get p7m file content

Question

I'm looking for fixing my code in order to get a .p7m file content as I do running a simple bash command:

openssl smime -decrypt -verify -inform DER -in TestDocument.pdf.p7m -noverify -out TestDocument.pdf

so I'd like to implement that with Go and found go.mozilla.org/pkcs7 package and an example as follow:

package main

import (
    "io/ioutil"
    "log"

    "go.mozilla.org/pkcs7"
)

func main() {
    content, err := ioutil.ReadFile("TestDocument.pdf.p7m")
    if err != nil {
        log.Fatal(err)
    }
    p7, err := pkcs7.Parse(content)
    if err != nil {
        log.Fatal(err)
    }
    if err := ioutil.WriteFile("TestDocument.pdf", p7.Content, 0777); err != nil {
        log.Fatal(err)
    }
}

and compiling it, I get this error: ber2der: Invalid BER format. Could you please help me to fix that?

Answer 1

I fixed it, missing a little part:

package main

import (
    "encoding/pem"
    "io/ioutil"
    "log"
    "os"

    "go.mozilla.org/pkcs7"
)

func main() {
    content, err := ioutil.ReadFile("TestDocument.pdf.p7m")
    if err != nil {
        log.Fatal(err)
    }
    p7, err := pkcs7.Parse(content)
    if err != nil {
        log.Fatal(err)
    }
    pem.Encode(os.Stdout, &pem.Block{Type: "PKCS7", Bytes: content})
    if err := ioutil.WriteFile("TestDocument.pdf", p7.Content, 0777); err != nil {
        log.Fatal(err)
    }
}