cajeta.hash.SipHash — SipHash-2-4, a 64-bit DoS-resistant keyed hash. Use when the input is attacker-controlled and a hash-map or cache lookup depends on it (HTTP request keys, JWT claim names, user-supplied cache keys): the 128-bit key prevents an attacker from precomputing colliding inputs because they don’t know the key. For internal, non-attacker inputs use XXHash3 instead — roughly 10x faster per byte.

int8[] data = heap int8[12];
int64 h = SipHash.hashKeyed(data, 12, 17, 42);   // one-shot, keyed

SipHash s = heap SipHash(17, 42);
s.writeString("user-key");
int64 digest = s.finish();

Methods

Signature
One-shot statics
`static int64 hashKeyed(int8[] data, int64 len, int64 keyLow, int64 keyHigh)` ⚑	Keyed digest of `data[0..len)` — the common case, no streaming object required
`static int64 hashStringKeyed(String s, int64 keyLow, int64 keyHigh)` ⚑	Keyed digest of a `String`’s UTF-8 bytes
Streaming
`SipHash(int64 keyLow, int64 keyHigh)` ⚑	Construct a streaming SipHash with the 128-bit key as two `int64` halves
`void update(int8[] data, int64 len)`	Absorb `data[0..len)` into the running digest
`void reset()`	Re-initialize the state from the stored key so the instance can be reused
`int64 finish()`	Finalize the streamed input and return the 64-bit digest
`Hasher` typed writes
`void writeBoolean(boolean v)`	Absorb `v` as one byte: `1` for true, `0` for false
`void writeInt8(int8 v)`	Absorb the raw byte of `v`
`void writeInt16(int16 v)`	Absorb the 2 raw bytes of `v`
`void writeInt32(int32 v)`	Absorb the 4 raw bytes of `v`
`void writeInt64(int64 v)`	Absorb the 8 raw bytes of `v`
`void writeUInt8(uint8 v)`	Absorb the raw byte of `v`
`void writeUInt16(uint16 v)`	Absorb the 2 raw bytes of `v`
`void writeUInt32(uint32 v)`	Absorb the 4 raw bytes of `v`
`void writeUInt64(uint64 v)`	Absorb the 8 raw bytes of `v`
`void writeFloat32(float32 v)`	Absorb the 4 raw bytes of `v`
`void writeFloat64(float64 v)`	Absorb the 8 raw bytes of `v`
`void writeBytes(int8[] data)`	Absorb every byte of `data`
`void writeBytesRange(int8[] data, int64 offset, int64 length)`	Absorb `length` bytes of `data` (v1: `offset` is ignored)
`void writeString(String s)`	Absorb a `String`’s UTF-8 bytes
`void writeObject(Object obj)`	Absorb `obj.hash()` as 8 bytes

⚑ = @EntryPoint

SipHash

Methods

See also