diff --git a/go.mod b/go.mod
index 05a2212..b96a5a8 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,6 @@ module github.com/transparency-dev/incubator
 go 1.25.0
 
 require (
-	filippo.io/torchwood v0.9.0
 	github.com/cockroachdb/pebble v1.1.5
 	github.com/go-git/go-git/v5 v5.19.0
 	github.com/google/go-cmp v0.7.0
@@ -14,6 +13,7 @@ require (
 	golang.org/x/mod v0.36.0
 	golang.org/x/sync v0.20.0
 	k8s.io/klog/v2 v2.140.0
+	rsc.io/tmp/mpt v0.2.0
 )
 
 require (
@@ -31,7 +31,6 @@ require (
 	github.com/cockroachdb/redact v1.1.5 // indirect
 	github.com/cockroachdb/tokenbucket v0.0.0-20230807174530-cc333fc44b06 // indirect
 	github.com/cyphar/filepath-securejoin v0.6.1 // indirect
-	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/emirpasic/gods v1.18.1 // indirect
 	github.com/getsentry/sentry-go v0.27.0 // indirect
 	github.com/go-git/gcfg v1.5.1-0.20230307220236-3a3c6141e376 // indirect
@@ -42,7 +41,6 @@ require (
 	github.com/golang/groupcache v0.0.0-20241129210726-2c02b8208cf8 // indirect
 	github.com/golang/protobuf v1.5.4 // indirect
 	github.com/golang/snappy v0.0.4 // indirect
-	github.com/google/uuid v1.6.0 // indirect
 	github.com/hashicorp/golang-lru/v2 v2.0.7 // indirect
 	github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99 // indirect
 	github.com/kevinburke/ssh_config v1.2.0 // indirect
@@ -50,16 +48,13 @@ require (
 	github.com/klauspost/cpuid/v2 v2.3.0 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
 	github.com/kr/text v0.2.0 // indirect
-	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
-	github.com/ncruces/go-strftime v0.1.9 // indirect
 	github.com/pjbgf/sha1cd v0.6.0 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/prometheus/client_golang v1.15.0 // indirect
 	github.com/prometheus/client_model v0.3.0 // indirect
 	github.com/prometheus/common v0.42.0 // indirect
 	github.com/prometheus/procfs v0.9.0 // indirect
-	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
 	github.com/rogpeppe/go-internal v1.14.1 // indirect
 	github.com/sergi/go-diff v1.3.2-0.20230802210424-5b0b94c5c0d3 // indirect
 	github.com/skeema/knownhosts v1.3.1 // indirect
@@ -75,9 +70,4 @@ require (
 	golang.org/x/text v0.36.0 // indirect
 	google.golang.org/protobuf v1.36.11 // indirect
 	gopkg.in/warnings.v0 v0.1.2 // indirect
-	modernc.org/libc v1.65.7 // indirect
-	modernc.org/mathutil v1.7.1 // indirect
-	modernc.org/memory v1.11.0 // indirect
