ripple/fossil: deduplicate using content-defined chunking

This implements casync-style content-defined chunking and deduplication.

Change-Id: I42a9b98e1140bed462a5ae1e0aba508bebc9fa0e

4 files changed, 627 insertions, 27 deletions

diff --git a/ripple/fossil/src/chunker/buz.rs b/ripple/fossil/src/chunker/buz.rs
new file mode 100644
index 0000000..7e10b9f
--- /dev/null
+++ b/ripple/fossil/src/chunker/buz.rs
@@ -0,0 +1,102 @@
+// SPDX-FileCopyrightText: edef <edef@unfathomable.blue>
+// SPDX-License-Identifier: OSL-3.0
+
+use std::mem;
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct Hash(pub u32);
+
+impl Hash {
+	pub fn from(data: &[u8]) -> Hash {
+		let mut x: u32 = 0;
+		for &b in data {
+			x = x.rotate_left(1) ^ expand(b);
+		}
+		Hash(x)
+	}
+}
+
+#[derive(Clone)]
+pub struct Rolling<const N: usize> {
+	i: usize,
+	x: u32,
+	/// `window[i]`   is the least recently written byte
+	/// `window[i-1]` is the most  recently written byte
+	window: [u8; N],
+}
+
+impl<const N: usize> Rolling<N> {
+	pub fn from_slice(input: &[u8]) -> Rolling<N> {
+		Self::try_from_slice(input).expect("need at least Rolling::WINDOW_SIZE bytes")
+	}
+
+	pub fn try_from_slice(input: &[u8]) -> Option<Rolling<N>> {
+		let last_chunk = input.rchunks_exact(N).next()?;
+
+		let mut window = [0; N];
+		window.copy_from_slice(last_chunk);
+
+		Some(Self::new(&window))
+	}
+
+	pub fn new(window: &[u8; N]) -> Rolling<N> {
+		Rolling {
+			i: 0,
+			x: Hash::from(window).0,
+			window: *window,
+		}
+	}
+
+	pub fn push(&mut self, next: u8) {
+		unsafe {
+			let ptr = self.window.get_unchecked_mut(self.i as usize);
+			let prev = mem::replace(ptr, next);
+
+			self.i = (self.i + 1) % N;
+			self.x = self.x.rotate_left(1) ^ expand(prev).rotate_left(N as u32) ^ expand(next);
+		}
+	}
+
+	pub fn sum(&self) -> Hash {
+		Hash(self.x)
+	}
+}
+
+fn expand(byte: u8) -> u32 {
+	TABLE[byte as usize]
+}
+
+const TABLE: [u32; 256] = [
+	0x458be752, 0xc10748cc, 0xfbbcdbb8, 0x6ded5b68, 0xb10a82b5, 0x20d75648, 0xdfc5665f, 0xa8428801,
+	0x7ebf5191, 0x841135c7, 0x65cc53b3, 0x280a597c, 0x16f60255, 0xc78cbc3e, 0x294415f5, 0xb938d494,
+	0xec85c4e6, 0xb7d33edc, 0xe549b544, 0xfdeda5aa, 0x882bf287, 0x3116737c, 0x05569956, 0xe8cc1f68,
+	0x0806ac5e, 0x22a14443, 0x15297e10, 0x50d090e7, 0x4ba60f6f, 0xefd9f1a7, 0x5c5c885c, 0x82482f93,
+	0x9bfd7c64, 0x0b3e7276, 0xf2688e77, 0x8fad8abc, 0xb0509568, 0xf1ada29f, 0xa53efdfe, 0xcb2b1d00,
+	0xf2a9e986, 0x6463432b, 0x95094051, 0x5a223ad2, 0x9be8401b, 0x61e579cb, 0x1a556a14, 0x5840fdc2,
+	0x9261ddf6, 0xcde002bb, 0x52432bb0, 0xbf17373e, 0x7b7c222f, 0x2955ed16, 0x9f10ca59, 0xe840c4c9,
+	0xccabd806, 0x14543f34, 0x1462417a, 0x0d4a1f9c, 0x087ed925, 0xd7f8f24c, 0x7338c425, 0xcf86c8f5,
+	0xb19165cd, 0x9891c393, 0x325384ac, 0x0308459d, 0x86141d7e, 0xc922116a, 0xe2ffa6b6, 0x53f52aed,
+	0x2cd86197, 0xf5b9f498, 0xbf319c8f, 0xe0411fae, 0x977eb18c, 0xd8770976, 0x9833466a, 0xc674df7f,
+	0x8c297d45, 0x8ca48d26, 0xc49ed8e2, 0x7344f874, 0x556f79c7, 0x6b25eaed, 0xa03e2b42, 0xf68f66a4,
+	0x8e8b09a2, 0xf2e0e62a, 0x0d3a9806, 0x9729e493, 0x8c72b0fc, 0x160b94f6, 0x450e4d3d, 0x7a320e85,
+	0xbef8f0e1, 0x21d73653, 0x4e3d977a, 0x1e7b3929, 0x1cc6c719, 0xbe478d53, 0x8d752809, 0xe6d8c2c6,
+	0x275f0892, 0xc8acc273, 0x4cc21580, 0xecc4a617, 0xf5f7be70, 0xe795248a, 0x375a2fe9, 0x425570b6,
+	0x8898dcf8, 0xdc2d97c4, 0x0106114b, 0x364dc22f, 0x1e0cad1f, 0xbe63803c, 0x5f69fac2, 0x4d5afa6f,
+	0x1bc0dfb5, 0xfb273589, 0x0ea47f7b, 0x3c1c2b50, 0x21b2a932, 0x6b1223fd, 0x2fe706a8, 0xf9bd6ce2,
+	0xa268e64e, 0xe987f486, 0x3eacf563, 0x1ca2018c, 0x65e18228, 0x2207360a, 0x57cf1715, 0x34c37d2b,
+	0x1f8f3cde, 0x93b657cf, 0x31a019fd, 0xe69eb729, 0x8bca7b9b, 0x4c9d5bed, 0x277ebeaf, 0xe0d8f8ae,
