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// Copyright 2017 Brian Smith.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
//! PKCS#8 is specified in [RFC 5958].
//!
//! [RFC 5958]: https://tools.ietf.org/html/rfc5958.
use crate::{ec, error, io::der};
use core;
use untrusted;
pub(crate) enum Version {
V1Only,
V1OrV2,
V2Only,
}
/// A template for constructing PKCS#8 documents.
///
/// Note that this only works for ECC.
pub(crate) struct Template {
pub bytes: &'static [u8],
// The range within `bytes` that holds the value (not including the tag and
// length) for use in the PKCS#8 document's privateKeyAlgorithm field.
pub alg_id_range: core::ops::Range<usize>,
// `bytes[alg_id_range][curve_id_index..]` contains the OID identifying the,
// curve, including the tag and length.
pub curve_id_index: usize,
// `bytes` will be split into two parts at `private_key_index`, where the
// first part is written before the private key and the second part is
// written after the private key. The public key is written after the second
// part.
pub private_key_index: usize,
}
impl Template {
#[inline]
fn alg_id_value(&self) -> &[u8] { &self.bytes[self.alg_id_range.start..self.alg_id_range.end] }
#[inline]
pub fn curve_oid(&self) -> &[u8] { &self.alg_id_value()[self.curve_id_index..] }
}
/// Parses an unencrypted PKCS#8 private key, verifies that it is the right type
/// of key, and returns the key value.
///
/// PKCS#8 is specified in [RFC 5958].
///
/// [RFC 5958]: https://tools.ietf.org/html/rfc5958.
pub(crate) fn unwrap_key<'a>(
template: &Template, version: Version, input: untrusted::Input<'a>,
) -> Result<(untrusted::Input<'a>, Option<untrusted::Input<'a>>), error::KeyRejected> {
unwrap_key_(template.alg_id_value(), version, input)
}
/// Parses an unencrypted PKCS#8 private key, verifies that it is the right type
/// of key, and returns the key value.
///
/// `alg_id` must be the encoded value (not including the outermost `SEQUENCE`
/// tag and length) of the `AlgorithmIdentifier` that identifies the key type.
/// The result will be an encoded `RSAPrivateKey` or `ECPrivateKey` or similar.
///
/// PKCS#8 is specified in [RFC 5958].
///
/// [RFC 5958]: https://tools.ietf.org/html/rfc5958.
pub(crate) fn unwrap_key_<'a>(
alg_id: &[u8], version: Version, input: untrusted::Input<'a>,
) -> Result<(untrusted::Input<'a>, Option<untrusted::Input<'a>>), error::KeyRejected> {
input.read_all(error::KeyRejected::invalid_encoding(), |input| {
der::nested(
input,
der::Tag::Sequence,
error::KeyRejected::invalid_encoding(),
|input| unwrap_key__(alg_id, version, input),
)
})
}
fn unwrap_key__<'a>(
alg_id: &[u8], version: Version, input: &mut untrusted::Reader<'a>,
) -> Result<(untrusted::Input<'a>, Option<untrusted::Input<'a>>), error::KeyRejected> {
let actual_version = der::small_nonnegative_integer(input)
.map_err(|error::Unspecified| error::KeyRejected::invalid_encoding())?;
// Do things in a specific order to return more useful errors:
// 1. Check for completely unsupported version.
// 2. Check for algorithm mismatch.
// 3. Check for algorithm-specific version mismatch.
if actual_version > 1 {
return Err(error::KeyRejected::version_not_supported());
};
let actual_alg_id = der::expect_tag_and_get_value(input, der::Tag::Sequence)
.map_err(|error::Unspecified| error::KeyRejected::invalid_encoding())?;
if actual_alg_id != alg_id {
return Err(error::KeyRejected::wrong_algorithm());
}
let require_public_key = match (actual_version, version) {
(0, Version::V1Only) => false,
(0, Version::V1OrV2) => false,
(1, Version::V1OrV2) | (1, Version::V2Only) => true,
_ => {
return Err(error::KeyRejected::version_not_supported());
},
};
let private_key = der::expect_tag_and_get_value(input, der::Tag::OctetString)
.map_err(|error::Unspecified| error::KeyRejected::invalid_encoding())?;
// Ignore any attributes that are present.
if input.peek(der::Tag::ContextSpecificConstructed0 as u8) {
let _ = der::expect_tag_and_get_value(input, der::Tag::ContextSpecificConstructed0)
.map_err(|error::Unspecified| error::KeyRejected::invalid_encoding())?;
}
let public_key = if require_public_key {
if input.at_end() {
return Err(error::KeyRejected::public_key_is_missing());
}
let public_key = der::nested(
input,
der::Tag::ContextSpecificConstructed1,
error::Unspecified,
der::bit_string_with_no_unused_bits,
)
.map_err(|error::Unspecified| error::KeyRejected::invalid_encoding())?;
Some(public_key)
} else {
None
};
Ok((private_key, public_key))
}
/// A generated PKCS#8 document.
pub struct Document {
bytes: [u8; ec::PKCS8_DOCUMENT_MAX_LEN],
len: usize,
}
impl AsRef<[u8]> for Document {
#[inline]
fn as_ref(&self) -> &[u8] { &self.bytes[..self.len] }
}
pub(crate) fn wrap_key(template: &Template, private_key: &[u8], public_key: &[u8]) -> Document {
let mut result = Document {
bytes: [0; ec::PKCS8_DOCUMENT_MAX_LEN],
len: template.bytes.len() + private_key.len() + public_key.len(),
};
wrap_key_(
template,
private_key,
public_key,
&mut result.bytes[..result.len],
);
result
}
/// Formats a private key "prefix||private_key||middle||public_key" where
/// `template` is "prefix||middle" split at position `private_key_index`.
fn wrap_key_(template: &Template, private_key: &[u8], public_key: &[u8], bytes: &mut [u8]) {
let (before_private_key, after_private_key) =
template.bytes.split_at(template.private_key_index);
let private_key_end_index = template.private_key_index + private_key.len();
bytes[..template.private_key_index].copy_from_slice(before_private_key);
bytes[template.private_key_index..private_key_end_index].copy_from_slice(&private_key);
bytes[private_key_end_index..(private_key_end_index + after_private_key.len())]
.copy_from_slice(after_private_key);
bytes[(private_key_end_index + after_private_key.len())..].copy_from_slice(public_key);
}