-	modernc.org/sqlite v1.37.1 // indirect
-	zombiezen.com/go/sqlite v1.4.2 // indirect
 )
diff --git a/go.sum b/go.sum
index fd512e7..1af5b6a 100644
--- a/go.sum
+++ b/go.sum
@@ -1,7 +1,5 @@
 dario.cat/mergo v1.0.0 h1:AGCNq9Evsj31mOgNPcLyXc+4PNABt905YmuqPYYpBWk=
 dario.cat/mergo v1.0.0/go.mod h1:uNxQE+84aUszobStD9th8a29P2fMDhsBdgRYvZOxGmk=
-filippo.io/torchwood v0.9.0 h1:2W156cI7K3MyxEyNTuS1C9lYEW7y1u7PoHLmvgNsiZc=
-filippo.io/torchwood v0.9.0/go.mod h1:zOJguxdmaODUQScAvC80bV6N0SOA9U+bFZG1DwJU6N8=
 github.com/DataDog/zstd v1.4.5 h1:EndNeuB0l9syBZhut0wns3gV1hL8zX8LIu6ZiVHWLIQ=
 github.com/DataDog/zstd v1.4.5/go.mod h1:1jcaCB/ufaK+sKp1NBhlGmpz41jOoPQ35bpF36t7BBo=
 github.com/Microsoft/go-winio v0.5.2/go.mod h1:WpS1mjBmmwHBEWmogvA2mj8546UReBk4v8QkMxJ6pZY=
@@ -41,8 +39,6 @@ github.com/cyphar/filepath-securejoin v0.6.1/go.mod h1:A8hd4EnAeyujCJRrICiOWqjS1
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
-github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
 github.com/elazarl/goproxy v1.7.2 h1:Y2o6urb7Eule09PjlhQRGNsqRfPmYI3KKQLFpCAV3+o=
 github.com/elazarl/goproxy v1.7.2/go.mod h1:82vkLNir0ALaW14Rc399OTTjyNREgmdL2cVoIbS6XaE=
 github.com/emirpasic/gods v1.18.1 h1:FXtiHYKDGKCW2KzwZKx0iC0PQmdlorYgdFG9jPXJ1Bc=
@@ -78,8 +74,6 @@ github.com/golang/snappy v0.0.4 h1:yAGX7huGHXlcLOEtBnF4w7FQwA26wojNCwOYAEhLjQM=
 github.com/golang/snappy v0.0.4/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
-github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
-github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gorilla/mux v1.8.1 h1:TuBL49tXwgrFYWhqrNgrUNEY92u81SPhu7sTdzQEiWY=
 github.com/gorilla/mux v1.8.1/go.mod h1:AKf9I4AEqPTmMytcMc0KkNouC66V3BtZ4qD5fmWSiMQ=
 github.com/hashicorp/golang-lru/v2 v2.0.7 h1:a+bsQ5rvGLjzHuww6tVxozPZFVghXaHOwFs4luLUK2k=
@@ -101,12 +95,8 @@ github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
-github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
-github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/matttproud/golang_protobuf_extensions v1.0.4 h1:mmDVorXM7PCGKw94cs5zkfA9PSy5pEvNWRP0ET0TIVo=
 github.com/matttproud/golang_protobuf_extensions v1.0.4/go.mod h1:BSXmuO+STAnVfrANrmjBb36TMTDstsz7MSK+HVaYKv4=
-github.com/ncruces/go-strftime v0.1.9 h1:bY0MQC28UADQmHmaF5dgpLmImcShSi2kHU9XLdhx/f4=
-github.com/ncruces/go-strftime v0.1.9/go.mod h1:Fwc5htZGVVkseilnfgOVb9mKy6w1naJmn9CehxcKcls=
