diff --git a/config/api_config.go b/config/api_config.go
index 25a77f6a..e68d73c4 100644
--- a/config/api_config.go
+++ b/config/api_config.go
@@ -1,3 +1,6 @@
+// Copyright (C) 2024, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
 package config
 
 import (
diff --git a/go.mod b/go.mod
index 584b6c2d..301b50cf 100644
--- a/go.mod
+++ b/go.mod
@@ -11,8 +11,8 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/kms v1.35.5
 	github.com/ethereum/go-ethereum v1.13.8
 	github.com/hashicorp/golang-lru/v2 v2.0.7
-	github.com/onsi/ginkgo/v2 v2.20.1
-	github.com/onsi/gomega v1.34.1
+	github.com/onsi/ginkgo/v2 v2.20.2
+	github.com/onsi/gomega v1.34.2
 	github.com/pingcap/errors v0.11.4
 	github.com/pkg/errors v0.9.1
 	github.com/prometheus/client_golang v1.20.2
@@ -22,7 +22,7 @@ require (
 	github.com/stretchr/testify v1.9.0
 	go.uber.org/mock v0.4.0
 	go.uber.org/zap v1.27.0
-	google.golang.org/grpc v1.65.0
+	google.golang.org/grpc v1.66.0
 	google.golang.org/protobuf v1.34.2
 )
 
