failure in go.crypto and GnuPG interoperability

[Casey Marshall]

go.crypto is interpreting the plaintext input as text and mangling it,
as the input is binary. If you encrypt with:

cWrt, err := openpgp.Encrypt(cBuf, ents, nil,
&openpgp.FileHints{IsBinary: true}, nil)

you should see output identical to the input.

-Casey

On 01/30/2014 06:30 AM, Bernd Fix wrote:
> I am working on an application that is encrypting content with the
> openpgp functions from the go.crypto framework. This content is later to
> be decrypted using the GnuPG application on a Linux box. There seems to
> be an incompatibility between go.crypto and the GnuPG that fails to
> decrypt the original content correctly - the decrypted content for
> larger files is smaller than the original input.
> 
> I am using Debian7 with the tip version of Go, the current go.crypto
> repository and GnuPG 1.4.12. The following steps will reproduce the problem:
> 
> (1) create a file with random content (1MB in this case):
> 
>     dd if=/dev/urandom of=xxx.in count=2048
> 
> (2) create a local keyring for testing:
> 
>     gpg --home . --gen-key
> 
> I used RSA-4096 keys and "testtest" as a password; if you use a
> different password, change the source code of the test app; create only
> one key in the keyring!
> 
> (3) compile the test app from the source code below:
> 
>     go build test.go
> 
> (4) Run the test app:
> 
>     ./test
> 
> The output "Compare: 0" indicates that the encryption/decryption cycle
> in go.crypto worked fine and delivered the expected result.
> 
> (5) Decrypt output using GnuPG:
> 
>     gpg --home . -o xxx.out -d xxx.in.gpg
> 
> Compare the two files; you will see something like:
> 
>     -rw-r--r-- 1 test test 1048576 Jan 30 13:06 xxx.in
>     -rw-r--r-- 1 test test 1044505 Jan 30 13:18 xxx.out
> 
> 
> The two files don't match and neither the test app nor GnuPG showed any
> warning or error message. Am I doing something wrong or what is going on
> here?
> 
> Regards, Bernd.
> 
> =====[test.go]=================================================
> 
> package main
> 
> import (
>     "bytes"
>     "code.google.com/p/go.crypto/openpgp"
>     "fmt"
>     "io"
>     "io/ioutil"
>     "os"
> )
> 
> const (
>     FILE  = "xxx.in"
>     GNUPG = "secring.gpg"
>     PASSP = "testtest"
> )
> 
> func main() {
>     rdr, err := os.Open(GNUPG)
>     if err != nil {
>         panic(err.Error())
>     }
>     defer rdr.Close()
>     ents, err := openpgp.ReadKeyRing(rdr)
>     if err != nil {
>         panic(err.Error())
>     }
> 
>     f, err := os.Open(FILE)
>     if err != nil {
>         panic(err.Error())
>     }
>     plain, err := ioutil.ReadAll(f)
>     if err != nil {
>         panic(err.Error())
>     }
> 
>     cBuf := new(bytes.Buffer)
>     cWrt, err := openpgp.Encrypt(cBuf, ents, nil, nil, nil)
>     if err != nil {
>         panic(err.Error())
>     }
>     cWrt.Write(plain)
>     cWrt.Close()
>     cipher := cBuf.Bytes()
> 
>     out, err := os.Create(FILE + ".gpg")
>     if err != nil {
>         panic(err.Error())
>     }
>     out.Write(cipher)
>     out.Close()
> 
>     cBuf = bytes.NewBuffer(cipher)
>     pBuf := new(bytes.Buffer)
>     md, err := openpgp.ReadMessage(
>         cBuf,
>         ents,
>         func(keys []openpgp.Key, symmetric bool) ([]byte, error) {
>             priv := keys[0].PrivateKey
>             if priv.Encrypted {
>                 priv.Decrypt([]byte(PASSP))
>             }
>             buf := new(bytes.Buffer)
>             priv.Serialize(buf)
>             return buf.Bytes(), nil
>         },
>         nil)
>     if err != nil {
>         panic(err.Error())
>     }
>     buf := make([]byte, 1024)
>     for {
>         n, err := md.UnverifiedBody.Read(buf)
>         pBuf.Write(buf[:n])
>         if err != nil {
>             if err == io.EOF {
>                 err = nil
>                 break
>             }
>             panic(err.Error())
>         }
>     }
>     plain2 := pBuf.Bytes()
>     fmt.Printf("Compare: %d\n", bytes.Compare(plain, plain2))
> }
> 
> 
> 
> 
> _______________________________________________
> Gnupg-devel mailing list
> Gnupg-devel at gnupg.org
> http://lists.gnupg.org/mailman/listinfo/gnupg-devel
> 

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