 github.com/onsi/gomega v1.34.1 h1:EUMJIKUjM8sKjYbtxQI9A4z2o+rruxnzNvpknOXie6k=
 github.com/onsi/gomega v1.34.1/go.mod h1:kU1QgUvBDLXBJq618Xvm2LUX6rSAfRaFRTcdOeDLwwY=
 github.com/pingcap/errors v0.11.4 h1:lFuQV/oaUMGcD2tqt+01ROSmJs75VG1ToEOkZIZ4nE4=
@@ -126,8 +116,6 @@ github.com/prometheus/common v0.42.0 h1:EKsfXEYo4JpWMHH5cg+KOUWeuJSov1Id8zGR8eeI
 github.com/prometheus/common v0.42.0/go.mod h1:xBwqVerjNdUDjgODMpudtOMwlOwf2SaTr1yjz4b7Zbc=
 github.com/prometheus/procfs v0.9.0 h1:wzCHvIvM5SxWqYvwgVL7yJY8Lz3PKn49KQtpgMYJfhI=
 github.com/prometheus/procfs v0.9.0/go.mod h1:+pB4zwohETzFnmlpe6yd2lSc+0/46IYZRB/chUwxUZY=
-github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec h1:W09IVJc94icq4NjY3clb7Lk8O1qJ8BdBEF8z0ibU0rE=
-github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
 github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
 github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
 github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
@@ -193,7 +181,6 @@ golang.org/x/sys v0.0.0-20210124154548-22da62e12c0c/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.43.0 h1:Rlag2XtaFTxp19wS8MXlJwTvoh8ArU6ezoyFsMyCTNI=
 golang.org/x/sys v0.43.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
@@ -228,31 +215,5 @@ gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 k8s.io/klog/v2 v2.140.0 h1:Tf+J3AH7xnUzZyVVXhTgGhEKnFqye14aadWv7bzXdzc=
 k8s.io/klog/v2 v2.140.0/go.mod h1:o+/RWfJ6PwpnFn7OyAG3QnO47BFsymfEfrz6XyYSSp0=
-lukechampine.com/blake3 v1.4.1 h1:I3Smz7gso8w4/TunLKec6K2fn+kyKtDxr/xcQEN84Wg=
-lukechampine.com/blake3 v1.4.1/go.mod h1:QFosUxmjB8mnrWFSNwKmvxHpfY72bmD2tQ0kBMM3kwo=
-modernc.org/cc/v4 v4.26.1 h1:+X5NtzVBn0KgsBCBe+xkDC7twLb/jNVj9FPgiwSQO3s=
-modernc.org/cc/v4 v4.26.1/go.mod h1:uVtb5OGqUKpoLWhqwNQo/8LwvoiEBLvZXIQ/SmO6mL0=
-modernc.org/ccgo/v4 v4.28.0 h1:rjznn6WWehKq7dG4JtLRKxb52Ecv8OUGah8+Z/SfpNU=
-modernc.org/ccgo/v4 v4.28.0/go.mod h1:JygV3+9AV6SmPhDasu4JgquwU81XAKLd3OKTUDNOiKE=
-modernc.org/fileutil v1.3.1 h1:8vq5fe7jdtEvoCf3Zf9Nm0Q05sH6kGx0Op2CPx1wTC8=
-modernc.org/fileutil v1.3.1/go.mod h1:HxmghZSZVAz/LXcMNwZPA/DRrQZEVP9VX0V4LQGQFOc=
-modernc.org/gc/v2 v2.6.5 h1:nyqdV8q46KvTpZlsw66kWqwXRHdjIlJOhG6kxiV/9xI=
-modernc.org/gc/v2 v2.6.5/go.mod h1:YgIahr1ypgfe7chRuJi2gD7DBQiKSLMPgBQe9oIiito=
-modernc.org/libc v1.65.7 h1:Ia9Z4yzZtWNtUIuiPuQ7Qf7kxYrxP1/jeHZzG8bFu00=
-modernc.org/libc v1.65.7/go.mod h1:011EQibzzio/VX3ygj1qGFt5kMjP0lHb0qCW5/D/pQU=