@@ -80,7 +80,7 @@ require (
 	github.com/golang/snappy v0.0.5-0.20220116011046-fa5810519dcb // indirect
 	github.com/google/btree v1.1.2 // indirect
 	github.com/google/go-cmp v0.6.0 // indirect
-	github.com/google/pprof v0.0.0-20240727154555-813a5fbdbec8 // indirect
+	github.com/google/pprof v0.0.0-20240827171923-fa2c70bbbfe5 // indirect
 	github.com/google/renameio/v2 v2.0.0 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/gorilla/mux v1.8.0 // indirect
@@ -146,14 +146,14 @@ require (
 	golang.org/x/crypto v0.26.0 // indirect
 	golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56 // indirect
 	golang.org/x/net v0.28.0 // indirect
-	golang.org/x/sys v0.23.0 // indirect
+	golang.org/x/sys v0.24.0 // indirect
 	golang.org/x/term v0.23.0 // indirect
 	golang.org/x/text v0.17.0 // indirect
 	golang.org/x/time v0.3.0 // indirect
 	golang.org/x/tools v0.24.0 // indirect
 	gonum.org/v1/gonum v0.11.0 // indirect
-	google.golang.org/genproto/googleapis/api v0.0.0-20240528184218-531527333157 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20240528184218-531527333157 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20240604185151-ef581f913117 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20240604185151-ef581f913117 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/natefinch/lumberjack.v2 v2.0.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
diff --git a/go.sum b/go.sum
index 556ff3b2..4be54bcb 100644
--- a/go.sum
+++ b/go.sum
@@ -336,8 +336,8 @@ github.com/google/pprof v0.0.0-20201203190320-1bf35d6f28c2/go.mod h1:kpwsk12EmLe
 github.com/google/pprof v0.0.0-20201218002935-b9804c9f04c2/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
 github.com/google/pprof v0.0.0-20210407192527-94a9f03dee38/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
 github.com/google/pprof v0.0.0-20230207041349-798e818bf904/go.mod h1:uglQLonpP8qtYCYyzA+8c/9qtqgA3qsXGYqCPKARAFg=
-github.com/google/pprof v0.0.0-20240727154555-813a5fbdbec8 h1:FKHo8hFI3A+7w0aUQuYXQ+6EN5stWmeY/AZqtM8xk9k=
-github.com/google/pprof v0.0.0-20240727154555-813a5fbdbec8/go.mod h1:K1liHPHnj73Fdn/EKuT8nrFqBihUSKXoLYU0BuatOYo=
+github.com/google/pprof v0.0.0-20240827171923-fa2c70bbbfe5 h1:5iH8iuqE5apketRbSFBy+X1V0o+l+8NF1avt4HWl7cA=
+github.com/google/pprof v0.0.0-20240827171923-fa2c70bbbfe5/go.mod h1:vavhavw2zAxS5dIdcRluK6cSGGPlZynqzFM8NdvU144=
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
 github.com/google/renameio/v2 v2.0.0 h1:UifI23ZTGY8Tt29JbYFiuyIU3eX+RNFtUwefq9qAhxg=
 github.com/google/renameio/v2 v2.0.0/go.mod h1:BtmJXm5YlszgC+TD4HOEEUFgkJP3nLxehU6hfe7jRt4=
@@ -494,16 +494,16 @@ github.com/onsi/ginkgo v1.16.4/go.mod h1:dX+/inL/fNMqNlz0e9LfyB9TswhZpCVdJM/Z6Vv
 github.com/onsi/ginkgo v1.16.5 h1:8xi0RTUf59SOSfEtZMvwTvXYMzG4gV23XVHOZiXNtnE=
 github.com/onsi/ginkgo v1.16.5/go.mod h1:+E8gABHa3K6zRBolWtd+ROzc/U5bkGt0FwiG042wbpU=
 github.com/onsi/ginkgo/v2 v2.1.3/go.mod h1:vw5CSIxN1JObi/U8gcbwft7ZxR2dgaR70JSE3/PpL4c=
-github.com/onsi/ginkgo/v2 v2.20.1 h1:YlVIbqct+ZmnEph770q9Q7NVAz4wwIiVNahee6JyUzo=
-github.com/onsi/ginkgo/v2 v2.20.1/go.mod h1:lG9ey2Z29hR41WMVthyJBGUBcBhGOtoPF2VFMvBXFCI=
+github.com/onsi/ginkgo/v2 v2.20.2 h1:7NVCeyIWROIAheY21RLS+3j2bb52W0W82tkberYytp4=
+github.com/onsi/ginkgo/v2 v2.20.2/go.mod h1:K9gyxPIlb+aIvnZ8bd9Ak+YP18w3APlR+5coaZoE2ag=
 github.com/onsi/gomega v1.4.1/go.mod h1:C1qb7wdrVGGVU+Z6iS04AVkA3Q65CEZX59MT0QO5uiA=
 github.com/onsi/gomega v1.4.3/go.mod h1:ex+gbHU/CVuBBDIJjb2X0qEXbFg53c61hWP/1CpauHY=
 github.com/onsi/gomega v1.7.1/go.mod h1:XdKZgCCFLUoM/7CFJVPcG8C1xQ1AJ0vpAezJrB7JYyY=
 github.com/onsi/gomega v1.10.1/go.mod h1:iN09h71vgCQne3DLsj+A5owkum+a2tYe+TOCB1ybHNo=
 github.com/onsi/gomega v1.17.0/go.mod h1:HnhC7FXeEQY45zxNK3PPoIUhzk/80Xly9PcubAlGdZY=
 github.com/onsi/gomega v1.19.0/go.mod h1:LY+I3pBVzYsTBU1AnDwOSxaYi9WoWiqgwooUqq9yPro=
-github.com/onsi/gomega v1.34.1 h1:EUMJIKUjM8sKjYbtxQI9A4z2o+rruxnzNvpknOXie6k=
-github.com/onsi/gomega v1.34.1/go.mod h1:kU1QgUvBDLXBJq618Xvm2LUX6rSAfRaFRTcdOeDLwwY=