+	0xd150821c, 0x31381871, 0xafc3f1b0, 0x927db328, 0xe95effac, 0x305a47bd, 0x426ba35b, 0x1233af3f,
+	0x686a5b83, 0x50e072e5, 0xd9d3bb2a, 0x8befc475, 0x487f0de6, 0xc88dff89, 0xbd664d5e, 0x971b5d18,
+	0x63b14847, 0xd7d3c1ce, 0x7f583cf3, 0x72cbcb09, 0xc0d0a81c, 0x7fa3429b, 0xe9158a1b, 0x225ea19a,
+	0xd8ca9ea3, 0xc763b282, 0xbb0c6341, 0x020b8293, 0xd4cd299d, 0x58cfa7f8, 0x91b4ee53, 0x37e4d140,
+	0x95ec764c, 0x30f76b06, 0x5ee68d24, 0x679c8661, 0xa41979c2, 0xf2b61284, 0x4fac1475, 0x0adb49f9,
+	0x19727a23, 0x15a7e374, 0xc43a18d5, 0x3fb1aa73, 0x342fc615, 0x924c0793, 0xbee2d7f0, 0x8a279de9,
+	0x4aa2d70c, 0xe24dd37f, 0xbe862c0b, 0x177c22c2, 0x5388e5ee, 0xcd8a7510, 0xf901b4fd, 0xdbc13dbc,
+	0x6c0bae5b, 0x64efe8c7, 0x48b02079, 0x80331a49, 0xca3d8ae6, 0xf3546190, 0xfed7108b, 0xc49b941b,
+	0x32baf4a9, 0xeb833a4a, 0x88a3f1a5, 0x3a91ce0a, 0x3cc27da1, 0x7112e684, 0x4a3096b1, 0x3794574c,
+	0xa3c8b6f3, 0x1d213941, 0x6e0a2e00, 0x233479f1, 0x0f4cd82f, 0x6093edd2, 0x5d7d209e, 0x464fe319,
+	0xd4dcac9e, 0x0db845cb, 0xfb5e4bc3, 0xe0256ce1, 0x09fb4ed1, 0x0914be1e, 0xa5bdb2c3, 0xc6eb57bb,
+	0x30320350, 0x3f397e91, 0xa67791bc, 0x86bc0e2c, 0xefa0a7e2, 0xe9ff7543, 0xe733612c, 0xd185897b,
+	0x329e5388, 0x91dd236b, 0x2ecb0d93, 0xf4d82a3d, 0x35b5c03f, 0xe4e606f0, 0x05b21843, 0x37b45964,
+	0x5eff22f4, 0x6027f4cc, 0x77178b3c, 0xae507131, 0x7bf7cabc, 0xf9c18d66, 0x593ade65, 0xd95ddf11,
+];
diff --git a/ripple/fossil/src/chunker/mod.rs b/ripple/fossil/src/chunker/mod.rs
new file mode 100644
index 0000000..0045646
--- /dev/null
+++ b/ripple/fossil/src/chunker/mod.rs
@@ -0,0 +1,432 @@
+// SPDX-FileCopyrightText: edef <edef@unfathomable.blue>
+// SPDX-License-Identifier: OSL-3.0
+
+use std::mem;
+
+mod buz;
+
+pub const MIN_CHUNK_SIZE: usize = AVG_CHUNK_SIZE / 4;
+pub const AVG_CHUNK_SIZE: usize = 64 * 1024;
+pub const MAX_CHUNK_SIZE: usize = AVG_CHUNK_SIZE * 4;
+
+fn discriminator_from_average(avg: u64) -> u32 {
+	let avg = avg as f64;
+	(avg / (-1.42888852e-7 * avg + 1.33237515)) as u32
+}
+
+#[derive(Clone)]
+pub struct Chunker<'a> {
+	buffer: &'a [u8],
+}
+
+impl<'a> Chunker<'a> {
+	pub fn from(buffer: &'a [u8]) -> Chunker<'a> {
+		Chunker { buffer }
+	}
+}
+
+impl<'a> Iterator for Chunker<'a> {
+	type Item = &'a [u8];
+	fn next(&mut self) -> Option<&'a [u8]> {
+		if self.buffer.is_empty() {
+			return None;
+		}
+
+		if self.buffer.len() <= MIN_CHUNK_SIZE {
+			return Some(mem::take(&mut self.buffer));
+		}
+
+		let bytes = self
+			.buffer
+			.iter()
+			.cloned()
+			.enumerate()
+			.take(MAX_CHUNK_SIZE)
+			.skip(MIN_CHUNK_SIZE);
+
+		let d = discriminator_from_average(AVG_CHUNK_SIZE as u64);
+		let mut hasher = buz::Rolling::<48>::from_slice(&self.buffer[..MIN_CHUNK_SIZE]);
+		let chunk;
+		for (idx, byte) in bytes {
+			hasher.push(byte);
+			let buz::Hash(x) = hasher.sum();
+			if x % d == d.wrapping_sub(1) {
+				// split point
+				(chunk, self.buffer) = self.buffer.split_at(idx + 1);
+				return Some(chunk);
+			}
+		}
+
+		(chunk, self.buffer) = self.buffer.split_at(MAX_CHUNK_SIZE.min(self.buffer.len()));
+		Some(chunk)
+	}
+
+	fn size_hint(&self) -> (usize, Option<usize>) {
+		if self.buffer.is_empty() {
+			return (0, Some(0));
+		}
+		let min = (self.buffer.len() + MAX_CHUNK_SIZE - 1) / MAX_CHUNK_SIZE;
+		let max = (self.buffer.len() + MIN_CHUNK_SIZE - 1) / MIN_CHUNK_SIZE;
+		(min, Some(max))
+	}
+}
+
+#[cfg(test)]
+mod test {
+	use std::io::Read;
+
+	fn generate(length: usize) -> Vec<u8> {
+		let mut h = blake3::Hasher::new();
+		h.update(b"test vector");
+		let mut buf = vec![0; length];
+		h.finalize_xof().read_exact(&mut buf).unwrap();
+		buf
+	}
+
+	const GOLDEN: &[[u8; 32]] = &[
+		[
+			0x66, 0x77, 0xd1, 0xf7, 0x78, 0xbf, 0x7b, 0x42, 0x91, 0x15, 0x16, 0xda, 0xde, 0xae,