-modernc.org/mathutil v1.7.1 h1:GCZVGXdaN8gTqB1Mf/usp1Y/hSqgI2vAGGP4jZMCxOU=
-modernc.org/mathutil v1.7.1/go.mod h1:4p5IwJITfppl0G4sUEDtCr4DthTaT47/N3aT6MhfgJg=
-modernc.org/memory v1.11.0 h1:o4QC8aMQzmcwCK3t3Ux/ZHmwFPzE6hf2Y5LbkRs+hbI=
-modernc.org/memory v1.11.0/go.mod h1:/JP4VbVC+K5sU2wZi9bHoq2MAkCnrt2r98UGeSK7Mjw=
-modernc.org/opt v0.1.4 h1:2kNGMRiUjrp4LcaPuLY2PzUfqM/w9N23quVwhKt5Qm8=
-modernc.org/opt v0.1.4/go.mod h1:03fq9lsNfvkYSfxrfUhZCWPk1lm4cq4N+Bh//bEtgns=
-modernc.org/sortutil v1.2.1 h1:+xyoGf15mM3NMlPDnFqrteY07klSFxLElE2PVuWIJ7w=
-modernc.org/sortutil v1.2.1/go.mod h1:7ZI3a3REbai7gzCLcotuw9AC4VZVpYMjDzETGsSMqJE=
-modernc.org/sqlite v1.37.1 h1:EgHJK/FPoqC+q2YBXg7fUmES37pCHFc97sI7zSayBEs=
-modernc.org/sqlite v1.37.1/go.mod h1:XwdRtsE1MpiBcL54+MbKcaDvcuej+IYSMfLN6gSKV8g=
-modernc.org/strutil v1.2.1 h1:UneZBkQA+DX2Rp35KcM69cSsNES9ly8mQWD71HKlOA0=
-modernc.org/strutil v1.2.1/go.mod h1:EHkiggD70koQxjVdSBM3JKM7k6L0FbGE5eymy9i3B9A=
-modernc.org/token v1.1.0 h1:Xl7Ap9dKaEs5kLoOQeQmPWevfnk/DM5qcLcYlA8ys6Y=
-modernc.org/token v1.1.0/go.mod h1:UGzOrNV1mAFSEB63lOFHIpNRUVMvYTc6yu1SMY/XTDM=
-zombiezen.com/go/sqlite v1.4.2 h1:KZXLrBuJ7tKNEm+VJcApLMeQbhmAUOKA5VWS93DfFRo=
-zombiezen.com/go/sqlite v1.4.2/go.mod h1:5Kd4taTAD4MkBzT25mQ9uaAlLjyR0rFhsR6iINO70jc=
+rsc.io/tmp/mpt v0.2.0 h1:EORjerXrh5u8VU0INROMFgclr2HVO2XzSx9j4wmsTak=
+rsc.io/tmp/mpt v0.2.0/go.mod h1:aP1ILCaUW9I5rFbt2z0/8KYz/0FDaYfPW2zEArs+OIQ=
diff --git a/vindex/api/api.go b/vindex/api/api.go
index 8dce265..f2900b1 100644
--- a/vindex/api/api.go
+++ b/vindex/api/api.go
@@ -44,13 +44,6 @@ type LookupResponse struct {
 	// These values represent the lookup operation in the index at the root hash
 	// committed to by OutputLogLeaf. The values contain all indices for the given
 	// key, and the proof binds these values at this key at the index root hash.
-	IndexValue []uint64    `json:"index_value"`
-	IndexProof []IndexNode `json:"index_proof"`
-}
-
-// IndexNode is a node in the Verifiable Index.
-type IndexNode struct {
-	LabelBitLen uint32            `json:"label_bit_len"`
-	LabelPath   []byte            `json:"label_path"`
-	Hash        [sha256.Size]byte `json:"hash"`
+	IndexValue []uint64 `json:"index_value"`
+	IndexProof []byte   `json:"index_proof"`
 }
diff --git a/vindex/client/client.go b/vindex/client/client.go
index 4e9821d..2b28b8f 100644
--- a/vindex/client/client.go
+++ b/vindex/client/client.go
@@ -16,6 +16,7 @@
 package client
 
