diff --git a/asn1time.go b/asn1time.go
deleted file mode 100644
index 694bf7f..0000000
--- a/asn1time.go
+++ /dev/null
@@ -1,257 +0,0 @@
-// Copyright (C) 2016 Opsmate, Inc.
-//
-// This Source Code Form is subject to the terms of the Mozilla
-// Public License, v. 2.0. If a copy of the MPL was not distributed
-// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
-//
-// This software is distributed WITHOUT A WARRANTY OF ANY KIND.
-// See the Mozilla Public License for details.
-
-package certspotter
-
-import (
-	"encoding/asn1"
-	"errors"
-	"strconv"
-	"time"
-	"unicode"
-)
-
-const (
-	tagUTCTime         = 23
-	tagGeneralizedTime = 24
-)
-
-func isDigit(b byte) bool {
-	return unicode.IsDigit(rune(b))
-}
-
-func bytesToInt(bytes []byte) (int, error) {
-	return strconv.Atoi(string(bytes))
-}
-
-func parseUTCTime(bytes []byte) (time.Time, error) {
-	var err error
-	var year, month, day int
-	var hour, min, sec int
-	var tz *time.Location
-
-	// YYMMDDhhmm
-	if len(bytes) < 10 {
-		return time.Time{}, errors.New("UTCTime is too short")
-	}
-	year, err = bytesToInt(bytes[0:2])
-	if err != nil {
-		return time.Time{}, errors.New("UTCTime contains invalid integer: " + err.Error())
-	}
-
-	month, err = bytesToInt(bytes[2:4])
-	if err != nil {
-		return time.Time{}, errors.New("UTCTime contains invalid integer: " + err.Error())
-	}
-
-	day, err = bytesToInt(bytes[4:6])
-	if err != nil {
-		return time.Time{}, errors.New("UTCTime contains invalid integer: " + err.Error())
-	}
-
-	hour, err = bytesToInt(bytes[6:8])
-	if err != nil {
-		return time.Time{}, errors.New("UTCTime contains invalid integer: " + err.Error())
-	}
-
-	min, err = bytesToInt(bytes[8:10])
-	if err != nil {
-		return time.Time{}, errors.New("UTCTime contains invalid integer: " + err.Error())
-	}
-
-	bytes = bytes[10:]
-
-	// (optional) ss
-	if len(bytes) >= 2 && isDigit(bytes[0]) {
-		sec, err = bytesToInt(bytes[0:2])
-		if err != nil {
-			return time.Time{}, errors.New("UTCTime contains invalid integer: " + err.Error())
-		}
-		bytes = bytes[2:]
-	}
-
-	// timezone (required but allow it to be omitted, since this is a common error)
-	if len(bytes) >= 1 {
-		if bytes[0] == 'Z' {
-			tz = time.UTC
-			bytes = bytes[1:]
-		} else if bytes[0] == '+' {
-			// +hhmm
-			if len(bytes) < 5 {
-				return time.Time{}, errors.New("UTCTime positive timezone offset is too short")
-			}
-			tzHour, err := bytesToInt(bytes[1:3])
-			if err != nil {
-				return time.Time{}, errors.New("UTCTime contains invalid integer: " + err.Error())
-			}
-
-			tzMin, err := bytesToInt(bytes[3:5])
-			if err != nil {
-				return time.Time{}, errors.New("UTCTime contains invalid integer: " + err.Error())
-			}
-
-			tz = time.FixedZone("", tzHour*3600+tzMin*60)
-			bytes = bytes[5:]
-		} else if bytes[0] == '-' {
-			// -hhmm
-			if len(bytes) < 5 {
-				return time.Time{}, errors.New("UTCTime negative timezone offset is too short")
-			}
-			tzHour, err := bytesToInt(bytes[1:3])
-			if err != nil {
-				return time.Time{}, errors.New("UTCTime contains invalid integer: " + err.Error())
-			}
-
-			tzMin, err := bytesToInt(bytes[3:5])
-			if err != nil {
-				return time.Time{}, errors.New("UTCTime contains invalid integer: " + err.Error())
-			}
-
-			tz = time.FixedZone("", -1*(tzHour*3600+tzMin*60))
-			bytes = bytes[5:]
-		}
-	} else {
-		tz = time.UTC
-	}
-
-	if len(bytes) > 0 {
-		return time.Time{}, errors.New("UTCTime has trailing garbage")
-	}
-
-	// https://tools.ietf.org/html/rfc5280#section-4.1.2.5.1
-	if year >= 50 {
-		year = 1900 + year
-	} else {
-		year = 2000 + year
-	}
-
-	return time.Date(year, time.Month(month), day, hour, min, sec, 0, tz), nil