+			0x69, 0x17, 0x59, 0xe9, 0x73, 0xe8, 0x5b, 0xa2, 0xa0, 0x92, 0x6f, 0x98, 0x76, 0x8c,
+			0xbb, 0xb4, 0x74, 0xc7,
+		],
+		[
+			0xad, 0xd6, 0xc0, 0x6e, 0x0e, 0xef, 0xb5, 0x3b, 0x1f, 0x8b, 0xeb, 0xac, 0x21, 0xa8,
+			0xf7, 0x0c, 0xc9, 0xeb, 0xc8, 0x20, 0x22, 0xf0, 0xfe, 0x0a, 0x72, 0x15, 0x15, 0x21,
+			0x32, 0x7d, 0xe5, 0x0a,
+		],
+		[
+			0xbc, 0xd0, 0x68, 0x57, 0x0a, 0x66, 0x70, 0xf3, 0x3e, 0x81, 0xc9, 0xa8, 0x7d, 0xac,
+			0xd9, 0xde, 0x80, 0xb9, 0x8a, 0x19, 0x8d, 0x54, 0xcd, 0xd7, 0x5e, 0x76, 0xca, 0x0f,
+			0xb0, 0x0d, 0x53, 0x11,
+		],
+		[
+			0x91, 0x16, 0x6f, 0x72, 0x92, 0x3d, 0x00, 0xbb, 0x46, 0x82, 0x7a, 0xc5, 0x35, 0xda,
+			0x0c, 0x6e, 0x20, 0xbc, 0x1a, 0xb0, 0xb8, 0x40, 0x58, 0x0b, 0xf4, 0xc4, 0xe3, 0xbe,
+			0xb7, 0x81, 0xeb, 0xd8,
+		],
+		[
+			0x51, 0x59, 0xea, 0xdf, 0xd1, 0x41, 0x38, 0x11, 0xa9, 0x91, 0xb3, 0xf4, 0x91, 0x8c,
+			0x7b, 0x61, 0x38, 0x4a, 0x04, 0x59, 0x1f, 0xe9, 0xc1, 0xa6, 0x01, 0x19, 0x32, 0x5b,
+			0xfa, 0x3b, 0x24, 0x92,
+		],
+		[
+			0x7c, 0x64, 0x0c, 0xa5, 0xe8, 0x3a, 0x25, 0xeb, 0xaf, 0xe3, 0x1e, 0x5b, 0x58, 0xd4,
+			0x8b, 0xb8, 0x0a, 0xa5, 0x50, 0x5d, 0x18, 0x8a, 0x79, 0x38, 0xe3, 0x71, 0x61, 0x6d,
+			0x24, 0x4b, 0x0d, 0x07,
+		],
+		[
+			0x6c, 0x4b, 0xc6, 0x17, 0xf2, 0xaf, 0x9b, 0xa6, 0x81, 0xd4, 0x1b, 0xf1, 0x77, 0xce,
+			0xcf, 0x0b, 0xb7, 0xbf, 0x3a, 0x54, 0xc7, 0x26, 0x5f, 0x8c, 0x43, 0x5a, 0x40, 0x61,
+			0xf5, 0x5c, 0x47, 0x75,
+		],
+		[
+			0x98, 0x74, 0xd1, 0x45, 0x30, 0xe9, 0x47, 0x0c, 0xcf, 0x76, 0x52, 0x65, 0x85, 0x96,
+			0xf6, 0x90, 0x6f, 0x1d, 0x84, 0x24, 0xe1, 0x4f, 0x08, 0x55, 0x03, 0xf8, 0xe8, 0x8f,
+			0x10, 0xb4, 0xec, 0xc8,
+		],
+		[
+			0xd2, 0x87, 0x27, 0x3d, 0xa5, 0x7d, 0x31, 0x75, 0x56, 0x82, 0xb7, 0x13, 0x4c, 0xea,
+			0x68, 0xbf, 0xc4, 0x1c, 0x0b, 0xb9, 0xce, 0x64, 0xb1, 0x90, 0xfb, 0xde, 0x2a, 0xd8,
+			0xce, 0xc0, 0x1b, 0x2c,
+		],
+		[
+			0x68, 0xbd, 0xfb, 0x6c, 0x99, 0xf5, 0x3e, 0x82, 0xf6, 0x9e, 0x6a, 0xa6, 0x01, 0x56,
+			0x00, 0x3f, 0xab, 0x8e, 0x9c, 0xf7, 0x98, 0x93, 0x1a, 0x70, 0xef, 0x2b, 0x19, 0x5b,
+			0x1c, 0xf0, 0x1e, 0x38,
+		],
+		[
+			0xae, 0x9f, 0xa2, 0x52, 0x89, 0x7b, 0xda, 0xcf, 0x65, 0x09, 0x93, 0xd1, 0xe0, 0x96,
+			0x73, 0xb6, 0xfb, 0xa6, 0x0f, 0x58, 0x02, 0xec, 0x79, 0x22, 0xf8, 0xa7, 0xea, 0xe8,
+			0x16, 0x60, 0x6d, 0x1b,
+		],
+		[
+			0x8b, 0x9e, 0x83, 0xc2, 0x45, 0x75, 0x9c, 0x3a, 0xf4, 0x0f, 0x4b, 0xb4, 0xbd, 0x82,
+			0xa1, 0x62, 0x66, 0xde, 0xd3, 0x2f, 0xda, 0xf6, 0xfc, 0x12, 0xc9, 0x57, 0x40, 0xe2,
+			0x18, 0x90, 0x89, 0x67,
+		],
+		[
+			0x6b, 0x0d, 0x3f, 0x9b, 0xec, 0x24, 0xb2, 0xf7, 0x90, 0x8c, 0x75, 0x28, 0x57, 0xc9,
+			0x6f, 0x9e, 0xa7, 0x78, 0x94, 0x31, 0xaf, 0xa4, 0xa4, 0x61, 0x9c, 0x6e, 0xa7, 0xf9,
+			0x64, 0x60, 0x48, 0xcd,
+		],
+		[
+			0xbd, 0x04, 0x1a, 0x0c, 0x3e, 0xe2, 0x3e, 0x3a, 0xe6, 0x6c, 0x5b, 0xcd, 0x8d, 0x8a,
+			0x1e, 0xfe, 0x4d, 0xd5, 0xac, 0x14, 0xd5, 0xe6, 0x59, 0x40, 0x0e, 0xa0, 0xcf, 0x75,
+			0x32, 0xc6, 0xb6, 0x7a,
+		],
+		[
+			0x66, 0x73, 0x94, 0x96, 0x23, 0x81, 0x69, 0x26, 0x34, 0x94, 0x4d, 0x20, 0xf3, 0x6d,
+			0x67, 0x3d, 0xb6, 0xb9, 0x9b, 0xc7, 0xa7, 0x7c, 0x22, 0xc3, 0x56, 0xd1, 0x58, 0xe5,
+			0x4e, 0x55, 0x0a, 0x33,
+		],
+		[
+			0x26, 0xdd, 0xfc, 0x31, 0xac, 0xfc, 0xd2, 0x57, 0x9d, 0x52, 0x65, 0xdc, 0xf3, 0xe0,
+			0x8a, 0xde, 0x13, 0x04, 0x5f, 0xee, 0xc4, 0xf4, 0x35, 0xce, 0xb6, 0xcf, 0xd1, 0x7f,
+			0xc0, 0xc5, 0x4b, 0x7f,
+		],
+		[
+			0xe2, 0xd5, 0x6a, 0xb7, 0xdb, 0x71, 0x1d, 0x4d, 0xb2, 0xb4, 0xdb, 0xee, 0x94, 0x4c,
+			0xac, 0x92, 0x6e, 0xdc, 0xf3, 0xfd, 0x92, 0x44, 0xf1, 0x79, 0x66, 0x2a, 0x1e, 0x70,
+			0xd6, 0x2e, 0xb4, 0x6b,
+		],
+		[
+			0x86, 0x5d, 0x5f, 0x60, 0x75, 0x3d, 0xff, 0x7b, 0xac, 0x50, 0xa3, 0x11, 0x82, 0x7a,
