diff --git a/migration/convert.go b/migration/convert.go
index 85a5fa6..1bb0f3d 100644
--- a/migration/convert.go
+++ b/migration/convert.go
@@ -6,23 +6,6 @@ import (
 	"net/url"
 )
 
-var (
-	typeString = map[Payload_OtpParameters_OtpType]string{
-		Payload_OtpParameters_OTP_TYPE_HOTP: "hotp",
-		Payload_OtpParameters_OTP_TYPE_TOTP: "totp",
-	}
-	algString = map[Payload_OtpParameters_Algorithm]string{
-		Payload_OtpParameters_ALGORITHM_SHA1:   "SHA1",
-		Payload_OtpParameters_ALGORITHM_SHA256: "SHA256",
-		Payload_OtpParameters_ALGORITHM_SHA512: "SHA512",
-		Payload_OtpParameters_ALGORITHM_MD5:    "MD5",
-	}
-	digitsString = map[Payload_OtpParameters_DigitCount]string{
-		Payload_OtpParameters_DIGIT_COUNT_SIX:   "6",
-		Payload_OtpParameters_DIGIT_COUNT_EIGHT: "8",
-	}
-)
-
 // SecretString returns Secret as a base32 encoded String
 func (op *Payload_OtpParameters) SecretString() string {
 	return base32.StdEncoding.WithPadding(base32.NoPadding).EncodeToString(op.Secret)
@@ -50,11 +33,11 @@ func (op *Payload_OtpParameters) URL() *url.URL {
 	}
 	// optional
 	if op.Algorithm != Payload_OtpParameters_ALGORITHM_UNSPECIFIED {
-		v.Add("algorithm", algString[op.Algorithm])
+		v.Add("algorithm", op.Algorithm.Name())
 	}
 	// optional
 	if op.Digits != Payload_OtpParameters_DIGIT_COUNT_UNSPECIFIED {
-		v.Add("digits", digitsString[op.Digits])
+		v.Add("digits", fmt.Sprint(op.Digits.Count()))
 	}
 	// required if type is hotp
 	if op.Type == Payload_OtpParameters_OTP_TYPE_HOTP {
@@ -66,7 +49,7 @@ func (op *Payload_OtpParameters) URL() *url.URL {
 	}
 	return &url.URL{
 		Scheme:   "otpauth",
-		Host:     typeString[op.Type],
+		Host:     op.Type.Name(),
 		Path:     op.Name,
 		RawQuery: v.Encode(),
 	}
diff --git a/migration/evaluate.go b/migration/evaluate.go
index 750c367..0ee3f46 100644
--- a/migration/evaluate.go
+++ b/migration/evaluate.go
@@ -2,37 +2,12 @@ package migration
 
 import (
 	"crypto/hmac"
-	"crypto/md5"
-	"crypto/sha1"
-	"crypto/sha256"
-	"crypto/sha512"
 	"encoding/binary"
 	"fmt"
-	"hash"
 	"math"
 	"time"
 )
 
-var (
-	hashFunc = map[Payload_OtpParameters_Algorithm]func() hash.Hash{
-		Payload_OtpParameters_ALGORITHM_UNSPECIFIED: sha1.New, // default
-		Payload_OtpParameters_ALGORITHM_SHA1:        sha1.New,
-		Payload_OtpParameters_ALGORITHM_SHA256:      sha256.New,
-		Payload_OtpParameters_ALGORITHM_SHA512:      sha512.New,
-		Payload_OtpParameters_ALGORITHM_MD5:         md5.New,
-	}
-	digitCount = map[Payload_OtpParameters_DigitCount]int{
-		Payload_OtpParameters_DIGIT_COUNT_UNSPECIFIED: 6, // default
-		Payload_OtpParameters_DIGIT_COUNT_SIX:         6,
-		Payload_OtpParameters_DIGIT_COUNT_EIGHT:       8,
-	}
-	countFunc = map[Payload_OtpParameters_OtpType]func(*Payload_OtpParameters) uint64{
-		Payload_OtpParameters_OTP_TYPE_UNSPECIFIED: totp, // default
-		Payload_OtpParameters_OTP_TYPE_HOTP:        hotp,
-		Payload_OtpParameters_OTP_TYPE_TOTP:        totp,
-	}
-)
-
 const (
 	offset = 5 * time.Second  // offset into future
 	period = 30 * time.Second // default value period
@@ -56,15 +31,15 @@ func (op *Payload_OtpParameters) Seconds() float64 {
 
