Ecdsa.recover_sig: def of bend-collections-laws-crypto@1.0.0.0
Import: import bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/ecdsa.bend as Ecdsa
Lines 260-264 of bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/ecdsa.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/ecdsa.bend&start_line=260&end_line=264

import Base
import bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/bytes.bend as B

def recover_sig(+h: List<&2, U32>, +sig: List<&2, U32>) -> Maybe<&2, List<&2, U32>>:
  +r = B.of_be(B.prefix(32n, sig))
  +s = B.of_be(B.prefix(32n, B.suffix(32n, sig)))
  +id = U32.to_nat(B.head(B.suffix(64n, sig)))
  recover_ok(hash_scalar(h), r, s, id, Bool.and(Bool.and(scalar_ok(r), scalar_ok(s)), Nat.is_lt(id, 4n)))

Uses (13):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool.and
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Maybe
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.is_lt
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.to_nat
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/bytes.bend&name=head
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/bytes.bend&name=of_be
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/bytes.bend&name=prefix
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/bytes.bend&name=suffix
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/ecdsa.bend&name=hash_scalar
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/ecdsa.bend&name=recover_ok
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/ecdsa.bend&name=scalar_ok