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I'm trying to build a native Segwit transaction programmatically, however, whenever I attempt to broadcast the transaction, it returns this error: non-mandatory-script-verify-flag (Non-canonical DER signature)

My raw, unsigned tx (testnet) is here:

0200000001fd45159c94d5dcf0804e7aba6e5862445a3c41fb5ec21184fe3a41a1a6dbb5b40000000000ffffffff02a351000000000000160014d1ca74222bb5a5c1b43fae117e811b2320a286a66500000000000000160014d1ca74222bb5a5c1b43fae117e811b2320a286a600000000

My signed tx here:

02000000000101fd45159c94d5dcf0804e7aba6e5862445a3c41fb5ec21184fe3a41a1a6dbb5b40000000000ffffffff02a351000000000000160014d1ca74222bb5a5c1b43fae117e811b2320a286a66500000000000000160014d1ca74222bb5a5c1b43fae117e811b2320a286a6024630440220465c93c725454f7bda3e3453ce09e99f7636560935be9377c3ae1138cfa0bb4702206f45290b2c06fc7e2298c6778fbccd1a805e34535247c49e098bc7229e74533421034ac1bb1bc5fd7a9b173f6a136a40e4be64841c77d7f66ead444e101e0134812700000000

Both decoded look okay to me, so I I think it it's either the sighash or signing of the sighash that's going wrong. The sighash I get of the unsigned tx, for the only input is: e54c499bfef6f5f0b12b819de82220aa7de532f9b72ae0f74638a647e147f884

This is created using: https://docs.rs/bitcoin/0.25.1/bitcoin/util/bip143/struct.SigHashCache.html#method.signature_hash

using SigHashType::All passing the pubKeyScript and value (22,000)

and when signing the sighash I get: 30440220465c93c725454f7bda3e3453ce09e99f7636560935be9377c3ae1138cfa0bb4702206f45290b2c06fc7e2298c6778fbccd1a805e34535247c49e098bc7229e745334

I am completely stuck on what to try next. Any direction would be appreciated.

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1 Answer 1

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You're missing the sighash flag byte at the end of the signature.

"Signature" objects in Bitcoin Script consist of the actual DER-encoded ECDSA signature, plus the sighash type byte (in your case, 0x01 for SIGHASH_ALL).

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  • Thanks for the quick reply. I had noticed that, however, after adding that byte I get Signature must be zero for failed CHECK(MULTI)SIG operation instead.
    – Kyle
    Oct 23, 2020 at 3:25
  • 1
    That means you signed the wrong sighash, mostly likely.
    – Pieter Wuille
    Oct 23, 2020 at 3:38
  • In the end it was because I was using a p2pwkh when creating the sighash instead of the required p2pkh :/.
    – Kyle
    Oct 23, 2020 at 14:12

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