+			0xb8, 0xfe, 0xde, 0xbc, 0xb1, 0x0a, 0xfd, 0xea, 0xa8, 0x08, 0xaa, 0x28, 0xfc, 0x95,
+			0x72, 0x04, 0x72, 0x13,
+		],
+		[
+			0xa6, 0x2d, 0xcc, 0x3a, 0x2e, 0x8e, 0xe9, 0xf2, 0x87, 0xc7, 0xcc, 0xa8, 0xc8, 0xa3,
+			0x18, 0x33, 0xc9, 0x43, 0x31, 0x4a, 0xab, 0xfe, 0xaf, 0xc1, 0x1d, 0xc6, 0x22, 0x3d,
+			0xf3, 0x54, 0x45, 0xe2,
+		],
+		[
+			0x75, 0x1d, 0x1f, 0x3d, 0x94, 0x8e, 0x7d, 0x27, 0x22, 0x7f, 0x1a, 0x0e, 0xcc, 0x61,
+			0xef, 0xbd, 0x41, 0x16, 0x53, 0xb9, 0x5b, 0x78, 0x05, 0x06, 0x80, 0x60, 0xa3, 0x17,
+			0x4f, 0x01, 0x10, 0x51,
+		],
+		[
+			0x4e, 0x0f, 0x4d, 0x71, 0x65, 0x10, 0xa5, 0x81, 0xff, 0xfe, 0x62, 0x6b, 0x15, 0x94,
+			0x17, 0x4c, 0x6d, 0x12, 0x85, 0xbe, 0x74, 0xcb, 0x56, 0x04, 0xc7, 0x38, 0x8f, 0xb7,
+			0x6e, 0xaa, 0xfd, 0x12,
+		],
+		[
+			0xe4, 0xb8, 0x64, 0x03, 0x92, 0xe5, 0x71, 0x89, 0x31, 0xfc, 0xc7, 0xe9, 0xee, 0xcd,
+			0x92, 0xfb, 0x92, 0xb0, 0x1d, 0x32, 0x34, 0xa1, 0x91, 0xd4, 0x7f, 0x5b, 0x8b, 0x37,
+			0xb8, 0x60, 0x2d, 0x6a,
+		],
+		[
+			0xc6, 0x3c, 0x17, 0xc0, 0x94, 0x0d, 0x16, 0xec, 0xc6, 0x67, 0x1f, 0xd1, 0x7a, 0xec,
+			0x12, 0x10, 0xf3, 0xf6, 0x1e, 0x59, 0x4b, 0x29, 0xab, 0x1c, 0xd4, 0xf6, 0xd1, 0x2e,
+			0x8a, 0xd7, 0x42, 0xc1,
+		],
+		[
+			0x8d, 0x59, 0x07, 0x06, 0x8c, 0x84, 0x68, 0x2a, 0x02, 0xb0, 0xe3, 0x2a, 0x88, 0x64,
+			0x28, 0x1a, 0xbf, 0x58, 0x74, 0xb5, 0xf9, 0x75, 0x5f, 0xd8, 0xc8, 0x4d, 0xa6, 0x9b,
+			0xd3, 0x40, 0x19, 0x05,
+		],
+		[
+			0x45, 0xa7, 0xc6, 0x21, 0xb3, 0x14, 0x14, 0x95, 0x74, 0x2e, 0xa4, 0xdc, 0x1f, 0x11,
+			0xe0, 0x77, 0xd5, 0xf3, 0x68, 0xe2, 0xc1, 0x9a, 0xb9, 0x83, 0xed, 0xd4, 0xf6, 0x77,
+			0x83, 0x09, 0x8f, 0x54,
+		],
+		[
+			0x94, 0x79, 0x72, 0xb1, 0x57, 0x2a, 0xb5, 0x2d, 0x81, 0x87, 0x9b, 0x32, 0xa8, 0xbf,
+			0xa8, 0xb6, 0x69, 0xff, 0x82, 0x69, 0x37, 0x69, 0x56, 0x7f, 0x26, 0xa4, 0xf2, 0x6c,
+			0x9a, 0xfd, 0x7e, 0x1a,
+		],
+		[
+			0x6f, 0x7f, 0x6d, 0xf1, 0x1f, 0xbb, 0x57, 0x2b, 0x2f, 0x29, 0x9f, 0x3d, 0x4e, 0x00,
+			0xd3, 0x75, 0x9b, 0xf2, 0x9f, 0x5d, 0xd4, 0xe5, 0x07, 0x9e, 0x46, 0xe0, 0x73, 0x3e,
+			0x68, 0x52, 0xa4, 0x99,
+		],
+		[
+			0xbb, 0x38, 0x7e, 0xc3, 0x7b, 0x3f, 0xe4, 0x9d, 0x05, 0xcc, 0x38, 0xa0, 0xe2, 0x3e,
+			0xb0, 0x95, 0x23, 0x43, 0x92, 0x2b, 0x83, 0x77, 0x10, 0xe4, 0x33, 0x7d, 0xe9, 0x75,
+			0xac, 0xdd, 0xe4, 0xcf,
+		],
+		[
+			0x32, 0x36, 0x32, 0x5b, 0x9f, 0xa9, 0x47, 0xd3, 0xfb, 0xca, 0xc0, 0x4e, 0x3d, 0x4a,
+			0xa6, 0xb8, 0x42, 0x16, 0x91, 0x43, 0xf2, 0x20, 0x04, 0x8d, 0x12, 0xb9, 0xb2, 0xa4,
+			0xc8, 0x97, 0xff, 0x99,
+		],
+		[
+			0x91, 0x11, 0xf3, 0xae, 0x36, 0x81, 0x03, 0xa5, 0x11, 0x74, 0xcd, 0x39, 0x06, 0x38,
+			0x1b, 0xa6, 0x87, 0x06, 0x28, 0x8a, 0x8a, 0x12, 0xbd, 0x35, 0xf6, 0x3c, 0xfe, 0xa9,
+			0x4a, 0x5b, 0x4e, 0x99,
+		],
+		[
+			0x68, 0x58, 0x3d, 0x1b, 0x52, 0xcb, 0x10, 0x28, 0x13, 0x1c, 0x99, 0x3b, 0xba, 0x09,
+			0x0b, 0x61, 0xc1, 0x51, 0x16, 0x03, 0xd9, 0x53, 0xba, 0x92, 0x6b, 0x45, 0x52, 0x8b,
+			0x90, 0x3c, 0xe1, 0x64,
+		],
+		[
+			0x5c, 0x26, 0xc4, 0xc9, 0x46, 0x08, 0x4d, 0x5d, 0xd2, 0xd7, 0x1e, 0xc7, 0xab, 0x95,
+			0xe8, 0xa6, 0xc1, 0x03, 0xff, 0x1f, 0x48, 0x1f, 0x2a, 0x8f, 0xe6, 0xa7, 0x05, 0x3c,
+			0xbb, 0xde, 0x9e, 0xbc,
+		],
+		[
+			0xf2, 0x25, 0xf0, 0xee, 0xd0, 0xa8, 0x2c, 0x50, 0x1b, 0x02, 0xaf, 0xd4, 0x56, 0x7b,
+			0x45, 0xea, 0x10, 0xf6, 0x8f, 0xb7, 0x2c, 0xe2, 0xe7, 0x88, 0xc6, 0x52, 0x91, 0x5d,
+			0xfe, 0x18, 0x4a, 0x0e,
+		],
+		[
+			0xb0, 0x38, 0xfe, 0x27, 0x98, 0xc4, 0x4d, 0xad, 0xfa, 0x07, 0x09, 0xa4, 0x40, 0xc8,
+			0x5a, 0x85, 0x69, 0xb5, 0xbd, 0xf3, 0xac, 0xb2, 0x82, 0x2e, 0x55, 0x22, 0xb4, 0x19,
+			0xf6, 0x30, 0xde, 0x82,
+		],
+		[
+			0x5f, 0x98, 0x00, 0xfd, 0x1d, 0x88, 0xf0, 0x00, 0x39, 0x20, 0x70, 0x5c, 0x2b, 0x81,
+			0xb3, 0x2d, 0x31, 0x7c, 0x1c, 0xa8, 0xcc, 0x21, 0x09, 0xb5, 0xfc, 0xd0, 0xae, 0x59,
