src/libstd/hash.rs - third_party/rust - Git at Google

 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.

 /*!
  * Implementation of SipHash 2-4
  *
  * See: http://131002.net/siphash/
  *
  * Consider this as a main "general-purpose" hash for all hashtables: it
  * runs at good speed (competitive with spooky and city) and permits
  * cryptographically strong _keyed_ hashing. Key your hashtables from a
  * CPRNG like rand::rng.
  */

 #[allow(missing_doc)];

 use container::Container;
 use iter::Iterator;
 use option::{Some, None};
 use rt::io::Writer;
 use str::OwnedStr;
 use to_bytes::IterBytes;
 use vec::ImmutableVector;
 use num::ToStrRadix;

 // Alias `SipState` to `State`.
 pub use State = hash::SipState;

 /**
  * Types that can meaningfully be hashed should implement this.
  *
  * Note that this trait is likely to change somewhat as it is
  * closely related to `to_bytes::IterBytes` and in almost all
  * cases presently the two are (and must be) used together.
  *
  * In general, most types only need to implement `IterBytes`,
  * and the implementation of `Hash` below will take care of
  * the rest. This is the recommended approach, since constructing
  * good keyed hash functions is quite difficult.
  */
 pub trait Hash {
     /**
      * Compute a "keyed" hash of the value implementing the trait,
      * taking `k0` and `k1` as "keying" parameters that randomize or
      * otherwise perturb the hash function in such a way that a
      * hash table built using such "keyed hash functions" cannot
      * be made to perform linearly by an attacker controlling the
      * hashtable's contents.
      *
      * In practical terms, we implement this using the SipHash 2-4
      * function and require most types to only implement the
      * IterBytes trait, that feeds SipHash.
      */
     fn hash_keyed(&self, k0: u64, k1: u64) -> u64;

     #[inline]
     fn hash(&self) -> u64 { self.hash_keyed(0,0) }
 }

 /// Streaming hash-functions should implement this.
 pub trait Streaming {
     fn input(&mut self, &[u8]);
     // These can be refactored some when we have default methods.
     fn result_bytes(&mut self) -> ~[u8];
     fn result_str(&mut self) -> ~str;
     fn result_u64(&mut self) -> u64;
     fn reset(&mut self);
 }

 impl<A:IterBytes> Hash for A {
     #[inline]
     fn hash_keyed(&self, k0: u64, k1: u64) -> u64 {
         let mut s = State::new(k0, k1);
         do self.iter_bytes(true) |bytes| {
             s.input(bytes);
             true
         };
         s.result_u64()
     }
 }

 fn hash_keyed_2<A: IterBytes,
                 B: IterBytes>(a: &A, b: &B, k0: u64, k1: u64) -> u64 {
     let mut s = State::new(k0, k1);
     do a.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     do b.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     s.result_u64()
 }

 fn hash_keyed_3<A: IterBytes,
                 B: IterBytes,
                 C: IterBytes>(a: &A, b: &B, c: &C, k0: u64, k1: u64) -> u64 {
     let mut s = State::new(k0, k1);
     do a.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     do b.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     do c.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     s.result_u64()
 }

 fn hash_keyed_4<A: IterBytes,
                 B: IterBytes,
                 C: IterBytes,
                 D: IterBytes>(
                 a: &A,
                 b: &B,
                 c: &C,
                 d: &D,
                 k0: u64,
                 k1: u64)
                 -> u64 {
     let mut s = State::new(k0, k1);
     do a.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     do b.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     do c.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     do d.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     s.result_u64()
 }

 fn hash_keyed_5<A: IterBytes,
                 B: IterBytes,
                 C: IterBytes,
                 D: IterBytes,
                 E: IterBytes>(
                 a: &A,
                 b: &B,
                 c: &C,
                 d: &D,
                 e: &E,
                 k0: u64,
                 k1: u64)
                 -> u64 {
     let mut s = State::new(k0, k1);
     do a.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     do b.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     do c.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     do d.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     do e.iter_bytes(true) |bytes| {
         s.input(bytes);
         true
     };
     s.result_u64()
 }

 #[inline]
 pub fn default_state() -> State {
     State::new(0, 0)
 }

 struct SipState {
     k0: u64,
     k1: u64,
     length: uint, // how many bytes we've processed
     v0: u64,      // hash state
     v1: u64,
     v2: u64,
     v3: u64,
     tail: [u8, ..8], // unprocessed bytes
     ntail: uint,  // how many bytes in tail are valid
 }

 impl SipState {
     #[inline]
     fn new(key0: u64, key1: u64) -> SipState {
         let mut state = SipState {
             k0: key0,
             k1: key1,
             length: 0,
             v0: 0,
             v1: 0,
             v2: 0,
             v3: 0,
             tail: [ 0, 0, 0, 0, 0, 0, 0, 0 ],
             ntail: 0,
         };
         state.reset();
         state
     }
 }

 // sadly, these macro definitions can't appear later,
 // because they're needed in the following defs;
 // this design could be improved.

