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/*
* (C) 2018 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include "cli.h"
#if defined(BOTAN_HAS_RSA) && defined(BOTAN_HAS_AEAD_MODES) && defined(BOTAN_HAS_EME_OAEP) && defined(BOTAN_HAS_SHA2_32) && defined(BOTAN_HAS_PEM_CODEC) && defined(BOTAN_TARGET_OS_HAS_FILESYSTEM)
#include <botan/pubkey.h>
#include <botan/x509_key.h>
#include <botan/pkcs8.h>
#include <botan/der_enc.h>
#include <botan/ber_dec.h>
#include <botan/oids.h>
#include <botan/aead.h>
#include <botan/pem.h>
#include <botan/rng.h>
namespace Botan_CLI {
namespace {
class PK_Encrypt final : public Command
{
public:
PK_Encrypt() : Command("pk_encrypt --aead=AES-256/GCM pubkey datafile") {}
std::string group() const override
{
return "pubkey";
}
std::string description() const override
{
return "Encrypt a file using a RSA public key";
}
void go() override
{
std::unique_ptr<Botan::Public_Key> key(Botan::X509::load_key(get_arg("pubkey")));
if(!key)
{
throw CLI_Error("Unable to load public key");
}
if(key->algo_name() != "RSA")
{
throw CLI_Usage_Error("This function requires an RSA key");
}
const std::string OAEP_HASH = "SHA-256";
const std::string aead_algo = get_arg("aead");
std::unique_ptr<Botan::AEAD_Mode> aead =
Botan::AEAD_Mode::create(aead_algo, Botan::ENCRYPTION);
if(!aead)
throw CLI_Usage_Error("The AEAD '" + aead_algo + "' is not available");
const Botan::OID aead_oid = Botan::OID::from_string(aead_algo);
if(aead_oid.empty())
throw CLI_Usage_Error("No OID defined for AEAD '" + aead_algo + "'");
Botan::secure_vector<uint8_t> data;
auto insert_fn = [&](const uint8_t b[], size_t l)
{
data.insert(data.end(), b, b + l);
};
this->read_file(get_arg("datafile"), insert_fn);
const Botan::AlgorithmIdentifier hash_id(OAEP_HASH, Botan::AlgorithmIdentifier::USE_EMPTY_PARAM);
const Botan::AlgorithmIdentifier pk_alg_id("RSA/OAEP", hash_id.BER_encode());
Botan::PK_Encryptor_EME enc(*key, rng(), "OAEP(" + OAEP_HASH + ")");
const Botan::secure_vector<uint8_t> file_key = rng().random_vec(aead->key_spec().maximum_keylength());
const std::vector<uint8_t> encrypted_key = enc.encrypt(file_key, rng());
const Botan::secure_vector<uint8_t> nonce = rng().random_vec(aead->default_nonce_length());
aead->set_key(file_key);
aead->set_associated_data_vec(encrypted_key);
aead->start(nonce);
aead->finish(data);
std::vector<uint8_t> buf;
Botan::DER_Encoder der(buf);
der.start_cons(Botan::SEQUENCE)
.encode(pk_alg_id)
.encode(encrypted_key, Botan::OCTET_STRING)
.encode(aead_oid)
.encode(nonce, Botan::OCTET_STRING)
.encode(data, Botan::OCTET_STRING)
.end_cons();
output() << Botan::PEM_Code::encode(buf, "PUBKEY ENCRYPTED MESSAGE", 72);
}
};
BOTAN_REGISTER_COMMAND("pk_encrypt", PK_Encrypt);
class PK_Decrypt final : public Command
{
public:
PK_Decrypt() : Command("pk_decrypt privkey datafile") {}
std::string group() const override
{
return "pubkey";
}
std::string description() const override
{
return "Decrypt a file using a RSA private key";
}
void go() override
{
Botan::DataSource_Stream input_stream(get_arg("privkey"));
auto get_pass = [this]() { return get_passphrase("Password"); };
std::unique_ptr<Botan::Private_Key> key = Botan::PKCS8::load_key(input_stream, get_pass);
if(!key)
{
throw CLI_Error("Unable to load public key");
}
if(key->algo_name() != "RSA")
{
throw CLI_Usage_Error("This function requires an RSA key");
}
Botan::secure_vector<uint8_t> data;
std::vector<uint8_t> encrypted_key;
std::vector<uint8_t> nonce;
Botan::AlgorithmIdentifier pk_alg_id;
Botan::OID aead_oid;
try
{
Botan::DataSource_Stream input(get_arg("datafile"));
Botan::BER_Decoder(Botan::PEM_Code::decode_check_label(input, "PUBKEY ENCRYPTED MESSAGE"))
.start_cons(Botan::SEQUENCE)
.decode(pk_alg_id)
.decode(encrypted_key, Botan::OCTET_STRING)
.decode(aead_oid)
.decode(nonce, Botan::OCTET_STRING)
.decode(data, Botan::OCTET_STRING)
.end_cons();
}
catch(Botan::Decoding_Error&)
{
error_output() << "Parsing input file failed: invalid format?\n";
return set_return_code(1);
}
const std::string aead_algo = Botan::OIDS::oid2str_or_empty(aead_oid);
if(aead_algo == "")
{
error_output() << "Ciphertext was encrypted with an unknown algorithm";
return set_return_code(1);
}
if(pk_alg_id.get_oid() != Botan::OID::from_string("RSA/OAEP"))
{
error_output() << "Ciphertext was encrypted with something other than RSA/OAEP";
return set_return_code(1);
}
Botan::AlgorithmIdentifier oaep_hash_id;
Botan::BER_Decoder(pk_alg_id.get_parameters()).decode(oaep_hash_id);
const std::string oaep_hash = Botan::OIDS::oid2str_or_empty(oaep_hash_id.get_oid());
if(oaep_hash.empty())
{
error_output() << "Unknown hash function used with OAEP, OID " << oaep_hash_id.get_oid().to_string() << "\n";
return set_return_code(1);
}
if(oaep_hash_id.get_parameters().empty() == false)
{
error_output() << "Unknown OAEP parameters used\n";
return set_return_code(1);
}
std::unique_ptr<Botan::AEAD_Mode> aead =
Botan::AEAD_Mode::create_or_throw(aead_algo, Botan::DECRYPTION);
const size_t expected_keylen = aead->key_spec().maximum_keylength();
Botan::PK_Decryptor_EME dec(*key, rng(), "OAEP(" + oaep_hash + ")");
const Botan::secure_vector<uint8_t> file_key =
dec.decrypt_or_random(encrypted_key.data(),
encrypted_key.size(),
expected_keylen,
rng());
aead->set_key(file_key);
aead->set_associated_data_vec(encrypted_key);
aead->start(nonce);
try
{
aead->finish(data);
output().write(reinterpret_cast<const char*>(data.data()), data.size());
}
catch(Botan::Integrity_Failure&)
{
error_output() << "Message authentication failure, possible ciphertext tampering\n";
return set_return_code(1);
}
}
};
BOTAN_REGISTER_COMMAND("pk_decrypt", PK_Decrypt);
}
}
#endif
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