package nametransform // Filename encryption / decryption functions import ( "crypto/aes" "encoding/base64" "fmt" "github.com/rfjakob/eme" "github.com/rfjakob/gocryptfs/internal/cryptocore" ) type NameTransform struct { cryptoCore *cryptocore.CryptoCore longNames bool DirIVCache dirIVCache } func New(c *cryptocore.CryptoCore, longNames bool) *NameTransform { return &NameTransform{ cryptoCore: c, longNames: longNames, } } // DecryptName - decrypt base64-encoded encrypted filename "cipherName" // Used by DecryptPathDirIV(). // The encryption is either CBC or EME, depending on "useEME". // // This function is exported because it allows for a very efficient readdir // implementation (read IV once, decrypt all names using this function). func (n *NameTransform) DecryptName(cipherName string, iv []byte) (string, error) { bin, err := base64.URLEncoding.DecodeString(cipherName) if err != nil { return "", err } if len(bin)%aes.BlockSize != 0 { return "", fmt.Errorf("Decoded length %d is not a multiple of the AES block size", len(bin)) } bin = eme.Transform(n.cryptoCore.BlockCipher, iv, bin, eme.DirectionDecrypt) bin, err = unPad16(bin) if err != nil { return "", err } plain := string(bin) return plain, err } // encryptName - encrypt "plainName", return base64-encoded "cipherName64". // Used internally by EncryptPathDirIV(). // The encryption is either CBC or EME, depending on "useEME". // // This function is exported because fusefrontend needs access to the full (not hashed) // name if longname is used. Otherwise you should use EncryptPathDirIV() func (n *NameTransform) EncryptName(plainName string, iv []byte) (cipherName64 string) { bin := []byte(plainName) bin = pad16(bin) bin = eme.Transform(n.cryptoCore.BlockCipher, iv, bin, eme.DirectionEncrypt) cipherName64 = base64.URLEncoding.EncodeToString(bin) return cipherName64 }