+			0xdb, 0x45, 0xbf, 0x03,
+		],
+		[
+			0xf5, 0x92, 0xf4, 0x5f, 0xb9, 0x29, 0x1c, 0xc1, 0xee, 0xf1, 0x12, 0xf8, 0x0d, 0xc4,
+			0x92, 0x3a, 0xc8, 0x45, 0x5b, 0x1e, 0x2b, 0xae, 0xfc, 0xb4, 0x35, 0x21, 0x15, 0xcf,
+			0xc8, 0xc8, 0x3b, 0x19,
+		],
+		[
+			0xc2, 0x2e, 0x11, 0x46, 0x01, 0x5f, 0x0c, 0xa2, 0x6a, 0xe1, 0x13, 0x6d, 0x30, 0xd4,
+			0x86, 0xdf, 0xdd, 0xe0, 0x30, 0x8f, 0x3e, 0xaa, 0x1c, 0xd3, 0xf3, 0xda, 0x4c, 0x72,
+			0xdb, 0xe3, 0xe3, 0x23,
+		],
+		[
+			0xf9, 0x98, 0x5c, 0xcd, 0x6e, 0x19, 0xbf, 0xfa, 0xeb, 0x28, 0xf5, 0xf1, 0xab, 0xea,
+			0x25, 0x8d, 0xd4, 0xa7, 0xb7, 0x11, 0x95, 0x4f, 0xed, 0x9b, 0x0d, 0xba, 0x08, 0x83,
+			0xc4, 0x97, 0xad, 0x65,
+		],
+		[
+			0x76, 0xb1, 0x15, 0x9a, 0x9a, 0x76, 0xac, 0x13, 0x7e, 0xfa, 0x0f, 0x3c, 0xaa, 0x70,
+			0xb5, 0x9a, 0x60, 0x4d, 0xb9, 0x5b, 0x48, 0xd0, 0x38, 0x85, 0x1d, 0x4a, 0xcb, 0xa9,
+			0xe0, 0x4d, 0x41, 0x10,
+		],
+		[
+			0xbe, 0xf5, 0xbb, 0x3b, 0x80, 0x96, 0x52, 0x07, 0x8a, 0x39, 0xdc, 0xf4, 0xc4, 0x36,
+			0x34, 0xd5, 0x2f, 0xb3, 0xf4, 0x81, 0xde, 0x92, 0x7f, 0x7b, 0xcc, 0x0c, 0xc6, 0x82,
+			0x10, 0xd0, 0xdb, 0xa4,
+		],
+		[
+			0x91, 0x8b, 0x9a, 0x12, 0x12, 0x04, 0x84, 0x7a, 0x08, 0x03, 0x88, 0x0d, 0x59, 0x0a,
+			0xe1, 0x79, 0xd8, 0x21, 0x28, 0x96, 0xa4, 0x93, 0x3e, 0x66, 0xc3, 0xf0, 0x0d, 0x7f,
+			0x63, 0xc7, 0xc0, 0x0b,
+		],
+		[
+			0xa8, 0x0b, 0x46, 0xe0, 0x44, 0x86, 0xe1, 0xa4, 0xe8, 0x39, 0x61, 0x73, 0x69, 0x59,
+			0xed, 0xf4, 0x63, 0xfd, 0x1a, 0x55, 0x9b, 0x12, 0xf3, 0xa1, 0xab, 0x4c, 0x89, 0x3b,
+			0xb9, 0x31, 0x8b, 0xbf,
+		],
+		[
+			0x9f, 0xc1, 0x32, 0x3f, 0xcf, 0x6b, 0x96, 0xd8, 0x26, 0xbe, 0x3e, 0x73, 0x30, 0xed,
+			0x53, 0x10, 0xe7, 0x9d, 0x35, 0x72, 0x1e, 0x67, 0xe6, 0x77, 0x4f, 0x6b, 0xa8, 0xd3,
+			0xdf, 0xd7, 0x13, 0x66,
+		],
+		[
+			0x6a, 0x6b, 0x9c, 0xfa, 0xcd, 0x49, 0xb5, 0xd4, 0x17, 0x9f, 0xaa, 0xe0, 0x25, 0x9a,
+			0xf4, 0xa4, 0x46, 0x39, 0x56, 0xff, 0x6f, 0xdf, 0x5f, 0x6f, 0xa5, 0xa2, 0x52, 0x98,
+			0xe4, 0x1b, 0x64, 0x05,
+		],
+		[
+			0x15, 0xd2, 0x00, 0x5b, 0x94, 0xa4, 0xa0, 0xa7, 0x93, 0xce, 0x66, 0x89, 0xc3, 0xa6,
+			0xa6, 0x5e, 0x5c, 0xa1, 0x51, 0x4e, 0x3b, 0xf2, 0xbd, 0x9d, 0xc5, 0x27, 0x3c, 0x34,
+			0xaa, 0xc6, 0x7b, 0xfc,
+		],
+		[
+			0x85, 0xeb, 0xa0, 0x53, 0xce, 0xdd, 0xfc, 0x1e, 0x2d, 0x16, 0x09, 0xb0, 0x3d, 0xd1,
+			0x1f, 0x3c, 0xf0, 0x71, 0x2d, 0xa2, 0xbd, 0x1e, 0xb6, 0x1a, 0x27, 0x0c, 0xe1, 0x34,
+			0x42, 0x49, 0x8c, 0x41,
+		],
+		[
+			0xd1, 0xaf, 0xae, 0x46, 0x0e, 0xb6, 0xc3, 0x7e, 0xb7, 0x83, 0x45, 0xab, 0xc5, 0x2e,
+			0xc4, 0x3b, 0x16, 0x52, 0x84, 0x0f, 0xbf, 0x4f, 0x79, 0x0c, 0x2b, 0xa7, 0x98, 0xc5,
+			0x4d, 0x0b, 0x17, 0xff,
+		],
+		[
+			0x0e, 0xb6, 0x4e, 0xf4, 0x49, 0x54, 0xa9, 0x5d, 0x51, 0xf1, 0xf4, 0x5e, 0xf7, 0x56,
+			0xe1, 0x84, 0x7b, 0xaa, 0x25, 0x3b, 0xa4, 0xa0, 0xe4, 0xf6, 0x5f, 0xc5, 0x55, 0x12,
+			0x57, 0x1f, 0x30, 0x27,
+		],
+		[
+			0xc6, 0x43, 0x9d, 0x8c, 0x49, 0x8c, 0x45, 0xb9, 0x05, 0x14, 0xe3, 0x07, 0xdf, 0x1f,
+			0xa9, 0x9f, 0x41, 0xf2, 0xd0, 0xe1, 0xde, 0x90, 0xa8, 0x52, 0xa0, 0x55, 0x40, 0xa1,
+			0x94, 0xf7, 0xad, 0xd3,
+		],
+		[
+			0x8f, 0x8a, 0xc3, 0x9c, 0x0d, 0xbc, 0xf7, 0xd6, 0x65, 0xda, 0x26, 0x0a, 0x82, 0x6d,
+			0x88, 0xe0, 0x88, 0xd8, 0xba, 0x73, 0x81, 0xce, 0x5d, 0x1e, 0xa6, 0xdd, 0x88, 0x94,
+			0x56, 0x89, 0x17, 0xa6,
+		],
+		[
+			0x97, 0xe1, 0xbf, 0xc8, 0x8f, 0x16, 0x99, 0xce, 0x00, 0x44, 0x9c, 0x5a, 0x5f, 0x69,
+			0xb0, 0xfd, 0xf6, 0xc9, 0x94, 0x10, 0x73, 0x53, 0x10, 0xf2, 0xb6, 0x22, 0x2a, 0x6f,
+			0x25, 0x67, 0xbe, 0xc2,
+		],
+		[
+			0x80, 0x02, 0x68, 0x53, 0x7b, 0x24, 0xe0, 0x19, 0x7b, 0x10, 0x9c, 0x47, 0x77, 0xab,
+			0x0f, 0x4c, 0x09, 0x28, 0x5d, 0xa5, 0x54, 0xd1, 0x25, 0x65, 0x97, 0x4d, 0x45, 0xd2,
+			0xa0, 0x71, 0xec, 0x2d,
+		],
+		[
