ml_dsa/
pkcs8.rs

1//! PKCS#8 private key encoding support.
2
3use crate::{
4    EncodedVerifyingKey, ExpandedSigningKey, MlDsa44, MlDsa65, MlDsa87, MlDsaParams, Signature,
5    SigningKey, VerifyingKey,
6};
7pub use ::pkcs8::*;
8use ::pkcs8::{
9    der::{
10        AnyRef, Reader, TagNumber,
11        asn1::{ContextSpecific, OctetStringRef},
12    },
13    spki::{AlgorithmIdentifier, AssociatedAlgorithmIdentifier, SignatureAlgorithmIdentifier},
14};
15use const_oid::db::fips204;
16
17#[cfg(feature = "alloc")]
18use pkcs8::{
19    der::{
20        Encode, TagMode,
21        asn1::{BitString, BitStringRef},
22    },
23    spki::SignatureBitStringEncoding,
24};
25
26/// Tag number for the seed value.
27const SEED_TAG_NUMBER: TagNumber = TagNumber(0);
28
29/// ML-KEM seed serialized as ASN.1.
30type SeedString<'a> = ContextSpecific<&'a OctetStringRef>;
31
32impl AssociatedAlgorithmIdentifier for MlDsa44 {
33    type Params = AnyRef<'static>;
34
35    const ALGORITHM_IDENTIFIER: AlgorithmIdentifierRef<'static> = AlgorithmIdentifierRef {
36        oid: fips204::ID_ML_DSA_44,
37        parameters: None,
38    };
39}
40
41impl AssociatedAlgorithmIdentifier for MlDsa65 {
42    type Params = AnyRef<'static>;
43
44    const ALGORITHM_IDENTIFIER: AlgorithmIdentifierRef<'static> = AlgorithmIdentifierRef {
45        oid: fips204::ID_ML_DSA_65,
46        parameters: None,
47    };
48}
49
50impl AssociatedAlgorithmIdentifier for MlDsa87 {
51    type Params = AnyRef<'static>;
52
53    const ALGORITHM_IDENTIFIER: AlgorithmIdentifierRef<'static> = AlgorithmIdentifierRef {
54        oid: fips204::ID_ML_DSA_87,
55        parameters: None,
56    };
57}
58
59impl<P> AssociatedAlgorithmIdentifier for Signature<P>
60where
61    P: MlDsaParams,
62    P: AssociatedAlgorithmIdentifier<Params = AnyRef<'static>>,
63{
64    type Params = AnyRef<'static>;
65
66    const ALGORITHM_IDENTIFIER: AlgorithmIdentifierRef<'static> = P::ALGORITHM_IDENTIFIER;
67}
68
69#[cfg(feature = "alloc")]
70impl<P: MlDsaParams> SignatureBitStringEncoding for Signature<P> {
71    fn to_bitstring(&self) -> der::Result<BitString> {
72        BitString::new(0, self.encode().to_vec())
73    }
74}
75
76impl<P> SignatureAlgorithmIdentifier for SigningKey<P>
77where
78    P: MlDsaParams,
79    P: AssociatedAlgorithmIdentifier<Params = AnyRef<'static>>,
80{
81    type Params = AnyRef<'static>;
82
83    const SIGNATURE_ALGORITHM_IDENTIFIER: AlgorithmIdentifier<Self::Params> =
84        Signature::<P>::ALGORITHM_IDENTIFIER;
85}
86
87impl<P> TryFrom<PrivateKeyInfoRef<'_>> for SigningKey<P>
88where
89    P: MlDsaParams,
90    P: AssociatedAlgorithmIdentifier<Params = AnyRef<'static>>,
91{
92    type Error = Error;
93
94    fn try_from(private_key_info: PrivateKeyInfoRef<'_>) -> Result<Self> {
95        private_key_info
96            .algorithm
97            .assert_algorithm_oid(P::ALGORITHM_IDENTIFIER.oid)?;
98
99        let mut reader = der::SliceReader::new(private_key_info.private_key.as_bytes())?;
100        let seed_string =
101            SeedString::decode_implicit(&mut reader, SEED_TAG_NUMBER)?.ok_or(KeyError::Invalid)?;
102        let seed = seed_string
103            .value
104            .as_bytes()
105            .try_into()