 macro_rules! u8to64_le (
     ($buf:expr, $i:expr) =>
     ($buf[0+$i] as u64 |
      $buf[1+$i] as u64 << 8 |
      $buf[2+$i] as u64 << 16 |
      $buf[3+$i] as u64 << 24 |
      $buf[4+$i] as u64 << 32 |
      $buf[5+$i] as u64 << 40 |
      $buf[6+$i] as u64 << 48 |
      $buf[7+$i] as u64 << 56)
 )

 macro_rules! rotl (
     ($x:expr, $b:expr) =>
     (($x << $b) | ($x >> (64 - $b)))
 )

 macro_rules! compress (
     ($v0:expr, $v1:expr, $v2:expr, $v3:expr) =>
     ({
         $v0 += $v1; $v1 = rotl!($v1, 13); $v1 ^= $v0;
         $v0 = rotl!($v0, 32);
         $v2 += $v3; $v3 = rotl!($v3, 16); $v3 ^= $v2;
         $v0 += $v3; $v3 = rotl!($v3, 21); $v3 ^= $v0;
         $v2 += $v1; $v1 = rotl!($v1, 17); $v1 ^= $v2;
         $v2 = rotl!($v2, 32);
     })
 )


 impl Writer for SipState {
     // Methods for io::writer
     #[inline]
     fn write(&mut self, msg: &[u8]) {
         let length = msg.len();
         self.length += length;

         let mut needed = 0u;

         if self.ntail != 0 {
             needed = 8 - self.ntail;

             if length < needed {
                 let mut t = 0;
                 while t < length {
                     self.tail[self.ntail+t] = msg[t];
                     t += 1;
                 }
                 self.ntail += length;
                 return;
             }

             let mut t = 0;
             while t < needed {
                 self.tail[self.ntail+t] = msg[t];
                 t += 1;
             }

             let m = u8to64_le!(self.tail, 0);

             self.v3 ^= m;
             compress!(self.v0, self.v1, self.v2, self.v3);
             compress!(self.v0, self.v1, self.v2, self.v3);
             self.v0 ^= m;

             self.ntail = 0;
         }

         // Buffered tail is now flushed, process new input.
         let len = length - needed;
         let end = len & (!0x7);
         let left = len & 0x7;

         let mut i = needed;
         while i < end {
             let mi = u8to64_le!(msg, i);

             self.v3 ^= mi;
             compress!(self.v0, self.v1, self.v2, self.v3);
             compress!(self.v0, self.v1, self.v2, self.v3);
             self.v0 ^= mi;

             i += 8;
         }

         let mut t = 0u;
         while t < left {
             self.tail[t] = msg[i+t];
             t += 1
         }
         self.ntail = left;
     }

     fn flush(&mut self) {
         // No-op
     }
 }

 impl Streaming for SipState {
     #[inline]
     fn input(&mut self, buf: &[u8]) {
         self.write(buf);
     }

     #[inline]
     fn result_u64(&mut self) -> u64 {
         let mut v0 = self.v0;
         let mut v1 = self.v1;
         let mut v2 = self.v2;
         let mut v3 = self.v3;

         let mut b : u64 = (self.length as u64 & 0xff) << 56;

         if self.ntail > 0 { b |= self.tail[0] as u64 <<  0; }
         if self.ntail > 1 { b |= self.tail[1] as u64 <<  8; }
         if self.ntail > 2 { b |= self.tail[2] as u64 << 16; }
         if self.ntail > 3 { b |= self.tail[3] as u64 << 24; }
         if self.ntail > 4 { b |= self.tail[4] as u64 << 32; }
         if self.ntail > 5 { b |= self.tail[5] as u64 << 40; }
         if self.ntail > 6 { b |= self.tail[6] as u64 << 48; }

         v3 ^= b;
         compress!(v0, v1, v2, v3);
         compress!(v0, v1, v2, v3);
         v0 ^= b;

         v2 ^= 0xff;
         compress!(v0, v1, v2, v3);
         compress!(v0, v1, v2, v3);
         compress!(v0, v1, v2, v3);
         compress!(v0, v1, v2, v3);

         return (v0 ^ v1 ^ v2 ^ v3);
     }

     fn result_bytes(&mut self) -> ~[u8] {
         let h = self.result_u64();
         ~[(h >> 0) as u8,
           (h >> 8) as u8,
           (h >> 16) as u8,
           (h >> 24) as u8,
           (h >> 32) as u8,
           (h >> 40) as u8,
           (h >> 48) as u8,
           (h >> 56) as u8,
         ]
     }

     fn result_str(&mut self) -> ~str {
         let r = self.result_bytes();
         let mut s = ~"";
         for b in r.iter() {
             s.push_str((*b as uint).to_str_radix(16u));
         }
         s
     }

     #[inline]
     fn reset(&mut self) {
         self.length = 0;
         self.v0 = self.k0 ^ 0x736f6d6570736575;
         self.v1 = self.k1 ^ 0x646f72616e646f6d;
         self.v2 = self.k0 ^ 0x6c7967656e657261;
         self.v3 = self.k1 ^ 0x7465646279746573;
         self.ntail = 0;
     }
 }

 #[cfg(test)]
 mod tests {
     use super::*;
     use prelude::*;

     // Hash just the bytes of the slice, without length prefix
     struct Bytes<'self>(&'self [u8]);
     impl<'self> IterBytes for Bytes<'self> {
         fn iter_bytes(&self, _lsb0: bool, f: &fn(&[u8]) -> bool) -> bool {
             f(**self)
         }
     }

