crypto_bigint/uint/encoding/
der.rs

1//! Support for decoding/encoding [`Uint`] as an ASN.1 DER `INTEGER`.
2
3use crate::{hybrid_array::Array, ArrayEncoding, Uint};
4use ::der::{
5    asn1::{AnyRef, UintRef},
6    DecodeValue, EncodeValue, FixedTag, Length, Tag,
7};
8
9impl<'a, const LIMBS: usize> TryFrom<AnyRef<'a>> for Uint<LIMBS>
10where
11    Uint<LIMBS>: ArrayEncoding,
12{
13    type Error = der::Error;
14
15    fn try_from(any: AnyRef<'a>) -> der::Result<Uint<LIMBS>> {
16        UintRef::try_from(any)?.try_into()
17    }
18}
19
20impl<'a, const LIMBS: usize> TryFrom<UintRef<'a>> for Uint<LIMBS>
21where
22    Uint<LIMBS>: ArrayEncoding,
23{
24    type Error = der::Error;
25
26    fn try_from(bytes: UintRef<'a>) -> der::Result<Uint<LIMBS>> {
27        let mut array = Array::default();
28        let offset = array.len().saturating_sub(bytes.len().try_into()?);
29        array[offset..].copy_from_slice(bytes.as_bytes());
30        Ok(Uint::from_be_byte_array(array))
31    }
32}
33
34impl<'a, const LIMBS: usize> DecodeValue<'a> for Uint<LIMBS>
35where
36    Uint<LIMBS>: ArrayEncoding,
37{
38    fn decode_value<R: der::Reader<'a>>(reader: &mut R, header: der::Header) -> der::Result<Self> {
39        UintRef::decode_value(reader, header)?.try_into()
40    }
41}
42
43impl<const LIMBS: usize> EncodeValue for Uint<LIMBS>
44where
45    Uint<LIMBS>: ArrayEncoding,
46{
47    fn value_len(&self) -> der::Result<Length> {
48        // TODO(tarcieri): more efficient length calculation
49        let array = self.to_be_byte_array();
50        UintRef::new(&array)?.value_len()
51    }
52
53    fn encode_value(&self, encoder: &mut impl der::Writer) -> der::Result<()> {
54        let array = self.to_be_byte_array();
55        UintRef::new(&array)?.encode_value(encoder)
56    }
57}
58
59impl<const LIMBS: usize> FixedTag for Uint<LIMBS>
60where
61    Uint<LIMBS>: ArrayEncoding,
62{
63    const TAG: Tag = Tag::Integer;
64}
crypto_bigint/uint/encoding/der.rs

crypto_bigint/uint/encoding/
der.rs
