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use std::io;
use nom::bytes::streaming::take;
use nom::combinator::{map, map_res, rest_len};
use nom::number::streaming::be_u8;
use zeroize::Zeroize;
use crate::crypto::aead::AeadAlgorithm;
use crate::crypto::public_key::PublicKeyAlgorithm;
use crate::crypto::sym::SymmetricKeyAlgorithm;
use crate::errors::{IResult, Result};
use crate::types::*;
/// A list of params that are used to represent the values of possibly encrypted key,
/// from imports and exports.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum SecretParams {
Plain(PlainSecretParams),
Encrypted(EncryptedSecretParams),
}
impl Zeroize for SecretParams {
fn zeroize(&mut self) {
match self {
SecretParams::Plain(p) => p.zeroize(),
SecretParams::Encrypted(_) => { /* encrypted params do not need zeroing */ }
}
}
}
impl SecretParams {
pub fn is_encrypted(&self) -> bool {
match self {
SecretParams::Plain(_) => false,
SecretParams::Encrypted(_) => true,
}
}
pub fn from_slice(
data: &[u8],
key_ver: KeyVersion,
alg: PublicKeyAlgorithm,
params: &PublicParams,
) -> Result<Self> {
let (_, params) = parse_secret_fields(key_ver, alg, params)(data)?;
// Version 6 secret keys may only use "S2K Usage" 0, 253 or 254
//
// See: https://www.rfc-editor.org/rfc/rfc9580.html#section-3.7.2.1-8
if key_ver == KeyVersion::V6 && ![0, 253, 254].contains(¶ms.string_to_key_id()) {
bail!(
"Illegal S2K Usage setting {} for a V6 key",
params.string_to_key_id()
)
}
Ok(params)
}
pub fn string_to_key_id(&self) -> u8 {
match self {
SecretParams::Plain(k) => k.string_to_key_id(),
SecretParams::Encrypted(k) => k.string_to_key_id(),
}
}
pub fn checksum(&self) -> Vec<u8> {
match self {
SecretParams::Plain(k) => k.checksum_simple(),
SecretParams::Encrypted(k) => k.checksum(),
}
}
pub fn to_writer<W: io::Write>(&self, writer: &mut W, version: KeyVersion) -> Result<()> {
match self {
SecretParams::Plain(k) => k.to_writer(writer, version),
SecretParams::Encrypted(k) => k.to_writer(writer, version),
}
}
}
/// Parse possibly encrypted private fields of a key.
fn parse_secret_fields(
key_ver: KeyVersion,
alg: PublicKeyAlgorithm,
public_params: &PublicParams,
) -> impl Fn(&[u8]) -> IResult<&[u8], SecretParams> + '_ {
move |i: &[u8]| {
// We've already consumed the public fields, and have arrived at the private key-specific
// part of this secret key packet
// (see https://www.rfc-editor.org/rfc/rfc9580.html#name-secret-key-packet-formats)
let (i, s2k_usage) = map_res(be_u8, S2kUsage::try_from)(i)?;
let (i, s2k_len) = if key_ver == KeyVersion::V6 && s2k_usage != S2kUsage::Unprotected {
// Only for a version 6 packet where the secret key material is encrypted (that is,
// where the previous octet is not zero), a 1-octet scalar octet count of the
// cumulative length of all the following conditionally included S2K parameter fields.
let (i, len) = be_u8(i)?;
if len == 0 {
return Err(nom::Err::Error(crate::errors::Error::InvalidInput));
}
(i, Some(len))
} else {
(i, None)
};
// expected length of the remaining data after consuming the conditionally included
// s2k parameter fields
let after_s2k = match s2k_len {
Some(len) => {
let len = len as usize;
if i.len() < len {
return Err(nom::Err::Error(crate::errors::Error::InvalidInput));
}
Some(i.len() - len)
}
None => None,
};
let (i, enc_params) = match s2k_usage {
// 0 is no encryption
S2kUsage::Unprotected => (i, S2kParams::Unprotected),
// symmetric key algorithm
S2kUsage::LegacyCfb(sym_alg) => {
let (i, iv) = take(sym_alg.block_size())(i)?;
(
i,
S2kParams::LegacyCfb {
sym_alg,
iv: iv.to_vec(),
},
)
}
S2kUsage::Aead => {
let (i, sym_alg) = map_res(be_u8, SymmetricKeyAlgorithm::try_from)(i)?;
let (i, aead_mode) = map_res(be_u8, AeadAlgorithm::try_from)(i)?;
let (i, len) = if key_ver == KeyVersion::V6 {
// Only for a version 6 packet, and if the S2K usage octet was 253 or 254,
// a 1-octet count of the size of the one field following this octet.
map(be_u8, Some)(i)?
} else {
(i, None)
};
let (i, s2k) = s2k_parser(i)?;
// if we got a length field (in v6), check that it contained a consistent value
if let Some(len) = len {
if s2k.len()? != len {
return Err(nom::Err::Error(crate::errors::Error::Message(format!(
"String2Key length {} doesn't match for s2k type {:?}",
len, s2k
))));
}
}
let (i, nonce) = take(aead_mode.nonce_size())(i)?;
(
i,
S2kParams::Aead {
sym_alg,
aead_mode,
s2k,
nonce: nonce.to_vec(),
},
)
}
// symmetric key + string-to-key
S2kUsage::Cfb => {
let (i, sym_alg) = map_res(be_u8, SymmetricKeyAlgorithm::try_from)(i)?;
let (i, len) = if key_ver == KeyVersion::V6 {
// Only for a version 6 packet, and if the S2K usage octet was 253 or 254,
// a 1-octet count of the size of the one field following this octet.
map(be_u8, Some)(i)?
} else {
(i, None)
};
let (i, s2k) = s2k_parser(i)?;
// if we got a length field (in v6), check that it contained a consistent value
if let Some(len) = len {
if s2k.len()? != len {
return Err(nom::Err::Error(crate::errors::Error::Message(format!(
"String2Key length {} doesn't match for s2k type {:?}",
len, s2k
))));
}
}
let (i, iv) = take(sym_alg.block_size())(i)?;
(
i,
S2kParams::Cfb {
sym_alg,
s2k,
iv: iv.to_vec(),
},
)
}
S2kUsage::MalleableCfb => {
let (i, sym_alg) = map_res(be_u8, SymmetricKeyAlgorithm::try_from)(i)?;
let (i, s2k) = s2k_parser(i)?;
let (i, iv) = take(sym_alg.block_size())(i)?;
(
i,
S2kParams::Cfb {
sym_alg,
s2k,
iv: iv.to_vec(),
},
)
}
};
if let Some(after_s2k) = after_s2k {
if i.len() != after_s2k {
return Err(nom::Err::Error(crate::errors::Error::Message(
"Unexpected length of S2K parameter fields".to_string(),
)));
}
}
let (i, len) = rest_len(i)?;
let (i, data) = take(len)(i)?;
let res = match s2k_usage {
S2kUsage::Unprotected => {
let repr = PlainSecretParams::from_slice(data, alg, public_params)?;
SecretParams::Plain(repr)
}
_ => SecretParams::Encrypted(EncryptedSecretParams::new(data.to_vec(), enc_params)),
};
Ok((i, res))
}
}