair));

        let (blinded_pub, subcred1) = id_pub.compute_blinded_key(when).unwrap();

        let (blinded_pub2, blinded_keypair, subcred2) =

            id_keypair.compute_blinded_key(when).unwrap();

        assert_eq!(subcred1.as_ref(), subcred2.as_ref());

        assert_eq!(blinded_pub.0.to_bytes(), blinded_pub2.0.to_bytes());

        assert_eq!(blinded_pub.id(), blinded_pub2.id());

        let message = b"Here is a terribly important string to authenticate.";

        let other_message = b"Hey, that is not what I signed!";

        let sign = blinded_keypair.sign(message);

        assert!(blinded_pub.as_ref().verify(message, &sign).is_ok());

        assert!(blinded_pub.as_ref().verify(other_message, &sign).is_err());

    }

    #[test]

    fn key_blinding_testvec() {

        // Test vectors generated with C tor.

        let id = HsId::from(hex!(

            "833990B085C1A688C1D4C8B1F6B56AFAF5A2ECA674449E1D704F83765CCB7BC6"

        ));

        let id_pubkey = HsIdKey::try_from(id).unwrap();

        let id_seckey = HsIdKeypair::from(

            ed25519::ExpandedKeypair::from_secret_key_bytes(hex!(

                "D8C7FF0E31295B66540D789AF3E3DF992038A9592EEA01D8B7CBA06D6E66D159

                 4D6167696320576F7264733A20737065697373636F62616C742062697669756D"

            ))

            .unwrap(),

        );

        let time_period = TimePeriod::new(

            humantime::parse_duration("1 day").unwrap(),

            humantime::parse_rfc3339("1973-05-20T01:50:33Z").unwrap(),

            humantime::parse_duration("12 hours").unwrap(),

        )

        .unwrap();

        assert_eq!(time_period.interval_num, 1234);

        let h = id_pubkey.blinding_factor(b"", time_period);

        assert_eq!(

            h,

            hex!("379E50DB31FEE6775ABD0AF6FB7C371E060308F4F847DB09FE4CFE13AF602287")

        );

        let (blinded_pub1, subcred1) = id_pubkey.compute_blinded_key(time_period).unwrap();

        assert_eq!(

            blinded_pub1.0.to_bytes(),

            hex!("3A50BF210E8F9EE955AE0014F7A6917FB65EBF098A86305ABB508D1A7291B6D5")

        );

        assert_eq!(

            subcred1.as_ref(),

            &hex!("635D55907816E8D76398A675A50B1C2F3E36B42A5CA77BA3A0441285161AE07D")

        );

        let (blinded_pub2, blinded_sec, subcred2) =

            id_seckey.compute_blinded_key(time_period).unwrap();

        assert_eq!(blinded_pub1.0.to_bytes(), blinded_pub2.0.to_bytes());

        assert_eq!(subcred1.as_ref(), subcred2.as_ref());

        assert_eq!(

            blinded_sec.0.to_secret_key_bytes(),

            hex!(

                "A958DC83AC885F6814C67035DE817A2C604D5D2F715282079448F789B656350B

                 4540FE1F80AA3F7E91306B7BF7A8E367293352B14A29FDCC8C19F3558075524B"

            )

        );

    }

    #[test]

    fn parse_client_desc_enc_key() {

        use HsClientDescEncKeyParseError::*;

        /// Valid base32-encoded x25519 public key.

        const VALID_KEY_BASE32: &str = "dz4q5xqlb4ldnbs72iarrml4ephk3du4i7o2cgiva5lwr6wkquja";

        // Some keys that are in the wrong format

        const WRONG_FORMAT: &[&str] = &["a:b:c:d:e", "descriptor:", "descriptor:x25519", ""];

        for key in WRONG_FORMAT {

            let err = HsClientDescEncKey::from_str(key).unwrap_err();

            assert_eq!(err, InvalidFormat);

        }

        let err =

            HsClientDescEncKey::from_str(&format!("foo:descriptor:x25519:{VALID_KEY_BASE32}"))

                .unwrap_err();

        assert_eq!(err, InvalidFormat);

        // A key with an invalid auth type

        let err = HsClientDescEncKey::from_str("bar:x25519:aa==").unwrap_err();

        assert_eq!(err, InvalidAuthType("bar".into()));

        // A key with an invalid key type

        let err = HsClientDescEncKey::from_str("descriptor:not-x25519:aa==").unwrap_err();

        assert_eq!(err, InvalidKeyType("not-x25519".into()));

        // A key with an invalid base32 part

        let err = HsClientDescEncKey::from_str("descriptor:x25519:aa==").unwrap_err();

        assert!(matches!(err, InvalidBase32(_)));

        // A valid client desc enc key

        let _key =

            HsClientDescEncKey::from_str(&format!("descriptor:x25519:{VALID_KEY_BASE32}")).unwrap();

        // Roundtrip

        let desc_enc_key = HsClientDescEncKey::from(curve25519::PublicKey::from(

            &curve25519::StaticSecret::random_from_rng(testing_rng()),

        ));

        assert_eq!(

            desc_enc_key,

            HsClientDescEncKey::from_str(&desc_enc_key.to_string()).unwrap()

        );

    }

}