593 lines
16 KiB
Go
593 lines
16 KiB
Go
/*-
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* Copyright 2014 Square Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package jose
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import (
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"crypto"
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"crypto/aes"
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"crypto/ecdsa"
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"crypto/rand"
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"crypto/rsa"
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"crypto/sha1"
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"crypto/sha256"
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"errors"
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"fmt"
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"math/big"
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"golang.org/x/crypto/ed25519"
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josecipher "gopkg.in/square/go-jose.v2/cipher"
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"gopkg.in/square/go-jose.v2/json"
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)
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// A generic RSA-based encrypter/verifier
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type rsaEncrypterVerifier struct {
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publicKey *rsa.PublicKey
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}
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// A generic RSA-based decrypter/signer
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type rsaDecrypterSigner struct {
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privateKey *rsa.PrivateKey
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}
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// A generic EC-based encrypter/verifier
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type ecEncrypterVerifier struct {
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publicKey *ecdsa.PublicKey
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}
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type edEncrypterVerifier struct {
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publicKey ed25519.PublicKey
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}
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// A key generator for ECDH-ES
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type ecKeyGenerator struct {
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size int
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algID string
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publicKey *ecdsa.PublicKey
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}
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// A generic EC-based decrypter/signer
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type ecDecrypterSigner struct {
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privateKey *ecdsa.PrivateKey
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}
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type edDecrypterSigner struct {
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privateKey ed25519.PrivateKey
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}
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// newRSARecipient creates recipientKeyInfo based on the given key.
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func newRSARecipient(keyAlg KeyAlgorithm, publicKey *rsa.PublicKey) (recipientKeyInfo, error) {
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// Verify that key management algorithm is supported by this encrypter
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switch keyAlg {
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case RSA1_5, RSA_OAEP, RSA_OAEP_256:
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default:
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return recipientKeyInfo{}, ErrUnsupportedAlgorithm
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}
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if publicKey == nil {
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return recipientKeyInfo{}, errors.New("invalid public key")
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}
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return recipientKeyInfo{
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keyAlg: keyAlg,
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keyEncrypter: &rsaEncrypterVerifier{
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publicKey: publicKey,
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},
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}, nil
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}
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// newRSASigner creates a recipientSigInfo based on the given key.
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func newRSASigner(sigAlg SignatureAlgorithm, privateKey *rsa.PrivateKey) (recipientSigInfo, error) {
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// Verify that key management algorithm is supported by this encrypter
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switch sigAlg {
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case RS256, RS384, RS512, PS256, PS384, PS512:
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default:
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return recipientSigInfo{}, ErrUnsupportedAlgorithm
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}
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if privateKey == nil {
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return recipientSigInfo{}, errors.New("invalid private key")
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}
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return recipientSigInfo{
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sigAlg: sigAlg,
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publicKey: staticPublicKey(&JSONWebKey{
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Key: privateKey.Public(),
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}),
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signer: &rsaDecrypterSigner{
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privateKey: privateKey,
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},
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}, nil
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}
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func newEd25519Signer(sigAlg SignatureAlgorithm, privateKey ed25519.PrivateKey) (recipientSigInfo, error) {
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if sigAlg != EdDSA {
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return recipientSigInfo{}, ErrUnsupportedAlgorithm
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}
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if privateKey == nil {
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return recipientSigInfo{}, errors.New("invalid private key")
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}
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return recipientSigInfo{
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sigAlg: sigAlg,
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publicKey: staticPublicKey(&JSONWebKey{
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Key: privateKey.Public(),
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}),
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signer: &edDecrypterSigner{
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privateKey: privateKey,
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},
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}, nil
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}
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// newECDHRecipient creates recipientKeyInfo based on the given key.