+github.com/onsi/gomega v1.34.2 h1:pNCwDkzrsv7MS9kpaQvVb1aVLahQXyJ/Tv5oAZMI3i8=
+github.com/onsi/gomega v1.34.2/go.mod h1:v1xfxRgk0KIsG+QOdm7p8UosrOzPYRo60fd3B/1Dukc=
 github.com/pelletier/go-toml v1.2.0/go.mod h1:5z9KED0ma1S8pY6P1sdut58dfprrGBbd/94hg7ilaic=
 github.com/pelletier/go-toml/v2 v2.0.8 h1:0ctb6s9mE31h0/lhu+J6OPmVeDxJn+kYnJc2jZR9tGQ=
 github.com/pelletier/go-toml/v2 v2.0.8/go.mod h1:vuYfssBdrU2XDZ9bYydBu6t+6a6PYNcZljzZR9VXg+4=
@@ -851,8 +851,8 @@ golang.org/x/sys v0.0.0-20220908164124-27713097b956/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.11.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.23.0 h1:YfKFowiIMvtgl1UERQoTPPToxltDeZfbj4H7dVUCwmM=
-golang.org/x/sys v0.23.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.24.0 h1:Twjiwq9dn6R1fQcyiK+wQyHWfaz/BJB+YIpzU/Cv3Xg=
+golang.org/x/sys v0.24.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.23.0 h1:F6D4vR+EHoL9/sWAWgAR1H2DcHr4PareCbAaCo1RpuU=
@@ -1003,10 +1003,10 @@ google.golang.org/genproto v0.0.0-20201214200347-8c77b98c765d/go.mod h1:FWY/as6D
 google.golang.org/genproto v0.0.0-20210108203827-ffc7fda8c3d7/go.mod h1:FWY/as6DDZQgahTzZj3fqbO1CbirC29ZNUFHwi0/+no=
 google.golang.org/genproto v0.0.0-20210226172003-ab064af71705/go.mod h1:FWY/as6DDZQgahTzZj3fqbO1CbirC29ZNUFHwi0/+no=
 google.golang.org/genproto v0.0.0-20210624195500-8bfb893ecb84/go.mod h1:SzzZ/N+nwJDaO1kznhnlzqS8ocJICar6hYhVyhi++24=
-google.golang.org/genproto/googleapis/api v0.0.0-20240528184218-531527333157 h1:7whR9kGa5LUwFtpLm2ArCEejtnxlGeLbAyjFY8sGNFw=
-google.golang.org/genproto/googleapis/api v0.0.0-20240528184218-531527333157/go.mod h1:99sLkeliLXfdj2J75X3Ho+rrVCaJze0uwN7zDDkjPVU=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20240528184218-531527333157 h1:Zy9XzmMEflZ/MAaA7vNcoebnRAld7FsPW1EeBB7V0m8=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20240528184218-531527333157/go.mod h1:EfXuqaE1J41VCDicxHzUDm+8rk+7ZdXzHV0IhO/I6s0=
+google.golang.org/genproto/googleapis/api v0.0.0-20240604185151-ef581f913117 h1:+rdxYoE3E5htTEWIe15GlN6IfvbURM//Jt0mmkmm6ZU=
+google.golang.org/genproto/googleapis/api v0.0.0-20240604185151-ef581f913117/go.mod h1:OimBR/bc1wPO9iV4NC2bpyjy3VnAwZh5EBPQdtaE5oo=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20240604185151-ef581f913117 h1:1GBuWVLM/KMVUv1t1En5Gs+gFZCNd360GGb4sSxtrhU=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20240604185151-ef581f913117/go.mod h1:EfXuqaE1J41VCDicxHzUDm+8rk+7ZdXzHV0IhO/I6s0=
 google.golang.org/grpc v1.12.0/go.mod h1:yo6s7OP7yaDglbqo1J04qKzAhqBH6lvTonzMVmEdcZw=
 google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=
 google.golang.org/grpc v1.20.1/go.mod h1:10oTOabMzJvdu6/UiuZezV6QK5dSlG84ov/aaiqXj38=
@@ -1025,8 +1025,8 @@ google.golang.org/grpc v1.33.2/go.mod h1:JMHMWHQWaTccqQQlmk3MJZS+GWXOdAesneDmEnv
 google.golang.org/grpc v1.34.0/go.mod h1:WotjhfgOW/POjDeRt8vscBtXq+2VjORFy659qA51WJ8=
 google.golang.org/grpc v1.35.0/go.mod h1:qjiiYl8FncCW8feJPdyg3v6XW24KsRHe+dy9BAGRRjU=
 google.golang.org/grpc v1.38.0/go.mod h1:NREThFqKR1f3iQ6oBuvc5LadQuXVGo9rkm5ZGrQdJfM=
-google.golang.org/grpc v1.65.0 h1:bs/cUb4lp1G5iImFFd3u5ixQzweKizoZJAwBNLR42lc=
-google.golang.org/grpc v1.65.0/go.mod h1:WgYC2ypjlB0EiQi6wdKixMqukr6lBc0Vo+oOgjrM5ZQ=
+google.golang.org/grpc v1.66.0 h1:DibZuoBznOxbDQxRINckZcUvnCEvrW9pcWIE2yF9r1c=
+google.golang.org/grpc v1.66.0/go.mod h1:s3/l6xSSCURdVfAnL+TqCNMyTDAGN6+lZeVxnZR128Y=
 google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8=
 google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64/go.mod h1:kwYJMbMJ01Woi6D6+Kah6886xMZcty6N08ah7+eCXa0=
 google.golang.org/protobuf v0.0.0-20200228230310-ab0ca4ff8a60/go.mod h1:cfTl7dwQJ+fmap5saPgwCLgHXTUD7jkjRqWcaiX5VyM=
diff --git a/relayer/config/config.go b/relayer/config/config.go
index 57ea0822..3f643dd2 100644
--- a/relayer/config/config.go
+++ b/relayer/config/config.go
@@ -8,6 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"net/url"
+	"time"
 