     #[test]
     fn test_siphash() {
         let vecs : [[u8, ..8], ..64] = [
             [ 0x31, 0x0e, 0x0e, 0xdd, 0x47, 0xdb, 0x6f, 0x72, ],
             [ 0xfd, 0x67, 0xdc, 0x93, 0xc5, 0x39, 0xf8, 0x74, ],
             [ 0x5a, 0x4f, 0xa9, 0xd9, 0x09, 0x80, 0x6c, 0x0d, ],
             [ 0x2d, 0x7e, 0xfb, 0xd7, 0x96, 0x66, 0x67, 0x85, ],
             [ 0xb7, 0x87, 0x71, 0x27, 0xe0, 0x94, 0x27, 0xcf, ],
             [ 0x8d, 0xa6, 0x99, 0xcd, 0x64, 0x55, 0x76, 0x18, ],
             [ 0xce, 0xe3, 0xfe, 0x58, 0x6e, 0x46, 0xc9, 0xcb, ],
             [ 0x37, 0xd1, 0x01, 0x8b, 0xf5, 0x00, 0x02, 0xab, ],
             [ 0x62, 0x24, 0x93, 0x9a, 0x79, 0xf5, 0xf5, 0x93, ],
             [ 0xb0, 0xe4, 0xa9, 0x0b, 0xdf, 0x82, 0x00, 0x9e, ],
             [ 0xf3, 0xb9, 0xdd, 0x94, 0xc5, 0xbb, 0x5d, 0x7a, ],
             [ 0xa7, 0xad, 0x6b, 0x22, 0x46, 0x2f, 0xb3, 0xf4, ],
             [ 0xfb, 0xe5, 0x0e, 0x86, 0xbc, 0x8f, 0x1e, 0x75, ],
             [ 0x90, 0x3d, 0x84, 0xc0, 0x27, 0x56, 0xea, 0x14, ],
             [ 0xee, 0xf2, 0x7a, 0x8e, 0x90, 0xca, 0x23, 0xf7, ],
             [ 0xe5, 0x45, 0xbe, 0x49, 0x61, 0xca, 0x29, 0xa1, ],
             [ 0xdb, 0x9b, 0xc2, 0x57, 0x7f, 0xcc, 0x2a, 0x3f, ],
             [ 0x94, 0x47, 0xbe, 0x2c, 0xf5, 0xe9, 0x9a, 0x69, ],
             [ 0x9c, 0xd3, 0x8d, 0x96, 0xf0, 0xb3, 0xc1, 0x4b, ],
             [ 0xbd, 0x61, 0x79, 0xa7, 0x1d, 0xc9, 0x6d, 0xbb, ],
             [ 0x98, 0xee, 0xa2, 0x1a, 0xf2, 0x5c, 0xd6, 0xbe, ],
             [ 0xc7, 0x67, 0x3b, 0x2e, 0xb0, 0xcb, 0xf2, 0xd0, ],
             [ 0x88, 0x3e, 0xa3, 0xe3, 0x95, 0x67, 0x53, 0x93, ],
             [ 0xc8, 0xce, 0x5c, 0xcd, 0x8c, 0x03, 0x0c, 0xa8, ],
             [ 0x94, 0xaf, 0x49, 0xf6, 0xc6, 0x50, 0xad, 0xb8, ],
             [ 0xea, 0xb8, 0x85, 0x8a, 0xde, 0x92, 0xe1, 0xbc, ],
             [ 0xf3, 0x15, 0xbb, 0x5b, 0xb8, 0x35, 0xd8, 0x17, ],
             [ 0xad, 0xcf, 0x6b, 0x07, 0x63, 0x61, 0x2e, 0x2f, ],
             [ 0xa5, 0xc9, 0x1d, 0xa7, 0xac, 0xaa, 0x4d, 0xde, ],
             [ 0x71, 0x65, 0x95, 0x87, 0x66, 0x50, 0xa2, 0xa6, ],
             [ 0x28, 0xef, 0x49, 0x5c, 0x53, 0xa3, 0x87, 0xad, ],
             [ 0x42, 0xc3, 0x41, 0xd8, 0xfa, 0x92, 0xd8, 0x32, ],
             [ 0xce, 0x7c, 0xf2, 0x72, 0x2f, 0x51, 0x27, 0x71, ],
             [ 0xe3, 0x78, 0x59, 0xf9, 0x46, 0x23, 0xf3, 0xa7, ],
             [ 0x38, 0x12, 0x05, 0xbb, 0x1a, 0xb0, 0xe0, 0x12, ],
             [ 0xae, 0x97, 0xa1, 0x0f, 0xd4, 0x34, 0xe0, 0x15, ],
             [ 0xb4, 0xa3, 0x15, 0x08, 0xbe, 0xff, 0x4d, 0x31, ],
             [ 0x81, 0x39, 0x62, 0x29, 0xf0, 0x90, 0x79, 0x02, ],
             [ 0x4d, 0x0c, 0xf4, 0x9e, 0xe5, 0xd4, 0xdc, 0xca, ],
             [ 0x5c, 0x73, 0x33, 0x6a, 0x76, 0xd8, 0xbf, 0x9a, ],
             [ 0xd0, 0xa7, 0x04, 0x53, 0x6b, 0xa9, 0x3e, 0x0e, ],
             [ 0x92, 0x59, 0x58, 0xfc, 0xd6, 0x42, 0x0c, 0xad, ],
             [ 0xa9, 0x15, 0xc2, 0x9b, 0xc8, 0x06, 0x73, 0x18, ],
             [ 0x95, 0x2b, 0x79, 0xf3, 0xbc, 0x0a, 0xa6, 0xd4, ],
             [ 0xf2, 0x1d, 0xf2, 0xe4, 0x1d, 0x45, 0x35, 0xf9, ],
             [ 0x87, 0x57, 0x75, 0x19, 0x04, 0x8f, 0x53, 0xa9, ],
             [ 0x10, 0xa5, 0x6c, 0xf5, 0xdf, 0xcd, 0x9a, 0xdb, ],
             [ 0xeb, 0x75, 0x09, 0x5c, 0xcd, 0x98, 0x6c, 0xd0, ],
             [ 0x51, 0xa9, 0xcb, 0x9e, 0xcb, 0xa3, 0x12, 0xe6, ],
             [ 0x96, 0xaf, 0xad, 0xfc, 0x2c, 0xe6, 0x66, 0xc7, ],
             [ 0x72, 0xfe, 0x52, 0x97, 0x5a, 0x43, 0x64, 0xee, ],
             [ 0x5a, 0x16, 0x45, 0xb2, 0x76, 0xd5, 0x92, 0xa1, ],
             [ 0xb2, 0x74, 0xcb, 0x8e, 0xbf, 0x87, 0x87, 0x0a, ],
             [ 0x6f, 0x9b, 0xb4, 0x20, 0x3d, 0xe7, 0xb3, 0x81, ],
             [ 0xea, 0xec, 0xb2, 0xa3, 0x0b, 0x22, 0xa8, 0x7f, ],
             [ 0x99, 0x24, 0xa4, 0x3c, 0xc1, 0x31, 0x57, 0x24, ],
             [ 0xbd, 0x83, 0x8d, 0x3a, 0xaf, 0xbf, 0x8d, 0xb7, ],
             [ 0x0b, 0x1a, 0x2a, 0x32, 0x65, 0xd5, 0x1a, 0xea, ],
             [ 0x13, 0x50, 0x79, 0xa3, 0x23, 0x1c, 0xe6, 0x60, ],
             [ 0x93, 0x2b, 0x28, 0x46, 0xe4, 0xd7, 0x06, 0x66, ],
             [ 0xe1, 0x91, 0x5f, 0x5c, 0xb1, 0xec, 0xa4, 0x6c, ],
             [ 0xf3, 0x25, 0x96, 0x5c, 0xa1, 0x6d, 0x62, 0x9f, ],
             [ 0x57, 0x5f, 0xf2, 0x8e, 0x60, 0x38, 0x1b, 0xe5, ],
             [ 0x72, 0x45, 0x06, 0xeb, 0x4c, 0x32, 0x8a, 0x95, ]
         ];