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func newECDHRecipient(keyAlg KeyAlgorithm, publicKey *ecdsa.PublicKey) (recipientKeyInfo, error) {
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// Verify that key management algorithm is supported by this encrypter
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switch keyAlg {
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case ECDH_ES, ECDH_ES_A128KW, ECDH_ES_A192KW, ECDH_ES_A256KW:
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default:
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return recipientKeyInfo{}, ErrUnsupportedAlgorithm
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}
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if publicKey == nil || !publicKey.Curve.IsOnCurve(publicKey.X, publicKey.Y) {
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return recipientKeyInfo{}, errors.New("invalid public key")
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}
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return recipientKeyInfo{
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keyAlg: keyAlg,
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keyEncrypter: &ecEncrypterVerifier{
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publicKey: publicKey,
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},
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}, nil
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}
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// newECDSASigner creates a recipientSigInfo based on the given key.
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func newECDSASigner(sigAlg SignatureAlgorithm, privateKey *ecdsa.PrivateKey) (recipientSigInfo, error) {
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// Verify that key management algorithm is supported by this encrypter
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switch sigAlg {
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case ES256, ES384, ES512:
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default:
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return recipientSigInfo{}, ErrUnsupportedAlgorithm
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}
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if privateKey == nil {
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return recipientSigInfo{}, errors.New("invalid private key")
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}
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return recipientSigInfo{
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sigAlg: sigAlg,
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publicKey: staticPublicKey(&JSONWebKey{
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Key: privateKey.Public(),
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}),
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signer: &ecDecrypterSigner{
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privateKey: privateKey,
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},
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}, nil
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}
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// Encrypt the given payload and update the object.
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func (ctx rsaEncrypterVerifier) encryptKey(cek []byte, alg KeyAlgorithm) (recipientInfo, error) {
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encryptedKey, err := ctx.encrypt(cek, alg)
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if err != nil {
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return recipientInfo{}, err
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}
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return recipientInfo{
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encryptedKey: encryptedKey,
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header: &rawHeader{},
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}, nil
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}
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// Encrypt the given payload. Based on the key encryption algorithm,
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// this will either use RSA-PKCS1v1.5 or RSA-OAEP (with SHA-1 or SHA-256).
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func (ctx rsaEncrypterVerifier) encrypt(cek []byte, alg KeyAlgorithm) ([]byte, error) {
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switch alg {
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case RSA1_5:
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return rsa.EncryptPKCS1v15(RandReader, ctx.publicKey, cek)
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case RSA_OAEP:
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return rsa.EncryptOAEP(sha1.New(), RandReader, ctx.publicKey, cek, []byte{})
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case RSA_OAEP_256:
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return rsa.EncryptOAEP(sha256.New(), RandReader, ctx.publicKey, cek, []byte{})
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}
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return nil, ErrUnsupportedAlgorithm
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}
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// Decrypt the given payload and return the content encryption key.
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func (ctx rsaDecrypterSigner) decryptKey(headers rawHeader, recipient *recipientInfo, generator keyGenerator) ([]byte, error) {
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return ctx.decrypt(recipient.encryptedKey, headers.getAlgorithm(), generator)
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}
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// Decrypt the given payload. Based on the key encryption algorithm,
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// this will either use RSA-PKCS1v1.5 or RSA-OAEP (with SHA-1 or SHA-256).
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func (ctx rsaDecrypterSigner) decrypt(jek []byte, alg KeyAlgorithm, generator keyGenerator) ([]byte, error) {
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// Note: The random reader on decrypt operations is only used for blinding,
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// so stubbing is meanlingless (hence the direct use of rand.Reader).
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switch alg {
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case RSA1_5:
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defer func() {
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// DecryptPKCS1v15SessionKey sometimes panics on an invalid payload
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// because of an index out of bounds error, which we want to ignore.
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// This has been fixed in Go 1.3.1 (released 2014/08/13), the recover()
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// only exists for preventing crashes with unpatched versions.
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// See: https://groups.google.com/forum/#!topic/golang-dev/7ihX6Y6kx9k
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// See: https://code.google.com/p/go/source/detail?r=58ee390ff31602edb66af41ed10901ec95904d33
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_ = recover()
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}()
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// Perform some input validation.