 import (
+	"bytes"
 	"context"
 	"crypto/sha256"
 	"encoding/binary"
@@ -27,7 +28,6 @@ import (
 	"net/http"
 	"net/url"
 
-	"filippo.io/torchwood/prefix"
 	"github.com/transparency-dev/formats/log"
 	"github.com/transparency-dev/incubator/vindex"
 	"github.com/transparency-dev/incubator/vindex/api"
@@ -37,15 +37,16 @@ import (
 	"github.com/transparency-dev/tessera/client"
 	"golang.org/x/mod/sumdb/note"
 	"k8s.io/klog/v2"
+	"rsc.io/tmp/mpt"
 )
 
-func VerifyLookupResponse(keyHash [sha256.Size]byte, resp api.LookupResponse, outV note.Verifier) ([]uint64, []byte, error) {
+func VerifyLookupResponse(keyHash [sha256.Size]byte, resp api.LookupResponse, inV, outV note.Verifier) ([]uint64, []byte, error) {
 	// Currently the response contains the RFC6962 style response type; leaf, proof, etc.
 	// What if we flip this all around, and the OutputLog part of the response
 	// only returns an index into the output log, and the client has to look up
 	// that leaf, checkpoint, and generate inclusion proof?
 
-	cp, _, _, err := log.ParseCheckpoint(resp.OutputLogCP, outV.Name(), outV)
+	olcp, _, _, err := log.ParseCheckpoint(resp.OutputLogCP, outV.Name(), outV)
 	if err != nil {
 		return nil, nil, fmt.Errorf("failed to parse output log checkpoint: %v", err)
 	}
@@ -54,8 +55,8 @@ func VerifyLookupResponse(keyHash [sha256.Size]byte, resp api.LookupResponse, ou
 	for i := range olp {
 		olp[i] = resp.OutputLogProof[i][:]
 	}
-	oli := cp.Size - 1 // TODO(mhutchinson): include this in the response?
-	if err := proof.VerifyInclusion(rfc6962.DefaultHasher, oli, cp.Size, outLeafHash[:], olp, cp.Hash); err != nil {
+	oli := olcp.Size - 1 // TODO(mhutchinson): include this in the response?
+	if err := proof.VerifyInclusion(rfc6962.DefaultHasher, oli, olcp.Size, outLeafHash[:], olp, olcp.Hash); err != nil {
 		return nil, nil, fmt.Errorf("failed to verify inclusion in output log: %v", err)
 	}
 
@@ -72,26 +73,26 @@ func VerifyLookupResponse(keyHash [sha256.Size]byte, resp api.LookupResponse, ou
 	}
 	vindexLeafHash := idxLeafHash.Sum(nil)
 
-	pns := make([]prefix.ProofNode, len(resp.IndexProof))
-	for i, p := range resp.IndexProof {
-		label, err := prefix.NewLabel(p.LabelBitLen, p.LabelPath)
-		if err != nil {
-			return nil, nil, fmt.Errorf("failed to create label: %v", err)
-		}
-		pns[i] = prefix.ProofNode{
-			Label: label,
-			Hash:  p.Hash,
-		}
+	origin := inV.Name()
+	if origin == "sum.golang.org" {
+		origin = "go.sum database tree"
+	}
+	ilcp, _, _, err := log.ParseCheckpoint(inCp, origin, inV)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to parse input log checkpoint: %v", err)
 	}
 
-	if len(resp.IndexValue) > 0 {
-		if err := prefix.VerifyMembershipProof(sha256.Sum256, keyHash, [32]byte(vindexLeafHash), pns, mapRoot); err != nil {
-			return nil, nil, fmt.Errorf("failed to verify membership: %v", err)
-		}
-	} else {
-		if err := prefix.VerifyNonMembershipProof(sha256.Sum256, keyHash, pns, mapRoot); err != nil {
-			return nil, nil, fmt.Errorf("failed to verify non-membership: %v", err)
-		}
+	snap := mpt.Snapshot{
+		Version: int64(ilcp.Size),
+		Hash:    mapRoot,
+	}
+	kvHash, ok, err := mpt.Verify(snap, keyHash, resp.IndexProof)
+	if err != nil {
+		return nil, nil, fmt.Errorf("mpt.Verify(): %v", err)
+	}
+
+	if ok && !bytes.Equal(kvHash[:], vindexLeafHash) {
+		return nil, nil, fmt.Errorf("failed to verify membership: %x != %x", kvHash, vindexLeafHash)
 	}
 
 	return resp.IndexValue, inCp, nil
@@ -100,7 +101,7 @@ func VerifyLookupResponse(keyHash [sha256.Size]byte, resp api.LookupResponse, ou
 // NewVIndexClient returns a client that can perform verified lookups into the index at the
 // given base URL, using the supplied verifier to check checkpoint signatures on the output
 // log.
-func NewVIndexClient(vindexUrl string, outV note.Verifier) (*VIndexClient, error) {
+func NewVIndexClient(vindexUrl string, inV, outV note.Verifier) (*VIndexClient, error) {
 	viu, err := url.Parse(vindexUrl)
 	if err != nil {
 		return nil, fmt.Errorf("failed to parse URL: %v", err)
@@ -109,6 +110,7 @@ func NewVIndexClient(vindexUrl string, outV note.Verifier) (*VIndexClient, error
 
 	return &VIndexClient{
 		lookupURL: lookupURL,
+		inV:       inV,
 		outV:      outV,
 	}, nil
 }
@@ -116,7 +118,7 @@ func NewVIndexClient(vindexUrl string, outV note.Verifier) (*VIndexClient, error
 // VIndexClient allows verified lookups into a verifiable index.
 type VIndexClient struct {
 	lookupURL *url.URL
-	outV      note.Verifier
+	inV, outV note.Verifier
 }
 
 // Lookup returns all indices, in ascending order, where the given key appears in the Input Log.
@@ -137,7 +139,7 @@ func (c VIndexClient) Lookup(ctx context.Context, key string) ([]uint64, []byte,
 		return nil, nil, fmt.Errorf("lookup failed: %v", err)
 	}
 