         let k0 = 0x_07_06_05_04_03_02_01_00_u64;
         let k1 = 0x_0f_0e_0d_0c_0b_0a_09_08_u64;
         let mut buf : ~[u8] = ~[];
         let mut t = 0;
         let mut stream_inc = SipState::new(k0, k1);
         let mut stream_full = SipState::new(k0, k1);

         fn to_hex_str(r: &[u8, ..8]) -> ~str {
             let mut s = ~"";
             for b in r.iter() {
                 s.push_str((*b as uint).to_str_radix(16u));
             }
             s
         }

         while t < 64 {
             debug!("siphash test %?", t);
             let vec = u8to64_le!(vecs[t], 0);
             let out = Bytes(buf.as_slice()).hash_keyed(k0, k1);
             debug!("got %?, expected %?", out, vec);
             assert_eq!(vec, out);

             stream_full.reset();
             stream_full.input(buf);
             let f = stream_full.result_str();
             let i = stream_inc.result_str();
             let v = to_hex_str(&vecs[t]);
             debug!("%d: (%s) => inc=%s full=%s", t, v, i, f);

             assert!(f == i && f == v);

             buf.push(t as u8);
             stream_inc.input([t as u8]);

             t += 1;
         }
     }

     #[test] #[cfg(target_arch = "arm")]
     fn test_hash_uint() {
         let val = 0xdeadbeef_deadbeef_u64;
         assert!((val as u64).hash() != (val as uint).hash());
         assert_eq!((val as u32).hash(), (val as uint).hash());
     }
     #[test] #[cfg(target_arch = "x86_64")]
     fn test_hash_uint() {
         let val = 0xdeadbeef_deadbeef_u64;
         assert_eq!((val as u64).hash(), (val as uint).hash());
         assert!((val as u32).hash() != (val as uint).hash());
     }
     #[test] #[cfg(target_arch = "x86")]
     fn test_hash_uint() {
         let val = 0xdeadbeef_deadbeef_u64;
         assert!((val as u64).hash() != (val as uint).hash());
         assert_eq!((val as u32).hash(), (val as uint).hash());
     }

     #[test]
     fn test_hash_idempotent() {
         let val64 = 0xdeadbeef_deadbeef_u64;
         val64.hash() == val64.hash();
         let val32 = 0xdeadbeef_u32;
         val32.hash() == val32.hash();
     }

     #[test]
     fn test_hash_no_bytes_dropped_64() {
         let val = 0xdeadbeef_deadbeef_u64;

         assert!(val.hash() != zero_byte(val, 0).hash());
         assert!(val.hash() != zero_byte(val, 1).hash());
         assert!(val.hash() != zero_byte(val, 2).hash());
         assert!(val.hash() != zero_byte(val, 3).hash());
         assert!(val.hash() != zero_byte(val, 4).hash());
         assert!(val.hash() != zero_byte(val, 5).hash());
         assert!(val.hash() != zero_byte(val, 6).hash());
         assert!(val.hash() != zero_byte(val, 7).hash());

         fn zero_byte(val: u64, byte: uint) -> u64 {
             assert!(byte < 8);
             val & !(0xff << (byte * 8))
         }
     }

     #[test]
     fn test_hash_no_bytes_dropped_32() {
         let val = 0xdeadbeef_u32;

         assert!(val.hash() != zero_byte(val, 0).hash());
         assert!(val.hash() != zero_byte(val, 1).hash());
         assert!(val.hash() != zero_byte(val, 2).hash());
         assert!(val.hash() != zero_byte(val, 3).hash());

         fn zero_byte(val: u32, byte: uint) -> u32 {
             assert!(byte < 4);
             val & !(0xff << (byte * 8))
         }
     }

     #[test]
     fn test_float_hashes_differ() {
         assert!(0.0.hash() != 1.0.hash());
         assert!(1.0.hash() != (-1.0).hash());
     }

     #[test]
     fn test_float_hashes_of_zero() {
         assert_eq!(0.0.hash(), (-0.0).hash());
     }

     #[test]
     fn test_hash_no_concat_alias() {
         let s = ("aa", "bb");
         let t = ("aabb", "");
         let u = ("a", "abb");

         let v = (&[1u8], &[0u8, 0], &[0u8]);
         let w = (&[1u8, 0, 0, 0], &[], &[]);

         assert!(v != w);
         assert!(s.hash() != t.hash() && s.hash() != u.hash());
         assert!(v.hash() != w.hash());
     }
 }
	// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
	// file at the top-level directory of this distribution and at
	// http://rust-lang.org/COPYRIGHT.
	//
	// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	// option. This file may not be copied, modified, or distributed
	// except according to those terms.

