    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80
    81
    82
    83
    84
    85
    86
    87
    88
    89
    90
    91
    92
    93
    94
    95
    96
    97
    98
    99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    143
    144
    145
    146
    147
    148
    149
    150
    151
    152
    153
    154
    155

    //! Registry asymmetric authentication support. See [RFC 3231] for more.
    //!
    //! [RFC 3231]: https://rust-lang.github.io/rfcs/3231-cargo-asymmetric-tokens.html

    use pasetors::keys::AsymmetricPublicKey;
    use pasetors::keys::AsymmetricSecretKey;
    use pasetors::paserk;
    use pasetors::paserk::FormatAsPaserk;
    use pasetors::version3;
    use pasetors::version3::PublicToken;
    use time::format_description::well_known::Rfc3339;
    use time::OffsetDateTime;

    use crate::core::SourceId;
    use crate::ops::RegistryCredentialConfig;
    use crate::CargoResult;

    use super::Mutation;
    use super::Secret;

    /// The main body of an asymmetric token as describe in RFC 3231.
    #[derive(serde::Serialize)]
    struct Message<'a> {
        iat: &'a str,
        #[serde(skip_serializing_if = "Option::is_none")]
        sub: Option<&'a str>,
        #[serde(skip_serializing_if = "Option::is_none")]
        mutation: Option<&'a str>,
        #[serde(skip_serializing_if = "Option::is_none")]
        name: Option<&'a str>,
        #[serde(skip_serializing_if = "Option::is_none")]
        vers: Option<&'a str>,
        #[serde(skip_serializing_if = "Option::is_none")]
        cksum: Option<&'a str>,
        #[serde(skip_serializing_if = "Option::is_none")]
        challenge: Option<&'a str>,
        /// This field is not yet used. This field can be set to a value >1 to
        /// indicate a breaking change in the token format.
        #[serde(skip_serializing_if = "Option::is_none")]
        v: Option<u8>,
    }

    /// The footer of an asymmetric token as describe in RFC 3231.
    #[derive(serde::Serialize)]
    struct Footer<'a> {
        url: &'a str,
        kip: paserk::Id,
    }

    /// Checks that a secret key is valid, and returns the associated public key in
    /// Paserk format.
    pub fn paserk_public_from_paserk_secret(secret_key: Secret<&str>) -> Option<String> {
        let secret: Secret<AsymmetricSecretKey<version3::V3>> =
            secret_key.map(|key| key.try_into()).transpose().ok()?;
        let public: AsymmetricPublicKey<version3::V3> = secret
            .as_ref()
            .map(|key| key.try_into())
            .transpose()
            .ok()?
            .expose();
        let mut paserk_pub_key = String::new();
        FormatAsPaserk::fmt(&public, &mut paserk_pub_key).unwrap();
        Some(paserk_pub_key)
    }

    /// Generates a public token from a registry's `credential` configuration for
    /// authenticating to a `source_id`
    ///
    /// An optional `mutation` for authenticating a mutation operation aganist the
    /// registry.
    pub fn public_token_from_credential(
        credential: RegistryCredentialConfig,
        source_id: &SourceId,
        mutation: Option<&'_ Mutation<'_>>,
    ) -> CargoResult<Secret<String>> {
        let RegistryCredentialConfig::AsymmetricKey((secret_key, secret_key_subject)) = credential else {
            anyhow::bail!("credential must be an asymmetric secret key")
        };

        let secret: Secret<AsymmetricSecretKey<version3::V3>> =
            secret_key.map(|key| key.as_str().try_into()).transpose()?;
        let public: AsymmetricPublicKey<version3::V3> = secret
            .as_ref()
            .map(|key| key.try_into())
            .transpose()?
            .expose();
        let kip = (&public).try_into()?;
        let iat = OffsetDateTime::now_utc();

        let message = Message {
            iat: &iat.format(&Rfc3339)?,
            sub: secret_key_subject.as_deref(),
            mutation: mutation.and_then(|m| {
                Some(match m {
                    Mutation::PrePublish => return None,
                    Mutation::Publish { .. } => "publish",
                    Mutation::Yank { .. } => "yank",
                    Mutation::Unyank { .. } => "unyank",
                    Mutation::Owners { .. } => "owners",
                })
            }),
            name: mutation.and_then(|m| {
                Some(match m {
                    Mutation::PrePublish => return None,
                    Mutation::Publish { name, .. }
                    | Mutation::Yank { name, .. }
                    | Mutation::Unyank { name, .. }
                    | Mutation::Owners { name, .. } => *name,
                })
            }),
            vers: mutation.and_then(|m| {
                Some(match m {
                    Mutation::PrePublish | Mutation::Owners { .. } => return None,
                    Mutation::Publish { vers, .. }
                    | Mutation::Yank { vers, .. }
                    | Mutation::Unyank { vers, .. } => *vers,
                })
            }),
            cksum: mutation.and_then(|m| {
                Some(match m {
                    Mutation::PrePublish
                    | Mutation::Yank { .. }
                    | Mutation::Unyank { .. }
                    | Mutation::Owners { .. } => return None,
                    Mutation::Publish { cksum, .. } => *cksum,
                })
            }),
            challenge: None, // todo: PASETO with challenges
            v: None,
        };

        let footer = Footer {
            url: &source_id.url().to_string(),
            kip,
        };

        let secret = secret
            .map(|secret| {
                PublicToken::sign(
                    &secret,
                    serde_json::to_string(&message)
                        .expect("cannot serialize")
                        .as_bytes(),
                    Some(
                        serde_json::to_string(&footer)
                            .expect("cannot serialize")
                            .as_bytes(),
                    ),
                    None,
                )
            })
            .transpose()?;

        Ok(secret)
    }