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

//! PKCS#1 OtherPrimeInfo support.

use der::{asn1::UIntBytes, Decodable, Decoder, Encodable, Sequence};

/// PKCS#1 OtherPrimeInfo as defined in [RFC 8017 Appendix 1.2].
///
/// ASN.1 structure containing an additional prime in a multi-prime RSA key.
///
/// ```text
/// OtherPrimeInfo ::= SEQUENCE {
///     prime             INTEGER,  -- ri
///     exponent          INTEGER,  -- di
///     coefficient       INTEGER   -- ti
/// }
/// ```
///
/// [RFC 8017 Appendix 1.2]: https://datatracker.ietf.org/doc/html/rfc8017#appendix-A.1.2
#[derive(Clone)]
#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
pub struct OtherPrimeInfo<'a> {
    /// Prime factor `r_i` of `n`, where `i` >= 3.
    pub prime: UIntBytes<'a>,

    /// Exponent: `d_i = d mod (r_i - 1)`.
    pub exponent: UIntBytes<'a>,

    /// CRT coefficient: `t_i = (r_1 * r_2 * ... * r_(i-1))^(-1) mod r_i`.
    pub coefficient: UIntBytes<'a>,
}

impl<'a> Decodable<'a> for OtherPrimeInfo<'a> {
    fn decode(decoder: &mut Decoder<'a>) -> der::Result<Self> {
        decoder.sequence(|decoder| {
            Ok(Self {
                prime: decoder.decode()?,
                exponent: decoder.decode()?,
                coefficient: decoder.decode()?,
            })
        })
    }
}

impl<'a> Sequence<'a> for OtherPrimeInfo<'a> {
    fn fields<F, T>(&self, f: F) -> der::Result<T>
    where
        F: FnOnce(&[&dyn Encodable]) -> der::Result<T>,
    {
        f(&[&self.prime, &self.exponent, &self.coefficient])
    }
}