	/*!
	* Implementation of SipHash 2-4
	*
	* See: http://131002.net/siphash/
	*
	* Consider this as a main "general-purpose" hash for all hashtables: it
	* runs at good speed (competitive with spooky and city) and permits
	* cryptographically strong _keyed_ hashing. Key your hashtables from a
	* CPRNG like rand::rng.
	*/

	#[allow(missing_doc)];

	use container::Container;
	use iter::Iterator;
	use option::{Some, None};
	use rt::io::Writer;
	use str::OwnedStr;
	use to_bytes::IterBytes;
	use vec::ImmutableVector;
	use num::ToStrRadix;

	// Alias `SipState` to `State`.
	pub use State = hash::SipState;

	/**
	* Types that can meaningfully be hashed should implement this.
	*
	* Note that this trait is likely to change somewhat as it is
	* closely related to `to_bytes::IterBytes` and in almost all
	* cases presently the two are (and must be) used together.
	*
	* In general, most types only need to implement `IterBytes`,
	* and the implementation of `Hash` below will take care of
	* the rest. This is the recommended approach, since constructing
	* good keyed hash functions is quite difficult.
	*/
	pub trait Hash {
	/**
	* Compute a "keyed" hash of the value implementing the trait,
	* taking `k0` and `k1` as "keying" parameters that randomize or
	* otherwise perturb the hash function in such a way that a
	* hash table built using such "keyed hash functions" cannot
	* be made to perform linearly by an attacker controlling the
	* hashtable's contents.
	*
	* In practical terms, we implement this using the SipHash 2-4
	* function and require most types to only implement the
	* IterBytes trait, that feeds SipHash.
	*/
	fn hash_keyed(&self, k0: u64, k1: u64) -> u64;

	#[inline]
	fn hash(&self) -> u64 { self.hash_keyed(0,0) }
	}

	/// Streaming hash-functions should implement this.
	pub trait Streaming {
	fn input(&mut self, &[u8]);
	// These can be refactored some when we have default methods.
	fn result_bytes(&mut self) -> ~[u8];
	fn result_str(&mut self) -> ~str;
	fn result_u64(&mut self) -> u64;
	fn reset(&mut self);
	}

	impl<A:IterBytes> Hash for A {
	#[inline]
	fn hash_keyed(&self, k0: u64, k1: u64) -> u64 {
	let mut s = State::new(k0, k1);
	do self.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	s.result_u64()
	}
	}

	fn hash_keyed_2<A: IterBytes,
	B: IterBytes>(a: &A, b: &B, k0: u64, k1: u64) -> u64 {
	let mut s = State::new(k0, k1);
	do a.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	do b.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	s.result_u64()
	}

	fn hash_keyed_3<A: IterBytes,
	B: IterBytes,
	C: IterBytes>(a: &A, b: &B, c: &C, k0: u64, k1: u64) -> u64 {
	let mut s = State::new(k0, k1);
	do a.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	do b.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	do c.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	s.result_u64()
	}

	fn hash_keyed_4<A: IterBytes,
	B: IterBytes,
	C: IterBytes,
	D: IterBytes>(
	a: &A,
	b: &B,
	c: &C,
	d: &D,
	k0: u64,
	k1: u64)
	-> u64 {
	let mut s = State::new(k0, k1);
	do a.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	do b.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	do c.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	do d.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	s.result_u64()
	}

	fn hash_keyed_5<A: IterBytes,
	B: IterBytes,
	C: IterBytes,
	D: IterBytes,
	E: IterBytes>(
	a: &A,
	b: &B,
	c: &C,
	d: &D,
	e: &E,
	k0: u64,
	k1: u64)
	-> u64 {
	let mut s = State::new(k0, k1);
	do a.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	do b.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	do c.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	do d.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	do e.iter_bytes(true) \|bytes\| {
	s.input(bytes);
	true
	};
	s.result_u64()
	}

	#[inline]
	pub fn default_state() -> State {
	State::new(0, 0)
	}

	struct SipState {
	k0: u64,
	k1: u64,
	length: uint, // how many bytes we've processed
	v0: u64, // hash state
	v1: u64,
	v2: u64,
	v3: u64,
	tail: [u8, ..8], // unprocessed bytes
	ntail: uint, // how many bytes in tail are valid
	}

	impl SipState {
	#[inline]
	fn new(key0: u64, key1: u64) -> SipState {
	let mut state = SipState {
	k0: key0,
	k1: key1,
	length: 0,
	v0: 0,
	v1: 0,
	v2: 0,
	v3: 0,
	tail: [ 0, 0, 0, 0, 0, 0, 0, 0 ],
	ntail: 0,
	};
	state.reset();
	state
	}
	}

	// sadly, these macro definitions can't appear later,
	// because they're needed in the following defs;
	// this design could be improved.

