diff --git a/PENDING.md b/PENDING.md
index d93d0adb3..0447beee0 100644
--- a/PENDING.md
+++ b/PENDING.md
@@ -23,6 +23,7 @@
 
 * [\#3669] Ensure consistency in message naming, codec registration, and JSON
 tags.
+* [\#3751] Disable (temporarily) support for ED25519 account key pairs.
 
 ### Tendermint
 
diff --git a/x/auth/ante.go b/x/auth/ante.go
index fc6e8f5ad..376f36018 100644
--- a/x/auth/ante.go
+++ b/x/auth/ante.go
@@ -188,7 +188,10 @@ func processSig(
 		consumeSimSigGas(ctx.GasMeter(), pubKey, sig, params)
 	}
 
-	consumeSigVerificationGas(ctx.GasMeter(), sig.Signature, pubKey, params)
+	if res := consumeSigVerificationGas(ctx.GasMeter(), sig.Signature, pubKey, params); !res.IsOK() {
+		return nil, res
+	}
+
 	if !simulate && !pubKey.VerifyBytes(signBytes, sig.Signature) {
 		return nil, sdk.ErrUnauthorized("signature verification failed").Result()
 	}
@@ -256,14 +259,20 @@ func ProcessPubKey(acc Account, sig StdSignature, simulate bool) (crypto.PubKey,
 // by the concrete type.
 //
 // TODO: Design a cleaner and flexible way to match concrete public key types.
-func consumeSigVerificationGas(meter sdk.GasMeter, sig []byte, pubkey crypto.PubKey, params Params) {
+func consumeSigVerificationGas(
+	meter sdk.GasMeter, sig []byte, pubkey crypto.PubKey, params Params,
+) sdk.Result {
+
 	pubkeyType := strings.ToLower(fmt.Sprintf("%T", pubkey))
+
 	switch {
 	case strings.Contains(pubkeyType, "ed25519"):
 		meter.ConsumeGas(params.SigVerifyCostED25519, "ante verify: ed25519")
+		return sdk.ErrInvalidPubKey("ED25519 public keys are unsupported").Result()
 
 	case strings.Contains(pubkeyType, "secp256k1"):
 		meter.ConsumeGas(params.SigVerifyCostSecp256k1, "ante verify: secp256k1")
+		return sdk.Result{}
 
 	case strings.Contains(pubkeyType, "multisigthreshold"):
 		var multisignature multisig.Multisignature
@@ -271,9 +280,10 @@ func consumeSigVerificationGas(meter sdk.GasMeter, sig []byte, pubkey crypto.Pub
 
 		multisigPubKey := pubkey.(multisig.PubKeyMultisigThreshold)
 		consumeMultisignatureVerificationGas(meter, multisignature, multisigPubKey, params)
+		return sdk.Result{}
 
 	default:
-		panic(fmt.Sprintf("unrecognized signature type: %s", pubkeyType))
+		return sdk.ErrInvalidPubKey(fmt.Sprintf("unrecognized public key type: %s", pubkeyType)).Result()
 	}
 }
 
diff --git a/x/auth/ante_test.go b/x/auth/ante_test.go
index 9a554080a..8d1db6f1a 100644
--- a/x/auth/ante_test.go
+++ b/x/auth/ante_test.go
@@ -585,19 +585,21 @@ func TestConsumeSignatureVerificationGas(t *testing.T) {
 		name        string
 		args        args
 		gasConsumed uint64
-		wantPanic   bool
+		shouldErr   bool
 	}{
-		{"PubKeyEd25519", args{sdk.NewInfiniteGasMeter(), nil, ed25519.GenPrivKey().PubKey(), params}, DefaultSigVerifyCostED25519, false},
+		{"PubKeyEd25519", args{sdk.NewInfiniteGasMeter(), nil, ed25519.GenPrivKey().PubKey(), params}, DefaultSigVerifyCostED25519, true},
 		{"PubKeySecp256k1", args{sdk.NewInfiniteGasMeter(), nil, secp256k1.GenPrivKey().PubKey(), params}, DefaultSigVerifyCostSecp256k1, false},
 		{"Multisig", args{sdk.NewInfiniteGasMeter(), multisignature1.Marshal(), multisigKey1, params}, expectedCost1, false},
 		{"unknown key", args{sdk.NewInfiniteGasMeter(), nil, nil, params}, 0, true},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			if tt.wantPanic {
-				require.Panics(t, func() { consumeSigVerificationGas(tt.args.meter, tt.args.sig, tt.args.pubkey, tt.args.params) })
+			res := consumeSigVerificationGas(tt.args.meter, tt.args.sig, tt.args.pubkey, tt.args.params)
+
+			if tt.shouldErr {
+				require.False(t, res.IsOK())
 			} else {
-				consumeSigVerificationGas(tt.args.meter, tt.args.sig, tt.args.pubkey, tt.args.params)
+				require.True(t, res.IsOK())
 				require.Equal(t, tt.gasConsumed, tt.args.meter.GasConsumed(), fmt.Sprintf("%d != %d", tt.gasConsumed, tt.args.meter.GasConsumed()))
 			}
 		})
diff --git a/x/auth/test_utils.go b/x/auth/test_utils.go
index 096b3897a..800622b42 100644
--- a/x/auth/test_utils.go
+++ b/x/auth/test_utils.go
@@ -4,7 +4,7 @@ package auth
 import (
 	abci "github.com/tendermint/tendermint/abci/types"
 	"github.com/tendermint/tendermint/crypto"
-	"github.com/tendermint/tendermint/crypto/ed25519"
+	"github.com/tendermint/tendermint/crypto/secp256k1"
 	dbm "github.com/tendermint/tendermint/libs/db"
 	"github.com/tendermint/tendermint/libs/log"
 
