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imgproxy/crypt.go
2018-11-15 18:35:06 +06:00

42 lines
826 B
Go

package main
import (
"crypto/hmac"
"crypto/sha256"
"encoding/base64"
"errors"
)
var (
errInvalidToken = errors.New("Invalid token")
errInvalidTokenEncoding = errors.New("Invalid token encoding")
)
type securityKey []byte
func validatePath(token, path string) error {
messageMAC, err := base64.RawURLEncoding.DecodeString(token)
if err != nil {
return errInvalidTokenEncoding
}
for i := 0; i < len(conf.Keys); i++ {
if hmac.Equal(messageMAC, signatureFor(path, i)) {
return nil
}
}
return errInvalidToken
}
func signatureFor(str string, pairInd int) []byte {
mac := hmac.New(sha256.New, conf.Keys[pairInd])
mac.Write(conf.Salts[pairInd])
mac.Write([]byte(str))
expectedMAC := mac.Sum(nil)
if conf.SignatureSize < 32 {
return expectedMAC[:conf.SignatureSize]
}
return expectedMAC
}