-	return VerifyLookupResponse(kh, resp, c.outV)
+	return VerifyLookupResponse(kh, resp, c.inV, c.outV)
 }
 
 func (c VIndexClient) lookupUnverified(ctx context.Context, kh [sha256.Size]byte) (api.LookupResponse, error) {
diff --git a/vindex/cmd/client/client.go b/vindex/cmd/client/client.go
index 2a6b669..a0b32ec 100644
--- a/vindex/cmd/client/client.go
+++ b/vindex/cmd/client/client.go
@@ -104,11 +104,15 @@ func newVIndexClientFromFlags() *client.VIndexClient {
 	if *outLogPubKey == "" {
 		klog.Exitf("out_log_pub_key must be provided")
 	}
+	inV, err := note.NewVerifier(*inLogPubKey)
+	if err != nil {
+		klog.Exitf("failed to construct input log verifier: %v", err)
+	}
 	outV, err := note.NewVerifier(*outLogPubKey)
 	if err != nil {
 		klog.Exitf("failed to construct output log verifier: %v", err)
 	}
-	c, err := client.NewVIndexClient(*vindexBaseURL, outV)
+	c, err := client.NewVIndexClient(*vindexBaseURL, inV, outV)
 	if err != nil {
 		klog.Exitf("failed to construct VIndex Client: %v", err)
 	}
diff --git a/vindex/cmd/sumdbverify/client.go b/vindex/cmd/sumdbverify/client.go
index e359997..1e390af 100644
--- a/vindex/cmd/sumdbverify/client.go
+++ b/vindex/cmd/sumdbverify/client.go
@@ -50,6 +50,7 @@ import (
 
 var (
 	baseURL      = flag.String("base_url", "", "The base URL of the server hosting the logs and vindex.")
+	inLogPubKey  = flag.String("in_log_pub_key", "sum.golang.org+033de0ae+Ac4zctda0e5eza+HJyk9SxEdh+s3Ux18htTTAD8OuAn8", "The input log public key.")
 	outLogPubKey = flag.String("out_log_pub_key", "", "The public key to use to verify the output log checkpoint.")
 	modRoot      = flag.String("mod_root", "", "The path to a go module checked out locally via git.")
 )
@@ -472,6 +473,10 @@ func parseLeaf(idx uint64, data []byte) (string, modData, error) {
 }
 
 func newVIndexClientFromFlags() *client.VIndexClient {
+	inV, err := note.NewVerifier(*inLogPubKey)
+	if err != nil {
+		klog.Exitf("failed to construct Input Log verifier: %v", err)
+	}
 	outV, err := note.NewVerifier(*outLogPubKey)
 	if err != nil {
 		klog.Exitf("failed to construct VIndex verifier: %v", err)
@@ -480,7 +485,7 @@ func newVIndexClientFromFlags() *client.VIndexClient {
 	if err != nil {
 		klog.Exitf("failed to construct VIndex URL: %v", err)
 	}
-	c, err := client.NewVIndexClient(u, outV)
+	c, err := client.NewVIndexClient(u, inV, outV)
 	if err != nil {
 		klog.Exitf("failed to construct VIndex Client: %v", err)
 	}
@@ -488,7 +493,7 @@ func newVIndexClientFromFlags() *client.VIndexClient {
 }
 
 func newInputLogClientFromFlags() *client.InputLogClient {
-	v, err := note.NewVerifier("sum.golang.org+033de0ae+Ac4zctda0e5eza+HJyk9SxEdh+s3Ux18htTTAD8OuAn8")
+	v, err := note.NewVerifier(*inLogPubKey)
 	if err != nil {
 		klog.Exitf("failed to construct Input Log verifier: %v", err)
 	}
diff --git a/vindex/map.go b/vindex/map.go
index c83d8b0..2e3b0dc 100644
--- a/vindex/map.go
+++ b/vindex/map.go
@@ -28,6 +28,7 @@ import (
 	"fmt"
 	"io"
 	"iter"
+	"math"
 	"os"
 	"path"
 	"slices"
@@ -35,14 +36,13 @@ import (
 	"sync"
 	"time"
 
