meowlib/asymcrypt.go

package meowlib

import (
	"encoding/base64"
	"time"

	"github.com/ProtonMail/gopenpgp/v2/crypto"
	"github.com/ProtonMail/gopenpgp/v2/helper"
	"github.com/pkg/errors"
	"github.com/rs/zerolog/log"
)

type KeyPair struct {
	Public    string    `json:"public,omitempty"`
	Private   string    `json:"private,omitempty"`
	Generated time.Time `json:"generated,omitempty"`
}

type KeysArray []KeyPair

func NewKeyPair() KeyPair {
	var kp KeyPair
	keys, err := crypto.GenerateKey("name", "mail", "x25519", 0)
	if err != nil {
		log.Error().Msg("Key generation failed")
	}
	kp.Generated = time.Now()
	pub, err := keys.GetArmoredPublicKey()
	if err != nil {
		log.Error().Msg("Public key extraction failed")
	}
	kp.Public = base64.StdEncoding.EncodeToString([]byte(pub))
	priv, err := keys.Armor()
	if err != nil {
		log.Error().Msg("Private key extraction failed")
	}
	kp.Private = base64.StdEncoding.EncodeToString([]byte(priv))
	return kp
}

func (Kp *KeyPair) GetCryptoKeyObject() *crypto.Key {
	priv, err := base64.StdEncoding.DecodeString(Kp.Private)
	if err != nil {
		log.Error().Msg("Create key from armoured b64 failed")
	}
	key, err := crypto.NewKeyFromArmored(string(priv))
	if err != nil {
		log.Error().Msg("Create key from armoured failed")
	}
	return key
}

func AsymEncrypt(publicKey string, data []byte) ([]byte, error) {
	pub, err := base64.StdEncoding.DecodeString(publicKey)
	if err != nil {
		log.Error().Msg("Message encryption b64 failed")
	}
	ciphertext, err := encryptMessage(string(pub), crypto.NewPlainMessage(data))
	if err != nil {
		log.Error().Msg("Message encryption failed")
		return nil, err
	}

	return ciphertext.GetBinary(), err
}

func AsymDecrypt(PrivateKey string, data []byte) ([]byte, error) {
	priv, err := base64.StdEncoding.DecodeString(PrivateKey)
	if err != nil {
		log.Error().Msg("Message decryption b64 failed")
	}
	decrypted, err := decryptMessage(string(priv), nil, crypto.NewPGPMessage(data))
	if err != nil {
		log.Error().Msg("Message decryption failed")
	}
	return decrypted.GetBinary(), err
}

func AsymEncryptArmored(PublicKey string, data []byte) ([]byte, error) {
	pub, err := base64.StdEncoding.DecodeString(PublicKey)
	if err != nil {
		log.Error().Msg("Message encryption b64 failed")
	}
	armor, err := helper.EncryptBinaryMessageArmored(string(pub), data)
	if err != nil {
		log.Error().Msg("Message encryption failed")
	}
	return []byte(armor), err
}

func AsymDecryptArmored(PrivateKey string, data []byte) ([]byte, error) {
	priv, err := base64.StdEncoding.DecodeString(PrivateKey)
	if err != nil {
		log.Error().Msg("Message decryption b64 failed")
	}
	decrypted, err := helper.DecryptBinaryMessageArmored(string(priv), nil, string(data))
	if err != nil {
		log.Error().Msg("Message decryption failed")
	}
	return []byte(decrypted), err
}

func AsymEncryptAndSign(PublicEncryptionKey string, PrivateSignatureKey string, data []byte) ([]byte, []byte, error) {
	pub, err := base64.StdEncoding.DecodeString(PublicEncryptionKey)
	if err != nil {
		log.Error().Msg("Message encryption and sign b64 failed")
	}
	priv, err := base64.StdEncoding.DecodeString(PrivateSignatureKey)
	if err != nil {
		log.Error().Msg("Message encryption and sign b64 failed")
	}
	encrypted, signature, err := helper.EncryptSignBinaryDetached(string(pub), string(priv), nil, data)
	if err != nil {
		log.Error().Msg("Message encryption and sign failed")
	}
	return []byte(encrypted), []byte(signature), err
}

func AsymDecryptAndCheck(MyPrivateEncryptionKey string, MyContactPublicKey string, data []byte, Signature []byte) (DecryptedMessage []byte, err error) {
	priv, err := base64.StdEncoding.DecodeString(MyPrivateEncryptionKey)
	if err != nil {
		log.Error().Msg("Message decryption and sign b64 failed")
	}
	pub, err := base64.StdEncoding.DecodeString(MyContactPublicKey)
	if err != nil {
		log.Error().Msg("Message decryption and sign b64 failed")
	}
	DecryptedMessage, err = helper.DecryptVerifyBinaryDetached(string(pub), string(priv), nil, data, string(Signature))
	if err != nil {
		log.Error().Msg("Message decryption and sign failed")
	}
	return DecryptedMessage, err
}

func encryptMessage(key string, message *crypto.PlainMessage) (*crypto.PGPMessage, error) {
	publicKeyRing, err := createPublicKeyRing(key)
	if err != nil {
		return nil, err
	}

	ciphertext, err := publicKeyRing.Encrypt(message, nil)
	if err != nil {
		return nil, errors.Wrap(err, "gopenpgp: unable to encrypt message")
	}

	return ciphertext, nil
}

func decryptMessage(privateKey string, passphrase []byte, ciphertext *crypto.PGPMessage) (*crypto.PlainMessage, error) {
	privateKeyObj, err := crypto.NewKeyFromArmored(privateKey)
	if err != nil {
		return nil, errors.Wrap(err, "gopenpgp: unable to parse the private key")
	}

	privateKeyUnlocked, err := privateKeyObj.Unlock(passphrase)
	if err != nil {
		return nil, errors.Wrap(err, "gopenpgp: unable to unlock key")
	}

	defer privateKeyUnlocked.ClearPrivateParams()

	privateKeyRing, err := crypto.NewKeyRing(privateKeyUnlocked)
	if err != nil {
		return nil, errors.Wrap(err, "gopenpgp: unable to create the private key ring")
	}

	message, err := privateKeyRing.Decrypt(ciphertext, nil, 0)
	if err != nil {
		return nil, errors.Wrap(err, "gopenpgp: unable to decrypt message")
	}

	return message, nil
}

func createPublicKeyRing(publicKey string) (*crypto.KeyRing, error) {
	publicKeyObj, err := crypto.NewKeyFromArmored(publicKey)
	if err != nil {
		return nil, errors.Wrap(err, "gopenpgp: unable to parse public key")
	}

	if publicKeyObj.IsPrivate() {
		publicKeyObj, err = publicKeyObj.ToPublic()
		if err != nil {
			return nil, errors.Wrap(err, "gopenpgp: unable to extract public key from private key")
		}
	}

	publicKeyRing, err := crypto.NewKeyRing(publicKeyObj)
	if err != nil {
		return nil, errors.Wrap(err, "gopenpgp: unable to create new keyring")
	}

	return publicKeyRing, nil
}