diff options
author | lloyd <[email protected]> | 2011-04-04 03:43:52 +0000 |
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committer | lloyd <[email protected]> | 2011-04-04 03:43:52 +0000 |
commit | 3b9bfbd07c3723662832caf5b1efe04de28b656d (patch) | |
tree | ee2a9324f384efead6e5bb87ac8374e7e8734c90 /doc/examples/fpe.cpp | |
parent | 04db054f1ae8de572ee9c0cfe227e76f84096bd6 (diff) |
Convert most of the documentation to reStructured Text, adding
a makefile to build it with Sphinx (http://sphinx.pocoo.org/).
Previously credits.txt listed public domain code sources; instead
directly credit the authors in the relevant files and delete that
file.
Drop the draft FIPS 140 security policy; I can't imagine FIPS 140
validation will ever happen, and if it does, I don't want
anything to do with it.
Also drop the internals doc, which was so out of date (and
incomplete) as to be worthless.
Move the tutorials and InSiTo pdfs into old/ for the time being,
until anything relevant from them can be filtered out and
converted into RST.
Diffstat (limited to 'doc/examples/fpe.cpp')
-rw-r--r-- | doc/examples/fpe.cpp | 151 |
1 files changed, 0 insertions, 151 deletions
diff --git a/doc/examples/fpe.cpp b/doc/examples/fpe.cpp deleted file mode 100644 index 9b18d4879..000000000 --- a/doc/examples/fpe.cpp +++ /dev/null @@ -1,151 +0,0 @@ -/* -* (C) 2009 Jack Lloyd -* -* Distributed under the terms of the Botan license -*/ - -/* -* Encrypt credit cards numbers with valid checksums into other credit -* card numbers with valid checksums using format preserving encryption. -*/ - -#include <botan/fpe.h> -#include <botan/sha160.h> -#include <botan/init.h> - -using namespace Botan; - -#include <iostream> -#include <stdexcept> - -namespace { - -byte luhn_checksum(u64bit cc_number) - { - byte sum = 0; - - bool alt = false; - while(cc_number) - { - byte 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(u64bit cc_number) - { - return (luhn_checksum(cc_number) == 0); - } - -u64bit cc_rank(u64bit cc_number) - { - // Remove Luhn checksum - return cc_number / 10; - } - -u64bit cc_derank(u64bit cc_number) - { - for(u32bit i = 0; i != 10; ++i) - if(luhn_check(cc_number * 10 + i)) - return (cc_number * 10 + i); - return 0; - } - -/* -* Use the SHA-1 hash of the account name or ID as a tweak -*/ -SecureVector<byte> sha1(const std::string& acct_name) - { - SHA_160 hash; - hash.update(acct_name); - return hash.final(); - } - -u64bit encrypt_cc_number(u64bit cc_number, - const SymmetricKey& key, - const std::string& acct_name) - { - BigInt n = 1000000000000000; - - u64bit cc_ranked = cc_rank(cc_number); - - BigInt c = fpe_encrypt(n, cc_ranked, key, sha1(acct_name)); - - if(c.bits() > 50) - throw std::runtime_error("FPE produced a number too large"); - - u64bit enc_cc = 0; - for(u32bit i = 0; i != 7; ++i) - enc_cc = (enc_cc << 8) | c.byte_at(6-i); - return cc_derank(enc_cc); - } - -u64bit decrypt_cc_number(u64bit enc_cc, - const SymmetricKey& key, - const std::string& acct_name) - { - BigInt n = 1000000000000000; - - u64bit cc_ranked = cc_rank(enc_cc); - - BigInt c = fpe_decrypt(n, cc_ranked, key, sha1(acct_name)); - - if(c.bits() > 50) - throw std::runtime_error("FPE produced a number too large"); - - u64bit dec_cc = 0; - for(u32bit i = 0; i != 7; ++i) - dec_cc = (dec_cc << 8) | c.byte_at(6-i); - return cc_derank(dec_cc); - } - -} - -int main(int argc, char* argv[]) - { - LibraryInitializer init; - - if(argc != 4) - { - std::cout << "Usage: " << argv[0] << " cc-number acct-name passwd\n"; - return 1; - } - - u64bit cc_number = atoll(argv[1]); - std::string acct_name = argv[2]; - std::string passwd = argv[3]; - - std::cout << "Input was: " << cc_number << ' ' - << luhn_check(cc_number) << '\n'; - - /** - * In practice something like PBKDF2 with a salt and high iteration - * count would be a good idea. - */ - SymmetricKey key = sha1(passwd); - - u64bit enc_cc = encrypt_cc_number(cc_number, key, acct_name); - - std::cout << "Encrypted: " << enc_cc - << ' ' << luhn_check(enc_cc) << '\n'; - - u64bit dec_cc = decrypt_cc_number(enc_cc, key, acct_name); - - std::cout << "Decrypted: " << dec_cc - << ' ' << luhn_check(dec_cc) << '\n'; - - if(dec_cc != cc_number) - std::cout << "Something went wrong :( Bad CC checksum?\n"; - } |