portainer/api/crypto/ecdsa.go

140 lines
3.6 KiB
Go

package crypto
import (
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/x509"
"encoding/base64"
"encoding/hex"
"math/big"
"github.com/portainer/libcrypto"
)
const (
// PrivateKeyPemHeader represents the header that is appended to the PEM file when
// storing the private key.
PrivateKeyPemHeader = "EC PRIVATE KEY"
// PublicKeyPemHeader represents the header that is appended to the PEM file when
// storing the public key.
PublicKeyPemHeader = "ECDSA PUBLIC KEY"
)
// ECDSAService is a service used to create digital signatures when communicating with
// an agent based environment. It will automatically generates a key pair using ECDSA or
// can also reuse an existing ECDSA key pair.
type ECDSAService struct {
privateKey *ecdsa.PrivateKey
publicKey *ecdsa.PublicKey
encodedPubKey string
secret string
}
// NewECDSAService returns a pointer to a ECDSAService.
// An optional secret can be specified
func NewECDSAService(secret string) *ECDSAService {
return &ECDSAService{
secret: secret,
}
}
// EncodedPublicKey returns the encoded version of the public that can be used
// to be shared with other services. It's the hexadecimal encoding of the public key
// content.
func (service *ECDSAService) EncodedPublicKey() string {
return service.encodedPubKey
}
// PEMHeaders returns the ECDSA PEM headers.
func (service *ECDSAService) PEMHeaders() (string, string) {
return PrivateKeyPemHeader, PublicKeyPemHeader
}
// ParseKeyPair parses existing private/public key pair content and associate
// the parsed keys to the service.
func (service *ECDSAService) ParseKeyPair(private, public []byte) error {
privateKey, err := x509.ParseECPrivateKey(private)
if err != nil {
return err
}
service.privateKey = privateKey
encodedKey := hex.EncodeToString(public)
service.encodedPubKey = encodedKey
publicKey, err := x509.ParsePKIXPublicKey(public)
if err != nil {
return err
}
service.publicKey = publicKey.(*ecdsa.PublicKey)
return nil
}
// GenerateKeyPair will create a new key pair using ECDSA.
func (service *ECDSAService) GenerateKeyPair() ([]byte, []byte, error) {
pubkeyCurve := elliptic.P256()
privatekey, err := ecdsa.GenerateKey(pubkeyCurve, rand.Reader)
if err != nil {
return nil, nil, err
}
service.privateKey = privatekey
service.publicKey = &privatekey.PublicKey
private, err := x509.MarshalECPrivateKey(service.privateKey)
if err != nil {
return nil, nil, err
}
public, err := x509.MarshalPKIXPublicKey(service.publicKey)
if err != nil {
return nil, nil, err
}
encodedKey := hex.EncodeToString(public)
service.encodedPubKey = encodedKey
return private, public, nil
}
// CreateSignature creates a digital signature.
// It automatically hash a specific message using MD5 and creates a signature from
// that hash.
// If a secret is associated to the service, it will be used instead of the specified
// message.
// It then encodes the generated signature in base64.
func (service *ECDSAService) CreateSignature(message string) (string, error) {
if service.secret != "" {
message = service.secret
}
hash := libcrypto.HashFromBytes([]byte(message))
r := big.NewInt(0)
s := big.NewInt(0)
r, s, err := ecdsa.Sign(rand.Reader, service.privateKey, hash)
if err != nil {
return "", err
}
keyBytes := service.privateKey.Params().BitSize / 8
rBytes := r.Bytes()
rBytesPadded := make([]byte, keyBytes)
copy(rBytesPadded[keyBytes-len(rBytes):], rBytes)
sBytes := s.Bytes()
sBytesPadded := make([]byte, keyBytes)
copy(sBytesPadded[keyBytes-len(sBytes):], sBytes)
signature := append(rBytesPadded, sBytesPadded...)
return base64.RawStdEncoding.EncodeToString(signature), nil
}