diff --git a/src/algo_suite.h b/src/algo_suite.h
index 2ec2eab..a068a86 100644
--- a/src/algo_suite.h
+++ b/src/algo_suite.h
@@ -21,9 +21,10 @@
 
 #include <map>
 #include <string>
+
 class algorithm;
+
 typedef std::map<std::string, algorithm*> algorithm_suite;
 
 void fill_algorithm_suite (algorithm_suite&);
-
 #endif
diff --git a/src/chacha.cpp b/src/chacha.cpp
index dbdec9a..fb09d93 100644
--- a/src/chacha.cpp
+++ b/src/chacha.cpp
@@ -75,7 +75,7 @@ void chacha20::init()
 	for (int i = 0; i < 10; ++i) key[i] = 0;
 	for (int i = 0; i < 2; ++i) counter[i] = 0;
 
-	blockpos = 256;
+	blockpos = 64;
 }
 
 void chacha20::load_key (const byte*begin, const byte*end)
@@ -116,7 +116,7 @@ void chacha20::gen (size_t n, byte*out)
 
 	//fill in whole blocks
 	while (n >= 64) {
-		if (out) chacha_gen (key, counter, (uint32_t*) &out);
+		if (out) chacha_gen (key, counter, (uint32_t*) out);
 
 		chacha_incr_counter (counter);
 		out += 64;
diff --git a/src/cube_hash.h b/src/cube_hash.h
index 3f8ff3c..7de86f8 100644
--- a/src/cube_hash.h
+++ b/src/cube_hash.h
@@ -61,21 +61,22 @@ public:
 		bpos = 0;
 	}
 
-	void eat (const std::vector<byte>&a) {
+	void eat (const byte*a, const byte*aend) {
 		int apos = 0;
+		int asize = aend - a;
 		if (bpos) {
-			for (; bpos < B && apos < a.size(); ++bpos, ++apos)
+			for (; bpos < B && apos < asize; ++bpos, ++apos)
 				buf[bpos] = a[apos];
 			if (bpos == B) {
 				state.process_block (buf);
 				bpos = 0;
 			}
 		}
-		while (apos + B <= a.size() ) {
+		while (apos + B <= asize ) {
 			state.process_block (& (a[apos]) );
 			apos += B;
 		}
-		for (; apos < a.size(); ++apos, ++bpos)
+		for (; apos < asize; ++apos, ++bpos)
 			buf[bpos] = a[apos];
 	}
 
diff --git a/src/hash.cpp b/src/hash.cpp
index e62d5c6..9575025 100644
--- a/src/hash.cpp
+++ b/src/hash.cpp
@@ -18,6 +18,8 @@
 
 #include "hash.h"
 
+#include "str_match.h"
+
 #include "sha_hash.h"
 #include "rmd_hash.h"
 #include "tiger_hash.h"
@@ -29,7 +31,7 @@ hash_proc::suite_t& hash_proc::suite()
 
 #define do_hash(name,type) \
 	static factoryof<hash_proc,type> type##_var; \
-	s[name]=&type##_var;
+	s[to_unicase(name)]=&type##_var;
 
 	if (s.empty() ) {
 		do_hash ("CUBE512", cube512proc);
diff --git a/src/hash.h b/src/hash.h
index 2a49cfa..1f8f6c1 100644
--- a/src/hash.h
+++ b/src/hash.h
@@ -40,10 +40,15 @@ class hash_proc
 public:
 	virtual uint size() = 0;
 	virtual void init() = 0;
-	virtual void eat (const std::vector<byte>&) = 0;
+
+	virtual void eat (const byte*begin, const byte*end) = 0;
 	virtual std::vector<byte> finish() = 0;
 	virtual ~hash_proc() {}
 
+	void eat (const std::vector<byte>&a) {
+		return eat (& (a[0]), & (a[a.size()]) );
+	}
+
 	typedef std::map<std::string, factoryof<hash_proc>*> suite_t;
 	static suite_t& suite();
 };
diff --git a/src/hashfile.cpp b/src/hashfile.cpp
index db746a1..484612f 100644
--- a/src/hashfile.cpp
+++ b/src/hashfile.cpp
@@ -42,8 +42,8 @@ class size64proc : public hash_proc
 		s = 0;
 	}
 