	macro_rules! u8to64_le (
	($buf:expr, $i:expr) =>
	($buf[0+$i] as u64 \|
	$buf[1+$i] as u64 << 8 \|
	$buf[2+$i] as u64 << 16 \|
	$buf[3+$i] as u64 << 24 \|
	$buf[4+$i] as u64 << 32 \|
	$buf[5+$i] as u64 << 40 \|
	$buf[6+$i] as u64 << 48 \|
	$buf[7+$i] as u64 << 56)
	)

	macro_rules! rotl (
	($x:expr, $b:expr) =>
	(($x << $b) \| ($x >> (64 - $b)))
	)

	macro_rules! compress (
	($v0:expr, $v1:expr, $v2:expr, $v3:expr) =>
	({
	$v0 += $v1; $v1 = rotl!($v1, 13); $v1 ^= $v0;
	$v0 = rotl!($v0, 32);
	$v2 += $v3; $v3 = rotl!($v3, 16); $v3 ^= $v2;
	$v0 += $v3; $v3 = rotl!($v3, 21); $v3 ^= $v0;
	$v2 += $v1; $v1 = rotl!($v1, 17); $v1 ^= $v2;
	$v2 = rotl!($v2, 32);
	})
	)


	impl Writer for SipState {
	// Methods for io::writer
	#[inline]
	fn write(&mut self, msg: &[u8]) {
	let length = msg.len();
	self.length += length;

	let mut needed = 0u;

	if self.ntail != 0 {
	needed = 8 - self.ntail;

	if length < needed {
	let mut t = 0;
	while t < length {
	self.tail[self.ntail+t] = msg[t];
	t += 1;
	}
	self.ntail += length;
	return;
	}

	let mut t = 0;
	while t < needed {
	self.tail[self.ntail+t] = msg[t];
	t += 1;
	}

	let m = u8to64_le!(self.tail, 0);

	self.v3 ^= m;
	compress!(self.v0, self.v1, self.v2, self.v3);
	compress!(self.v0, self.v1, self.v2, self.v3);
	self.v0 ^= m;

	self.ntail = 0;
	}

	// Buffered tail is now flushed, process new input.
	let len = length - needed;
	let end = len & (!0x7);
	let left = len & 0x7;

	let mut i = needed;
	while i < end {
	let mi = u8to64_le!(msg, i);

	self.v3 ^= mi;
	compress!(self.v0, self.v1, self.v2, self.v3);
	compress!(self.v0, self.v1, self.v2, self.v3);
	self.v0 ^= mi;

	i += 8;
	}

	let mut t = 0u;
	while t < left {
	self.tail[t] = msg[i+t];
	t += 1
	}
	self.ntail = left;
	}

	fn flush(&mut self) {
	// No-op
	}
	}

	impl Streaming for SipState {
	#[inline]
	fn input(&mut self, buf: &[u8]) {
	self.write(buf);
	}

	#[inline]
	fn result_u64(&mut self) -> u64 {
	let mut v0 = self.v0;
	let mut v1 = self.v1;
	let mut v2 = self.v2;
	let mut v3 = self.v3;

	let mut b : u64 = (self.length as u64 & 0xff) << 56;

	if self.ntail > 0 { b \|= self.tail[0] as u64 << 0; }
	if self.ntail > 1 { b \|= self.tail[1] as u64 << 8; }
	if self.ntail > 2 { b \|= self.tail[2] as u64 << 16; }
	if self.ntail > 3 { b \|= self.tail[3] as u64 << 24; }
	if self.ntail > 4 { b \|= self.tail[4] as u64 << 32; }
	if self.ntail > 5 { b \|= self.tail[5] as u64 << 40; }
	if self.ntail > 6 { b \|= self.tail[6] as u64 << 48; }

	v3 ^= b;
	compress!(v0, v1, v2, v3);
	compress!(v0, v1, v2, v3);
	v0 ^= b;

	v2 ^= 0xff;
	compress!(v0, v1, v2, v3);
	compress!(v0, v1, v2, v3);
	compress!(v0, v1, v2, v3);
	compress!(v0, v1, v2, v3);

	return (v0 ^ v1 ^ v2 ^ v3);
	}

	fn result_bytes(&mut self) -> ~[u8] {
	let h = self.result_u64();
	~[(h >> 0) as u8,
	(h >> 8) as u8,
	(h >> 16) as u8,
	(h >> 24) as u8,
	(h >> 32) as u8,
	(h >> 40) as u8,
	(h >> 48) as u8,
	(h >> 56) as u8,
	]
	}

	fn result_str(&mut self) -> ~str {
	let r = self.result_bytes();
	let mut s = ~"";
	for b in r.iter() {
	s.push_str((*b as uint).to_str_radix(16u));
	}
	s
	}

	#[inline]
	fn reset(&mut self) {
	self.length = 0;
	self.v0 = self.k0 ^ 0x736f6d6570736575;
	self.v1 = self.k1 ^ 0x646f72616e646f6d;
	self.v2 = self.k0 ^ 0x6c7967656e657261;
	self.v3 = self.k1 ^ 0x7465646279746573;
	self.ntail = 0;
	}
	}

	#[cfg(test)]
	mod tests {
	use super::*;
	use prelude::*;

	// Hash just the bytes of the slice, without length prefix
	struct Bytes<'self>(&'self [u8]);
	impl<'self> IterBytes for Bytes<'self> {
	fn iter_bytes(&self, _lsb0: bool, f: &fn(&[u8]) -> bool) -> bool {
	f(**self)
	}
	}

