diff options
author | lloyd <[email protected]> | 2011-04-08 14:57:49 +0000 |
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committer | lloyd <[email protected]> | 2011-04-08 14:57:49 +0000 |
commit | fc62f7f284387a180e42402e8706965a666efba7 (patch) | |
tree | 9abe74c670993c111bd3a5bf5fb568767f9e75be /doc/examples/rsa_dec.cpp | |
parent | 438f3eb73e494fcab82b239452d712bec06f48c9 (diff) |
More pubkey doc updates
Diffstat (limited to 'doc/examples/rsa_dec.cpp')
-rw-r--r-- | doc/examples/rsa_dec.cpp | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/doc/examples/rsa_dec.cpp b/doc/examples/rsa_dec.cpp new file mode 100644 index 000000000..81592328c --- /dev/null +++ b/doc/examples/rsa_dec.cpp @@ -0,0 +1,129 @@ +/* +* (C) 2002-2010 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +/* +Decrypt an encrypted RSA private key. Then use that key to decrypt a +message. This program can decrypt messages generated by rsa_enc, and uses the +same key format as that generated by rsa_kgen. +*/ + +#include <iostream> +#include <fstream> +#include <string> +#include <memory> + +#include <botan/botan.h> +#include <botan/pubkey.h> +#include <botan/rsa.h> +using namespace Botan; + +SecureVector<byte> b64_decode(const std::string&); +SymmetricKey derive_key(const std::string&, const SymmetricKey&, u32bit); + +const std::string SUFFIX = ".enc"; + +int main(int argc, char* argv[]) + { + if(argc != 4) + { + std::cout << "Usage: " << argv[0] << " keyfile messagefile passphrase" + << std::endl; + return 1; + } + + Botan::LibraryInitializer init; + + try + { + AutoSeeded_RNG rng; + + std::auto_ptr<PKCS8_PrivateKey> key( + PKCS8::load_key(argv[1], rng, argv[3])); + + RSA_PrivateKey* rsakey = dynamic_cast<RSA_PrivateKey*>(key.get()); + if(!rsakey) + { + std::cout << "The loaded key is not a RSA key!\n"; + return 1; + } + + std::ifstream message(argv[2]); + if(!message) + { + std::cout << "Couldn't read the message file." << std::endl; + return 1; + } + + std::string outfile(argv[2]); + outfile = outfile.replace(outfile.find(SUFFIX), SUFFIX.length(), ""); + + std::ofstream plaintext(outfile.c_str(), std::ios::binary); + if(!plaintext) + { + std::cout << "Couldn't write the plaintext to " + << outfile << std::endl; + return 1; + } + + std::string enc_masterkey_str; + std::getline(message, enc_masterkey_str); + std::string mac_str; + std::getline(message, mac_str); + + SecureVector<byte> enc_masterkey = b64_decode(enc_masterkey_str); + + PK_Decryptor_EME decryptor(*rsakey, "EME1(SHA-1)"); + + SecureVector<byte> masterkey = decryptor.decrypt(enc_masterkey); + + SymmetricKey cast_key = derive_key("CAST", masterkey, 16); + InitializationVector iv = derive_key("IV", masterkey, 8); + SymmetricKey mac_key = derive_key("MAC", masterkey, 16); + + Pipe pipe(new Base64_Decoder, + get_cipher("CAST-128/CBC/PKCS7", cast_key, iv, DECRYPTION), + new Fork( + 0, + new Chain( + new MAC_Filter("HMAC(SHA-1)", mac_key, 12), + new Base64_Encoder + ) + ) + ); + + pipe.start_msg(); + message >> pipe; + pipe.end_msg(); + + std::string our_mac = pipe.read_all_as_string(1); + + if(our_mac != mac_str) + std::cout << "WARNING: MAC in message failed to verify\n"; + + plaintext << pipe.read_all_as_string(0); + } + catch(std::exception& e) + { + std::cout << "Exception caught: " << e.what() << std::endl; + return 1; + } + return 0; + } + +SecureVector<byte> b64_decode(const std::string& in) + { + Pipe pipe(new Base64_Decoder); + pipe.process_msg(in); + return pipe.read_all(); + } + +SymmetricKey derive_key(const std::string& param, + const SymmetricKey& masterkey, + u32bit outputlength) + { + std::auto_ptr<KDF> kdf(get_kdf("KDF2(SHA-1)")); + return kdf->derive_key(outputlength, masterkey.bits_of(), param); + } |