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115 lines
3.8 KiB
115 lines
3.8 KiB
from coincurve.context import GLOBAL_CONTEXT, Context
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from coincurve.types import Hasher
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from coincurve.utils import bytes_to_int, int_to_bytes, sha256
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from ._libsecp256k1 import ffi, lib
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MAX_SIG_LENGTH = 72
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CDATA_SIG_LENGTH = 64
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def cdata_to_der(cdata, context: Context = GLOBAL_CONTEXT) -> bytes:
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der = ffi.new('unsigned char[%d]' % MAX_SIG_LENGTH)
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der_length = ffi.new('size_t *', MAX_SIG_LENGTH)
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lib.secp256k1_ecdsa_signature_serialize_der(context.ctx, der, der_length, cdata)
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return bytes(ffi.buffer(der, der_length[0]))
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def der_to_cdata(der: bytes, context: Context = GLOBAL_CONTEXT):
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cdata = ffi.new('secp256k1_ecdsa_signature *')
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parsed = lib.secp256k1_ecdsa_signature_parse_der(context.ctx, cdata, der, len(der))
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if not parsed:
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raise ValueError('The DER-encoded signature could not be parsed.')
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return cdata
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def recover(message: bytes, recover_sig, hasher: Hasher = sha256, context: Context = GLOBAL_CONTEXT):
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msg_hash = hasher(message) if hasher is not None else message
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if len(msg_hash) != 32:
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raise ValueError('Message hash must be 32 bytes long.')
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pubkey = ffi.new('secp256k1_pubkey *')
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recovered = lib.secp256k1_ecdsa_recover(context.ctx, pubkey, recover_sig, msg_hash)
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if recovered:
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return pubkey
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raise Exception('failed to recover ECDSA public key')
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def serialize_recoverable(recover_sig, context: Context = GLOBAL_CONTEXT) -> bytes:
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output = ffi.new('unsigned char[%d]' % CDATA_SIG_LENGTH)
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recid = ffi.new('int *')
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lib.secp256k1_ecdsa_recoverable_signature_serialize_compact(context.ctx, output, recid, recover_sig)
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return bytes(ffi.buffer(output, CDATA_SIG_LENGTH)) + int_to_bytes(recid[0])
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def deserialize_recoverable(serialized: bytes, context: Context = GLOBAL_CONTEXT):
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if len(serialized) != 65:
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raise ValueError('Serialized signature must be 65 bytes long.')
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ser_sig, rec_id = serialized[:64], bytes_to_int(serialized[64:])
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if not 0 <= rec_id <= 3:
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raise ValueError('Invalid recovery id.')
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recover_sig = ffi.new('secp256k1_ecdsa_recoverable_signature *')
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parsed = lib.secp256k1_ecdsa_recoverable_signature_parse_compact(context.ctx, recover_sig, ser_sig, rec_id)
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if not parsed:
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raise ValueError('Failed to parse recoverable signature.')
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return recover_sig
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"""
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Warning:
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The functions below may change and are not tested!
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"""
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def serialize_compact(raw_sig, context: Context = GLOBAL_CONTEXT): # no cov
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output = ffi.new('unsigned char[%d]' % CDATA_SIG_LENGTH)
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res = lib.secp256k1_ecdsa_signature_serialize_compact(context.ctx, output, raw_sig)
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assert res == 1
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return bytes(ffi.buffer(output, CDATA_SIG_LENGTH))
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def deserialize_compact(ser_sig: bytes, context: Context = GLOBAL_CONTEXT): # no cov
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if len(ser_sig) != 64:
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raise Exception('invalid signature length')
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raw_sig = ffi.new('secp256k1_ecdsa_signature *')
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res = lib.secp256k1_ecdsa_signature_parse_compact(context.ctx, raw_sig, ser_sig)
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assert res == 1
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return raw_sig
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def signature_normalize(raw_sig, context: Context = GLOBAL_CONTEXT): # no cov
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"""
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Check and optionally convert a signature to a normalized lower-S form.
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This function always return a tuple containing a boolean (True if
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not previously normalized or False if signature was already
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normalized), and the normalized signature.
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"""
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sigout = ffi.new('secp256k1_ecdsa_signature *')
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res = lib.secp256k1_ecdsa_signature_normalize(context.ctx, sigout, raw_sig)
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return not not res, sigout
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def recoverable_convert(recover_sig, context: Context = GLOBAL_CONTEXT): # no cov
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normal_sig = ffi.new('secp256k1_ecdsa_signature *')
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lib.secp256k1_ecdsa_recoverable_signature_convert(context.ctx, normal_sig, recover_sig)
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return normal_sig
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