📅 Original date posted:2015-02-01
📝 Original message:Thanks for the clarification. Yes, I referred to CompactSize using the lingo of https://en.bitcoin.it/wiki/Protocol_documentation
I am not sure if it is current concern. Apparently an exception is thrown if non-canonical CompactSize in a transaction s parsed.
Is it ensured that transactions are always parsed before computing their hash?
Tamas Blummer
On Feb 1, 2015, at 11:44 AM, Wladimir <laanwj at gmail.com> wrote:
>
> On Sun, 1 Feb 2015, Tamas Blummer wrote:
>
>> I wonder of consequences if var_int is used in its longer than necessary forms (e.g encoding 1 as 0xfd0100 instead of 0x01)
>
> In serialize.h lingo you are talking about CompactSize, not VarInt.
>
> CompactSizes indeed have redundancy in their representation, i.e. the same number can be represented as up to four different byte sequences.
>
> VARINTs have a different format that (AFAIK) isn't used anywhere in the block chain. See WriteVarInt / ReadVarInt. These were designed to not have any redundancy in their representation.
>
>> This is already of interest if applying size limit to a block, since transaction count is var_int but is not part of the hashed header or the
>> merkle tree.
>
> Are you sure that this is a current concern? Non-canonical CompactSizes are forbidden - in serialize.h this is flagged in ReadCompactSize.
>
> Wladimir
>
>
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Tamas Blummer [ARCHIVE] /
npub1cc…ex8m8
2023-06-07 15:29:14
in reply to nevent1q…v7rr
Author Public Key
npub1ccegg9n9lnx6huppxg43m95488yur7pfemkn3pz0agjws5ffvtts0ex8m8Published at
2023-06-07 15:29:14Event JSON
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"content": "📅 Original date posted:2015-02-01\n📝 Original message:Thanks for the clarification. Yes, I referred to CompactSize using the lingo of https://en.bitcoin.it/wiki/Protocol_documentation\n\nI am not sure if it is current concern. Apparently an exception is thrown if non-canonical CompactSize in a transaction s parsed.\nIs it ensured that transactions are always parsed before computing their hash?\n\nTamas Blummer\n\nOn Feb 1, 2015, at 11:44 AM, Wladimir \u003claanwj at gmail.com\u003e wrote:\n\n\u003e \n\u003e On Sun, 1 Feb 2015, Tamas Blummer wrote:\n\u003e \n\u003e\u003e I wonder of consequences if var_int is used in its longer than necessary forms (e.g encoding 1 as 0xfd0100 instead of 0x01)\n\u003e \n\u003e In serialize.h lingo you are talking about CompactSize, not VarInt.\n\u003e \n\u003e CompactSizes indeed have redundancy in their representation, i.e. the same number can be represented as up to four different byte sequences.\n\u003e \n\u003e VARINTs have a different format that (AFAIK) isn't used anywhere in the block chain. See WriteVarInt / ReadVarInt. These were designed to not have any redundancy in their representation.\n\u003e \n\u003e\u003e This is already of interest if applying size limit to a block, since transaction count is var_int but is not part of the hashed header or the\n\u003e\u003e merkle tree.\n\u003e \n\u003e Are you sure that this is a current concern? Non-canonical CompactSizes are forbidden - in serialize.h this is flagged in ReadCompactSize.\n\u003e \n\u003e Wladimir\n\u003e \n\u003e \n\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20150201/189a978e/attachment.html\u003e\n-------------- next part --------------\nA non-text attachment was scrubbed...\nName: signature.asc\nType: application/pgp-signature\nSize: 496 bytes\nDesc: Message signed with OpenPGP using GPGMail\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20150201/189a978e/attachment.sig\u003e",
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