From 7701f4235bf960b093735c416d4eb27840a5a98f Mon Sep 17 00:00:00 2001 From: lloyd Date: Tue, 15 Feb 2011 23:45:27 +0000 Subject: Add the NIST AES key wrap algorithm, as specified in RFC 3394 and http://csrc.nist.gov/groups/ST/toolkit/documents/kms/key-wrap.pdf --- src/constructs/rfc3394/info.txt | 1 + src/constructs/rfc3394/rfc3394.cpp | 121 +++++++++++++++++++++++++++++++++++++ src/constructs/rfc3394/rfc3394.h | 44 ++++++++++++++ 3 files changed, 166 insertions(+) create mode 100644 src/constructs/rfc3394/info.txt create mode 100644 src/constructs/rfc3394/rfc3394.cpp create mode 100644 src/constructs/rfc3394/rfc3394.h (limited to 'src/constructs') diff --git a/src/constructs/rfc3394/info.txt b/src/constructs/rfc3394/info.txt new file mode 100644 index 000000000..496f3e138 --- /dev/null +++ b/src/constructs/rfc3394/info.txt @@ -0,0 +1 @@ +define RFC3394_KEYWRAP diff --git a/src/constructs/rfc3394/rfc3394.cpp b/src/constructs/rfc3394/rfc3394.cpp new file mode 100644 index 000000000..d6909c94a --- /dev/null +++ b/src/constructs/rfc3394/rfc3394.cpp @@ -0,0 +1,121 @@ +/* +* AES Key Wrap (RFC 3394) +* (C) 2011 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +#include +#include +#include +#include +#include +#include + +namespace Botan { + +namespace { + +BlockCipher* make_aes(size_t keylength, + Algorithm_Factory& af) + { + if(keylength == 16) + return af.make_block_cipher("AES-128"); + else if(keylength == 24) + return af.make_block_cipher("AES-192"); + else if(keylength == 32) + return af.make_block_cipher("AES-256"); + else + throw std::invalid_argument("Bad KEK length for NIST keywrap"); + } + +} + +SecureVector rfc3394_keywrap(const MemoryRegion& key, + const SymmetricKey& kek, + Algorithm_Factory& af) + { + if(key.size() % 8 != 0) + throw std::invalid_argument("Bad input key size for NIST key wrap"); + + std::auto_ptr aes(make_aes(kek.length(), af)); + aes->set_key(kek); + + const size_t n = key.size() / 8; + + SecureVector R((n + 1) * 8); + SecureVector A(16); + + for(size_t i = 0; i != 8; ++i) + A[i] = 0xA6; + + copy_mem(&R[8], key.begin(), key.size()); + + for(size_t j = 0; j <= 5; ++j) + { + for(size_t i = 1; i <= n; ++i) + { + const u32bit t = (n * j) + i; + + copy_mem(&A[8], &R[8*i], 8); + + aes->encrypt(&A[0]); + copy_mem(&R[8*i], &A[8], 8); + + byte t_buf[4] = { 0 }; + store_be(t, t_buf); + xor_buf(&A[4], &t_buf[0], 4); + } + } + + copy_mem(&R[0], &A[0], 8); + + return R; + } + +SecureVector rfc3394_keyunwrap(const MemoryRegion& key, + const SymmetricKey& kek, + Algorithm_Factory& af) + { + if(key.size() < 16 || key.size() % 8 != 0) + throw std::invalid_argument("Bad input key size for NIST key unwrap"); + + std::auto_ptr aes(make_aes(kek.length(), af)); + aes->set_key(kek); + + const size_t n = (key.size() - 8) / 8; + + SecureVector R(n * 8); + SecureVector A(16); + + for(size_t i = 0; i != 8; ++i) + A[i] = key[i]; + + copy_mem(&R[0], key.begin() + 8, key.size() - 8); + + for(size_t j = 0; j <= 5; ++j) + { + for(size_t i = n; i != 0; --i) + { + const u32bit t = (5 - j) * n + i; + + byte t_buf[4] = { 0 }; + store_be(t, t_buf); + + xor_buf(&A[4], &t_buf[0], 4); + + copy_mem(&A[8], &R[8*(i-1)], 8); + + aes->decrypt(&A[0]); + + copy_mem(&R[8*(i-1)], &A[8], 8); + } + } + + if(load_be(&A[0], 0) != 0xA6A6A6A6A6A6A6A6) + throw Integrity_Failure("NIST key unwrap failed"); + + return R; + } + +} diff --git a/src/constructs/rfc3394/rfc3394.h b/src/constructs/rfc3394/rfc3394.h new file mode 100644 index 000000000..7a4668735 --- /dev/null +++ b/src/constructs/rfc3394/rfc3394.h @@ -0,0 +1,44 @@ +/* +* AES Key Wrap (RFC 3394) +* (C) 2011 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +#ifndef BOTAN_AES_KEY_WRAP_H__ +#define BOTAN_AES_KEY_WRAP_H__ + +#include +#include + +namespace Botan { + +/** +* Encrypt a key under a key encryption key using the algorithm +* described in RFC 3394 +* +* @param key the plaintext key to encrypt +* @param kek the key encryption key +* @param af an algorithm factory +* @return key encrypted under kek +*/ +SecureVector BOTAN_DLL rfc3394_keywrap(const MemoryRegion& key, + const SymmetricKey& kek, + Algorithm_Factory& af); + +/** +* Decrypt a key under a key encryption key using the algorithm +* described in RFC 3394 +* +* @param key the encrypted key to decrypt +* @param kek the key encryption key +* @param af an algorithm factory +* @return key decrypted under kek +*/ +SecureVector BOTAN_DLL rfc3394_keyunwrap(const MemoryRegion& key, + const SymmetricKey& kek, + Algorithm_Factory& af); + +} + +#endif -- cgit v1.2.3