 	basecfg "github.com/ava-labs/awm-relayer/config"
 	"github.com/ava-labs/awm-relayer/peers"
@@ -67,6 +68,9 @@ type Config struct {
 	DeciderURL             string                   `mapstructure:"decider-url" json:"decider-url"`
 	SignatureCacheSize     uint64                   `mapstructure:"signature-cache-size" json:"signature-cache-size"`
 
+	// mapstructure doesn't handle time.Time out of the box so handle it manually
+	EtnaTime time.Time `json:"etna-time"`
+
 	// convenience field to fetch a blockchain's subnet ID
 	blockchainIDToSubnetID map[ids.ID]ids.ID
 	overwrittenOptions     []string
diff --git a/relayer/config/keys.go b/relayer/config/keys.go
index 1c426fe0..fa211fc2 100644
--- a/relayer/config/keys.go
+++ b/relayer/config/keys.go
@@ -24,4 +24,5 @@ const (
 	ManualWarpMessagesKey     = "manual-warp-messages"
 	DBWriteIntervalSecondsKey = "db-write-interval-seconds"
 	SignatureCacheSizeKey     = "signature-cache-size"
+	EtnaTimeKey               = "etna-time"
 )
diff --git a/relayer/config/viper.go b/relayer/config/viper.go
index 507bd952..4e0e279b 100644
--- a/relayer/config/viper.go
+++ b/relayer/config/viper.go
@@ -84,6 +84,9 @@ func BuildConfig(v *viper.Viper) (Config, error) {
 		return cfg, fmt.Errorf("failed to unmarshal viper config: %w", err)
 	}
 
+	// Manually set EtnaTime field since it's not automatically parseable using mapstructure
+	cfg.EtnaTime = v.GetTime(EtnaTimeKey)
+
 	// Explicitly overwrite the configured account private key
 	// If account-private-key is set as a flag or environment variable,
 	// overwrite all destination subnet configurations to use that key
diff --git a/relayer/main/main.go b/relayer/main/main.go
index 358561c7..3ee92351 100644
--- a/relayer/main/main.go
+++ b/relayer/main/main.go
@@ -227,6 +227,7 @@ func main() {
 			prometheus.DefaultRegisterer,
 		),
 		messageCreator,
+		cfg.EtnaTime,
 	)
 	if err != nil {
 		logger.Fatal("Failed to create signature aggregator", zap.Error(err))
diff --git a/signature-aggregator/README.md b/signature-aggregator/README.md
index 413a65d6..3f8b02ac 100644
--- a/signature-aggregator/README.md
+++ b/signature-aggregator/README.md
@@ -59,9 +59,9 @@ curl --location 'https://api.avax-test.network/ext/bc/C/rpc' \
    The topic of the message will be `0x56600c567728a800c0aa927500f831cb451df66a7af570eb4df4dfbf4674887d` which is the output of`cast keccak "SendWarpMessage(address,bytes32,bytes)"`
 4. Use the data field of the log message found in step 2 and send it to the locally running service via curl.
 ```bash
-curl --location 'http://localhost:8080/aggregate-signatures/by-raw-message' \
+curl --location 'http://localhost:8080/aggregate-signatures' \
 --header 'Content-Type: application/json' \
 --data '{
-    "data": "<hex encoded unsigned message bytes retrieved from the logs>",
+    "message": "<hex encoded unsigned message bytes retrieved from the logs>"
 }'
 ```
diff --git a/signature-aggregator/aggregator/aggregator.go b/signature-aggregator/aggregator/aggregator.go
index 01817491..cea134a7 100644
--- a/signature-aggregator/aggregator/aggregator.go
+++ b/signature-aggregator/aggregator/aggregator.go
@@ -19,6 +19,7 @@ import (
 	"github.com/ava-labs/avalanchego/proto/pb/p2p"
 	"github.com/ava-labs/avalanchego/proto/pb/sdk"
 	"github.com/ava-labs/avalanchego/subnets"
+	"github.com/ava-labs/avalanchego/utils/constants"
 	"github.com/ava-labs/avalanchego/utils/crypto/bls"
 	"github.com/ava-labs/avalanchego/utils/logging"
 	"github.com/ava-labs/avalanchego/utils/set"
@@ -27,6 +28,8 @@ import (
 	"github.com/ava-labs/awm-relayer/signature-aggregator/aggregator/cache"
 	"github.com/ava-labs/awm-relayer/signature-aggregator/metrics"
 	"github.com/ava-labs/awm-relayer/utils"
+	corethMsg "github.com/ava-labs/coreth/plugin/evm/message"
+	msg "github.com/ava-labs/subnet-evm/plugin/evm/message"
 	"go.uber.org/zap"
 	"google.golang.org/protobuf/proto"
 )
@@ -42,6 +45,9 @@ const (
 )
 