+			0x55, 0xbf, 0x83, 0x5b, 0xa6, 0xba, 0xb1, 0x43, 0x1b, 0x18, 0x23, 0xd9, 0x64, 0x93,
+			0x66, 0x0a, 0x92, 0x06, 0xfe, 0xa1, 0xec, 0xb5, 0xce, 0x95, 0x9f, 0x9f, 0x7d, 0xc4,
+			0x92, 0x49, 0x84, 0xfd,
+		],
+		[
+			0xdb, 0x6a, 0xcd, 0x67, 0x7a, 0x11, 0x65, 0x38, 0x56, 0x65, 0x89, 0xfd, 0x1b, 0x5f,
+			0x86, 0x19, 0x1f, 0xb9, 0x38, 0x94, 0x98, 0x5d, 0x6b, 0x30, 0x82, 0xce, 0xae, 0x3e,
+			0x53, 0x4c, 0xbb, 0x95,
+		],
+		[
+			0xd1, 0x83, 0xc3, 0xd4, 0xb0, 0x65, 0xf0, 0x77, 0xad, 0x50, 0x65, 0x24, 0xec, 0x07,
+			0x48, 0x1d, 0xe4, 0x9d, 0x2c, 0x6e, 0x94, 0xc9, 0x1d, 0x58, 0x43, 0x7a, 0x93, 0xaf,
+			0xff, 0x6e, 0xd2, 0xbd,
+		],
+		[
+			0x07, 0x17, 0x08, 0x3d, 0xcb, 0xb2, 0x4e, 0x38, 0x96, 0x1e, 0x68, 0x84, 0x39, 0xba,
+			0x3a, 0x40, 0xc2, 0x6a, 0x72, 0xcf, 0xf8, 0x2d, 0x56, 0x18, 0x44, 0x42, 0x9d, 0xa8,
+			0x08, 0x67, 0xfc, 0x10,
+		],
+		[
+			0xed, 0x8d, 0xdb, 0xbf, 0x6e, 0x1a, 0xd0, 0x0a, 0x34, 0x61, 0xac, 0xab, 0x32, 0x3f,
+			0x2a, 0x70, 0x51, 0xf7, 0x39, 0xb5, 0x63, 0xbb, 0xac, 0x83, 0xba, 0x56, 0x73, 0xc8,
+			0x4a, 0x60, 0x09, 0x24,
+		],
+		[
+			0x46, 0x63, 0x1d, 0x73, 0x51, 0xf6, 0xe2, 0x57, 0xa5, 0x6a, 0xbb, 0xb5, 0x88, 0x76,
+			0x3c, 0xeb, 0x89, 0xbe, 0xc5, 0x1b, 0x95, 0x9c, 0xc5, 0x30, 0x02, 0x21, 0xad, 0x35,
+			0x2f, 0xe5, 0xae, 0x51,
+		],
+		[
+			0x69, 0xcb, 0x42, 0x2a, 0xd8, 0x9b, 0xcc, 0xcc, 0x51, 0x3b, 0x58, 0xe9, 0x21, 0x61,
+			0xee, 0x81, 0xb1, 0x0d, 0x0a, 0xc4, 0xb1, 0xc7, 0xa0, 0x4f, 0x19, 0x76, 0x57, 0x5e,
+			0xd8, 0x53, 0x0a, 0xee,
+		],
+		[
+			0x9b, 0x39, 0x2e, 0x2e, 0xd5, 0x7f, 0x0f, 0x82, 0x04, 0xbb, 0x7c, 0xf6, 0x88, 0x39,
+			0xd9, 0xd1, 0x91, 0xc8, 0x06, 0x71, 0x36, 0x1d, 0x96, 0xc2, 0x9d, 0xdf, 0xc2, 0x6c,
+			0x18, 0xe1, 0x1b, 0x79,
+		],
+		[
+			0xe7, 0xe0, 0x6b, 0xfa, 0x7c, 0xcd, 0x85, 0x9e, 0x10, 0xb8, 0xac, 0x33, 0xae, 0x61,
+			0x5a, 0x29, 0x98, 0x2a, 0x65, 0xc1, 0x31, 0x33, 0xe2, 0x7e, 0xd2, 0x97, 0x5e, 0x9a,
+			0x67, 0xe2, 0x16, 0x52,
+		],
+		[
+			0x5b, 0x01, 0x92, 0x69, 0x45, 0xf7, 0xd6, 0x35, 0xf7, 0xca, 0x28, 0xa6, 0xd7, 0x1c,
+			0xd8, 0x8d, 0xac, 0x15, 0x6e, 0x00, 0xeb, 0xaa, 0xe4, 0x9c, 0x2f, 0xe5, 0x03, 0x95,
+			0x79, 0xf1, 0x55, 0xf1,
+		],
+		[
+			0x9d, 0x8f, 0x23, 0x51, 0xb6, 0xae, 0x39, 0xe9, 0xae, 0x13, 0x5c, 0xcb, 0x86, 0xb5,
+			0xdd, 0xc7, 0x77, 0xa8, 0x92, 0x23, 0x59, 0xb8, 0x1d, 0xea, 0x58, 0x64, 0x34, 0x0c,
+			0x13, 0xbe, 0x95, 0xba,
+		],
+		[
+			0xf2, 0x2f, 0x2d, 0x26, 0xa5, 0x78, 0xbe, 0x8d, 0xd2, 0xb1, 0xf9, 0xf4, 0x19, 0x01,
+			0x29, 0xd6, 0x87, 0xc6, 0xcf, 0x57, 0x46, 0xb1, 0x3c, 0x63, 0x15, 0x1c, 0x65, 0xee,
+			0x83, 0x7e, 0x16, 0x56,
+		],
+		[
+			0xd5, 0x81, 0x12, 0x6b, 0x6b, 0xdc, 0xc4, 0xc6, 0x84, 0x25, 0x04, 0xdd, 0xc9, 0x8c,
+			0xb1, 0x50, 0x56, 0x19, 0x6e, 0xbf, 0x69, 0x03, 0x12, 0x38, 0x93, 0x20, 0x98, 0xb7,
+			0xf2, 0x5e, 0x4c, 0xd6,
+		],
+		[
+			0x12, 0x4b, 0xbc, 0x2e, 0x30, 0x71, 0x18, 0xa5, 0x82, 0xd5, 0xae, 0x52, 0xfa, 0xfd,
+			0xbf, 0xcb, 0x75, 0x2b, 0x94, 0x8e, 0x9e, 0xc3, 0xaf, 0x56, 0xa1, 0x41, 0xdc, 0x57,
+			0xaf, 0x40, 0x50, 0xdb,
+		],
+		[
+			0xaa, 0xaa, 0x52, 0xad, 0xa4, 0xf5, 0xde, 0xd6, 0x92, 0x9e, 0xbf, 0xb9, 0x12, 0xfa,
+			0x70, 0x12, 0xa8, 0x19, 0x6e, 0x0c, 0xa4, 0xdf, 0x7c, 0x99, 0x88, 0x94, 0x2c, 0x3a,
+			0x98, 0x3d, 0xa6, 0x4e,
+		],
+	];
+
+	#[test]
+	fn golden() {
+		let data = generate(1024 * 64 * 64);
+		let chunks = super::Chunker::from(&data).map(blake3::hash);
+		for (actual, &expected) in chunks.zip(GOLDEN.iter()) {
+			assert_eq!(actual, blake3::Hash::from(expected));
+		}
+	}
+}
diff --git a/ripple/fossil/src/lib.rs b/ripple/fossil/src/lib.rs
index 3b2b3f8..4cea16a 100644
--- a/ripple/fossil/src/lib.rs
+++ b/ripple/fossil/src/lib.rs
@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: OSL-3.0
 
