1// Copyright 2020 Google LLC 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14// 15//////////////////////////////////////////////////////////////////////////////// 16 17package subtle 18 19import ( 20 "crypto/ed25519" 21) 22 23// ED25519Signer is an implementation of Signer for ED25519. 24type ED25519Signer struct { 25 privateKey *ed25519.PrivateKey 26} 27 28// NewED25519Signer creates a new instance of ED25519Signer. 29func NewED25519Signer(keyValue []byte) (*ED25519Signer, error) { 30 p := ed25519.NewKeyFromSeed(keyValue) 31 return NewED25519SignerFromPrivateKey(&p) 32} 33 34// NewED25519SignerFromPrivateKey creates a new instance of ED25519Signer 35func NewED25519SignerFromPrivateKey(privateKey *ed25519.PrivateKey) (*ED25519Signer, error) { 36 return &ED25519Signer{ 37 privateKey: privateKey, 38 }, nil 39} 40 41// Sign computes a signature for the given data. 42func (e *ED25519Signer) Sign(data []byte) ([]byte, error) { 43 r := ed25519.Sign(*e.privateKey, data) 44 if len(r) != ed25519.SignatureSize { 45 return nil, errInvalidED25519Signature 46 } 47 return r, nil 48} 49