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keyBytes := ctx.privateKey.PublicKey.N.BitLen() / 8
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if keyBytes != len(jek) {
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// Input size is incorrect, the encrypted payload should always match
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// the size of the public modulus (e.g. using a 2048 bit key will
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// produce 256 bytes of output). Reject this since it's invalid input.
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return nil, ErrCryptoFailure
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}
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cek, _, err := generator.genKey()
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if err != nil {
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return nil, ErrCryptoFailure
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}
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// When decrypting an RSA-PKCS1v1.5 payload, we must take precautions to
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// prevent chosen-ciphertext attacks as described in RFC 3218, "Preventing
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// the Million Message Attack on Cryptographic Message Syntax". We are
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// therefore deliberately ignoring errors here.
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_ = rsa.DecryptPKCS1v15SessionKey(rand.Reader, ctx.privateKey, jek, cek)
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return cek, nil
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case RSA_OAEP:
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// Use rand.Reader for RSA blinding
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return rsa.DecryptOAEP(sha1.New(), rand.Reader, ctx.privateKey, jek, []byte{})
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case RSA_OAEP_256:
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// Use rand.Reader for RSA blinding
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return rsa.DecryptOAEP(sha256.New(), rand.Reader, ctx.privateKey, jek, []byte{})
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}
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return nil, ErrUnsupportedAlgorithm
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}
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// Sign the given payload
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func (ctx rsaDecrypterSigner) signPayload(payload []byte, alg SignatureAlgorithm) (Signature, error) {
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var hash crypto.Hash
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switch alg {
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case RS256, PS256:
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hash = crypto.SHA256
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case RS384, PS384:
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hash = crypto.SHA384
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case RS512, PS512:
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hash = crypto.SHA512
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default:
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return Signature{}, ErrUnsupportedAlgorithm
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}
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hasher := hash.New()
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// According to documentation, Write() on hash never fails
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_, _ = hasher.Write(payload)
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hashed := hasher.Sum(nil)
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var out []byte
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var err error
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switch alg {
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case RS256, RS384, RS512:
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out, err = rsa.SignPKCS1v15(RandReader, ctx.privateKey, hash, hashed)
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case PS256, PS384, PS512:
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out, err = rsa.SignPSS(RandReader, ctx.privateKey, hash, hashed, &rsa.PSSOptions{
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SaltLength: rsa.PSSSaltLengthEqualsHash,
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})
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}
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if err != nil {
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return Signature{}, err
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}
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return Signature{
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Signature: out,
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protected: &rawHeader{},
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}, nil
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}
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// Verify the given payload
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func (ctx rsaEncrypterVerifier) verifyPayload(payload []byte, signature []byte, alg SignatureAlgorithm) error {
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var hash crypto.Hash
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switch alg {
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case RS256, PS256:
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hash = crypto.SHA256
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case RS384, PS384:
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hash = crypto.SHA384
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case RS512, PS512:
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hash = crypto.SHA512
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default:
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return ErrUnsupportedAlgorithm
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}
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hasher := hash.New()
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// According to documentation, Write() on hash never fails
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_, _ = hasher.Write(payload)
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hashed := hasher.Sum(nil)
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switch alg {
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case RS256, RS384, RS512:
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return rsa.VerifyPKCS1v15(ctx.publicKey, hash, hashed, signature)
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case PS256, PS384, PS512:
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return rsa.VerifyPSS(ctx.publicKey, hash, hashed, signature, nil)
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}
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return ErrUnsupportedAlgorithm
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}
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// Encrypt the given payload and update the object.
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func (ctx ecEncrypterVerifier) encryptKey(cek []byte, alg KeyAlgorithm) (recipientInfo, error) {
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switch alg {
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case ECDH_ES:
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// ECDH-ES mode doesn't wrap a key, the shared secret is used directly as the key.