 use {
+	crate::chunker::Chunker,
 	anyhow::{Context, Result},
 	byteorder::{BigEndian, ByteOrder},
 	prost::Message,
@@ -20,13 +21,15 @@ pub mod store {
 	include!(concat!(env!("OUT_DIR"), "/fossil.store.rs"));
 }
 
-const CHUNK_BYTES: usize = 0x400;
+mod chunker;
+
 const DIGEST_BYTES: usize = blake3::OUT_LEN;
 
 pub struct Store {
 	meta: sled::Tree,
 	blobs: sled::Tree,
-	chunks: RefCell<fs::File>,
+	chunks: sled::Tree,
+	chunks_file: RefCell<fs::File>,
 	chunks_tail: Cell<u64>,
 }
 
@@ -37,8 +40,9 @@ impl Store {
 		let db = sled::open(path)?;
 		let meta = (&*db).clone();
 		let blobs = db.open_tree("blobs")?;
+		let chunks = db.open_tree("chunks")?;
 
-		let chunks = fs::OpenOptions::new()
+		let chunks_file = fs::OpenOptions::new()
 			.read(true)
 			.append(true)
 			.create(true)
@@ -49,12 +53,13 @@ impl Store {
 			.map(|v| BigEndian::read_u64(&v))
 			.unwrap_or_default();
 
-		chunks.set_len(chunks_tail)?;
+		chunks_file.set_len(chunks_tail)?;
 
