how to get r, s, v out of signature? #544

1. 
   BernardoDeLaPlaz commented at 10:07 pm on July 31, 2018: none

   I see in secp256k1/include/secp256k1.h

   • The signature must consist of a 32-byte big endian R value, followed by a
   • 32-byte big endian S value. If R or S fall outside of [0..order-1], the
   • encoding is invalid. R and S with value 0 are allowed in the encoding.

   I take it this means that if I generate a signature in a secp256k1_pubkey I can look in the first 32 bytes to find R and the next 32 bytes to find S.

   …but how can I find ‘v’ ?

   Thanks.

2. 
   BernardoDeLaPlaz commented at 10:11 pm on July 31, 2018: none

   Ah…I need to use secp256k1_ecdsa_sign_recoverable() instead of secp256k1_ecdsa_sign() ?
3. 
   sipa commented at 10:13 pm on July 31, 2018: contributor

   You can’t convert a normal signature to a recoverable signature. You can try recid=0, recid=1, recid=2, recid=3 though, and see which one recovers your expected public key.
4. sipa closed this on Jul 31, 2018

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