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/* -*- Mode: rust; rust-indent-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
use byteorder::{NativeEndian, WriteBytesExt};
use digest::{Digest, DynDigest};
use pkcs11_bindings::*;
use rand::rngs::OsRng;
use rand::RngCore;
use rsclientcerts_util::error::{Error, ErrorType};
use rsclientcerts_util::{error_here, read_encoded_certificate_identifiers};
use std::convert::TryInto;
use std::iter::zip;
use crate::manager::CryptokiObject;
// The following ENCODED_OID_BYTES_* consist of the encoded bytes of an ASN.1
// OBJECT IDENTIFIER specifying the indicated OID (in other words, the full
// tag, length, and value).
pub const ENCODED_OID_BYTES_SECP256R1: &[u8] =
&[0x06, 0x08, 0x2a, 0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07];
pub const ENCODED_OID_BYTES_SECP384R1: &[u8] = &[0x06, 0x05, 0x2b, 0x81, 0x04, 0x00, 0x22];
pub const ENCODED_OID_BYTES_SECP521R1: &[u8] = &[0x06, 0x05, 0x2b, 0x81, 0x04, 0x00, 0x23];
// This is a helper function to take a value and lay it out in memory how
// PKCS#11 is expecting it.
pub fn serialize_uint<T: TryInto<u64>>(value: T) -> Result<Vec<u8>, Error> {
let value_size = std::mem::size_of::<T>();
let mut value_buf = Vec::with_capacity(value_size);
let value_as_u64 = value
.try_into()
.map_err(|_| error_here!(ErrorType::ValueTooLarge))?;
value_buf
.write_uint::<NativeEndian>(value_as_u64, value_size)
.map_err(|_| error_here!(ErrorType::LibraryFailure))?;
Ok(value_buf)
}
fn make_hasher(params: &CK_RSA_PKCS_PSS_PARAMS) -> Result<Box<dyn DynDigest>, Error> {
match params.hashAlg {
CKM_SHA256 => Ok(Box::new(sha2::Sha256::new())),
CKM_SHA384 => Ok(Box::new(sha2::Sha384::new())),
CKM_SHA512 => Ok(Box::new(sha2::Sha512::new())),
_ => Err(error_here!(ErrorType::LibraryFailure)),
}
}
// Implements MGF1 as per RFC 8017 appendix B.2.1.
fn mgf(
mgf_seed: &[u8],
mask_len: usize,
h_len: usize,
params: &CK_RSA_PKCS_PSS_PARAMS,
) -> Result<Vec<u8>, Error> {
// 1. If maskLen > 2^32 hLen, output "mask too long" and stop.
// (in practice, `mask_len` is going to be much smaller than this, so use a
// smaller, fixed limit to avoid problems on systems where usize is 32
// bits)
if mask_len > 1 << 30 {
return Err(error_here!(ErrorType::LibraryFailure));
}
// 2. Let T be the empty octet string.
let mut t = Vec::with_capacity(mask_len);
// 3. For counter from 0 to \ceil (maskLen / hLen) - 1, do the
// following:
for counter in 0..mask_len.div_ceil(h_len) {
// A. Convert counter to an octet string C of length 4 octets:
// C = I2OSP (counter, 4)
// (counter fits in u32 due to the length check earlier)
let c = u32::to_be_bytes(counter.try_into().unwrap());
// B. Concatenate the hash of the seed mgfSeed and C to the octet
// string T: T = T || Hash(mgfSeed || C)
let mut hasher = make_hasher(params)?;
hasher.update(mgf_seed);
hasher.update(&c);
t.extend_from_slice(&mut hasher.finalize());
}
// 4. Output the leading maskLen octets of T as the octet string mask.
t.truncate(mask_len);
Ok(t)
}
pub fn modulus_bit_length(modulus: &[u8]) -> usize {
let mut bit_length = modulus.len() * 8;
for byte in modulus {
if *byte != 0 {
// `byte` is a u8, so `leading_zeros()` will be at most 7.
let leading_zeros: usize = byte.leading_zeros().try_into().unwrap();
bit_length -= leading_zeros;
return bit_length;
}
bit_length -= 8;
}
bit_length
}
// Implements EMSA-PSS-ENCODE as per RFC 8017 section 9.1.1.
// This is necessary because while Android does support RSA-PSS, it expects to
// be given the entire message to be signed, not just the hash of the message,
// which is what NSS gives us.
// Additionally, this is useful for tokens that do not support RSA-PSS.
pub fn emsa_pss_encode(
m_hash: &[u8],
em_bits: usize,
params: &CK_RSA_PKCS_PSS_PARAMS,
) -> Result<Vec<u8>, Error> {
let em_len = em_bits.div_ceil(8);
let s_len: usize = params
.sLen
.try_into()
.map_err(|_| error_here!(ErrorType::LibraryFailure))?;
// 1. If the length of M is greater than the input limitation for
// the hash function (2^61 - 1 octets for SHA-1), output
// "message too long" and stop.