-	"filippo.io/torchwood/prefix"
-	"filippo.io/torchwood/prefix/prefixsqlite"
 	"github.com/cockroachdb/pebble"
 	"github.com/transparency-dev/formats/log"
 	"github.com/transparency-dev/incubator/vindex/api"
 	"github.com/transparency-dev/merkle/compact"
 	"github.com/transparency-dev/merkle/rfc6962"
 	"k8s.io/klog/v2"
+	"rsc.io/tmp/mpt"
 )
 
 const (
@@ -157,18 +157,9 @@ func NewVerifiableIndex(ctx context.Context, inputLog InputLog, mapFn MapFn, out
 		return nil, err
 	}
 
-	var vtreeStorage prefix.Storage
-	if opts.PersistIndex {
-		vtreeStorage, err = prefixsqlite.NewSQLiteStorage(ctx, path.Join(rootDir, "vindex.db"))
-	} else {
-		vtreeStorage = prefix.NewMemoryStorage()
-	}
-	if err != nil {
-		return nil, fmt.Errorf("failed to create SQL storage: %v", err)
-	}
-	if err := prefix.InitStorage(ctx, sha256.Sum256, vtreeStorage); err != nil {
-		return nil, fmt.Errorf("InitStorage: %s", err)
-	}
+	// TODO(mpt): This needs to be a file-backed tree before submitting
+	tree := mpt.NewMemTree()
+
 	mapper := &inputLogMapper{
 		inputLog:  inputLog,
 		mapFn:     mapFn,
@@ -181,8 +172,7 @@ func NewVerifiableIndex(ctx context.Context, inputLog InputLog, mapFn MapFn, out
 		walReader: reader,
 		db:        db,
 		outputLog: outputLog,
-		vindex:    *prefix.NewTree(sha256.Sum256, vtreeStorage),
-		vstore:    vtreeStorage,
+		vindex:    tree,
 		data:      map[[sha256.Size]byte][]uint64{},
 	}
 	// If we persisted the index then we don't need to rebuild it
@@ -351,8 +341,7 @@ type VerifiableIndex struct {
 	outputLog OutputLog
 
 	indexMu sync.RWMutex // covers vindex and data
-	vindex  prefix.Tree
-	vstore  prefix.Storage
+	vindex  mpt.Tree
 	data    map[[sha256.Size]byte][]uint64
 
 	// servingSize is the size of the input log we are serving for.
@@ -370,11 +359,11 @@ func (b *VerifiableIndex) Close() error {
 func (b *VerifiableIndex) Lookup(ctx context.Context, key [sha256.Size]byte) (api.LookupResponse, error) {
 	// Scope the lock to be as minimal as possible
 	// This looks up the indices from the in-memory map, and the proof from the vindex.
-	lookupLocked := func(key [sha256.Size]byte) (bool, []prefix.ProofNode, []uint64, error) {
+	lookupLocked := func(key [sha256.Size]byte) (mpt.Proof, []uint64, error) {
 		b.indexMu.RLock()
 		defer b.indexMu.RUnlock()
-		found, viProof, err := b.vindex.Lookup(ctx, key)
-		return found, viProof, b.data[key], err
+		proof, err := b.vindex.Prove(key)
+		return proof, b.data[key], err
 	}
 
 	result := api.LookupResponse{}
@@ -410,7 +399,7 @@ func (b *VerifiableIndex) Lookup(ctx context.Context, key [sha256.Size]byte) (ap
 	result.OutputLogLeaf = data
 	result.OutputLogProof = proof
 
-	found, viProof, allIndices, err := lookupLocked(key)
+	viProof, allIndices, err := lookupLocked(key)
 	if err != nil {
 		return result, fmt.Errorf("failed to get inclusion proof from vindex: %v", err)
 	}
@@ -424,17 +413,11 @@ func (b *VerifiableIndex) Lookup(ctx context.Context, key [sha256.Size]byte) (ap
 	}
 	result.IndexValue = allIndices
 
