algos_enc: work, fujisaki-okamoto encryption
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@ -91,7 +91,7 @@ static void message_pad (const bvector&in, std::vector<byte>&out, prng&rng)
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else out.resize ( ( (in.size() - 1) >> 3) + 2, 0);
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//copy message bits
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int i;
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uint i;
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for (i = 0; i < in.size(); ++i)
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if (in[i]) out[i >> 3] |= 1 << (i & 0x7);
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@ -105,9 +105,9 @@ static void message_pad (const bvector&in, std::vector<byte>&out, prng&rng)
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out[i >> 3] = in.size() & 0x7;
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//byte stage
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int overflow = out.size() & 0xff;
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int pad_block_start = out.size() >> 8;
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int pad_block_start_byte = pad_block_start << 8;
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uint overflow = out.size() & 0xff;
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uint pad_block_start = out.size() >> 8;
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uint pad_block_start_byte = pad_block_start << 8;
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//make space for the bytes
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out.resize ( (pad_block_start + 1) << 8, 0);
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@ -122,33 +122,200 @@ static void message_pad (const bvector&in, std::vector<byte>&out, prng&rng)
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static bool message_unpad (const std::vector<byte>&in, bvector&out)
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{
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//check byte padding sizes
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if (!in.size() ) return false;
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if (in.size() & 0xff) return false;
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//get rid of the byte padding
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uint byte_overflow = in[in.size() - 1];
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uint in_end = in.size() + byte_overflow - 256;
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//get bit padding information (now it's the last byte)
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if (!in_end) return false;
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uint bit_overflow = in[in_end - 1];
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//there must not be more than one byte of overflown bits
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if (bit_overflow >= 8) return false;
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//check if there's byte with overflow bits
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if (bit_overflow && (in_end < 2) ) return false;
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//convert to bvector
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uint msg_size = ( (in_end - (bit_overflow ? 2 : 1) ) << 3)
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+ bit_overflow;
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out.clear();
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out.resize (msg_size);
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for (uint i = 0; i < msg_size; ++i)
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out[i] = 1 & (in[i >> 3] >> (i & 0x7) );
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return true;
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}
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/*
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* Fujisaki-okamoto encryption scheme
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* Fujisaki-okamoto part
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*/
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#define min(a,b) ((a)<(b)?(a):(b))
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#include "sha_hash.h"
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#include "arcfour.h"
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/*
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* Generic F-O encryption function. Note that ranksize must be equal to
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*
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* floor(log(comb(ciphersize,errorcount))/log(2))
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*
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* otherwise it probably fails miserably.
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*/
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template < class pubkey_type,
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int plainsize,
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int ciphersize,
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int errorcount,
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class hash_type,
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int ranksize >
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static int fo_encrypt (const bvector&plain, bvector&cipher,
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sencode* pubkey, prng&rng)
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{
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uint i;
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//load the key
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pubkey_type Pub;
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if (Pub.unserialize (pubkey) ) return 1;
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//verify that key parameters match our scheme
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if (Pub.plain_size() != plainsize) return 1;
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if (Pub.cipher_size() != ciphersize) return 1;
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if (Pub.error_count() != errorcount) return 1;
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//create the unencrypted message part
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std::vector<byte> M;
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message_pad (plain, M, rng);
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//create the symmetric key
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std::vector<byte> K;
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K.resize (plainsize >> 3);
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for (i = 0; i < K.size(); ++i) K[i] = rng.random (256);
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//create the base for error vector
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std::vector<byte> H, M2;
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M2 = M;
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M2.insert (M2.end(), K.begin(), K.end() );
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hash_type hf;
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H = hf (M2);
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//prepare the error vector
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bvector ev_rank;
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ev_rank.resize (ranksize);
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for (i = 0; i < ranksize; ++i) ev_rank[i] = 1 & (H[ (i >> 3) % H.size()] >> (i & 0x7) );
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bvector ev;
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ev_rank.colex_unrank (ev, ciphersize, errorcount);
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//prepare plaintext
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bvector mce_plain;
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mce_plain.resize (plainsize);
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for (i = 0; i < plainsize; ++i) mce_plain[i] = 1 & (M[i >> 3] >> (i & 0x7) );
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//run McEliece
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if (Pub.encrypt (mce_plain, cipher, ev) ) return 2;
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//encrypt the message part (xor with arcfour)
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arcfour<byte> arc;
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arc.init (8);
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//whole key must be tossed in, so split if when necessary
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for (i = 0; i < (K.size() >> 8); ++i) {
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std::vector<byte> subkey (K.begin() + (i << 8),
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min (K.end(),
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K.begin() + ( (i + 1) << 8) ) );
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arc.load_key (subkey);
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}
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arc.discard (256);
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for (i = 0; i < M.size(); ++i) M[i] = M[i] ^ arc.gen();
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//append the message part to the ciphertext
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cipher.resize (ciphersize + (M.size() << 3) );
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for (i = 0; i < (M.size() << 3); ++i)
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cipher[ciphersize + i] = 1 & (M[i >> 3] >> (i & 0x7) );
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return 0;
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}
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template < class privkey_type,
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int plainsize,
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int ciphersize,
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int errorcount,
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class hash_type,
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int ranksize >
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static int fo_decrypt (const bvector&cipher, bvector&plain,
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sencode* privkey)
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{
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uint i;
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//load the key
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privkey_type Priv;
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if (Priv.unserialize (privkey) ) return 1;
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//verify that key parameters match the scheme
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if (Priv.plain_size() != plainsize) return 1;
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if (Priv.cipher_size() != ciphersize) return 1;
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if (Priv.error_count() != errorcount) return 1;
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//TODO
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//split the message into McE and Arcfour parts
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//decrypt the symmetric key
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//decrypt the message part
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//check the hash
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//unpad the message
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return -1;
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}
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/*
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* Instances for actual encryption/descryption algorithms
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*/
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int algo_mceqd128::encrypt (const bvector&plain, bvector&cipher,
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sencode* pubkey, prng&rng)
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{
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return -1;
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return fo_encrypt
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< mce_qd::pubkey,
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2048, 4096, 128,
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sha256hash,
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816 >
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(plain, cipher, pubkey, rng);
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}
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int algo_mceqd256::encrypt (const bvector&plain, bvector&cipher,
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sencode* pubkey, prng&rng)
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{
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return -1;
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return fo_encrypt
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< mce_qd::pubkey,
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4096, 8192, 256,
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sha512hash,
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1638 >
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(plain, cipher, pubkey, rng);
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}
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int algo_mceqd128::decrypt (const bvector&cipher, bvector&plain,
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sencode* privkey)
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{
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return -1;
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return fo_decrypt
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< mce_qd::privkey,
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2048, 4096, 128,
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sha256hash,
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816 >
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(cipher, plain, privkey);
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}
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int algo_mceqd256::decrypt (const bvector&cipher, bvector&plain,
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sencode* privkey)
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{
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return -1;
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return fo_decrypt
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< mce_qd::privkey,
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4096, 8192, 256,
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sha256hash,
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1638 >
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(cipher, plain, privkey);
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}
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@ -55,7 +55,7 @@ public:
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}
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std::string get_alg_id() {
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return "MCEQD256FO-SHA256-ARCFOUR";
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return "MCEQD256FO-SHA512-ARCFOUR";
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}
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int encrypt (const bvector&plain, bvector&cipher,
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