	#[test]
	fn test_siphash() {
	let vecs : [[u8, ..8], ..64] = [
	[ 0x31, 0x0e, 0x0e, 0xdd, 0x47, 0xdb, 0x6f, 0x72, ],
	[ 0xfd, 0x67, 0xdc, 0x93, 0xc5, 0x39, 0xf8, 0x74, ],
	[ 0x5a, 0x4f, 0xa9, 0xd9, 0x09, 0x80, 0x6c, 0x0d, ],
	[ 0x2d, 0x7e, 0xfb, 0xd7, 0x96, 0x66, 0x67, 0x85, ],
	[ 0xb7, 0x87, 0x71, 0x27, 0xe0, 0x94, 0x27, 0xcf, ],
	[ 0x8d, 0xa6, 0x99, 0xcd, 0x64, 0x55, 0x76, 0x18, ],
	[ 0xce, 0xe3, 0xfe, 0x58, 0x6e, 0x46, 0xc9, 0xcb, ],
	[ 0x37, 0xd1, 0x01, 0x8b, 0xf5, 0x00, 0x02, 0xab, ],
	[ 0x62, 0x24, 0x93, 0x9a, 0x79, 0xf5, 0xf5, 0x93, ],
	[ 0xb0, 0xe4, 0xa9, 0x0b, 0xdf, 0x82, 0x00, 0x9e, ],
	[ 0xf3, 0xb9, 0xdd, 0x94, 0xc5, 0xbb, 0x5d, 0x7a, ],
	[ 0xa7, 0xad, 0x6b, 0x22, 0x46, 0x2f, 0xb3, 0xf4, ],
	[ 0xfb, 0xe5, 0x0e, 0x86, 0xbc, 0x8f, 0x1e, 0x75, ],
	[ 0x90, 0x3d, 0x84, 0xc0, 0x27, 0x56, 0xea, 0x14, ],
	[ 0xee, 0xf2, 0x7a, 0x8e, 0x90, 0xca, 0x23, 0xf7, ],
	[ 0xe5, 0x45, 0xbe, 0x49, 0x61, 0xca, 0x29, 0xa1, ],
	[ 0xdb, 0x9b, 0xc2, 0x57, 0x7f, 0xcc, 0x2a, 0x3f, ],
	[ 0x94, 0x47, 0xbe, 0x2c, 0xf5, 0xe9, 0x9a, 0x69, ],
	[ 0x9c, 0xd3, 0x8d, 0x96, 0xf0, 0xb3, 0xc1, 0x4b, ],
	[ 0xbd, 0x61, 0x79, 0xa7, 0x1d, 0xc9, 0x6d, 0xbb, ],
	[ 0x98, 0xee, 0xa2, 0x1a, 0xf2, 0x5c, 0xd6, 0xbe, ],
	[ 0xc7, 0x67, 0x3b, 0x2e, 0xb0, 0xcb, 0xf2, 0xd0, ],
	[ 0x88, 0x3e, 0xa3, 0xe3, 0x95, 0x67, 0x53, 0x93, ],
	[ 0xc8, 0xce, 0x5c, 0xcd, 0x8c, 0x03, 0x0c, 0xa8, ],
	[ 0x94, 0xaf, 0x49, 0xf6, 0xc6, 0x50, 0xad, 0xb8, ],
	[ 0xea, 0xb8, 0x85, 0x8a, 0xde, 0x92, 0xe1, 0xbc, ],
	[ 0xf3, 0x15, 0xbb, 0x5b, 0xb8, 0x35, 0xd8, 0x17, ],
	[ 0xad, 0xcf, 0x6b, 0x07, 0x63, 0x61, 0x2e, 0x2f, ],
	[ 0xa5, 0xc9, 0x1d, 0xa7, 0xac, 0xaa, 0x4d, 0xde, ],
	[ 0x71, 0x65, 0x95, 0x87, 0x66, 0x50, 0xa2, 0xa6, ],
	[ 0x28, 0xef, 0x49, 0x5c, 0x53, 0xa3, 0x87, 0xad, ],
	[ 0x42, 0xc3, 0x41, 0xd8, 0xfa, 0x92, 0xd8, 0x32, ],
	[ 0xce, 0x7c, 0xf2, 0x72, 0x2f, 0x51, 0x27, 0x71, ],
	[ 0xe3, 0x78, 0x59, 0xf9, 0x46, 0x23, 0xf3, 0xa7, ],
	[ 0x38, 0x12, 0x05, 0xbb, 0x1a, 0xb0, 0xe0, 0x12, ],
	[ 0xae, 0x97, 0xa1, 0x0f, 0xd4, 0x34, 0xe0, 0x15, ],
	[ 0xb4, 0xa3, 0x15, 0x08, 0xbe, 0xff, 0x4d, 0x31, ],
	[ 0x81, 0x39, 0x62, 0x29, 0xf0, 0x90, 0x79, 0x02, ],
	[ 0x4d, 0x0c, 0xf4, 0x9e, 0xe5, 0xd4, 0xdc, 0xca, ],
	[ 0x5c, 0x73, 0x33, 0x6a, 0x76, 0xd8, 0xbf, 0x9a, ],
	[ 0xd0, 0xa7, 0x04, 0x53, 0x6b, 0xa9, 0x3e, 0x0e, ],
	[ 0x92, 0x59, 0x58, 0xfc, 0xd6, 0x42, 0x0c, 0xad, ],
	[ 0xa9, 0x15, 0xc2, 0x9b, 0xc8, 0x06, 0x73, 0x18, ],
	[ 0x95, 0x2b, 0x79, 0xf3, 0xbc, 0x0a, 0xa6, 0xd4, ],
	[ 0xf2, 0x1d, 0xf2, 0xe4, 0x1d, 0x45, 0x35, 0xf9, ],
	[ 0x87, 0x57, 0x75, 0x19, 0x04, 0x8f, 0x53, 0xa9, ],
	[ 0x10, 0xa5, 0x6c, 0xf5, 0xdf, 0xcd, 0x9a, 0xdb, ],
	[ 0xeb, 0x75, 0x09, 0x5c, 0xcd, 0x98, 0x6c, 0xd0, ],
	[ 0x51, 0xa9, 0xcb, 0x9e, 0xcb, 0xa3, 0x12, 0xe6, ],
	[ 0x96, 0xaf, 0xad, 0xfc, 0x2c, 0xe6, 0x66, 0xc7, ],
	[ 0x72, 0xfe, 0x52, 0x97, 0x5a, 0x43, 0x64, 0xee, ],
	[ 0x5a, 0x16, 0x45, 0xb2, 0x76, 0xd5, 0x92, 0xa1, ],
	[ 0xb2, 0x74, 0xcb, 0x8e, 0xbf, 0x87, 0x87, 0x0a, ],
	[ 0x6f, 0x9b, 0xb4, 0x20, 0x3d, 0xe7, 0xb3, 0x81, ],
	[ 0xea, 0xec, 0xb2, 0xa3, 0x0b, 0x22, 0xa8, 0x7f, ],
	[ 0x99, 0x24, 0xa4, 0x3c, 0xc1, 0x31, 0x57, 0x24, ],
	[ 0xbd, 0x83, 0x8d, 0x3a, 0xaf, 0xbf, 0x8d, 0xb7, ],
	[ 0x0b, 0x1a, 0x2a, 0x32, 0x65, 0xd5, 0x1a, 0xea, ],
	[ 0x13, 0x50, 0x79, 0xa3, 0x23, 0x1c, 0xe6, 0x60, ],
	[ 0x93, 0x2b, 0x28, 0x46, 0xe4, 0xd7, 0x06, 0x66, ],
	[ 0xe1, 0x91, 0x5f, 0x5c, 0xb1, 0xec, 0xa4, 0x6c, ],
	[ 0xf3, 0x25, 0x96, 0x5c, 0xa1, 0x6d, 0x62, 0x9f, ],
	[ 0x57, 0x5f, 0xf2, 0x8e, 0x60, 0x38, 0x1b, 0xe5, ],
	[ 0x72, 0x45, 0x06, 0xeb, 0x4c, 0x32, 0x8a, 0x95, ]
	];

