Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
93 lines
2.1 KiB
Go
93 lines
2.1 KiB
Go
package google
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import (
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"bytes"
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"crypto/hmac"
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"crypto/sha1"
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"encoding/base32"
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"encoding/binary"
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"fmt"
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"strings"
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"time"
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)
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type GoogleAuth struct {
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}
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func NewGoogleAuth() *GoogleAuth {
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return &GoogleAuth{}
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}
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func (ga *GoogleAuth) un() int64 {
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return time.Now().UnixNano() / 1000 / 30
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}
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func (ga *GoogleAuth) hmacSha1(key, data []byte) []byte {
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h := hmac.New(sha1.New, key)
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if total := len(data); total > 0 {
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h.Write(data)
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}
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return h.Sum(nil)
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}
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func (ga *GoogleAuth) base32encode(src []byte) string {
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return base32.StdEncoding.EncodeToString(src)
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}
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func (ga *GoogleAuth) base32decode(s string) ([]byte, error) {
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return base32.StdEncoding.DecodeString(s)
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}
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func (ga *GoogleAuth) toBytes(value int64) []byte {
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var result []byte
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mask := int64(0xFF)
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shifts := [8]uint16{56, 48, 40, 32, 24, 16, 8, 0}
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for _, shift := range shifts {
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result = append(result, byte((value>>shift)&mask))
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}
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return result
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}
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func (ga *GoogleAuth) toUint32(bts []byte) uint32 {
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return (uint32(bts[0]) << 24) + (uint32(bts[1]) << 16) +
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(uint32(bts[2]) << 8) + uint32(bts[3])
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}
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func (ga *GoogleAuth) oneTimePassword(key []byte, data []byte) uint32 {
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hash := ga.hmacSha1(key, data)
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offset := hash[len(hash)-1] & 0x0F
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hashParts := hash[offset : offset+4]
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hashParts[0] = hashParts[0] & 0x7F
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number := ga.toUint32(hashParts)
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return number % 1000000
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}
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func (ga *GoogleAuth) GetSecret() string {
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var buf bytes.Buffer
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binary.Write(&buf, binary.BigEndian, ga.un())
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return strings.ToUpper(ga.base32encode(ga.hmacSha1(buf.Bytes(), nil)))
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}
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func (ga *GoogleAuth) GetCode(secret string) (string, error) {
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secretUpper := strings.ToUpper(secret)
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secretKey, err := ga.base32decode(secretUpper)
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if err != nil {
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return "", err
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}
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number := ga.oneTimePassword(secretKey, ga.toBytes(time.Now().Unix()/30))
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return fmt.Sprintf("%06d", number), nil
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}
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func (ga *GoogleAuth) GetQrcode(user, secret string) string {
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return fmt.Sprintf("otpauth://totp/%s?secret=%s", user, secret)
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}
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func (ga *GoogleAuth) VerifyCode(secret, code string) (bool, error) {
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_code, err := ga.GetCode(secret)
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fmt.Println(_code, code, err)
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if err != nil {
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return false, err
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}
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return _code == code, nil
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}
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