 		Ok(Store {
 			blobs,
 			meta,
-			chunks: RefCell::new(chunks),
+			chunks,
+			chunks_file: RefCell::new(chunks_file),
 			chunks_tail: Cell::new(chunks_tail),
 		})
 	}
@@ -124,34 +129,66 @@ impl Store {
 	}
 
 	fn write_blob_inner(&self, ident: &Digest, outboard: Vec<u8>, data: &[u8]) {
-		let mut chunks_file = self.chunks.borrow_mut();
-		let offset = self.chunks_tail.get();
+		let mut chunks_file = self.chunks_file.borrow_mut();
+		let mut offset = self.chunks_tail.get();
+		let mut batch = sled::Batch::default();
 
-		chunks_file.write_all(data).unwrap();
-		let chunks_tail = offset + data.len() as u64;
+		let chunks = Chunker::from(data)
+			.map(|chunk_data| {
+				self.write_chunk(&mut chunks_file, &mut offset, &mut batch, chunk_data)
+			})
+			.collect::<Vec<_>>();
 
 		let blob_buf = store::Blob {
-			offset,
-			length: data.len() as u64,
+			chunks,
 			bao_inline: outboard,
 		}
 		.encode_to_vec();
 
 		let chunks_tail_buf = {
 			let mut buf = [0u8; 8];
-			BigEndian::write_u64(&mut buf, chunks_tail);
+			BigEndian::write_u64(&mut buf, offset);
 			buf
 		};
 
 		// TODO(edef): figure out fsync for durability
-		(&self.blobs, &self.meta)
-			.transaction(|(blobs, meta)| {
+		(&self.blobs, &self.chunks, &self.meta)
+			.transaction(|(blobs, chunks, meta)| {
+				chunks.apply_batch(&batch)?;
 				blobs.insert(&*ident.as_bytes(), &*blob_buf)?;
 				meta.insert("chunks_tail", &chunks_tail_buf)?;
 				Ok::<_, ConflictableTransactionError>(())
 			})
 			.unwrap();
-		self.chunks_tail.set(chunks_tail);
+		self.chunks_tail.set(offset);
+	}
+
+	fn write_chunk(
+		&self,
+		chunks_file: &mut fs::File,
+		offset: &mut u64,
+		batch: &mut sled::Batch,
+		data: &[u8],
+	) -> store::Chunk {
+		let ident = blake3::hash(data);
+		if let Some(chunk) = self.get_chunk(&ident) {
+			return chunk;
+		}
+
+		chunks_file.write_all(data).unwrap();
+		let chunk = store::Chunk {
+			offset: *offset,
+			length: data.len() as u32,
+		};
+		*offset += data.len() as u64;
+
+		batch.insert(ident.as_bytes(), chunk.encode_to_vec());
+		chunk
+	}
+
+	fn get_chunk(&self, ident: &Digest) -> Option<store::Chunk> {
+		let buf = self.chunks.get(&*ident.as_bytes()).unwrap()?;
+		Some(store::Chunk::decode(&*buf).unwrap())
 	}
 
 	pub fn read_blob(&self, ident: Digest) -> Vec<u8> {
@@ -168,15 +205,31 @@ impl Store {
 			.expect("blob not found");
 
 		let store::Blob {
-			offset,
-			length,
+			mut chunks,
 			bao_inline,
 		} = store::Blob::decode(&*buf).unwrap();
 
+		let mut blob_length: u64 = 0;
+		let chunks = chunks
+			.drain(..)
+			.map(|chunk| {
+				let chunk_offset = blob_length;
+				blob_length += chunk.length as u64;
+				(
+					chunk_offset,
+					Slice {
+						offset: chunk.offset,
+						length: chunk.length,
+					},
+				)
+			})
+			.collect();
+
 		Blob(bao::decode::Decoder::new_outboard(
 			RawBlob {
 				store: self,
-				slice: Slice { offset, length },
+				chunks,
+				length: blob_length,
 				position: 0,
 			},
 			io::Cursor::new(bao_inline),
@@ -211,29 +264,38 @@ impl io::Seek for Blob<'_> {
 #[derive(Debug)]
 struct Slice {
 	offset: u64,
-	length: u64,
+	length: u32,
 }
 
 struct RawBlob<'a> {
 	store: &'a Store,
-	slice: Slice,
+	chunks: BTreeMap<u64, Slice>,
+	length: u64,
 	position: u64,
 }
 
 impl io::Read for RawBlob<'_> {
 	fn read(&mut self, dst: &mut [u8]) -> io::Result<usize> {
+		let (&chunk_offset, chunk_slice) =
+			if let Some(entry) = self.chunks.range(..=self.position).next_back() {
+				entry
+			} else {
+				// empty blob
+				return Ok(0);
+			};
+
 		let prev_pos = self.position;
 		let next_pos = Ord::min(
 			self.position.saturating_add(dst.len() as u64),
-			self.slice.length,
+			chunk_offset + chunk_slice.length as u64,
 		);
 
 		let len = (next_pos - prev_pos) as usize;
 		let dst = &mut dst[..len];
 
-		let offset = self.slice.offset + prev_pos;
+		let offset = prev_pos - chunk_offset + chunk_slice.offset;
 		self.store
-			.chunks
+			.chunks_file
 			.borrow()
 			.read_exact_at(dst, offset)
 			.context("Couldn't read blob data")
@@ -257,12 +319,12 @@ impl io::Seek for RawBlob<'_> {
 	fn seek(&mut self, pos: io::SeekFrom) -> io::Result<u64> {
 		let pos = match pos {
 			io::SeekFrom::Start(n) => Some(n),
-			io::SeekFrom::End(n) => checked_add_signed(self.slice.length, n),
+			io::SeekFrom::End(n) => checked_add_signed(self.length, n),
 			io::SeekFrom::Current(n) => checked_add_signed(self.position, n),
 		};
 
 		match pos {
-			Some(n) if n <= self.slice.length => {
+			Some(n) if n <= self.length => {
 				self.position = n;
 				Ok(self.position)
 			}
diff --git a/ripple/fossil/src/store.proto b/ripple/fossil/src/store.proto
index cbeb16d..e0e3e59 100644
--- a/ripple/fossil/src/store.proto
+++ b/ripple/fossil/src/store.proto
@@ -30,7 +30,11 @@ message LinkNode {
 }
 
 message Blob {
-    uint64 offset = 1;
-    uint64 length = 2;
     bytes bao_inline = 3;
+    repeated Chunk chunks = 4;
+}
+
+message Chunk {
+    uint64 offset = 1;
+    uint32 length = 2;
 }