The sentence regarding allowing empty byte arrays to indicate an invalid ECDSA signature is confusing. I attempted to make it clearer. If I screwed it up or can make it even clearer, please let me know.
Thank you.
Previously BIP62 did not provide a compact way to delibrately encode an
invalid signature. For example in BIP19 if m != n with this change you
can provide compact OP_0's in the scriptSig rather than lengthy
DER-encoded signatures.
Note that we may want to further expand on this change in the future by
saying that only OP_0 is a "valid" invalid signature; BIP19 even with
this change is inherently malleable as the invalid signatures can be any
validly encoded DER signature.
This came up on the mailing list.
yyyy-mm-dd (ISO 8601) is the internationally accepted format for numeric
dates. This commit changes all BIPs to use that instead of dd-mm-yyyy.
It also updates BIP 0001 to prescribe the new format.
