diff --git a/pkg/infra/assembler.go b/pkg/infra/assembler.go
index 0778c9ed..2af52902 100644
--- a/pkg/infra/assembler.go
+++ b/pkg/infra/assembler.go
@@ -17,7 +17,7 @@ type Elements struct {
 }
 
 type Assembler struct {
-	Signer *Crypto
+	Signer Crypto
 }
 
 func (a *Assembler) assemble(e *Elements) (*Elements, error) {
diff --git a/pkg/infra/config.go b/pkg/infra/config.go
index 73865626..fa77f95e 100644
--- a/pkg/infra/config.go
+++ b/pkg/infra/config.go
@@ -1,7 +1,11 @@
 package infra
 
 import (
+	"crypto/ecdsa"
+	"crypto/x509"
+	"encoding/pem"
 	"io/ioutil"
+	"tape/internal/fabric/bccsp/utils"
 
 	"github.com/gogo/protobuf/proto"
 	"github.com/hyperledger/fabric-protos-go/msp"
@@ -65,7 +69,7 @@ func LoadConfig(f string) (Config, error) {
 	return config, nil
 }
 
-func (c Config) LoadCrypto() (*Crypto, error) {
+func (c Config) LoadCrypto() (*CryptoImpl, error) {
 	var allcerts []string
 	for _, p := range c.Endorsers {
 		allcerts = append(allcerts, p.TLSCACert)
@@ -98,7 +102,7 @@ func (c Config) LoadCrypto() (*Crypto, error) {
 		return nil, errors.Wrapf(err, "error get msp id")
 	}
 
-	return &Crypto{
+	return &CryptoImpl{
 		Creator:  name,
 		PrivKey:  priv,
 		SignCert: cert,
@@ -136,3 +140,34 @@ func (n *Node) loadConfig() error {
 	n.TLSCARootByte = TLSCARoot
 	return nil
 }
+
+func GetPrivateKey(f string) (*ecdsa.PrivateKey, error) {
+	in, err := ioutil.ReadFile(f)
+	if err != nil {
+		return nil, err
+	}
+
+	k, err := utils.PEMtoPrivateKey(in, []byte{})
+	if err != nil {
+		return nil, err
+	}
+
+	key, ok := k.(*ecdsa.PrivateKey)
+	if !ok {
+		return nil, errors.Errorf("expecting ecdsa key")
+	}
+
+	return key, nil
+}
+
+func GetCertificate(f string) (*x509.Certificate, []byte, error) {
+	in, err := ioutil.ReadFile(f)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	block, _ := pem.Decode(in)
+
+	c, err := x509.ParseCertificate(block.Bytes)
+	return c, in, err
+}
diff --git a/pkg/infra/crypto.go b/pkg/infra/crypto.go
index 6b9e7ad2..8827e791 100644
--- a/pkg/infra/crypto.go
+++ b/pkg/infra/crypto.go
@@ -6,16 +6,12 @@ import (
 	"crypto/sha256"
 	"crypto/x509"
 	"encoding/asn1"
-	"encoding/base64"
-	"encoding/pem"
-	"io/ioutil"
 	"math/big"
 
 	"tape/internal/fabric/bccsp/utils"
 	"tape/internal/fabric/common/crypto"
 
 	"github.com/hyperledger/fabric-protos-go/common"
-	"github.com/pkg/errors"
 )
 
 type CryptoConfig struct {
@@ -29,13 +25,13 @@ type ECDSASignature struct {
 	R, S *big.Int
 }
 
-type Crypto struct {
+type CryptoImpl struct {
 	Creator  []byte
 	PrivKey  *ecdsa.PrivateKey
 	SignCert *x509.Certificate
 }
 
-func (s *Crypto) Sign(message []byte) ([]byte, error) {
+func (s *CryptoImpl) Sign(message []byte) ([]byte, error) {
 	ri, si, err := ecdsa.Sign(rand.Reader, s.PrivKey, digest(message))
 	if err != nil {
 		return nil, err
@@ -49,11 +45,11 @@ func (s *Crypto) Sign(message []byte) ([]byte, error) {
 	return asn1.Marshal(ECDSASignature{ri, si})
 }
 
-func (s *Crypto) Serialize() ([]byte, error) {
+func (s *CryptoImpl) Serialize() ([]byte, error) {
 	return s.Creator, nil
 }
 
-func (s *Crypto) NewSignatureHeader() (*common.SignatureHeader, error) {
+func (s *CryptoImpl) NewSignatureHeader() (*common.SignatureHeader, error) {
 	creator, err := s.Serialize()
 	if err != nil {
 		return nil, err
@@ -74,43 +70,3 @@ func digest(in []byte) []byte {
 	h.Write(in)
 	return h.Sum(nil)
 }
-
-func toPEM(in []byte) ([]byte, error) {
-	d := make([]byte, base64.StdEncoding.DecodedLen(len(in)))
-	n, err := base64.StdEncoding.Decode(d, in)
-	if err != nil {
-		return nil, err
-	}
-	return d[:n], nil
-}
-
-func GetPrivateKey(f string) (*ecdsa.PrivateKey, error) {
-	in, err := ioutil.ReadFile(f)
-	if err != nil {
-		return nil, err
-	}
-
-	k, err := utils.PEMtoPrivateKey(in, []byte{})
-	if err != nil {
-		return nil, err
-	}
-
-	key, ok := k.(*ecdsa.PrivateKey)
-	if !ok {
-		return nil, errors.Errorf("expecting ecdsa key")
-	}
-
-	return key, nil
-}
-
-func GetCertificate(f string) (*x509.Certificate, []byte, error) {
-	in, err := ioutil.ReadFile(f)
-	if err != nil {
-		return nil, nil, err
-	}
-
-	block, _ := pem.Decode(in)
-
-	c, err := x509.ParseCertificate(block.Bytes)
-	return c, in, err
-}
diff --git a/pkg/infra/initiator.go b/pkg/infra/initiator.go
index 9fe13c5f..eaadbd9b 100644
--- a/pkg/infra/initiator.go
+++ b/pkg/infra/initiator.go
@@ -7,7 +7,7 @@ import (
 	"golang.org/x/time/rate"
 )
 