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return recipientInfo{
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header: &rawHeader{},
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}, nil
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case ECDH_ES_A128KW, ECDH_ES_A192KW, ECDH_ES_A256KW:
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default:
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return recipientInfo{}, ErrUnsupportedAlgorithm
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}
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generator := ecKeyGenerator{
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algID: string(alg),
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publicKey: ctx.publicKey,
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}
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switch alg {
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case ECDH_ES_A128KW:
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generator.size = 16
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case ECDH_ES_A192KW:
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generator.size = 24
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case ECDH_ES_A256KW:
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generator.size = 32
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}
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kek, header, err := generator.genKey()
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if err != nil {
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return recipientInfo{}, err
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}
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block, err := aes.NewCipher(kek)
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if err != nil {
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return recipientInfo{}, err
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}
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jek, err := josecipher.KeyWrap(block, cek)
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if err != nil {
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return recipientInfo{}, err
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}
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return recipientInfo{
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encryptedKey: jek,
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header: &header,
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}, nil
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}
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// Get key size for EC key generator
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func (ctx ecKeyGenerator) keySize() int {
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return ctx.size
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}
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// Get a content encryption key for ECDH-ES
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func (ctx ecKeyGenerator) genKey() ([]byte, rawHeader, error) {
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priv, err := ecdsa.GenerateKey(ctx.publicKey.Curve, RandReader)
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if err != nil {
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return nil, rawHeader{}, err
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}
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out := josecipher.DeriveECDHES(ctx.algID, []byte{}, []byte{}, priv, ctx.publicKey, ctx.size)
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b, err := json.Marshal(&JSONWebKey{
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Key: &priv.PublicKey,
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})
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if err != nil {
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return nil, nil, err
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}
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headers := rawHeader{
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headerEPK: makeRawMessage(b),
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}
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return out, headers, nil
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}
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// Decrypt the given payload and return the content encryption key.
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func (ctx ecDecrypterSigner) decryptKey(headers rawHeader, recipient *recipientInfo, generator keyGenerator) ([]byte, error) {
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epk, err := headers.getEPK()
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if err != nil {
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return nil, errors.New("square/go-jose: invalid epk header")
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}
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if epk == nil {
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return nil, errors.New("square/go-jose: missing epk header")
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}
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publicKey, ok := epk.Key.(*ecdsa.PublicKey)
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if publicKey == nil || !ok {
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return nil, errors.New("square/go-jose: invalid epk header")
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}
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if !ctx.privateKey.Curve.IsOnCurve(publicKey.X, publicKey.Y) {
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return nil, errors.New("square/go-jose: invalid public key in epk header")
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}
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apuData, err := headers.getAPU()
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if err != nil {
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return nil, errors.New("square/go-jose: invalid apu header")
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}
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apvData, err := headers.getAPV()
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if err != nil {
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return nil, errors.New("square/go-jose: invalid apv header")
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}
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deriveKey := func(algID string, size int) []byte {
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return josecipher.DeriveECDHES(algID, apuData.bytes(), apvData.bytes(), ctx.privateKey, publicKey, size)
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}
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var keySize int
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algorithm := headers.getAlgorithm()
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switch algorithm {
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case ECDH_ES:
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// ECDH-ES uses direct key agreement, no key unwrapping necessary.
