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package pki
import (
"bytes"
"crypto"
"crypto/ed25519"
"crypto/rand"
"encoding/pem"
"errors"
"fmt"
"io"
)
const (
PemLabelEd25519 = "ED25519 PRIVATE KEY" // TODO find correct label
)
type (
Ed25519PrivateKey struct {
private_key ed25519.PrivateKey
}
Ed25519PublicKey struct {
public_key ed25519.PublicKey
}
)
// Create a new private key of type ed25519.
func NewPrivateKeyEd25519() (*Ed25519PrivateKey, error) {
_, pr_raw, err := ed25519.GenerateKey(rand.Reader)
if err != nil {
return nil, err
}
return &Ed25519PrivateKey{pr_raw}, nil
}
// Restore an ed25519 private key from a raw byte stream.
// TODO does this have to be asn1? all other functions expect asn1
func LoadPrivateKeyEd25519(raw []byte) (*Ed25519PrivateKey, error) {
pr_loaded := make([]byte, ed25519.PrivateKeySize)
length := copy(pr_loaded, raw)
if length != ed25519.PrivateKeySize {
return nil, fmt.Errorf("private key length incorrect - got: %d - expected: %d", length, ed25519.PrivateKeySize)
}
return &Ed25519PrivateKey{pr_loaded}, nil
}
// TODO implement the raw API for the private key
func (pr *Ed25519PrivateKey) PrivateKey() crypto.PrivateKey {
return nil
}
// Return the public key for this private key.
func (pr *Ed25519PrivateKey) Public() PublicKey {
buf := bytes.NewBufferString(string(pr.private_key[:])) // create a bytes buffer to read the private key
pu_raw, _, err := ed25519.GenerateKey(buf) // use the already built private key again
if err != nil {
return nil
}
return &Ed25519PublicKey{pu_raw}
}
// Hash the message given the hash algorythm and sign the hash using the private key.
func (pr *Ed25519PrivateKey) Sign(message []byte, hash crypto.Hash) ([]byte, error) {
hashed_message := hash.New()
hashed_message.Write(message)
result := ed25519.Sign(pr.private_key, hashed_message.Sum(nil))[:]
return result, nil
}
// Export the private key into the Pem format.
func (pr Ed25519PrivateKey) MarshalPem() (io.WriterTo, error) {
pem_block, err := pr.ToPem()
if err != nil { // it does not currently return an error, but maybe that will change
return nil, err
}
return marshalledPemBlock(pem.EncodeToMemory(&pem_block)), nil
}
func (pr Ed25519PrivateKey) ToPem() (pem.Block, error) {
return pem.Block{Type: PemLabelEd25519, Bytes: pr.private_key[:]}, nil
}
// Load the public key from a raw byte stream.
// TODO should this be read from ASN.1? All other functions do that.
func LoadPublicKeyEd25519(raw []byte) (*Ed25519PublicKey, error) {
pu_loaded := make([]byte, ed25519.PublicKeySize)
length := copy(pu_loaded, raw)
if length != ed25519.PublicKeySize {
return nil, errors.New("public key length incorrect")
}
return &Ed25519PublicKey{pu_loaded}, nil
}
// ToPem returns the pem encoded public key.
func (pu Ed25519PublicKey) ToPem() (pem.Block, error) {
return pem.Block{Type: PemLabelPublic, Bytes: pu.public_key[:]}, nil
}
// Export the public key into the pem format.
func (pu Ed25519PublicKey) MarshalPem() (io.WriterTo, error) {
pem_block, err := pu.ToPem()
if err != nil {
return nil, err
}
return marshalledPemBlock(pem.EncodeToMemory(&pem_block)), nil
}
// Hash the message with the hash algorythm and check the signature against the result.
func (pu Ed25519PublicKey) Verify(message []byte, signature []byte, hash crypto.Hash) (bool, error) {
sig := make([]byte, ed25519.SignatureSize)
length := copy(sig[:], signature)
if length != ed25519.SignatureSize {
return false, errors.New("signature does not fit length")
}
hashed_message := hash.New()
hashed_message.Write(message)
return ed25519.Verify(pu.public_key, hashed_message.Sum(nil), sig), nil
}
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