-	if expectFound := len(allIndices) > 0; expectFound != found {
-		return result, fmt.Errorf("found = %t, but expected %t (number of indices: %d)", found, expectFound, len(allIndices))
-	}
-	result.IndexProof = make([]api.IndexNode, len(viProof))
-	for i, p := range viProof {
-		result.IndexProof[i] = api.IndexNode{
-			LabelBitLen: p.Label.BitLen(),
-			LabelPath:   p.Label.Bytes(),
-			Hash:        p.Hash,
-		}
-	}
+	// TODO(mpt): Do we want to reimplement this?
+	// if expectFound := len(allIndices) > 0; expectFound != found {
+	// 	return result, fmt.Errorf("found = %t, but expected %t (number of indices: %d)", found, expectFound, len(allIndices))
+	// }
+	result.IndexProof = viProof
 
 	return result, nil
 }
@@ -451,11 +434,15 @@ func (b *VerifiableIndex) Update(ctx context.Context) error {
 
 func (b *VerifiableIndex) publish(ctx context.Context, inCp []byte) error {
 	// Construct the leaf for the output log
-	rootNode, err := b.vstore.Load(ctx, prefix.RootLabel)
+
+	if b.servingSize > math.MaxInt64 {
+		return fmt.Errorf("servingSize %d exceeds MaxInt64", b.servingSize)
+	}
+	snap, err := b.vindex.Snap(int64(b.servingSize))
 	if err != nil {
-		return fmt.Errorf("failed to load vindex root: %v", err)
+		return fmt.Errorf("Snap(): %v", err)
 	}
-	outIdx, rawCp, err := b.outputLog.Append(ctx, MarshalLeaf(rootNode.Hash, inCp))
+	outIdx, rawCp, err := b.outputLog.Append(ctx, MarshalLeaf(snap.Hash, inCp))
 	if err != nil {
 		return fmt.Errorf("failed to append to output log: %v", err)
 	}
@@ -577,8 +564,7 @@ func (b *VerifiableIndex) buildMap(ctx context.Context, updateIndex bool) error
 				}
 			}
 
-			// Finally, we update the vindex
-			if err := b.vindex.Insert(ctx, h, [sha256.Size]byte(sum.Sum(nil))); err != nil {
+			if err := b.vindex.Set(h, [sha256.Size]byte(sum.Sum(nil))); err != nil {
 				return fmt.Errorf("Insert(): %s", err)
 			}
 		}
diff --git a/vindex/map_test.go b/vindex/map_test.go
index 769f28c..e2a6eed 100644
--- a/vindex/map_test.go
+++ b/vindex/map_test.go
@@ -102,7 +102,7 @@ func TestVerifiableIndex(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	indices, _, err := client.VerifyLookupResponse(kh, resp, v)
+	indices, _, err := client.VerifyLookupResponse(kh, resp, v, v)
 	if err != nil {
 		t.Fatalf("failed to verify vindex response: %v", err)
 	}
@@ -115,7 +115,7 @@ func TestVerifiableIndex(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	indices, _, err = client.VerifyLookupResponse(kh, resp, v)
+	indices, _, err = client.VerifyLookupResponse(kh, resp, v, v)
 	if err != nil {
 		t.Fatalf("failed to verify vindex response: %v", err)
 	}
@@ -128,7 +128,7 @@ func TestVerifiableIndex(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	indices, _, err = client.VerifyLookupResponse(kh, resp, v)
+	indices, _, err = client.VerifyLookupResponse(kh, resp, v, v)
 	if err != nil {
 		t.Fatalf("failed to verify vindex response: %v", err)
 	}
@@ -248,7 +248,7 @@ func TestVerifiableIndex_concurrency(t *testing.T) {
 				if err != nil {
 					return err
 				}
-				indices, _, err = client.VerifyLookupResponse(kh, resp, v)
+				indices, _, err = client.VerifyLookupResponse(kh, resp, v, v)
 				if err != nil {
 					return fmt.Errorf("failed to verify vindex response: %v", err)
 				}
@@ -261,7 +261,7 @@ func TestVerifiableIndex_concurrency(t *testing.T) {
 				if err != nil {
 					return err
 				}
-				indices, _, err = client.VerifyLookupResponse(kh, resp, v)
+				indices, _, err = client.VerifyLookupResponse(kh, resp, v, v)
 				if err != nil {
 					return fmt.Errorf("failed to verify vindex response: %v", err)
 				}