-func StartCreateProposal(num int, burst int, r float64, config Config, crypto *Crypto, raw chan *Elements, errorCh chan error) {
+func StartCreateProposal(num int, burst int, r float64, config Config, crypto Crypto, raw chan *Elements, errorCh chan error) {
 	limit := rate.Inf
 	ctx := context.Background()
 	if r > 0 {
diff --git a/pkg/infra/interface.go b/pkg/infra/interface.go
new file mode 100644
index 00000000..75b14a11
--- /dev/null
+++ b/pkg/infra/interface.go
@@ -0,0 +1,14 @@
+package infra
+
+import (
+	"github.com/hyperledger/fabric-protos-go/common"
+)
+
+//to do for #127 SM crypto
+//just need to do an impl for this interface and replace
+
+type Crypto interface {
+	NewSignatureHeader() (*common.SignatureHeader, error)
+	Serialize() ([]byte, error)
+	Sign(message []byte) ([]byte, error)
+}
diff --git a/pkg/infra/observer.go b/pkg/infra/observer.go
index 9ae8cfc8..bb53dd04 100644
--- a/pkg/infra/observer.go
+++ b/pkg/infra/observer.go
@@ -20,7 +20,7 @@ type Observer struct {
 	logger  *log.Logger
 }
 
-func CreateObservers(ctx context.Context, channel string, nodes []Node, crypto *Crypto, logger *log.Logger) (*Observers, error) {
+func CreateObservers(ctx context.Context, channel string, nodes []Node, crypto Crypto, logger *log.Logger) (*Observers, error) {
 	var workers []*Observer
 	for i, node := range nodes {
 		worker, err := CreateObserver(ctx, channel, node, crypto, logger)
@@ -39,7 +39,7 @@ func (o *Observers) Start(errorCh chan error, blockCh chan<- *AddressedBlock, no
 	}
 }
 
-func CreateObserver(ctx context.Context, channel string, node Node, crypto *Crypto, logger *log.Logger) (*Observer, error) {
+func CreateObserver(ctx context.Context, channel string, node Node, crypto Crypto, logger *log.Logger) (*Observer, error) {
 	seek, err := CreateSignedDeliverNewestEnv(channel, crypto)
 	if err != nil {
 		return nil, err
diff --git a/pkg/infra/proposal.go b/pkg/infra/proposal.go
index 4bec270e..ec1b1b51 100644
--- a/pkg/infra/proposal.go
+++ b/pkg/infra/proposal.go
@@ -13,7 +13,7 @@ import (
 	"github.com/pkg/errors"
 )
 
-func CreateProposal(signer *Crypto, channel, ccname, version string, args ...string) (*peer.Proposal, error) {
+func CreateProposal(signer Crypto, channel, ccname, version string, args ...string) (*peer.Proposal, error) {
 	var argsInByte [][]byte
 	for _, arg := range args {
 		argsInByte = append(argsInByte, []byte(arg))
@@ -40,7 +40,7 @@ func CreateProposal(signer *Crypto, channel, ccname, version string, args ...str
 	return prop, nil
 }
 
-func SignProposal(prop *peer.Proposal, signer *Crypto) (*peer.SignedProposal, error) {
+func SignProposal(prop *peer.Proposal, signer Crypto) (*peer.SignedProposal, error) {
 	propBytes, err := proto.Marshal(prop)
 	if err != nil {
 		return nil, err
@@ -54,7 +54,7 @@ func SignProposal(prop *peer.Proposal, signer *Crypto) (*peer.SignedProposal, er
 	return &peer.SignedProposal{ProposalBytes: propBytes, Signature: sig}, nil
 }
 
-func CreateSignedTx(proposal *peer.Proposal, signer *Crypto, resps []*peer.ProposalResponse) (*common.Envelope, error) {
+func CreateSignedTx(proposal *peer.Proposal, signer Crypto, resps []*peer.ProposalResponse) (*common.Envelope, error) {
 	if len(resps) == 0 {
 		return nil, errors.Errorf("at least one proposal response is required")
 	}
@@ -152,7 +152,7 @@ func CreateSignedTx(proposal *peer.Proposal, signer *Crypto, resps []*peer.Propo
 	return &common.Envelope{Payload: paylBytes, Signature: sig}, nil
 }
 
-func CreateSignedDeliverNewestEnv(ch string, signer *Crypto) (*common.Envelope, error) {
+func CreateSignedDeliverNewestEnv(ch string, signer Crypto) (*common.Envelope, error) {
 	start := &orderer.SeekPosition{
 		Type: &orderer.SeekPosition_Newest{
 			Newest: &orderer.SeekNewest{},