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return deriveKey(string(headers.getEncryption()), generator.keySize()), nil
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case ECDH_ES_A128KW:
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keySize = 16
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case ECDH_ES_A192KW:
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keySize = 24
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case ECDH_ES_A256KW:
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keySize = 32
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default:
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return nil, ErrUnsupportedAlgorithm
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}
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key := deriveKey(string(algorithm), keySize)
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block, err := aes.NewCipher(key)
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if err != nil {
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return nil, err
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}
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return josecipher.KeyUnwrap(block, recipient.encryptedKey)
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}
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func (ctx edDecrypterSigner) signPayload(payload []byte, alg SignatureAlgorithm) (Signature, error) {
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if alg != EdDSA {
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return Signature{}, ErrUnsupportedAlgorithm
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}
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sig, err := ctx.privateKey.Sign(RandReader, payload, crypto.Hash(0))
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if err != nil {
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return Signature{}, err
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}
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return Signature{
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Signature: sig,
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protected: &rawHeader{},
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}, nil
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}
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func (ctx edEncrypterVerifier) verifyPayload(payload []byte, signature []byte, alg SignatureAlgorithm) error {
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if alg != EdDSA {
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return ErrUnsupportedAlgorithm
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}
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ok := ed25519.Verify(ctx.publicKey, payload, signature)
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if !ok {
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return errors.New("square/go-jose: ed25519 signature failed to verify")
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}
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return nil
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}
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// Sign the given payload
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func (ctx ecDecrypterSigner) signPayload(payload []byte, alg SignatureAlgorithm) (Signature, error) {
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var expectedBitSize int
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var hash crypto.Hash
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switch alg {
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case ES256:
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expectedBitSize = 256
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hash = crypto.SHA256
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case ES384:
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expectedBitSize = 384
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hash = crypto.SHA384
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case ES512:
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expectedBitSize = 521
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hash = crypto.SHA512
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}
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curveBits := ctx.privateKey.Curve.Params().BitSize
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if expectedBitSize != curveBits {
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return Signature{}, fmt.Errorf("square/go-jose: expected %d bit key, got %d bits instead", expectedBitSize, curveBits)
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}
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hasher := hash.New()
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// According to documentation, Write() on hash never fails
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_, _ = hasher.Write(payload)
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hashed := hasher.Sum(nil)
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r, s, err := ecdsa.Sign(RandReader, ctx.privateKey, hashed)
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if err != nil {
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return Signature{}, err
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}
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keyBytes := curveBits / 8
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if curveBits%8 > 0 {
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keyBytes++
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}
|
|
|
|
// We serialize the outputs (r and s) into big-endian byte arrays and pad
|
|
// them with zeros on the left to make sure the sizes work out. Both arrays
|
|
// must be keyBytes long, and the output must be 2*keyBytes long.
|
|
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)
|
|
|
|
out := append(rBytesPadded, sBytesPadded...)
|
|
|
|
return Signature{
|
|
Signature: out,
|
|
protected: &rawHeader{},
|
|
}, nil
|
|
}
|
|
|
|
// Verify the given payload
|
|
func (ctx ecEncrypterVerifier) verifyPayload(payload []byte, signature []byte, alg SignatureAlgorithm) error {
|
|
var keySize int
|
|
var hash crypto.Hash
|
|
|
|
switch alg {
|
|
case ES256:
|
|
keySize = 32
|
|
hash = crypto.SHA256
|
|
case ES384:
|
|
keySize = 48
|
|
hash = crypto.SHA384
|
|
case ES512:
|
|
keySize = 66
|
|
hash = crypto.SHA512
|
|
default:
|
|
return ErrUnsupportedAlgorithm
|
|
}
|
|
|
|
if len(signature) != 2*keySize {
|
|
return fmt.Errorf("square/go-jose: invalid signature size, have %d bytes, wanted %d", len(signature), 2*keySize)
|
|
}
|
|
|
|
hasher := hash.New()
|
|
|
|
// According to documentation, Write() on hash never fails
|
|
_, _ = hasher.Write(payload)
|
|
hashed := hasher.Sum(nil)
|
|
|
|
r := big.NewInt(0).SetBytes(signature[:keySize])
|
|
s := big.NewInt(0).SetBytes(signature[keySize:])
|
|
|
|
match := ecdsa.Verify(ctx.publicKey, hashed, r, s)
|
|
if !match {
|
|
return errors.New("square/go-jose: ecdsa signature failed to verify")
|
|
}
|
|
|
|
return nil
|
|
}
|