# `EEVM.Precompiles.RIPEMD160`
[🔗](https://github.com/mw2000/eevm/blob/v0.1.0/lib/eevm/precompiles/ripemd160.ex#L1)

RIPEMD-160 precompile — address `0x03`.

### Output format (Yellow Paper §E.2)

Even though the digest is only 20 bytes, the precompile **always returns
32 bytes**: the 20-byte hash is **right-aligned** within the 32-byte word,
with 12 zero bytes prepended on the left.

```
[ 0x00 × 12 | RIPEMD160(input) × 20 ]
└────────────────────────── 32 bytes ──┘
```

### Gas schedule

| Component | Cost |
|-----------|------|
| Base      | 600  |
| Per word  | 120 (one word = 32 bytes, rounded up) |

# `execute`

```elixir
@spec execute(binary(), non_neg_integer()) ::
  {:ok, binary(), non_neg_integer()} | {:error, :out_of_gas}
```

Executes the RIPEMD-160 precompile.

Hashes `input` with RIPEMD-160 and returns a 32-byte binary: 12 zero bytes
followed by the 20-byte digest. Gas charged is
`600 + 120 * ceil(byte_size(input) / 32)`.

## Examples

    iex> {:ok, out, _gas} = EEVM.Precompiles.RIPEMD160.execute(<<>>, 10_000)
    iex> byte_size(out)
    32
    iex> binary_part(out, 0, 12)
    <<0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0>>

    iex> EEVM.Precompiles.RIPEMD160.execute(<<1::256>>, 5)
    {:error, :out_of_gas}

---

*Consult [api-reference.md](api-reference.md) for complete listing*