-	void eat (const std::vector<byte>&a) {
-		s += a.size();
+	void eat (const byte*a, const byte*aend) {
+		s += aend - a;
 	}
 
 	std::vector<byte> finish() {
diff --git a/src/sc.cpp b/src/sc.cpp
index 69dacaf..25ab89c 100644
--- a/src/sc.cpp
+++ b/src/sc.cpp
@@ -18,6 +18,8 @@
 
 #include "sc.h"
 
+#include "str_match.h"
+
 #include "arcfour.h"
 #include "xsynd.h"
 #include "chacha.h"
@@ -29,7 +31,7 @@ streamcipher::suite_t& streamcipher::suite()
 	static suite_t s;
 #define do_cipher(name,type) \
 	static factoryof<streamcipher,type> type##_var; \
-	s[name]=&type##_var;
+	s[to_unicase(name)]=&type##_var;
 
 	if (s.empty() ) {
 		do_cipher ("ARCFOUR", arcfour_t);
diff --git a/src/serialization.cpp b/src/serialization.cpp
index 735e698..135f3c9 100644
--- a/src/serialization.cpp
+++ b/src/serialization.cpp
@@ -681,7 +681,7 @@ bool hashfile::unserialize (sencode*s)
  *   ( streamcipher1 streamcipher2 )
  *   ( hash1 hash2 hash3 )
  *   int_blocksize
- *   seed_data
+ *   key_data
  * )
  */
 
@@ -695,13 +695,13 @@ sencode* symkey::serialize()
 	L->items.resize (5);
 	L->items[0] = new sencode_bytes (SYMKEY_IDENT);
 	L->items[3] = new sencode_int (blocksize);
-	L->items[4] = new sencode_bytes (seed);
+	L->items[4] = new sencode_bytes (key);
 
+	std::set<std::string>::iterator i, e;
 	LL = new sencode_list();
 	LL->items.resize (ciphers.size() );
 	k = 0;
-	for (std::set<std::string>::iterator
-	     i = ciphers.begin(), e = ciphers.end();
+	for (i = ciphers.begin(), e = ciphers.end();
 	     i != e; ++i)
 		LL->items[k++] = new sencode_bytes (*i);
 	L->items[1] = LL;
@@ -709,8 +709,7 @@ sencode* symkey::serialize()
 	LL = new sencode_list();
 	LL->items.resize (hashes.size() );
 	k = 0;
-	for (std::list<std::string>::iterator
-	     i = hashes.begin(), e = hashes.end();
+	for (i = hashes.begin(), e = hashes.end();
 	     i != e; ++i)
 		LL->items[k++] = new sencode_bytes (*i);
 	L->items[2] = LL;
@@ -734,8 +733,8 @@ bool symkey::unserialize (sencode*s)
 	sencode_bytes*B;
 
 	CAST_BYTES (L->items[4], B);
-	seed.clear();
-	seed.insert (seed.begin(), B->b.begin(), B->b.end() );
+	key.clear();
+	key.insert (key.begin(), B->b.begin(), B->b.end() );
 
 	sencode_list*LL;
 	uint i;
@@ -752,7 +751,8 @@ bool symkey::unserialize (sencode*s)
 	hashes.clear();
 	for (i = 0; i < LL->items.size(); ++i) {
 		CAST_BYTES (LL->items[i], B);
-		hashes.push_back (B->b);
+		if (hashes.count (B->b) ) return false;
+		hashes.insert (B->b);
 	}
 
 	return true;
diff --git a/src/sha_hash.h b/src/sha_hash.h
index 511841e..b11b44f 100644
--- a/src/sha_hash.h
+++ b/src/sha_hash.h
@@ -60,8 +60,8 @@ public:
 		state.Restart();
 	}
 