	let k0 = 0x_07_06_05_04_03_02_01_00_u64;
	let k1 = 0x_0f_0e_0d_0c_0b_0a_09_08_u64;
	let mut buf : ~[u8] = ~[];
	let mut t = 0;
	let mut stream_inc = SipState::new(k0, k1);
	let mut stream_full = SipState::new(k0, k1);

	fn to_hex_str(r: &[u8, ..8]) -> ~str {
	let mut s = ~"";
	for b in r.iter() {
	s.push_str((*b as uint).to_str_radix(16u));
	}
	s
	}

	while t < 64 {
	debug!("siphash test %?", t);
	let vec = u8to64_le!(vecs[t], 0);
	let out = Bytes(buf.as_slice()).hash_keyed(k0, k1);
	debug!("got %?, expected %?", out, vec);
	assert_eq!(vec, out);

	stream_full.reset();
	stream_full.input(buf);
	let f = stream_full.result_str();
	let i = stream_inc.result_str();
	let v = to_hex_str(&vecs[t]);
	debug!("%d: (%s) => inc=%s full=%s", t, v, i, f);

	assert!(f == i && f == v);

	buf.push(t as u8);
	stream_inc.input([t as u8]);

	t += 1;
	}
	}

	#[test] #[cfg(target_arch = "arm")]
	fn test_hash_uint() {
	let val = 0xdeadbeef_deadbeef_u64;
	assert!((val as u64).hash() != (val as uint).hash());
	assert_eq!((val as u32).hash(), (val as uint).hash());
	}
	#[test] #[cfg(target_arch = "x86_64")]
	fn test_hash_uint() {
	let val = 0xdeadbeef_deadbeef_u64;
	assert_eq!((val as u64).hash(), (val as uint).hash());
	assert!((val as u32).hash() != (val as uint).hash());
	}
	#[test] #[cfg(target_arch = "x86")]
	fn test_hash_uint() {
	let val = 0xdeadbeef_deadbeef_u64;
	assert!((val as u64).hash() != (val as uint).hash());
	assert_eq!((val as u32).hash(), (val as uint).hash());
	}

	#[test]
	fn test_hash_idempotent() {
	let val64 = 0xdeadbeef_deadbeef_u64;
	val64.hash() == val64.hash();
	let val32 = 0xdeadbeef_u32;
	val32.hash() == val32.hash();
	}

	#[test]
	fn test_hash_no_bytes_dropped_64() {
	let val = 0xdeadbeef_deadbeef_u64;

	assert!(val.hash() != zero_byte(val, 0).hash());
	assert!(val.hash() != zero_byte(val, 1).hash());
	assert!(val.hash() != zero_byte(val, 2).hash());
	assert!(val.hash() != zero_byte(val, 3).hash());
	assert!(val.hash() != zero_byte(val, 4).hash());
	assert!(val.hash() != zero_byte(val, 5).hash());
	assert!(val.hash() != zero_byte(val, 6).hash());
	assert!(val.hash() != zero_byte(val, 7).hash());

	fn zero_byte(val: u64, byte: uint) -> u64 {
	assert!(byte < 8);
	val & !(0xff << (byte * 8))
	}
	}

	#[test]
	fn test_hash_no_bytes_dropped_32() {
	let val = 0xdeadbeef_u32;

	assert!(val.hash() != zero_byte(val, 0).hash());
	assert!(val.hash() != zero_byte(val, 1).hash());
	assert!(val.hash() != zero_byte(val, 2).hash());
	assert!(val.hash() != zero_byte(val, 3).hash());

	fn zero_byte(val: u32, byte: uint) -> u32 {
	assert!(byte < 4);
	val & !(0xff << (byte * 8))
	}
	}

	#[test]
	fn test_float_hashes_differ() {
	assert!(0.0.hash() != 1.0.hash());
	assert!(1.0.hash() != (-1.0).hash());
	}

	#[test]
	fn test_float_hashes_of_zero() {
	assert_eq!(0.0.hash(), (-0.0).hash());
	}

	#[test]
	fn test_hash_no_concat_alias() {
	let s = ("aa", "bb");
	let t = ("aabb", "");
	let u = ("a", "abb");

	let v = (&[1u8], &[0u8, 0], &[0u8]);
	let w = (&[1u8, 0, 0, 0], &[], &[]);

	assert!(v != w);
	assert!(s.hash() != t.hash() && s.hash() != u.hash());
	assert!(v.hash() != w.hash());
	}
	}