// 2. Let mHash = Hash(M), an octet string of length hLen.
// 1 and 2 can be skipped because the message is already hashed as m_hash.
// 3. If emLen < hLen + sLen + 2, output "encoding error" and stop.
if em_len < m_hash.len() + s_len + 2 {
return Err(error_here!(ErrorType::LibraryFailure));
}
// 4. Generate a random octet string salt of length sLen; if sLen =
// 0, then salt is the empty string.
let salt = {
let mut salt = vec![0u8; s_len];
OsRng.fill_bytes(&mut salt);
salt
};
// 5. Let M' = (0x)00 00 00 00 00 00 00 00 || mHash || salt;
// M' is an octet string of length 8 + hLen + sLen with eight
// initial zero octets.
// 6. Let H = Hash(M'), an octet string of length hLen.
let mut hasher = make_hasher(params)?;
let h_len = hasher.output_size();
hasher.update(&[0, 0, 0, 0, 0, 0, 0, 0]);
hasher.update(m_hash);
hasher.update(&salt);
let h = hasher.finalize().to_vec();
// 7. Generate an octet string PS consisting of emLen - sLen - hLen
// - 2 zero octets. The length of PS may be 0.
// 8. Let DB = PS || 0x01 || salt; DB is an octet string of length
// emLen - hLen - 1.
// (7 and 8 are unnecessary as separate steps - see step 10)
// 9. Let dbMask = MGF(H, emLen - hLen - 1).
let mut db_mask = mgf(&h, em_len - h_len - 1, h_len, params)?;
// 10. Let maskedDB = DB \xor dbMask.
// (in practice, this means xoring `0x01 || salt` with the last `s_len + 1`
// bytes of `db_mask`)
let salt_index = db_mask.len() - s_len;
db_mask[salt_index - 1] ^= 1;
for (db_mask_byte, salt_byte) in zip(&mut db_mask[salt_index..], &salt) {
*db_mask_byte ^= salt_byte;
}
let mut masked_db = db_mask;
// 11. Set the leftmost 8emLen - emBits bits of the leftmost octet
// in maskedDB to zero.
// (bit_diff can only be 0 through 7, so it fits in u32)
let bit_diff: u32 = ((8 * em_len) - em_bits).try_into().unwrap();
// (again, bit_diff can only b 0 through 7, so the shift is sound)
masked_db[0] &= 0xffu8.checked_shr(bit_diff).unwrap();
// 12. Let EM = maskedDB || H || 0xbc.
let mut em = masked_db;
em.extend_from_slice(&h);
em.push(0xbc);
Ok(em)
}
/// A `CryptokiCert` holds all relevant information for a `CryptokiObject` with class
/// `CKO_CERTIFICATE`.
#[derive(Clone)]
pub struct CryptokiCert {
/// PKCS #11 object class. Will be `CKO_CERTIFICATE`.
class: Vec<u8>,
/// Whether or not this is on a token. Will be `CK_TRUE`.
token: Vec<u8>,
/// An identifier unique to this certificate. This must be the same as the ID for the private
/// key, so for simplicity, this will be the sha256 hash of the bytes of the certificate.
id: Vec<u8>,
/// The bytes of a human-readable label for this certificate.
label: Vec<u8>,
/// The DER bytes of the certificate.
value: Vec<u8>,
/// The DER bytes of the issuer distinguished name of the certificate.
issuer: Vec<u8>,
/// The DER bytes of the serial number of the certificate.
serial_number: Vec<u8>,
/// The DER bytes of the subject distinguished name of the certificate.
subject: Vec<u8>,
}
impl CryptokiCert {
pub fn new(der: Vec<u8>, label: Vec<u8>) -> Result<CryptokiCert, Error> {
let id = sha2::Sha256::digest(&der).to_vec();
let (serial_number, issuer, subject) = read_encoded_certificate_identifiers(&der)?;
Ok(CryptokiCert {
class: serialize_uint(CKO_CERTIFICATE)?,
token: serialize_uint(CK_TRUE)?,
id,
label,
value: der,
issuer,
serial_number,
subject,
})
}
}
impl CryptokiObject for CryptokiCert {
fn matches(&self, attrs: &[(CK_ATTRIBUTE_TYPE, Vec<u8>)]) -> bool {
for (attr_type, attr_value) in attrs {
let comparison = match *attr_type {
CKA_CLASS => &self.class,
CKA_TOKEN => &self.token,
CKA_LABEL => &self.label,
CKA_ID => &self.id,
CKA_VALUE => &self.value,
CKA_ISSUER => &self.issuer,
CKA_SERIAL_NUMBER => &self.serial_number,
CKA_SUBJECT => &self.subject,
_ => return false,
};
if attr_value.as_slice() != comparison {
return false;
}
}
true
}
fn get_attribute(&self, attribute: CK_ATTRIBUTE_TYPE) -> Option<&[u8]> {
let result = match attribute {
CKA_CLASS => &self.class,
CKA_TOKEN => &self.token,
CKA_LABEL => &self.label,
CKA_ID => &self.id,
CKA_VALUE => &self.value,
CKA_ISSUER => &self.issuer,
CKA_SERIAL_NUMBER => &self.serial_number,
CKA_SUBJECT => &self.subject,
_ => return None,
};
Some(result)
}
}
#[allow(clippy::upper_case_acronyms)]
#[derive(Clone, Copy, Debug)]
pub enum KeyType {
EC(usize),
RSA,
}
/// A `CryptokiKey` holds all relevant information for a `CryptokiObject` with class
/// `CKO_PRIVATE_KEY`.