106            .map_err(|_| KeyError::Invalid)?;
107        reader.finish()?;
108
109        Ok(SigningKey::from_seed(&seed))
110    }
111}
112
113#[cfg(feature = "alloc")]
114impl<P> EncodePrivateKey for SigningKey<P>
115where
116    P: MlDsaParams,
117    P: AssociatedAlgorithmIdentifier<Params = AnyRef<'static>>,
118{
119    fn to_pkcs8_der(&self) -> ::pkcs8::Result<SecretDocument> {
120        let seed_der = SeedString {
121            tag_mode: TagMode::Implicit,
122            tag_number: SEED_TAG_NUMBER,
123            value: OctetStringRef::new(self.as_seed())?,
124        }
125        .to_der()?;
126
127        let private_key = OctetStringRef::new(&seed_der)?;
128        let private_key_info = PrivateKeyInfoRef::new(P::ALGORITHM_IDENTIFIER, private_key);
129        ::pkcs8::SecretDocument::encode_msg(&private_key_info).map_err(::pkcs8::Error::Asn1)
130    }
131}
132
133impl<P> SignatureAlgorithmIdentifier for ExpandedSigningKey<P>
134where
135    P: MlDsaParams,
136    P: AssociatedAlgorithmIdentifier<Params = AnyRef<'static>>,
137{
138    type Params = AnyRef<'static>;
139
140    const SIGNATURE_ALGORITHM_IDENTIFIER: AlgorithmIdentifier<Self::Params> =
141        Signature::<P>::ALGORITHM_IDENTIFIER;
142}
143
144impl<P> TryFrom<PrivateKeyInfoRef<'_>> for ExpandedSigningKey<P>
145where
146    P: MlDsaParams,
147    P: AssociatedAlgorithmIdentifier<Params = AnyRef<'static>>,
148{
149    type Error = ::pkcs8::Error;
150
151    fn try_from(private_key_info: PrivateKeyInfoRef<'_>) -> Result<Self> {
152        SigningKey::try_from(private_key_info).map(|sk| sk.expanded_key().clone())
153    }
154}
155
156impl<P> SignatureAlgorithmIdentifier for VerifyingKey<P>
157where
158    P: MlDsaParams,
159    P: AssociatedAlgorithmIdentifier<Params = AnyRef<'static>>,
160{
161    type Params = AnyRef<'static>;
162
163    const SIGNATURE_ALGORITHM_IDENTIFIER: AlgorithmIdentifier<Self::Params> =
164        Signature::<P>::ALGORITHM_IDENTIFIER;
165}
166
167#[cfg(feature = "alloc")]
168impl<P> EncodePublicKey for VerifyingKey<P>
169where
170    P: MlDsaParams,
171    P: AssociatedAlgorithmIdentifier<Params = AnyRef<'static>>,
172{
173    fn to_public_key_der(&self) -> spki::Result<Document> {
174        let public_key = self.encode();
175        let subject_public_key = BitStringRef::new(0, &public_key)?;
176
177        SubjectPublicKeyInfo {
178            algorithm: P::ALGORITHM_IDENTIFIER,
179            subject_public_key,
180        }
181        .try_into()
182    }
183}
184
185impl<P> TryFrom<SubjectPublicKeyInfoRef<'_>> for VerifyingKey<P>
186where
187    P: MlDsaParams,
188    P: AssociatedAlgorithmIdentifier<Params = AnyRef<'static>>,
189{
190    type Error = spki::Error;
191
192    fn try_from(spki: SubjectPublicKeyInfoRef<'_>) -> spki::Result<Self> {
193        spki.algorithm
194            .assert_algorithm_oid(P::ALGORITHM_IDENTIFIER.oid)?;
195
196        let evk = EncodedVerifyingKey::<P>::try_from(
197            spki.subject_public_key
198                .as_bytes()
199                .ok_or_else(|| der::Tag::BitString.value_error().to_error())?,
200        )
201        .map_err(|_| spki::Error::KeyMalformed)?;
202
203        Ok(Self::decode(&evk))
204    }
205}
ml_dsa/pkcs8.rs

ml_dsa/
pkcs8.rs