 var (
+	codec       = msg.Codec
+	corethCodec = corethMsg.Codec
+
 	// Errors
 	errNotEnoughSignatures     = errors.New("failed to collect a threshold of signatures")
 	errNotEnoughConnectedStake = errors.New("failed to connect to a threshold of stake")
@@ -57,6 +63,7 @@ type SignatureAggregator struct {
 	subnetsMapLock          sync.RWMutex
 	metrics                 *metrics.SignatureAggregatorMetrics
 	cache                   *cache.Cache
+	etnaTime                time.Time
 }
 
 func NewSignatureAggregator(
@@ -65,6 +72,7 @@ func NewSignatureAggregator(
 	signatureCacheSize uint64,
 	metrics *metrics.SignatureAggregatorMetrics,
 	messageCreator message.Creator,
+	etnaTime time.Time,
 ) (*SignatureAggregator, error) {
 	cache, err := cache.NewCache(signatureCacheSize, logger)
 	if err != nil {
@@ -81,6 +89,7 @@ func NewSignatureAggregator(
 		messageCreator:          messageCreator,
 		currentRequestID:        atomic.Uint32{},
 		cache:                   cache,
+		etnaTime:                etnaTime,
 	}
 	sa.currentRequestID.Store(rand.Uint32())
 	return &sa, nil
@@ -174,14 +183,7 @@ func (s *SignatureAggregator) CreateSignedMessage(
 		))
 	}
 
-	reqBytes := networkP2P.ProtocolPrefix(networkP2P.SignatureRequestHandlerID)
-	messageBytes, err := proto.Marshal(
-		&sdk.SignatureRequest{
-			Message:       unsignedMessage.Bytes(),
-			Justification: justification,
-		},
-	)
-	reqBytes = append(reqBytes, messageBytes...)
+	reqBytes, err := s.marshalRequest(unsignedMessage, justification, sourceSubnet)
 	if err != nil {
 		msg := "Failed to marshal request bytes"
 		s.logger.Error(
@@ -517,15 +519,13 @@ func (s *SignatureAggregator) isValidSignatureResponse(
 		return blsSignatureBuf{}, false
 	}
 
-	sigResponse := sdk.SignatureResponse{}
-	err := proto.Unmarshal(appResponse.AppBytes, &sigResponse)
+	signature, err := s.unmarshalResponse(appResponse.AppBytes)
 	if err != nil {
 		s.logger.Error(
 			"Error unmarshaling signature response",
 			zap.Error(err),
 		)
 	}
-	signature := sigResponse.Signature
 
 	// If the node returned an empty signature, then it has not yet seen the warp message. Retry later.
 	emptySignature := blsSignatureBuf{}
@@ -560,9 +560,8 @@ func (s *SignatureAggregator) isValidSignatureResponse(
 		)
 		return blsSignatureBuf{}, false
 	}
-	blsSig := blsSignatureBuf{}
-	copy(blsSig[:], signature[:])
-	return blsSig, true
+
+	return signature, true
 }
 