-	void eat (const std::vector<byte>&a) {
-		state.Update (& (a[0]), a.size() );
+	void eat (const byte*a, const byte*aend) {
+		state.Update (a, aend - a);
 	}
 
 	std::vector<byte> finish() {
diff --git a/src/str_match.cpp b/src/str_match.cpp
index ccb55c9..d4ca38e 100644
--- a/src/str_match.cpp
+++ b/src/str_match.cpp
@@ -54,3 +54,9 @@ bool keyspec_matches (const std::string&search,
 
 	return matches_icase (name, search);
 }
+
+std::string to_unicase (std::string str)
+{
+	transform (str.begin(), str.end(), str.begin(), ::toupper);
+	return str;
+}
diff --git a/src/str_match.h b/src/str_match.h
index d603f0b..0118219 100644
--- a/src/str_match.h
+++ b/src/str_match.h
@@ -28,4 +28,6 @@ bool keyspec_matches (const std::string&search,
                       const std::string&name,
                       const std::string&keyid);
 
+std::string to_unicase (std::string);
+
 #endif
diff --git a/src/symkey.cpp b/src/symkey.cpp
index 336dbcf..9ada4bb 100644
--- a/src/symkey.cpp
+++ b/src/symkey.cpp
@@ -18,14 +18,320 @@
 
 #include "symkey.h"
 
-bool symkey::encrypt (std::istream&in, std::ostream&out)
-{
+#include "sc.h"
+#include "hash.h"
+#include "str_match.h"
+#include "iohelpers.h"
 
