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Refactor and de-duplicate the PKCS#8/#12 encryption code #13629

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Merged
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Oct 9, 2025
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Merged

Refactor and de-duplicate the PKCS#8/#12 encryption code #13629

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2 changes: 2 additions & 0 deletions src/rust/cryptography-key-parsing/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@

pub mod dsa;
pub mod ec;
pub mod pbe;
pub mod pem;
pub mod pkcs8;
pub mod rsa;
Expand Down Expand Up @@ -50,6 +51,7 @@ impl From<openssl::error::ErrorStack> for KeyParsingError {
pub type KeyParsingResult<T> = Result<T, KeyParsingError>;

pub enum KeySerializationError {
PasswordMustBeUtf8,
Write(asn1::WriteError),
OpenSSL(openssl::error::ErrorStack),
}
Expand Down
133 changes: 133 additions & 0 deletions src/rust/cryptography-key-parsing/src/pbe.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,133 @@
// This file is dual licensed under the terms of the Apache License, Version
// 2.0, and the BSD License. See the LICENSE file in the root of this repository
// for complete details.

use crate::{KeySerializationError, KeySerializationResult};

pub enum EncryptionAlgorithm {
PBESHA1And3KeyTripleDESCBC,
PBESv2SHA256AndAES256CBC,
}

impl EncryptionAlgorithm {
pub fn salt_length(&self) -> usize {
match self {
EncryptionAlgorithm::PBESHA1And3KeyTripleDESCBC => 8,
EncryptionAlgorithm::PBESv2SHA256AndAES256CBC => 16,
}
}

pub fn algorithm_identifier<'a>(
&self,
cipher_kdf_iter: u64,
salt: &'a [u8],
iv: &'a [u8],
) -> cryptography_x509::common::AlgorithmIdentifier<'a> {
match self {
EncryptionAlgorithm::PBESHA1And3KeyTripleDESCBC => {
cryptography_x509::common::AlgorithmIdentifier {
oid: asn1::DefinedByMarker::marker(),
params: cryptography_x509::common::AlgorithmParameters::PbeWithShaAnd3KeyTripleDesCbc(cryptography_x509::common::Pkcs12PbeParams{
salt,
iterations: cipher_kdf_iter,
}),
}
}
EncryptionAlgorithm::PBESv2SHA256AndAES256CBC => {
let kdf_algorithm_identifier = cryptography_x509::common::AlgorithmIdentifier {
oid: asn1::DefinedByMarker::marker(),
params: cryptography_x509::common::AlgorithmParameters::Pbkdf2(
cryptography_x509::common::PBKDF2Params {
salt,
iteration_count: cipher_kdf_iter,
key_length: None,
prf: Box::new(cryptography_x509::common::AlgorithmIdentifier {
oid: asn1::DefinedByMarker::marker(),
params:
cryptography_x509::common::AlgorithmParameters::HmacWithSha256(
Some(()),
),
}),
},
),
};
let encryption_algorithm_identifier =
cryptography_x509::common::AlgorithmIdentifier {
oid: asn1::DefinedByMarker::marker(),
params: cryptography_x509::common::AlgorithmParameters::Aes256Cbc(
iv[..16].try_into().unwrap(),
),
};

cryptography_x509::common::AlgorithmIdentifier {
oid: asn1::DefinedByMarker::marker(),
params: cryptography_x509::common::AlgorithmParameters::Pbes2(
cryptography_x509::common::PBES2Params {
key_derivation_func: Box::new(kdf_algorithm_identifier),
encryption_scheme: Box::new(encryption_algorithm_identifier),
},
),
}
}
}
}

pub fn encrypt(
&self,
password: &[u8],
cipher_kdf_iter: u64,
salt: &[u8],
iv: &[u8],
data: &[u8],
) -> KeySerializationResult<Vec<u8>> {
match self {
EncryptionAlgorithm::PBESHA1And3KeyTripleDESCBC => {
let password = std::str::from_utf8(password)
.map_err(|_| KeySerializationError::PasswordMustBeUtf8)?;

let key = cryptography_crypto::pkcs12::kdf(
password,
salt,
cryptography_crypto::pkcs12::KDF_ENCRYPTION_KEY_ID,
cipher_kdf_iter,
24,
openssl::hash::MessageDigest::sha1(),
)?;
let iv = cryptography_crypto::pkcs12::kdf(
password,
salt,
cryptography_crypto::pkcs12::KDF_IV_ID,
cipher_kdf_iter,
8,
openssl::hash::MessageDigest::sha1(),
)?;