 // aggregateSignatures constructs a BLS aggregate signature from the collected validator signatures. Also
@@ -594,3 +593,61 @@ func (s *SignatureAggregator) aggregateSignatures(
 	}
 	return aggSig, vdrBitSet, nil
 }
+
+// TODO: refactor this to remove special handling based on etnaTime
+// after Etna release, along with related config and testing code
+func (s *SignatureAggregator) marshalRequest(
+	unsignedMessage *avalancheWarp.UnsignedMessage,
+	justification []byte,
+	sourceSubnet ids.ID,
+) ([]byte, error) {
+	if !s.etnaTime.IsZero() && s.etnaTime.Before(time.Now()) {
+		// Post-Etna case
+		messageBytes, err := proto.Marshal(
+			&sdk.SignatureRequest{
+				Message:       unsignedMessage.Bytes(),
+				Justification: justification,
+			},
+		)
+		if err != nil {
+			return nil, err
+		}
+		return networkP2P.PrefixMessage(
+			networkP2P.ProtocolPrefix(networkP2P.SignatureRequestHandlerID),
+			messageBytes,
+		), nil
+	} else {
+		// Pre-Etna case
+		if sourceSubnet == constants.PrimaryNetworkID {
+			req := corethMsg.MessageSignatureRequest{
+				MessageID: unsignedMessage.ID(),
+			}
+			return corethMsg.RequestToBytes(corethCodec, req)
+		} else {
+			req := msg.MessageSignatureRequest{
+				MessageID: unsignedMessage.ID(),
+			}
+			return msg.RequestToBytes(codec, req)
+		}
+	}
+}
+
+func (s *SignatureAggregator) unmarshalResponse(responseBytes []byte) (blsSignatureBuf, error) {
+	if !s.etnaTime.IsZero() && s.etnaTime.Before(time.Now()) {
+		// Post-Etna case
+		var sigResponse sdk.SignatureResponse
+		err := proto.Unmarshal(responseBytes, &sigResponse)
+		if err != nil {
+			return blsSignatureBuf{}, err
+		}
+		return blsSignatureBuf(sigResponse.Signature), nil
+	} else {
+		// Pre-Etna case
+		var sigResponse msg.SignatureResponse
+		_, err := msg.Codec.Unmarshal(responseBytes, &sigResponse)
+		if err != nil {
+			return blsSignatureBuf{}, err
+		}
+		return sigResponse.Signature, nil
+	}
+}
diff --git a/signature-aggregator/config/config.go b/signature-aggregator/config/config.go
index 19b769d2..ec6d570e 100644
--- a/signature-aggregator/config/config.go
+++ b/signature-aggregator/config/config.go
@@ -5,6 +5,7 @@ package config
 
 import (
 	"fmt"
+	"time"
 
 	"github.com/ava-labs/avalanchego/utils/logging"
 	basecfg "github.com/ava-labs/awm-relayer/config"
@@ -34,6 +35,9 @@ type Config struct {
 	APIPort            uint16             `mapstructure:"api-port" json:"api-port"`
 	MetricsPort        uint16             `mapstructure:"metrics-port" json:"metrics-port"`
 	SignatureCacheSize uint64             `mapstructure:"signature-cache-size" json:"signature-cache-size"`
+
+	// mapstructure doesn't support time.Time out of the box so handle it manually
+	EtnaTime time.Time `json:"etna-time"`
 }
 
 func DisplayUsageText() {
diff --git a/signature-aggregator/config/keys.go b/signature-aggregator/config/keys.go
index 97829f77..d2f3e077 100644
--- a/signature-aggregator/config/keys.go
+++ b/signature-aggregator/config/keys.go
@@ -16,4 +16,5 @@ const (
 	APIPortKey            = "api-port"
 	MetricsPortKey        = "metrics-port"
 	SignatureCacheSizeKey = "signature-cache-size"
+	EtnaTimeKey           = "etna-time"
 )
diff --git a/signature-aggregator/config/viper.go b/signature-aggregator/config/viper.go
index dc33f918..0ca4a410 100644
--- a/signature-aggregator/config/viper.go
+++ b/signature-aggregator/config/viper.go
@@ -76,5 +76,8 @@ func BuildConfig(v *viper.Viper) (Config, error) {
 		return cfg, fmt.Errorf("failed to unmarshal viper config: %w", err)
 	}
 
