// takes as input a public key and a signed message
// returns whether the signature is valid or not
func Verify(verificationKey PublicKey, signedMessage SignedMessage) (verified bool, err error) {
// points to unsigned message after verifying
var messagePointer *C.uchar
messageBytes := make([]byte, len(signedMessage.Message)+1)
if len(signedMessage.Message) == 0 {
// must point somewhere valid, but the data won't be altered
// can't point to [0] because the slice is empty
messagePointer = (*C.uchar)(unsafe.Pointer(&messageBytes))
} else {
messagePointer = (*C.uchar)(unsafe.Pointer(&messageBytes[0]))
}
// points to an int so the C function can return the message length after verifying
var messageLen uint64
lenPointer := (*C.ulonglong)(unsafe.Pointer(&messageLen))
// points to the signed message as input for verification
signedMessageBytes := []byte(signedMessage.CombinedMessage())
signedMessagePointer := (*C.uchar)(unsafe.Pointer(&signedMessageBytes[0]))
// length of signed message, but as a C object
signedMessageLen := C.ulonglong(len(signedMessageBytes))
// pointer to the public key used to sign the message
verificationKeyPointer := (*C.uchar)(unsafe.Pointer(&verificationKey[0]))
// verify signature
success := C.crypto_sign_open(messagePointer, lenPointer, signedMessagePointer, signedMessageLen, verificationKeyPointer)
verified = success == 0
return
}
func SignOpen(messageOut []byte, sealedMessage []byte, pk []byte) int {
support.CheckSize(messageOut, len(sealedMessage)-SignBytes(), "message output")
support.CheckSize(pk, SignPublicKeyBytes(), "public key")
lenMessageOut := (C.ulonglong)(len(messageOut))
return int(C.crypto_sign_open(
(*C.uchar)(&messageOut[0]), (*C.ulonglong)(&lenMessageOut),
(*C.uchar)(&sealedMessage[0]), (C.ulonglong)(len(sealedMessage)),
(*C.uchar)(&pk[0])))
}
func CryptoSignOpen(sm []byte, pk []byte) ([]byte, int) {
support.CheckSize(pk, CryptoSignPublicKeyBytes(), "public key")
m := make([]byte, len(sm)-CryptoSignBytes())
var actualMSize C.ulonglong
exit := int(C.crypto_sign_open(
(*C.uchar)(&m[0]),
(&actualMSize),
(*C.uchar)(&sm[0]),
(C.ulonglong)(len(sm)),
(*C.uchar)(&pk[0])))
return m[:actualMSize], exit
}
// verify a signed message
func CryptoVerify(smsg, pk []byte) bool {
smsg_buff := NewBuffer(smsg)
defer smsg_buff.Free()
pk_buff := NewBuffer(pk)
defer pk_buff.Free()
if pk_buff.size != C.crypto_sign_publickeybytes() {
return false
}
mlen := C.ulonglong(0)
msg := malloc(C.size_t(len(smsg)))
defer msg.Free()
smlen := C.ulonglong(smsg_buff.size)
return C.crypto_sign_open(msg.uchar(), &mlen, smsg_buff.uchar(), smlen, pk_buff.uchar()) != -1
}
