(Go) Encrypt a file to a PKCS7 encrypted message using multiple certificates from different users

Demonstrates how to encrypt a file to a PKCS7 encrypted message using multiple certificates from different users. Any one of the users can decrypt using his/her own certificate + private key.

Note: When doing public key encryption, it is the public key that is used to encrypt. The private key is required for decryption.

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    // This example requires the Chilkat Crypt API to have been previously unlocked.
    // See Unlock Chilkat Crypt for sample code.

    crypt := chilkat.NewCrypt2()

    // Tell the crypt object to use 3 certificates.
    // Do this by calling AddEncryptCert for each certificate.

    // Load a digital certificate. 
    // We don't need the private key for encryption.
    // Only the public key is needed (which is included in a certificate).
    cert1 := chilkat.NewCert()
    success := cert1.LoadFromFile("qa_data/user1/cert_user1.pem")
    // Assume success for the example, but make sure your application checks for success/failure...
    crypt.AddEncryptCert(cert1)

    cert2 := chilkat.NewCert()
    success = cert2.LoadFromFile("qa_data/user2/cert_user2.pem")
    crypt.AddEncryptCert(cert2)

    cert3 := chilkat.NewCert()
    success = cert3.LoadFromFile("qa_data/user3/cert_user3.pem")
    crypt.AddEncryptCert(cert3)

    // Indicate that we want PKI encryption (i.e. public-key infrastructure)
    // to produce a CMS message (Cryptographic Message Syntax/PKCS7),
    // that is be created with RSAES-OAEP padding, SHA256, and AES-128 for the
    // bulk encryption.
    crypt.SetCryptAlgorithm("pki")
    crypt.SetPkcs7CryptAlg("aes")
    crypt.SetKeyLength(128)
    crypt.SetOaepHash("sha256")
    crypt.SetOaepPadding(true)

    // Load the file to be encrypted...
    fileData := chilkat.NewBinData()
    success = fileData.LoadFile("qa_data/jpg/penguins.jpg")
    // Your app should check for success/failure..

    // Encrypt the data.  The contents of the fileData object are replaced with the PKCS7 encrypted message.
    success = crypt.EncryptBd(fileData)
    if success != true {
        fmt.Println(crypt.LastErrorText())
        crypt.DisposeCrypt2()
        cert1.DisposeCert()
        cert2.DisposeCert()
        cert3.DisposeCert()
        fileData.DisposeBinData()
        return
    }

    // Save the PKCS7 encrypted message to a file..
    success = fileData.WriteFile("qa_output/pkcs7_encrypted.p7")

    // Now indicate that the PKCS7 output is to be returned in the base64 encoding.
    crypt.SetEncodingMode("base64")

    fmt.Println("OK.")

    crypt.DisposeCrypt2()
    cert1.DisposeCert()
    cert2.DisposeCert()
    cert3.DisposeCert()
    fileData.DisposeBinData()