+	// mapstructure doesn't support time.Time out of the box so handle it manually
+	cfg.EtnaTime = v.GetTime(EtnaTimeKey)
+
 	return cfg, nil
 }
diff --git a/signature-aggregator/main/main.go b/signature-aggregator/main/main.go
index 69b619a1..27edfd3b 100644
--- a/signature-aggregator/main/main.go
+++ b/signature-aggregator/main/main.go
@@ -117,6 +117,7 @@ func main() {
 		cfg.SignatureCacheSize,
 		metricsInstance,
 		messageCreator,
+		cfg.EtnaTime,
 	)
 	if err != nil {
 		logger.Fatal("Failed to create signature aggregator", zap.Error(err))
diff --git a/tests/e2e_test.go b/tests/e2e_test.go
index 48a61808..4a475334 100644
--- a/tests/e2e_test.go
+++ b/tests/e2e_test.go
@@ -174,4 +174,7 @@ var _ = ginkgo.Describe("[AWM Relayer Integration Tests", func() {
 	ginkgo.It("Signature Aggregator", func() {
 		SignatureAggregatorAPI(localNetworkInstance)
 	})
+	ginkgo.It("Etna Upgrade", func() {
+		EtnaUpgrade(localNetworkInstance)
+	})
 })
diff --git a/tests/etna_upgrade.go b/tests/etna_upgrade.go
new file mode 100644
index 00000000..ce39d824
--- /dev/null
+++ b/tests/etna_upgrade.go
@@ -0,0 +1,93 @@
+// Copyright (C) 2024, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package tests
+
+import (
+	"context"
+	"time"
+
+	testUtils "github.com/ava-labs/awm-relayer/tests/utils"
+	"github.com/ava-labs/teleporter/tests/interfaces"
+	"github.com/ava-labs/teleporter/tests/utils"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/log"
+	. "github.com/onsi/gomega"
+)
+
+// This tests basic functionality of the relayer post-etna upgrade
+// since other tests write zero value of time.Time
+// to the config  and therefore are testing the pre-etna case
+// - Relaying from Subnet A to Subnet B
+// - Relaying from Subnet B to Subnet A
+func EtnaUpgrade(network interfaces.LocalNetwork) {
+	subnetAInfo := network.GetPrimaryNetworkInfo()
+	subnetBInfo, _ := utils.GetTwoSubnets(network)
+	fundedAddress, fundedKey := network.GetFundedAccountInfo()
+	teleporterContractAddress := network.GetTeleporterContractAddress()
+	err := testUtils.ClearRelayerStorage()
+	Expect(err).Should(BeNil())
+	//
+	// Fund the relayer address on all subnets
+	//
+	ctx := context.Background()
+
+	log.Info("Funding relayer address on all subnets")
+	relayerKey, err := crypto.GenerateKey()
+	Expect(err).Should(BeNil())
+	testUtils.FundRelayers(ctx, []interfaces.SubnetTestInfo{subnetAInfo, subnetBInfo}, fundedKey, relayerKey)
+
+	//
+	// Set up relayer config
+	//
+	relayerConfig := testUtils.CreateDefaultRelayerConfig(
+		[]interfaces.SubnetTestInfo{subnetAInfo, subnetBInfo},
+		[]interfaces.SubnetTestInfo{subnetAInfo, subnetBInfo},
+		teleporterContractAddress,
+		fundedAddress,
+		relayerKey,
+	)
+	relayerConfig.EtnaTime = time.Now().AddDate(0, 0, -1)
+	// The config needs to be validated in order to be passed to database.GetConfigRelayerIDs
+	relayerConfig.Validate()
+
+	relayerConfigPath := testUtils.WriteRelayerConfig(relayerConfig, testUtils.DefaultRelayerCfgFname)
+
+	//
+	// Test Relaying from Subnet A to Subnet B
+	//
+	log.Info("Test Relaying from Subnet A to Subnet B")
+
+	log.Info("Starting the relayer")
+	relayerCleanup, readyChan := testUtils.RunRelayerExecutable(
+		ctx,
+		relayerConfigPath,
+		relayerConfig,
+	)
+	defer relayerCleanup()
+
+	// Wait for relayer to start up
+	startupCtx, startupCancel := context.WithTimeout(ctx, 15*time.Second)
+	defer startupCancel()
+	testUtils.WaitForChannelClose(startupCtx, readyChan)
+
+	log.Info("Sending transaction from Subnet A to Subnet B")
+	testUtils.RelayBasicMessage(
+		ctx,
+		subnetAInfo,
+		subnetBInfo,
+		teleporterContractAddress,
+		fundedKey,
+		fundedAddress,
+	)
+
+	log.Info("Test Relaying from Subnet B to Subnet A")
+	testUtils.RelayBasicMessage(
+		ctx,
+		subnetBInfo,
+		subnetAInfo,
+		teleporterContractAddress,
+		fundedKey,
+		fundedAddress,
+	)
+}