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path: root/account.go
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package acme

import (
	"crypto"
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/rand"
	"crypto/rsa"
	"encoding/base64"
	"io"
	"strings"

	"github.com/square/go-jose"
)

// KeySize is a default RSA key size
const KeySize = 2048

// Account ...
type Account struct {
	key    crypto.PrivateKey
	signer jose.Signer
}

func LoadAccount(fname string) (*Account, error) {
	key, err := LoadKeyFile(fname)
	if err != nil {
		return nil, err
	}
	return newAccount(key)
}

func NewAccount(size int) (*Account, error) {
	key, err := rsa.GenerateKey(rand.Reader, size)
	if err != nil {
		return nil, err
	}
	return newAccount(key)
}

func NewAccountEC() (*Account, error) {
	key, err := ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
	if err != nil {
		return nil, err
	}
	return newAccount(key)
}

func newAccount(key crypto.PrivateKey) (*Account, error) {
	switch k := key.(type) {
	case *rsa.PrivateKey:
		signer, err := jose.NewSigner(jose.RS256, k)
		return &Account{key: k, signer: signer}, err
	case *ecdsa.PrivateKey:
		signer, err := jose.NewSigner(jose.ES384, k)
		return &Account{key: k, signer: signer}, err
	default:
		return nil, errKeyType
	}
}

// Signer describes a signing interface
type Signer interface {
	Sign([]byte, jose.NonceSource) (io.Reader, error)
	KeyAuth(string) (string, error)
}

// Sign implements Signer interface
func (a *Account) Sign(msg []byte, n jose.NonceSource) (io.Reader, error) {
	a.signer.SetNonceSource(n)
	obj, err := a.signer.Sign(msg)
	if err != nil {
		return nil, err
	}
	return strings.NewReader(obj.FullSerialize()), nil
}

func (a *Account) KeyAuth(token string) (string, error) {
	var wk *jose.JsonWebKey
	switch k := a.key.(type) {
	case *rsa.PrivateKey:
		wk = &jose.JsonWebKey{Key: k.Public(), Algorithm: "RSA"}
	case *ecdsa.PrivateKey:
		wk = &jose.JsonWebKey{Key: k.Public(), Algorithm: "EC"}
	}
	thumb, err := wk.Thumbprint(crypto.SHA256)
	if err != nil {
		return "", err
	}
	return token + "." + base64.RawURLEncoding.EncodeToString(thumb), nil
}

func (a *Account) Save(fname string) error {
	fd, err := CreatePrivFile(fname)
	if err != nil {
		return err
	}
	defer fd.Close()
	return saveKey(fd, a.key)
}