Javascript only supports 64 bit floating points, which have uint precision up
to Math.pow(2, 53). We now support reading variable sized numbers up to that
size. If the number is bigger than that, then we need to use BN.
It should be possible to check to see if a message isForMe with only the
scanKeypair, and not the payloadKeypair. There was a bug where only the
scanKeypair was being used to produce the receiveKeypair, but this was a
mistake. Both the scanPubkey and payloadPubkey should be necessary to produce
the receivePubkey, and both the scanPrivkey and payloadPrivkey should be
necessary to produce the receivePrivkey. If an online computer has only the
public keys of both (and the scanPrivkey), then that is good enough to check
for isForMe.
This code should be regarded as being a proof-of-concept, and needs more review
before being used in production code. At least one thing is guaranteed to
change, and that is the format of a stealth address.
...the format of fromString and toString are deliberately not compatible with
bitcoind. The format here is supposed to be both human-readable, and
byte-for-byte isomorphic to the binary representation. In the future we will
need to add support for bitcoind-like strings, both for the test data (e.g.,
script_invalid.json) or for the bitcoind console style.
When parsing OP_PUSHDATAX commands, the the length of data might not require
the size integer of OP_PUSHDATAX. For instance, you might write 1 byte, and yet
use OP_PUSHDATA4. We need to record which OP_PUSHDATAX was used so that when we
write the buffer back out, we can write the same one. Also, the claimed length
may be different. For instance, we may OP_PUSHDATA of length 100 to the stack,
but there may only be 50 bytes left in the script. In that case, buf.length and
chunk.len will be different. I'm not sure if that would be considered a valid
script, but in any case, for script analysis, we need both values.
"Keypair" is a more explanatory name, and also should be less confused with
other kinds of keys (particularly "cipher keys", which are the keys used in
symmetric block ciphers, especially AES).
Ryan X. Charles
Christopher Jeffrey