-	return false;
+#include <sstream>
+
+bool symkey::is_valid()
+{
+	return blocksize >= 1024 &&
+	       blocksize < 0x10000000 && //256M
+	       !ciphers.empty() &&
+	       !hashes.empty() &&
+	       key.size() >= 32 && //not less than 256bits of key stuff
+	       key.size() < 2048;
+}
+
+bool symkey::create (const std::string&in, prng&rng)
+{
+	//first, find cipher and hash names
+	blocksize = 1024 * 1024;
+	uint keysize = 32;
+	std::stringstream ss (in);
+	std::string tok;
+	while (getline (ss, tok, ',') ) {
+		tok = to_unicase (tok);
+		if (tok == "SHORTBLOCK") blocksize = 1024;
+		else if (tok == "LONGBLOCK") blocksize = 64 * 1024 * 1024;
+		else if (tok == "LONGKEY") keysize = 256;
+		else if (streamcipher::suite().count (tok) )
+			ciphers.insert (tok);
+		else if (hash_proc::suite().count (tok) )
+			hashes.insert (tok);
+		else {
+			err ("symkey: unknown token: " << tok);
+			return false;
+		}
+	}
+
+	//increase keysize, if needed
+	for (std::set<std::string>::iterator
+	     i = ciphers.begin(), e = ciphers.end();
+	     i != e; ++i) {
+
+		instanceof<streamcipher> sc
+		(streamcipher::suite() [*i]->get() );
+		sc.collect();
+		if (sc->key_size() > keysize) keysize = sc->key_size();
+	}
+
+
+	//fill the key
+	key.resize (keysize);
+	for (uint i = 0; i < keysize; ++i) key[i] = rng.random (256);
+
+	if (!is_valid() ) {
+		err ("symkey: failed to produce valid symmetric key");
+		err ("symkey: check that at least one hash and cipher is used");
+		return false;
+	}
+
+	return true;
+}
+
+typedef std::list<instanceof<streamcipher> > scs_t;
+typedef std::list<instanceof<hash_proc> > hashes_t;
+
+bool symkey::encrypt (std::istream&in, std::ostream&out, prng&rng)
+{
+	if (!is_valid() ) return false;
+
+	/*
+	 * structure of symmetrically encrypted file:
+	 *
+	 * - one-time key part, key.size() bytes
+	 *  (repeat:
+	 * - 4B blocksize little-endian
+	 * - blocksize encrypted bytes
+	 * - sum(hashes's size) blocksize marker+bytes of block hashes
+	 *  )
+	 * - 4B less than blocksize (may be zero!)
+	 * - possibly incomplete last block (may be empty)
+	 * - hashes of last blocksize+block
+	 * - eof
+	 */
+
+	std::vector<byte> otkey;
+	otkey.resize (key.size() );
+	for (uint i = 0; i < otkey.size(); ++i) otkey[i] = rng.random (256);
+
+	/*
+	 * initialize the ciphers
+	 */
+
+	scs_t scs;
+	for (std::set<std::string>::iterator
+	     i = ciphers.begin(), e = ciphers.end();
+	     i != e; ++i) {
+		if (!streamcipher::suite().count (*i) ) {
+			err ("symkey: unsupported cipher: " << *i);
+			return false;
+		}
+		scs.push_back (streamcipher::suite() [*i]->get() );
+		scs.back().collect();
+		scs.back()->init();
+		scs.back()->load_key_vector (key);
+		scs.back()->load_key_vector (otkey);
+	}
+
+	/*
+	 * initialize the hashes
+	 */
+
+	uint hashes_size = 0;
+
+	hashes_t hs;
+	for (std::set<std::string>::iterator
+	     i = hashes.begin(), e = hashes.end();
+	     i != e; ++i) {
+		if (!hash_proc::suite().count (*i) ) {
+			err ("symkey: unsupported hash function: " << *i);
+			return false;
+		}
+		hs.push_back (hash_proc::suite() [*i]->get() );
+		hs.back().collect();
+
+		hashes_size += hs.back()->size();
+	}
+
+	/*
+	 * output the onetime key
+	 */
+
+	out.write ( (char*) & (otkey[0]), otkey.size() );
+
+	/*
+	 * process the blocks
+	 */
+
+	std::vector<byte>buf, cipbuf;
+	buf.resize (4 + blocksize + hashes_size);
+	cipbuf.resize (buf.size() );
+
+	for (;;) {
+		in.read ( (char*) & (buf[4]), blocksize);
+		uint bytes_read = in.gcount();
+
+		if (!in && !in.eof() ) {
+			err ("symkey: failed reading input");
+			return false;
+		}
+
+		//now we got bytes_read of key stuff ready in buf.
+		uint blksizeid = bytes_read;
+		for (uint i = 0; i < 4; ++i) {
+			buf[i] = blksizeid & 0xff;
+			blksizeid >>= 8;
+		}
+
+		//hashup!
+		uint hashpos = 4 + bytes_read;
+		for (hashes_t::iterator i = hs.begin(), e = hs.end();
+		     i != e; ++i) {
+			hash_proc&hp = **i;
+			hp.init();
+			hp.eat (& (buf[0]), & (buf[4 + bytes_read]) );
+			std::vector<byte> res = hp.finish();
+			for (uint j = 0; j < res.size(); ++j, ++hashpos)
+				buf[hashpos] = res[j];
+		}
+
+		//encrypt!
+		for (scs_t::iterator i = scs.begin(), e = scs.end();
+		     i != e; ++i) {
+			streamcipher&sc = **i;
+			sc.gen (hashpos, & (cipbuf[0]) );
+			for (uint j = 0; j < hashpos; ++j)
+				buf[j] = buf[j] ^ cipbuf[j];
+		}
+
+		//output!
+		out.write ( (char*) & (buf[0]), hashpos);
+		if (!out) {
+			err ("symkey: failed to write output");
+			return false;
+		}
+
+		//this was the last one
+		if (bytes_read < blocksize) break;
+	}
+
+	return true;
 }
 
 int symkey::decrypt (std::istream&in, std::ostream&out)
 {
+	if (!is_valid() ) return 1;
 
