CODEWITHSUNDEEP
goopenpgp
Daniel Alderman
Daniel Alderman

Reputation: 147

Decrypting a non ASCII armored PGP file in Go

Is it possible to decrypt binary .PGP file with Go's "golang.org/x/crypto/openpgp" library?

The following code works with an armored ASCII encoded file but throws EOF error with a binary PGP file. Is there a similar function to armor.Decode() that allows for the binary file to be decrypted?

func DecryptFile(encryptedFilePath string, decryptedFilePath string) error {
pubKey := decodePublicKey()
privKey := decodePrivateKey()

entity := createEntityFromKeys(pubKey, privKey)

file := readFile(encryptedFilePath)

block, err := armor.Decode(file)
if err != nil {
    log.Printf("Error reading OpenPGP Armor: %s", err)
    return err
}

if block.Type != "Message" {
    log.Println("Invalid message type")
    return err
}

var entityList openpgp.EntityList
entityList = append(entityList, entity)

messageDetails, err := openpgp.ReadMessage(block.Body, entityList, nil, nil)
if err != nil {
    log.Printf("Error reading message: %s", err)
    return err
}

compressed, err := gzip.NewReader(messageDetails.UnverifiedBody)
if err != nil {
    log.Printf("Invalid compression level: %s", err)
    return err
}
defer compressed.Close()

buffer := bytes.NewBuffer(nil)

n, err := io.Copy(buffer, compressed)
if err != nil {
    log.Printf("Error reading encrypted file: %s", err)
    return err
}

err = ioutil.WriteFile(decryptedFilePath, buffer.Bytes(), 0644)
if err != nil {
    log.Println(err)
    return err
}

log.Printf("Decrypted %d bytes\n", n)

return nil

}

Upvotes: 4

Views: 3002

Answers (1)

Napazca
Napazca

Reputation: 56

I encountered the same exact problem with PGP, also got EOF on my first trial.

The encrypted file is in binary(.pgp)

The private/public key in key ring armored file(.asc) like this:

----BEGIN PGP PUBLIC KEY BLOCK-----

-----END PGP PRIVATE KEY BLOCK-----

Here is the code that I use:

keyRing, err := os.Open("keyArmoredFile.asc")
if err != nil {
    log.Fatal(err)
}

entityList, err := openpgp.ReadArmoredKeyRing(keyRing)
if err != nil {
    log.Fatal(err)
}

entity := entityList[0]
passphraseByte := []byte("password")
err = entity.PrivateKey.Decrypt(passphraseByte)
if err != nil {
    log.Fatal(err)
}
for _, subkey := range entity.Subkeys {
    subkey.PrivateKey.Decrypt(passphraseByte)
}

encryptedContent, err := os.Open("encryptedFile.pgp")
if err != nil {
    log.Fatal(err)
}

md, err := openpgp.ReadMessage(encryptedContent, entityList, nil, nil)
if err != nil {
    log.Fatal(err)}

bytes, err := ioutil.ReadAll(md.UnverifiedBody)
if err != nil {
    log.Fatal(err)
}

// decryption result
decStr := string(bytes)

Reference: https://gist.github.com/stuart-warren/93750a142d3de4e8fdd2

Upvotes: 4

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