-}
-
-func parseGeneralizedTime(bytes []byte) (time.Time, error) {
-	var err error
-	var year, month, day int
-	var hour, min, sec, ms int
-	var tz *time.Location
-
-	// YYYYMMDDHH
-	if len(bytes) < 10 {
-		return time.Time{}, errors.New("GeneralizedTime is too short")
-	}
-	year, err = bytesToInt(bytes[0:4])
-	if err != nil {
-		return time.Time{}, errors.New("GeneralizedTime contains invalid integer: " + err.Error())
-	}
-
-	month, err = bytesToInt(bytes[4:6])
-	if err != nil {
-		return time.Time{}, errors.New("GeneralizedTime contains invalid integer: " + err.Error())
-	}
-
-	day, err = bytesToInt(bytes[6:8])
-	if err != nil {
-		return time.Time{}, errors.New("GeneralizedTime contains invalid integer: " + err.Error())
-	}
-
-	hour, err = bytesToInt(bytes[8:10])
-	if err != nil {
-		return time.Time{}, errors.New("GeneralizedTime contains invalid integer: " + err.Error())
-	}
-
-	bytes = bytes[10:]
-
-	// (optional) MM
-	if len(bytes) >= 2 && isDigit(bytes[0]) {
-		min, err = bytesToInt(bytes[0:2])
-		if err != nil {
-			return time.Time{}, errors.New("GeneralizedTime contains invalid integer: " + err.Error())
-		}
-		bytes = bytes[2:]
-		// (optional) SS
-		if len(bytes) >= 2 && isDigit(bytes[0]) {
-			sec, err = bytesToInt(bytes[0:2])
-			if err != nil {
-				return time.Time{}, errors.New("GeneralizedTime contains invalid integer: " + err.Error())
-			}
-			bytes = bytes[2:]
-			// (optional) .fff
-			if len(bytes) >= 1 && bytes[0] == '.' {
-				if len(bytes) < 4 {
-					return time.Time{}, errors.New("GeneralizedTime fractional seconds is too short")
-				}
-				ms, err = bytesToInt(bytes[1:4])
-				if err != nil {
-					return time.Time{}, errors.New("GeneralizedTime contains invalid integer: " + err.Error())
-				}
-				bytes = bytes[4:]
-			}
-		}
-	}
-
-	// timezone (Z or +hhmm or -hhmm or nothing)
-	if len(bytes) >= 1 {
-		if bytes[0] == 'Z' {
-			bytes = bytes[1:]
-			tz = time.UTC
-		} else if bytes[0] == '+' {
-			// +hhmm
-			if len(bytes) < 5 {
-				return time.Time{}, errors.New("GeneralizedTime positive timezone offset is too short")
-			}
-			tzHour, err := bytesToInt(bytes[1:3])
-			if err != nil {
-				return time.Time{}, errors.New("GeneralizedTime contains invalid integer: " + err.Error())
-			}
-
-			tzMin, err := bytesToInt(bytes[3:5])
-			if err != nil {
-				return time.Time{}, errors.New("GeneralizedTime contains invalid integer: " + err.Error())
-			}
-
-			tz = time.FixedZone("", tzHour*3600+tzMin*60)
-			bytes = bytes[5:]
-		} else if bytes[0] == '-' {
-			// -hhmm
-			if len(bytes) < 5 {
-				return time.Time{}, errors.New("GeneralizedTime negative timezone offset is too short")
-			}
-			tzHour, err := bytesToInt(bytes[1:3])
-			if err != nil {
-				return time.Time{}, errors.New("GeneralizedTime contains invalid integer: " + err.Error())
-			}
-
-			tzMin, err := bytesToInt(bytes[3:5])
-			if err != nil {
-				return time.Time{}, errors.New("GeneralizedTime contains invalid integer: " + err.Error())
-			}
-
-			tz = time.FixedZone("", -1*(tzHour*3600+tzMin*60))
-			bytes = bytes[5:]
-		}
-	} else {
-		tz = time.UTC
-	}
-
-	if len(bytes) > 0 {
-		return time.Time{}, errors.New("GeneralizedTime has trailing garbage")
-	}
-
-	return time.Date(year, time.Month(month), day, hour, min, sec, ms*1000*1000, tz), nil
-}
-
-func decodeASN1Time(value *asn1.RawValue) (time.Time, error) {
-	if !value.IsCompound && value.Class == 0 {
-		if value.Tag == tagUTCTime {
-			return parseUTCTime(value.Bytes)
-		} else if value.Tag == tagGeneralizedTime {
-			return parseGeneralizedTime(value.Bytes)
-		}
-	}
-	return time.Time{}, errors.New("Not a time value")
-}