@@ -67,7 +67,7 @@ func newCoins() sdk.Coins {
 }
 
 func keyPubAddr() (crypto.PrivKey, crypto.PubKey, sdk.AccAddress) {
-	key := ed25519.GenPrivKey()
+	key := secp256k1.GenPrivKey()
 	pub := key.PubKey()
 	addr := sdk.AccAddress(pub.Address())
 	return key, pub, addr
diff --git a/x/bank/app_test.go b/x/bank/app_test.go
index 824f48670..8703d71ec 100644
--- a/x/bank/app_test.go
+++ b/x/bank/app_test.go
@@ -11,7 +11,7 @@ import (
 
 	abci "github.com/tendermint/tendermint/abci/types"
 	"github.com/tendermint/tendermint/crypto"
-	"github.com/tendermint/tendermint/crypto/ed25519"
+	"github.com/tendermint/tendermint/crypto/secp256k1"
 )
 
 type (
@@ -32,12 +32,12 @@ type (
 )
 
 var (
-	priv1 = ed25519.GenPrivKey()
+	priv1 = secp256k1.GenPrivKey()
 	addr1 = sdk.AccAddress(priv1.PubKey().Address())
-	priv2 = ed25519.GenPrivKey()
+	priv2 = secp256k1.GenPrivKey()
 	addr2 = sdk.AccAddress(priv2.PubKey().Address())
-	addr3 = sdk.AccAddress(ed25519.GenPrivKey().PubKey().Address())
-	priv4 = ed25519.GenPrivKey()
+	addr3 = sdk.AccAddress(secp256k1.GenPrivKey().PubKey().Address())
+	priv4 = secp256k1.GenPrivKey()
 	addr4 = sdk.AccAddress(priv4.PubKey().Address())
 
 	coins     = sdk.Coins{sdk.NewInt64Coin("foocoin", 10)}
@@ -104,6 +104,36 @@ func getInitChainer(mapp *mock.App, keeper BaseKeeper) sdk.InitChainer {
 	}
 }
 
+func TestSendNotEnoughBalance(t *testing.T) {
+	mapp := getMockApp(t)
+	acc := &auth.BaseAccount{
+		Address: addr1,
+		Coins:   sdk.Coins{sdk.NewInt64Coin("foocoin", 67)},
+	}
+
+	mock.SetGenesis(mapp, []auth.Account{acc})
+
+	ctxCheck := mapp.BaseApp.NewContext(true, abci.Header{})
+
+	res1 := mapp.AccountKeeper.GetAccount(ctxCheck, addr1)
+	require.NotNil(t, res1)
+	require.Equal(t, acc, res1.(*auth.BaseAccount))
+
+	origAccNum := res1.GetAccountNumber()
+	origSeq := res1.GetSequence()
+
+	sendMsg := NewMsgSend(addr1, addr2, sdk.Coins{sdk.NewInt64Coin("foocoin", 100)})
+	mock.SignCheckDeliver(t, mapp.Cdc, mapp.BaseApp, []sdk.Msg{sendMsg}, []uint64{origAccNum}, []uint64{origSeq}, false, false, priv1)
+
+	mock.CheckBalance(t, mapp, addr1, sdk.Coins{sdk.NewInt64Coin("foocoin", 67)})
+
+	res2 := mapp.AccountKeeper.GetAccount(mapp.NewContext(true, abci.Header{}), addr1)
+	require.NotNil(t, res2)
+
+	require.True(t, res2.GetAccountNumber() == origAccNum)
+	require.True(t, res2.GetSequence() == origSeq+1)
+}
+
 func TestMsgMultiSendWithAccounts(t *testing.T) {
 	mapp := getMockApp(t)
 	acc := &auth.BaseAccount{
diff --git a/x/ibc/app_test.go b/x/ibc/app_test.go
index 626e9a5b0..0b1e7d9da 100644
--- a/x/ibc/app_test.go
+++ b/x/ibc/app_test.go
@@ -11,7 +11,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/mock"
 
 	abci "github.com/tendermint/tendermint/abci/types"
-	"github.com/tendermint/tendermint/crypto/ed25519"
+	"github.com/tendermint/tendermint/crypto/secp256k1"
 )
 
