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// {{{ Copyright (c) Paul R. Tagliamonte <paultag@gmail.com>, 2017
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE. }}}
package ykpiv
/*
#cgo pkg-config: ykpiv
#include <ykpiv.h>
#include <stdlib.h>
*/
import "C"
import (
"crypto/ecdsa"
"crypto/rsa"
"fmt"
"io"
"unsafe"
"crypto"
"pault.ag/go/ykpiv/internal/pkcs1v15"
)
// Decrypt implements the crypto.Decrypter interface.
// If the slot holds an RSA key, then it will decrypt the ciphertext with the
// private key backing the Slot we're operating on.
// If the slot holds an EC key, then we will perform ECDH and return the shared
// secret. In this case, msg must be the peer's public key in octet form, as
// specified in section 4.3.6 of ANSI X9.62.
//
// The `rand` argument is disregarded in favor of the on-chip RNG on the Yubikey
// The `opts` argument is not used at this time, but may in the future.
func (s Slot) Decrypt(rand io.Reader, msg []byte, opts crypto.DecrypterOpts) ([]byte, error) {
var cMessage = (*C.uchar)(C.CBytes(msg))
defer C.free(unsafe.Pointer(cMessage))
var cMessageLen = C.size_t(len(msg))
var cPlaintextLen = C.size_t(len(msg))
var cPlaintext = (*C.uchar)(C.malloc(cMessageLen))
defer C.free(unsafe.Pointer(cPlaintext))
algorithm, err := s.getAlgorithm()
if err != nil {
return nil, err
}
if err := getError(C.ykpiv_decipher_data(
s.yubikey.state,
cMessage, cMessageLen,
cPlaintext, &cPlaintextLen,
algorithm,
C.uchar(s.Id.Key),
), "decipher_data"); err != nil {
return nil, err
}
plaintext := C.GoBytes(unsafe.Pointer(cPlaintext), C.int(cPlaintextLen))
switch s.PublicKey.(type) {
case *rsa.PublicKey:
return pkcs1v15.Unpad(plaintext)
case *ecdsa.PublicKey:
return plaintext, nil
default:
return nil, fmt.Errorf("unknown slot key type")
}
}
// vim: foldmethod=marker
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