Add pk_encrypt/pk_decrypt commands

3 files changed, 250 insertions, 2 deletions

diff --git a/src/cli/cli.cpp b/src/cli/cli.cpp
index e3ff2a75f..a7914ba92 100644
--- a/src/cli/cli.cpp
+++ b/src/cli/cli.cpp
@@ -11,6 +11,10 @@
 #include <iostream>
 #include <fstream>
 
+#if defined(BOTAN_TARGET_OS_HAS_POSIX1)
+   #include <termios.h>
+#endif
+
 namespace Botan_CLI {
 
 Command::Command(const std::string& cmd_spec) : m_spec(cmd_spec)
@@ -182,8 +186,8 @@ void Command::read_file(const std::string& input_file,
    }
 
 void Command::do_read_file(std::istream& in,
-                  std::function<void (uint8_t[], size_t)> consumer_fn,
-                  size_t buf_size) const
+                           std::function<void (uint8_t[], size_t)> consumer_fn,
+                           size_t buf_size) const
    {
    // Avoid an infinite loop on --buf-size=0
    std::vector<uint8_t> buf(buf_size == 0 ? 4096 : buf_size);
@@ -206,6 +210,36 @@ Botan::RandomNumberGenerator& Command::rng()
    return *m_rng.get();
    }
 
+std::string Command::get_passphrase(const std::string& prompt)
+   {
+   error_output() << prompt << ": " << std::flush;
+   std::string pass;
+
+#if defined(BOTAN_TARGET_OS_HAS_POSIX1)
+
+   struct termios old_flags;
+   ::tcgetattr(fileno(stdin), &old_flags);
+   struct termios noecho_flags = old_flags;
+   noecho_flags.c_lflag &= ~ECHO;
+   noecho_flags.c_lflag |= ECHONL;
+
+   if(::tcsetattr(fileno(stdin), TCSANOW, &noecho_flags) != 0)
+      throw CLI_Error("Clearing terminal echo bit failed");
+
+   std::getline(std::cin, pass);
+
+   if(::tcsetattr(::fileno(stdin), TCSANOW, &old_flags) != 0)
+      throw CLI_Error("Restoring terminal echo bit failed");
+#else
+
+   // TODO equivalent for Windows ...
+   std::getline(std::cin, pass);
+
+#endif
+
+   return pass;
+   }
+
 // Registration code
 
 Command::Registration::Registration(const std::string& name, Command::cmd_maker_fn maker_fn)
diff --git a/src/cli/cli.h b/src/cli/cli.h
index 97128a722..fca8e5225 100644
--- a/src/cli/cli.h
+++ b/src/cli/cli.h
@@ -118,6 +118,8 @@ class Command
          return flag_set("verbose");
          }
 
+      std::string get_passphrase(const std::string& prompt);
+
       bool flag_set(const std::string& flag_name) const;
 
       std::string get_arg(const std::string& opt_name) const;
diff --git a/src/cli/pk_crypt.cpp b/src/cli/pk_crypt.cpp
new file mode 100644
index 000000000..69a8fdf02
--- /dev/null
+++ b/src/cli/pk_crypt.cpp
@@ -0,0 +1,212 @@
+/*
+* (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)
+
+#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>
+
+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::OIDS::lookup(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_NULL_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&)
+            {
+            output() << "Parsing input file failed: invalid format?\n";
+            set_return_code(1);
+            return;
+            }
+
+         const std::string aead_algo = Botan::OIDS::lookup(aead_oid);
+         if(aead_algo == "")
+            {
+            output() << "Ciphertext was encrypted with an unknown algorithm";
+            set_return_code(1);
+            return;
+            }
+
+         if(pk_alg_id.get_oid() != Botan::OIDS::lookup("RSA/OAEP"))
+            {
+            output() << "Ciphertext was encrypted with something other than RSA/OAEP";
+            set_return_code(1);
+            return;
+            }
+
+         Botan::AlgorithmIdentifier oaep_hash;
+         Botan::BER_Decoder(pk_alg_id.get_parameters()).decode(oaep_hash);
+
+         Botan::PK_Decryptor_EME dec(*key, rng(), "OAEP(" + Botan::OIDS::lookup(oaep_hash.get_oid()) + ")");
+
+         const Botan::secure_vector<uint8_t> file_key = dec.decrypt(encrypted_key);
+
+         std::unique_ptr<Botan::AEAD_Mode> aead =
+            Botan::AEAD_Mode::create_or_throw(aead_algo, Botan::DECRYPTION);
+
+         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&)
+            {
+            output() << "Message authentication failure, possible ciphertext tampering\n";
+            set_return_code(1);
+            return;
+            }
+         }
+   };
+
+BOTAN_REGISTER_COMMAND("pk_decrypt", PK_Decrypt);
+
+}
+
+}
+
+#endif