diff options
author | lloyd <[email protected]> | 2009-11-17 07:19:37 +0000 |
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committer | lloyd <[email protected]> | 2009-11-17 07:19:37 +0000 |
commit | e00b46cf9c1dcb364ebb7d5968d6ff9dcd600c4e (patch) | |
tree | 8ffb8d032f06bbcb7ab376c7469751a25b556dca /src/constructs/aont/package.cpp | |
parent | a98a9ff5f95bd4dca9c1eda11e27e712c869cd66 (diff) |
Move most code that relies heavily on Filters into src/filters.
Remove support for (unused) modset settings.
Move tss, fpe, cryptobox, and aont to new dir constructs
Diffstat (limited to 'src/constructs/aont/package.cpp')
-rw-r--r-- | src/constructs/aont/package.cpp | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/src/constructs/aont/package.cpp b/src/constructs/aont/package.cpp new file mode 100644 index 000000000..37bad46c8 --- /dev/null +++ b/src/constructs/aont/package.cpp @@ -0,0 +1,120 @@ +/* +* Rivest's Package Tranform +* +* (C) 2009 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +#include <botan/package.h> +#include <botan/filters.h> +#include <botan/ctr.h> +#include <botan/loadstor.h> +#include <botan/xor_buf.h> + +namespace Botan { + +namespace AllOrNothingTransform { + +void package(RandomNumberGenerator& rng, + BlockCipher* cipher, + const byte input[], u32bit input_len, + byte output[]) + { + if(!cipher->valid_keylength(cipher->BLOCK_SIZE)) + throw Invalid_Argument("AONT::package: Invalid cipher"); + + // The all-zero string which is used both as the CTR IV and as K0 + const std::string all_zeros(cipher->BLOCK_SIZE*2, '0'); + + SymmetricKey package_key(rng, cipher->BLOCK_SIZE); + + Pipe pipe(new StreamCipher_Filter(new CTR_BE(cipher), package_key)); + + pipe.process_msg(input, input_len); + pipe.read(output, pipe.remaining()); + + // Set K0 (the all zero key) + cipher->set_key(SymmetricKey(all_zeros)); + + SecureVector<byte> buf(cipher->BLOCK_SIZE); + + const u32bit blocks = + (input_len + cipher->BLOCK_SIZE - 1) / cipher->BLOCK_SIZE; + + byte* final_block = output + input_len; + clear_mem(final_block, cipher->BLOCK_SIZE); + + // XOR the hash blocks into the final block + for(u32bit i = 0; i != blocks; ++i) + { + u32bit left = std::min<u32bit>(cipher->BLOCK_SIZE, + input_len - cipher->BLOCK_SIZE * i); + + buf.clear(); + copy_mem(&buf[0], output + cipher->BLOCK_SIZE * i, left); + + for(u32bit j = 0; j != 4; ++j) + buf[cipher->BLOCK_SIZE - 1 - j] ^= get_byte(3-j, i); + + cipher->encrypt(buf); + + xor_buf(final_block, buf, cipher->BLOCK_SIZE); + } + + // XOR the random package key into the final block + xor_buf(final_block, package_key.begin(), cipher->BLOCK_SIZE); + } + +void unpackage(BlockCipher* cipher, + const byte input[], u32bit input_len, + byte output[]) + { + if(!cipher->valid_keylength(cipher->BLOCK_SIZE)) + throw Invalid_Argument("AONT::unpackage: Invalid cipher"); + + if(input_len < cipher->BLOCK_SIZE) + throw Invalid_Argument("AONT::unpackage: Input too short"); + + // The all-zero string which is used both as the CTR IV and as K0 + const std::string all_zeros(cipher->BLOCK_SIZE*2, '0'); + + cipher->set_key(SymmetricKey(all_zeros)); + + SecureVector<byte> package_key(cipher->BLOCK_SIZE); + SecureVector<byte> buf(cipher->BLOCK_SIZE); + + // Copy the package key (masked with the block hashes) + copy_mem(&package_key[0], + input + (input_len - cipher->BLOCK_SIZE), + cipher->BLOCK_SIZE); + + const u32bit blocks = ((input_len - 1) / cipher->BLOCK_SIZE); + + // XOR the blocks into the package key bits + for(u32bit i = 0; i != blocks; ++i) + { + u32bit left = std::min<u32bit>(cipher->BLOCK_SIZE, + input_len - cipher->BLOCK_SIZE * (i+1)); + + buf.clear(); + copy_mem(&buf[0], input + cipher->BLOCK_SIZE * i, left); + + for(u32bit j = 0; j != 4; ++j) + buf[cipher->BLOCK_SIZE - 1 - j] ^= get_byte(3-j, i); + + cipher->encrypt(buf); + + xor_buf(&package_key[0], buf, cipher->BLOCK_SIZE); + } + + Pipe pipe(new StreamCipher_Filter(new CTR_BE(cipher), package_key)); + + pipe.process_msg(input, input_len - cipher->BLOCK_SIZE); + + pipe.read(output, pipe.remaining()); + } + +} + +} |