def decode(mhash, encoding=None):
r"""Decode a multihash-encoded digest into a `Multihash`.
If `encoding` is `None`, a binary digest is assumed.
>>> mhash = b'\x11\x0a\x0b\xee\xc7\xb5\xea?\x0f\xdb\xc9]'
>>> mh = decode(mhash)
>>> mh == (Func.sha1, mhash[2:])
True
If the name of an `encoding` is specified, it is used to decode the digest
before parsing it (see `CodecReg` for supported codecs).
>>> import base64
>>> emhash = base64.b64encode(mhash)
>>> emh = decode(emhash, 'base64')
>>> emh == mh
True
If the `encoding` is not available, a `KeyError` is raised. If the digest
has an invalid format or contains invalid data, a `ValueError` is raised.
"""
mhash = bytes(mhash)
if encoding:
mhash = CodecReg.get_decoder(encoding)(mhash)
try:
func = mhash[0]
length = mhash[1]
digest = mhash[2:]
except IndexError as ie:
raise ValueError("multihash is too short") from ie
if length != len(digest):
raise ValueError(
"multihash length field does not match digest field length")
return Multihash(func, digest)
def encode(self, encoding=None):
r"""Encode into a multihash-encoded digest.
If `encoding` is `None`, a binary digest is produced:
>>> mh = Multihash(0x01, b'TEST')
>>> mh.encode()
b'\x01\x04TEST'
If the name of an `encoding` is specified, it is used to encode the
binary digest before returning it (see `CodecReg` for supported
codecs).
>>> mh.encode('base64')
b'AQRURVNU'
If the `encoding` is not available, a `KeyError` is raised.
"""
try:
fc = self.func.value
except AttributeError: # application-specific function code
fc = self.func
mhash = fc.to_bytes((fc.bit_length() + 7) // 8, 'big') + bytes([len(self.digest)]) + self.digest
if encoding:
mhash = CodecReg.get_encoder(encoding)(mhash)
return mhash
def encode(self, encoding=None):
r"""Encode into a multihash-encoded digest.
If `encoding` is `None`, a binary digest is produced:
>>> mh = Multihash(0x01, b'TEST')
>>> mh.encode()
b'\x01\x04TEST'
If the name of an `encoding` is specified, it is used to encode the
binary digest before returning it (see `CodecReg` for supported
codecs).
>>> mh.encode('base64')
b'AQRURVNU'
If the `encoding` is not available, a `KeyError` is raised.
"""
try:
fc = self.func.value
except AttributeError: # application-specific function code
fc = self.func
mhash = bytes([fc, len(self.digest)]) + self.digest
if encoding:
mhash = CodecReg.get_encoder(encoding)(mhash)
return mhash
def decode(mhash, encoding=None):
r"""Decode a multihash-encoded digest into a `Multihash`.
If `encoding` is `None`, a binary digest is assumed.
>>> mhash = b'\x11\x0a\x0b\xee\xc7\xb5\xea?\x0f\xdb\xc9]'
>>> mh = decode(mhash)
>>> mh == (Func.sha1, mhash[2:])
True
If the name of an `encoding` is specified, it is used to decode the digest
before parsing it (see `CodecReg` for supported codecs).
>>> import base64
>>> emhash = base64.b64encode(mhash)
>>> emh = decode(emhash, 'base64')
>>> emh == mh
True
If the `encoding` is not available, a `KeyError` is raised. If the digest
has an invalid format or contains invalid data, a `ValueError` is raised.
"""
mhash = bytes(mhash)
if encoding:
mhash = CodecReg.get_decoder(encoding)(mhash)
try:
func = mhash[0]
length = mhash[1]
digest = mhash[2:]
except IndexError as ie:
raise ValueError("multihash is too short") from ie
if length != len(digest):
raise ValueError(
"multihash length field does not match digest field length")
return Multihash(func, digest)