-	return 1;
+	std::vector<byte> otkey;
+	otkey.resize (key.size() );
+
+	/*
+	 * read otkey
+	 */
+
+	in.read ( (char*) & (otkey[0]), otkey.size() );
+	if (in.gcount() != (std::streamsize) otkey.size() || !in) {
+		err ("symkey: failed reading input");
+		return 1;
+	}
+
+	/*
+	 * initialize the ciphers
+	 */
+
+	scs_t scs;
+	for (std::set<std::string>::iterator
+	     i = ciphers.begin(), e = ciphers.end();
+	     i != e; ++i) {
+		if (!streamcipher::suite().count (*i) ) {
+			err ("symkey: unsupported cipher: " << *i);
+			return 1;
+		}
+		scs.push_back (streamcipher::suite() [*i]->get() );
+		scs.back().collect();
+		scs.back()->init();
+		scs.back()->load_key_vector (key);
+		scs.back()->load_key_vector (otkey);
+	}
+
+	/*
+	 * initialize the hashes
+	 */
+
+	uint hashes_size = 0;
+
+	hashes_t hs;
+	for (std::set<std::string>::iterator
+	     i = hashes.begin(), e = hashes.end();
+	     i != e; ++i) {
+		if (!hash_proc::suite().count (*i) ) {
+			err ("symkey: unsupported hash function: " << *i);
+			return 1;
+		}
+		hs.push_back (hash_proc::suite() [*i]->get() );
+		hs.back().collect();
+
+		hashes_size += hs.back()->size();
+	}
+
+	/*
+	 * process the blocks
+	 */
+
+	std::vector<byte> buf, cipbuf;
+	buf.resize (4 + blocksize + hashes_size);
+	cipbuf.resize (buf.size() );
+
+	for (;;) {
+		in.read ( (char*) & (buf[0]), buf.size() );
+		uint bytes_read = in.gcount();
+
+		if ( (!in && !in.eof() ) || bytes_read < 4 + hashes_size) {
+			err ("symkey: failed reading input");
+			return 1;
+		}
+
+		//decrypt!
+		for (scs_t::iterator i = scs.begin(), e = scs.end();
+		     i != e; ++i) {
+			streamcipher&sc = **i;
+			sc.gen (bytes_read, & (cipbuf[0]) );
+			for (uint j = 0; j < bytes_read; ++j)
+				buf[j] = buf[j] ^ cipbuf[j];
+		}
+
+		//verify the size
+		bytes_read -= (4 + hashes_size);
+
+		uint blksizeid = bytes_read;
+		for (uint i = 0; i < 4; ++i) {
+			if (buf[i] != (blksizeid & 0xff) ) {
+				err ("symkey: mangled input");
+				return 3;
+			}
+			blksizeid >>= 8;
+		}
+
+		//verify the hashes
+		uint hashpos = 4 + bytes_read;
+		for (hashes_t::iterator i = hs.begin(), e = hs.end();
+		     i != e; ++i) {
+			hash_proc&hp = **i;
+			hp.init();
+			hp.eat (& (buf[0]), & (buf[4 + bytes_read]) );
+			std::vector<byte> res = hp.finish();
+			for (uint j = 0; j < res.size(); ++j, ++hashpos)
+				if (buf[hashpos] != res[j]) {
+					err ("symkey: mangled input");
+					return 3;
+				}
+		}
+
+		//now that all is OK, output!
+		out.write ( (char*) & (buf[4]), bytes_read);
+
+		//last one
+		if (bytes_read < blocksize) break;
+	}
+
+	//did we read whole input?
+	if (!in.eof() ) {
+		err ("symkey: failed reading input");
+		return 1;
+	}
+	return 0;
 }
diff --git a/src/symkey.h b/src/symkey.h
index f0e960c..4cfe7cc 100644
--- a/src/symkey.h
+++ b/src/symkey.h
@@ -26,23 +26,26 @@
 #include <vector>
 
 #include "types.h"
+#include "generator.h"
 #include "sencode.h"
 
 class symkey
 {
 public:
-	std::set<std::string> ciphers;
-	std::list<std::string> hashes;
+	std::set<std::string> ciphers, hashes;
 
 	uint blocksize;
 
-	std::vector<byte> seed;
+	std::vector<byte> key;
 
 	sencode* serialize();
 	bool unserialize (sencode*);
 
-	bool encrypt (std::istream&, std::ostream&);
+	bool encrypt (std::istream&, std::ostream&, prng&);
 	int decrypt (std::istream&, std::ostream&);
+
+	bool is_valid();
+	bool create (const std::string&, prng&);
 };
 
 #endif