1 //! PKCS#1 OtherPrimeInfo support.
2 
3 use der::{
4     asn1::UintRef, DecodeValue, Encode, EncodeValue, Header, Length, Reader, Sequence, Writer,
5 };
6 
7 /// PKCS#1 OtherPrimeInfo as defined in [RFC 8017 Appendix 1.2].
8 ///
9 /// ASN.1 structure containing an additional prime in a multi-prime RSA key.
10 ///
11 /// ```text
12 /// OtherPrimeInfo ::= SEQUENCE {
13 ///     prime             INTEGER,  -- ri
14 ///     exponent          INTEGER,  -- di
15 ///     coefficient       INTEGER   -- ti
16 /// }
17 /// ```
18 ///
19 /// [RFC 8017 Appendix 1.2]: https://datatracker.ietf.org/doc/html/rfc8017#appendix-A.1.2
20 #[derive(Clone)]
21 pub struct OtherPrimeInfo<'a> {
22     /// Prime factor `r_i` of `n`, where `i` >= 3.
23     pub prime: UintRef<'a>,
24 
25     /// Exponent: `d_i = d mod (r_i - 1)`.
26     pub exponent: UintRef<'a>,
27 
28     /// CRT coefficient: `t_i = (r_1 * r_2 * ... * r_(i-1))^(-1) mod r_i`.
29     pub coefficient: UintRef<'a>,
30 }
31 
32 impl<'a> DecodeValue<'a> for OtherPrimeInfo<'a> {
decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> der::Result<Self>33     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> der::Result<Self> {
34         reader.read_nested(header.length, |reader| {
35             Ok(Self {
36                 prime: reader.decode()?,
37                 exponent: reader.decode()?,
38                 coefficient: reader.decode()?,
39             })
40         })
41     }
42 }
43 
44 impl EncodeValue for OtherPrimeInfo<'_> {
value_len(&self) -> der::Result<Length>45     fn value_len(&self) -> der::Result<Length> {
46         self.prime.encoded_len()? + self.exponent.encoded_len()? + self.coefficient.encoded_len()?
47     }
48 
encode_value(&self, writer: &mut impl Writer) -> der::Result<()>49     fn encode_value(&self, writer: &mut impl Writer) -> der::Result<()> {
50         self.prime.encode(writer)?;
51         self.exponent.encode(writer)?;
52         self.coefficient.encode(writer)?;
53         Ok(())
54     }
55 }
56 
57 impl<'a> Sequence<'a> for OtherPrimeInfo<'a> {}
58