#[derive(Clone)]
pub struct CryptokiKey {
/// PKCS #11 object class. Will be `CKO_PRIVATE_KEY`.
class: Vec<u8>,
/// Whether or not this is on a token. Will be `CK_TRUE`.
token: Vec<u8>,
/// An identifier unique to this key. This must be the same as the ID for a corresponding
/// certificate, so for simplicity, this will be the sha256 hash of the bytes of the
/// certificate.
id: Vec<u8>,
/// Whether or not this key is "private" (can it be exported?). Will be CK_TRUE (it can't be
/// exported).
private: Vec<u8>,
/// PKCS #11 key type. Will be `CKK_EC` for EC, and `CKK_RSA` for RSA.
key_type_attribute: Vec<u8>,
/// If this is an RSA key, this is the value of the modulus as an unsigned integer.
modulus: Option<Vec<u8>>,
/// If this is an EC key, this is the DER bytes of the OID identifying the curve the key is on.
ec_params: Option<Vec<u8>>,
/// An enum identifying this key's type.
key_type: KeyType,
}
impl CryptokiKey {
pub fn new(
modulus: Option<Vec<u8>>,
ec_params: Option<Vec<u8>>,
cert: &[u8],
) -> Result<CryptokiKey, Error> {
let (key_type, key_type_attribute) = if modulus.is_some() {
(KeyType::RSA, CKK_RSA)
} else if let Some(ec_params) = ec_params.as_ref() {
// Only secp256r1, secp384r1, and secp521r1 are supported.
let coordinate_width = match ec_params.as_slice() {
ENCODED_OID_BYTES_SECP256R1 => 32,
ENCODED_OID_BYTES_SECP384R1 => 48,
ENCODED_OID_BYTES_SECP521R1 => 66,
_ => return Err(error_here!(ErrorType::UnsupportedInput)),
};
(KeyType::EC(coordinate_width), CKK_EC)
} else {
return Err(error_here!(ErrorType::LibraryFailure));
};
let id = sha2::Sha256::digest(cert).to_vec();
Ok(CryptokiKey {
class: serialize_uint(CKO_PRIVATE_KEY)?,
token: serialize_uint(CK_TRUE)?,
id,
private: serialize_uint(CK_TRUE)?,
key_type_attribute: serialize_uint(key_type_attribute)?,
modulus,
ec_params,
key_type,
})
}
pub fn modulus(&self) -> &Option<Vec<u8>> {
&self.modulus
}
pub fn ec_params(&self) -> &Option<Vec<u8>> {
&self.ec_params
}
pub fn key_type(&self) -> KeyType {
self.key_type
}
}
impl CryptokiObject for CryptokiKey {
fn matches(&self, attrs: &[(CK_ATTRIBUTE_TYPE, Vec<u8>)]) -> bool {
for (attr_type, attr_value) in attrs {
let comparison = match *attr_type {
CKA_CLASS => &self.class,
CKA_TOKEN => &self.token,
CKA_ID => &self.id,
CKA_PRIVATE => &self.private,
CKA_KEY_TYPE => &self.key_type_attribute,
CKA_MODULUS => {
if let Some(modulus) = &self.modulus {
modulus
} else {
return false;
}
}
CKA_EC_PARAMS => {
if let Some(ec_params) = &self.ec_params {
ec_params
} else {
return false;
}
}
_ => return false,
};
if attr_value.as_slice() != comparison {
return false;
}
}
true
}
fn get_attribute(&self, attribute: CK_ATTRIBUTE_TYPE) -> Option<&[u8]> {
match attribute {
CKA_CLASS => Some(&self.class),
CKA_TOKEN => Some(&self.token),
CKA_ID => Some(&self.id),
CKA_PRIVATE => Some(&self.private),
CKA_KEY_TYPE => Some(&self.key_type_attribute),
CKA_MODULUS => match &self.modulus {
Some(modulus) => Some(modulus.as_slice()),
None => None,
},
CKA_EC_PARAMS => match &self.ec_params {
Some(ec_params) => Some(ec_params.as_slice()),
None => None,
},
_ => None,
}
}
}