 // initialize the mock application for this module
@@ -36,7 +36,7 @@ func TestIBCMsgs(t *testing.T) {
 	sourceChain := "source-chain"
 	destChain := "dest-chain"
 
-	priv1 := ed25519.GenPrivKey()
+	priv1 := secp256k1.GenPrivKey()
 	addr1 := sdk.AccAddress(priv1.PubKey().Address())
 	coins := sdk.Coins{sdk.NewInt64Coin("foocoin", 10)}
 	var emptyCoins sdk.Coins
diff --git a/x/mock/app.go b/x/mock/app.go
index a5dad50e6..3e24bee0d 100644
--- a/x/mock/app.go
+++ b/x/mock/app.go
@@ -177,7 +177,7 @@ func CreateGenAccounts(numAccs int, genCoins sdk.Coins) (genAccs []auth.Account,
 	addrKeysSlice := AddrKeysSlice{}
 
 	for i := 0; i < numAccs; i++ {
-		privKey := ed25519.GenPrivKey()
+		privKey := secp256k1.GenPrivKey()
 		pubKey := privKey.PubKey()
 		addr := sdk.AccAddress(pubKey.Address())
 
@@ -235,12 +235,12 @@ func GenTx(msgs []sdk.Msg, accnums []uint64, seq []uint64, priv ...crypto.PrivKe
 	return auth.NewStdTx(msgs, fee, sigs, memo)
 }
 
-// GeneratePrivKeys generates a total n Ed25519 private keys.
+// GeneratePrivKeys generates a total n secp256k1 private keys.
 func GeneratePrivKeys(n int) (keys []crypto.PrivKey) {
 	// TODO: Randomize this between ed25519 and secp256k1
 	keys = make([]crypto.PrivKey, n)
 	for i := 0; i < n; i++ {
-		keys[i] = ed25519.GenPrivKey()
+		keys[i] = secp256k1.GenPrivKey()
 	}
 
 	return
diff --git a/x/slashing/app_test.go b/x/slashing/app_test.go
index 0ae91f424..6f15e4aee 100644
--- a/x/slashing/app_test.go
+++ b/x/slashing/app_test.go
@@ -5,7 +5,7 @@ import (
 
 	"github.com/stretchr/testify/require"
 	abci "github.com/tendermint/tendermint/abci/types"
-	"github.com/tendermint/tendermint/crypto/ed25519"
+	"github.com/tendermint/tendermint/crypto/secp256k1"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/auth"
@@ -15,7 +15,7 @@ import (
 )
 
 var (
-	priv1 = ed25519.GenPrivKey()
+	priv1 = secp256k1.GenPrivKey()
 	addr1 = sdk.AccAddress(priv1.PubKey().Address())
 	coins = sdk.Coins{sdk.NewInt64Coin("foocoin", 10)}
 )
diff --git a/x/staking/test_common.go b/x/staking/test_common.go
index 2ddc53447..62cee84db 100644
--- a/x/staking/test_common.go
+++ b/x/staking/test_common.go
@@ -2,7 +2,7 @@ package staking
 
 import (
 	"github.com/tendermint/tendermint/crypto"
-	"github.com/tendermint/tendermint/crypto/ed25519"
+	"github.com/tendermint/tendermint/crypto/secp256k1"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/auth"
@@ -10,12 +10,12 @@ import (
 )
 
 var (
-	priv1 = ed25519.GenPrivKey()
+	priv1 = secp256k1.GenPrivKey()
 	addr1 = sdk.AccAddress(priv1.PubKey().Address())
-	priv2 = ed25519.GenPrivKey()
+	priv2 = secp256k1.GenPrivKey()
 	addr2 = sdk.AccAddress(priv2.PubKey().Address())
-	addr3 = sdk.AccAddress(ed25519.GenPrivKey().PubKey().Address())
-	priv4 = ed25519.GenPrivKey()
+	addr3 = sdk.AccAddress(secp256k1.GenPrivKey().PubKey().Address())
+	priv4 = secp256k1.GenPrivKey()
 	addr4 = sdk.AccAddress(priv4.PubKey().Address())
 	coins = sdk.Coins{sdk.NewCoin("foocoin", sdk.NewInt(10))}
 	fee   = auth.NewStdFee(