Ok(openssl::symm::encrypt(
openssl::symm::Cipher::des_ede3_cbc(),
&key,
Some(&iv),
data,
)?)
}
EncryptionAlgorithm::PBESv2SHA256AndAES256CBC => {
let sha256 = openssl::hash::MessageDigest::sha256();

let mut key = [0; 32];
openssl::pkcs5::pbkdf2_hmac(
password,
salt,
cipher_kdf_iter.try_into().unwrap(),
sha256,
&mut key,
)?;

Ok(openssl::symm::encrypt(
openssl::symm::Cipher::aes_256_cbc(),
&key,
Some(iv),
data,
)?)
}
}
}
}
51 changes: 6 additions & 45 deletions src/rust/cryptography-key-parsing/src/pkcs8.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@ use cryptography_x509::pkcs8::EncryptedPrivateKeyInfo;

#[cfg(not(CRYPTOGRAPHY_IS_BORINGSSL))]
use crate::MIN_DH_MODULUS_SIZE;
use crate::{ec, rsa, KeyParsingError, KeyParsingResult};
use crate::{ec, pbe, rsa, KeyParsingError, KeyParsingResult};

// RFC 5208 Section 5
#[derive(asn1::Asn1Read, asn1::Asn1Write)]
Expand Down Expand Up @@ -457,62 +457,23 @@ pub fn serialize_private_key(
Ok(asn1::write_single(&pki)?)
}

const KDF_ITERATION_COUNT: usize = 2048;
const KDF_ITERATION_COUNT: u64 = 2048;

pub fn serialize_encrypted_private_key(
pkey: &openssl::pkey::PKeyRef<openssl::pkey::Private>,
password: &[u8],
) -> crate::KeySerializationResult<Vec<u8>> {
let plaintext_der = serialize_private_key(pkey)?;

let e = pbe::EncryptionAlgorithm::PBESv2SHA256AndAES256CBC;

let mut salt = [0u8; 16];
let mut iv = [0u8; 16];
cryptography_openssl::rand::rand_bytes(&mut salt)?;
cryptography_openssl::rand::rand_bytes(&mut iv)?;

let cipher = openssl::symm::Cipher::aes_256_cbc();
let mut key = [0u8; 32];
openssl::pkcs5::pbkdf2_hmac(
password,
&salt,
KDF_ITERATION_COUNT,
openssl::hash::MessageDigest::sha256(),
&mut key,
)?;

let encrypted_data = openssl::symm::encrypt(cipher, &key, Some(&iv), &plaintext_der)?;

let kdf_algorithm = cryptography_x509::common::AlgorithmIdentifier {
oid: asn1::DefinedByMarker::marker(),
params: cryptography_x509::common::AlgorithmParameters::Pbkdf2(
cryptography_x509::common::PBKDF2Params {
salt: &salt,
iteration_count: KDF_ITERATION_COUNT as u64,
key_length: None,
prf: Box::new(cryptography_x509::common::AlgorithmIdentifier {
oid: asn1::DefinedByMarker::marker(),
params: cryptography_x509::common::AlgorithmParameters::HmacWithSha256(
Some(()),
),
}),
},
),
};

let encryption_algorithm = cryptography_x509::common::AlgorithmIdentifier {
oid: asn1::DefinedByMarker::marker(),
params: cryptography_x509::common::AlgorithmParameters::Aes256Cbc(iv),
};

let encryption_alg = cryptography_x509::common::AlgorithmIdentifier {
oid: asn1::DefinedByMarker::marker(),
params: cryptography_x509::common::AlgorithmParameters::Pbes2(
cryptography_x509::common::PBES2Params {
key_derivation_func: Box::new(kdf_algorithm),
encryption_scheme: Box::new(encryption_algorithm),
},
),
};
let encrypted_data = e.encrypt(password, KDF_ITERATION_COUNT, &salt, &iv, &plaintext_der)?;
let encryption_alg = e.algorithm_identifier(KDF_ITERATION_COUNT, &salt, &iv);

let epki = cryptography_x509::pkcs8::EncryptedPrivateKeyInfo {
encryption_algorithm: encryption_alg,
Expand Down
5 changes: 5 additions & 0 deletions src/rust/src/error.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -136,6 +136,11 @@ impl From<cryptography_key_parsing::KeyParsingError> for CryptographyError {
impl From<cryptography_key_parsing::KeySerializationError> for CryptographyError {
fn from(e: cryptography_key_parsing::KeySerializationError) -> CryptographyError {
match e {
cryptography_key_parsing::KeySerializationError::PasswordMustBeUtf8 => {
CryptographyError::Py(pyo3::exceptions::PyValueError::new_err(
"password must be valid UTF-8",
))
}
cryptography_key_parsing::KeySerializationError::Write(e) => {
CryptographyError::Asn1Write(e)
}
Expand Down
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