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package service
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"encoding/base64"
"fmt"
"io"
"golang.org/x/crypto/bcrypt"
)
type (
AuthService struct {
authRepository authRepository
}
authRepository interface {
GetPassphrase() []byte
GetBase64AesKey() []byte
}
)
var tokenSeed = []byte("this is a token for cerrado")
func NewAuthService(repostiory authRepository) *AuthService {
return &AuthService{
authRepository: repostiory,
}
}
func (a *AuthService) CheckAuth(username, password string) bool {
passphrase := a.authRepository.GetPassphrase()
pass := []byte(fmt.Sprintf("%s:%s", username, password))
err := bcrypt.CompareHashAndPassword(passphrase, pass)
return err == nil
}
func (a *AuthService) IssueToken() ([]byte, error) {
// TODO: do this block only once
base := a.authRepository.GetBase64AesKey()
dbuf, err := base64.StdEncoding.DecodeString(string(base))
if err != nil {
return nil, err
}
block, err := aes.NewCipher(dbuf)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
nonce := make([]byte, gcm.NonceSize())
if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
return nil, err
}
ciphertext := gcm.Seal(nonce, nonce, tokenSeed, nil)
return ciphertext, nil
}
func (a *AuthService) ValidateToken(token []byte) (bool, error) {
base := a.authRepository.GetBase64AesKey()
dbuf, err := base64.StdEncoding.DecodeString(string(base))
if err != nil {
return false, err
}
block, err := aes.NewCipher(dbuf)
if err != nil {
return false, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return false, err
}
nonceSize := gcm.NonceSize()
if len(token) < nonceSize {
return false, fmt.Errorf("ciphertext too short")
}
nonce, ciphertext := token[:nonceSize], token[nonceSize:]
plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
if err != nil {
return false, err
}
return bytes.Equal(tokenSeed, plaintext), nil
}
func GenerateHash(username, password string) (string, error) {
passphrase := fmt.Sprintf("%s:%s", username, password)
bytes, err := bcrypt.GenerateFromPassword([]byte(passphrase), 14)
if err != nil {
return "", err
}
return string(bytes), nil
}
func GenerateAesKey() (string, error) {
key := make([]byte, 32)
_, err := rand.Read(key)
if err != nil {
return "", err
}
return base64.StdEncoding.EncodeToString(key), nil
}
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