ssh_key/public/
dsa.rs

1//! Digital Signature Algorithm (DSA) public keys.
2
3use crate::{Error, Mpint, Result};
4use core::hash::{Hash, Hasher};
5use encoding::{CheckedSum, Decode, Encode, Reader, Writer};
6
7#[cfg(feature = "dsa")]
8use encoding::Uint;
9
10/// Digital Signature Algorithm (DSA) public key.
11///
12/// Described in [FIPS 186-4 § 4.1](https://csrc.nist.gov/publications/detail/fips/186/4/final).
13#[derive(Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
14pub struct DsaPublicKey {
15    /// Prime modulus.
16    p: Mpint,
17
18    /// Prime divisor of `p - 1`.
19    q: Mpint,
20
21    /// Generator of a subgroup of order `q` in the multiplicative group `GF(p)`, such that
22    /// `1 < g < p`.
23    g: Mpint,
24
25    /// The public key, where `y = gˣ mod p`.
26    y: Mpint,
27}
28
29impl DsaPublicKey {
30    /// Create a new [`DsaPublicKey`] with the following components:
31    ///
32    /// - `p`: prime modulus.
33    /// - `q`: prime divisor of `p - 1`.
34    /// - `g`: generator of a subgroup of order `q` in the multiplicative group `GF(p)`, such
35    ///   that `1 < g < p`.
36    /// - `y`: the public key, where `y = gˣ mod p`.
37    pub fn new(p: Mpint, q: Mpint, g: Mpint, y: Mpint) -> Result<Self> {
38        if p.is_positive() && q.is_positive() && g.is_positive() && y.is_positive() {
39            Ok(Self { p, q, g, y })
40        } else {
41            Err(Error::FormatEncoding)
42        }
43    }
44
45    /// Prime modulus.
46    pub fn p(&self) -> &Mpint {
47        &self.p
48    }
49
50    /// Prime divisor of `p - 1`.
51    pub fn q(&self) -> &Mpint {
52        &self.q
53    }
54
55    /// Generator of a subgroup of order `q` in the multiplicative group `GF(p)`, such that
56    /// `1 < g < p`.
57    pub fn g(&self) -> &Mpint {
58        &self.g
59    }
60
61    /// The public key, where `y = gˣ mod p`.
62    pub fn y(&self) -> &Mpint {
63        &self.y
64    }
65}
66
67impl Decode for DsaPublicKey {
68    type Error = Error;
69
70    fn decode(reader: &mut impl Reader) -> Result<Self> {
71        let p = Mpint::decode(reader)?;
72        let q = Mpint::decode(reader)?;
73        let g = Mpint::decode(reader)?;
74        let y = Mpint::decode(reader)?;
75        Self::new(p, q, g, y)
76    }
77}
78
79impl Encode for DsaPublicKey {
80    fn encoded_len(&self) -> encoding::Result<usize> {
81        [
82            self.p.encoded_len()?,
83            self.q.encoded_len()?,
84            self.g.encoded_len()?,
85            self.y.encoded_len()?,
86        ]
87        .checked_sum()
88    }
89
90    fn encode(&self, writer: &mut impl Writer) -> encoding::Result<()> {
91        self.p.encode(writer)?;
92        self.q.encode(writer)?;
93        self.g.encode(writer)?;
94        self.y.encode(writer)
95    }
96}
97
98impl Hash for DsaPublicKey {
99    #[inline]
100    fn hash<H: Hasher>(&self, state: &mut H) {
101        self.p.as_bytes().hash(state);
102        self.q.as_bytes().hash(state);
103        self.g.as_bytes().hash(state);
104        self.y.as_bytes().hash(state);
105    }
106}
107
108#[cfg(feature = "dsa")]
109impl TryFrom<DsaPublicKey> for dsa::VerifyingKey {
110    type Error = Error;
111
112    fn try_from(key: DsaPublicKey) -> Result<dsa::VerifyingKey> {
113        dsa::VerifyingKey::try_from(&key)
114    }
115}
116
117#[cfg(feature = "dsa")]
118impl TryFrom<&DsaPublicKey> for dsa::VerifyingKey {
119    type Error = Error;
120
121    fn try_from(key: &DsaPublicKey) -> Result<dsa::VerifyingKey> {
122        let p = Uint::try_from(&key.p)?;
123        let q = Uint::try_from(&key.q)?;
124        let g = Uint::try_from(&key.g)?;
125        let y = Uint::try_from(&key.y)?;
126
127        let components = dsa::Components::from_components(p, q, g)?;
128        dsa::VerifyingKey::from_components(components, y).map_err(|_| Error::Crypto)
129    }
130}
131
132#[cfg(feature = "dsa")]
133impl TryFrom<dsa::VerifyingKey> for DsaPublicKey {
134    type Error = Error;
135
136    fn try_from(key: dsa::VerifyingKey) -> Result<DsaPublicKey> {
137        DsaPublicKey::try_from(&key)
138    }
139}
140
141#[cfg(feature = "dsa")]
142impl TryFrom<&dsa::VerifyingKey> for DsaPublicKey {
143    type Error = Error;
144
145    fn try_from(key: &dsa::VerifyingKey) -> Result<DsaPublicKey> {
146        Ok(DsaPublicKey {
147            p: key.components().p().as_ref().try_into()?,
148            q: key.components().q().as_ref().try_into()?,
149            g: key.components().g().as_ref().try_into()?,
150            y: key.y().as_ref().try_into()?,
151        })
152    }
153}
ssh_key/public/dsa.rs

ssh_key/public/
dsa.rs