 // Evaluate OTP parameters
 func (op *Payload_OtpParameters) Evaluate() int {
-	h := hmac.New(hashFunc[op.Algorithm], op.Secret)
-	binary.Write(h, binary.BigEndian, countFunc[op.Type](op))
+	h := hmac.New(op.Algorithm.Hash(), op.Secret)
+	binary.Write(h, binary.BigEndian, op.Type.Count(op))
 	hashed := h.Sum(nil)
 	offset := hashed[h.Size()-1] & 15
 	result := binary.BigEndian.Uint32(hashed[offset:]) & (1<<31 - 1)
-	return int(result) % int(math.Pow10(digitCount[op.Digits]))
+	return int(result) % int(math.Pow10(op.Digits.Count()))
 }
 
 // EvaluateString returns OTP as formatted string
 func (op *Payload_OtpParameters) EvaluateString() string {
-	return fmt.Sprintf("%0*d", digitCount[op.Digits], op.Evaluate())
+	return fmt.Sprintf("%0*d", op.Digits.Count(), op.Evaluate())
 }
diff --git a/migration/generate.go b/migration/generate.go
deleted file mode 100644
index 37c3f5c..0000000
--- a/migration/generate.go
+++ /dev/null
@@ -1,3 +0,0 @@
-package migration
-
-//go:generate protoc --go_out=. --go_opt=paths=source_relative migration.proto
diff --git a/migration/migration.go b/migration/migration.go
new file mode 100644
index 0000000..5eb6851
--- /dev/null
+++ b/migration/migration.go
@@ -0,0 +1,65 @@
+package migration
+
+import (
+	"crypto/md5"
+	"crypto/sha1"
+	"crypto/sha256"
+	"crypto/sha512"
+	"hash"
+)
+
+//go:generate protoc --go_out=. --go_opt=paths=source_relative migration.proto
+
+var algorithmHash = []func() hash.Hash{
+	Payload_OtpParameters_ALGORITHM_UNSPECIFIED: sha1.New,
+	Payload_OtpParameters_ALGORITHM_SHA1:        sha1.New,
+	Payload_OtpParameters_ALGORITHM_SHA256:      sha256.New,
+	Payload_OtpParameters_ALGORITHM_SHA512:      sha512.New,
+	Payload_OtpParameters_ALGORITHM_MD5:         md5.New,
+}
+
+func (x Payload_OtpParameters_Algorithm) Hash() func() hash.Hash {
+	return algorithmHash[x]
+}
+
+var algorithmNames = []string{
+	Payload_OtpParameters_ALGORITHM_UNSPECIFIED: "SHA1",
+	Payload_OtpParameters_ALGORITHM_SHA1:        "SHA1",
+	Payload_OtpParameters_ALGORITHM_SHA256:      "SHA256",
+	Payload_OtpParameters_ALGORITHM_SHA512:      "SHA512",
+	Payload_OtpParameters_ALGORITHM_MD5:         "MD5",
+}
+
+func (x Payload_OtpParameters_Algorithm) Name() string {
+	return algorithmNames[x]
+}
+
+var digitCount = []int{
+	Payload_OtpParameters_DIGIT_COUNT_UNSPECIFIED: 6,
+	Payload_OtpParameters_DIGIT_COUNT_SIX:         6,
+	Payload_OtpParameters_DIGIT_COUNT_EIGHT:       8,
+}
+
+func (x Payload_OtpParameters_DigitCount) Count() int {
+	return digitCount[x]
+}
+
+var otpTypeFunc = []func(*Payload_OtpParameters) uint64{
+	Payload_OtpParameters_OTP_TYPE_UNSPECIFIED: totp,
+	Payload_OtpParameters_OTP_TYPE_HOTP:        hotp,
+	Payload_OtpParameters_OTP_TYPE_TOTP:        totp,
+}
+
+func (x Payload_OtpParameters_OtpType) Count(op *Payload_OtpParameters) uint64 {
+	return otpTypeFunc[x](op)
+}
+
+var otpTypeNames = []string{
+	Payload_OtpParameters_OTP_TYPE_UNSPECIFIED: "totp",
+	Payload_OtpParameters_OTP_TYPE_HOTP:        "hotp",
+	Payload_OtpParameters_OTP_TYPE_TOTP:        "totp",
+}
+
+func (x Payload_OtpParameters_OtpType) Name() string {
+	return otpTypeNames[x]
+}