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/*
* (C) 2014,2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include "cli.h"
#include <botan/hex.h>
#if defined(BOTAN_HAS_FPE_FE1) && defined(BOTAN_HAS_PBKDF)
#include <botan/fpe_fe1.h>
#include <botan/pbkdf.h>
namespace Botan_CLI {
namespace {
uint8_t luhn_checksum(uint64_t cc_number)
{
uint8_t sum = 0;
bool alt = false;
while(cc_number)
{
uint8_t digit = cc_number % 10;
if(alt)
{
digit *= 2;
if(digit > 9)
{
digit -= 9;
}
}
sum += digit;
cc_number /= 10;
alt = !alt;
}
return (sum % 10);
}
bool luhn_check(uint64_t cc_number)
{
return (luhn_checksum(cc_number) == 0);
}
uint64_t cc_rank(uint64_t cc_number)
{
// Remove Luhn checksum
return cc_number / 10;
}
uint64_t cc_derank(uint64_t cc_number)
{
for(size_t i = 0; i != 10; ++i)
{
if(luhn_check(cc_number * 10 + i))
{
return (cc_number * 10 + i);
}
}
return 0;
}
uint64_t encrypt_cc_number(uint64_t cc_number,
const Botan::secure_vector<uint8_t>& key,
const std::vector<uint8_t>& tweak)
{
const Botan::BigInt n = 1000000000000000;
const uint64_t cc_ranked = cc_rank(cc_number);
const Botan::BigInt c = Botan::FPE::fe1_encrypt(n, cc_ranked, key, tweak);
if(c.bits() > 50)
{
throw Botan::Internal_Error("FPE produced a number too large");
}
uint64_t enc_cc = 0;
for(size_t i = 0; i != 7; ++i)
{
enc_cc = (enc_cc << 8) | c.byte_at(6 - i);
}
return cc_derank(enc_cc);
}
uint64_t decrypt_cc_number(uint64_t enc_cc,
const Botan::secure_vector<uint8_t>& key,
const std::vector<uint8_t>& tweak)
{
const Botan::BigInt n = 1000000000000000;
const uint64_t cc_ranked = cc_rank(enc_cc);
const Botan::BigInt c = Botan::FPE::fe1_decrypt(n, cc_ranked, key, tweak);
if(c.bits() > 50)
{
throw CLI_Error("FPE produced a number too large");
}
uint64_t dec_cc = 0;
for(size_t i = 0; i != 7; ++i)
{
dec_cc = (dec_cc << 8) | c.byte_at(6 - i);
}
return cc_derank(dec_cc);
}
}
class CC_Encrypt final : public Command
{
public:
CC_Encrypt() : Command("cc_encrypt CC passphrase --tweak=") {}
std::string group() const override
{
return "misc";
}
std::string description() const override
{
return "Encrypt the passed valid credit card number using FPE encryption";
}
void go() override
{
const uint64_t cc_number = std::stoull(get_arg("CC"));
const std::vector<uint8_t> tweak = Botan::hex_decode(get_arg("tweak"));
const std::string pass = get_arg("passphrase");
std::unique_ptr<Botan::PBKDF> pbkdf(Botan::PBKDF::create("PBKDF2(SHA-256)"));
if(!pbkdf)
{
throw CLI_Error_Unsupported("PBKDF", "PBKDF2(SHA-256)");
}
Botan::secure_vector<uint8_t> key = pbkdf->pbkdf_iterations(32, pass, tweak.data(), tweak.size(), 100000);
output() << encrypt_cc_number(cc_number, key, tweak) << "\n";
}
};
BOTAN_REGISTER_COMMAND("cc_encrypt", CC_Encrypt);
class CC_Decrypt final : public Command
{
public:
CC_Decrypt() : Command("cc_decrypt CC passphrase --tweak=") {}
std::string group() const override
{
return "misc";
}
std::string description() const override
{
return "Decrypt the passed valid ciphertext credit card number using FPE decryption";
}
void go() override
{
const uint64_t cc_number = std::stoull(get_arg("CC"));
const std::vector<uint8_t> tweak = Botan::hex_decode(get_arg("tweak"));
const std::string pass = get_arg("passphrase");
std::unique_ptr<Botan::PBKDF> pbkdf(Botan::PBKDF::create("PBKDF2(SHA-256)"));
if(!pbkdf)
{
throw CLI_Error_Unsupported("PBKDF", "PBKDF2(SHA-256)");
}
Botan::secure_vector<uint8_t> key = pbkdf->pbkdf_iterations(32, pass, tweak.data(), tweak.size(), 100000);
output() << decrypt_cc_number(cc_number, key, tweak) << "\n";
}
};
BOTAN_REGISTER_COMMAND("cc_decrypt", CC_Decrypt);
}
#endif // FPE && PBKDF
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