def unblind(csig, bldkey, grpkey=ffi.NULL, sig=ffi.NULL):
"""
Unblinds a blindly converted group signature, for schemes that support it.
Optional parameters may be ignored in some schemes.
Parameters:
csig: A blindly converted group signature.
bldkey: The blinding keypair.
grpkey: Optional. The group key.
sig: Optional. The unblinded group signature.
Returns:
An object containing:
nym: A (possibly pseudonymized) identity of the signer.
msg: A (possibly obfuscated) signed message.
On error, an exception is thrown.
"""
msg = lib.message_init()
nym = lib.identity_init(csig.scheme)
if lib.groupsig_unblind(nym, sig, csig, grpkey, bldkey, msg) == lib.IERROR:
raise Exception('Error unblinding signature.')
return {
'nym': ffi.string(lib.identity_to_string(nym)),
'msg': ffi.string(lib.message_to_base64(msg))
}
return
def proof_to_string(proof):
_str = ffi.new("char *")
_str = lib.groupsig_proof_to_string(proof)
if _str == ffi.NULL:
raise Exception('Error converting proof to string.')
return ffi.string(_str).decode('utf8')
def identity_to_string(identity):
"""
Exports the given identity to a string.
Parameters:
identity: The identity to export.
Returns:
A string. On error, an Exception is thrown.
"""
string = lib.identity_to_string(identity)
if string == ffi.NULL:
raise Exception('Error converting id to string.')
return ffi.string(string).decode('utf8')
def blindsig_to_string(sig):
"""
Returns a human readable string corresponding to the given blinded signature.
Parameters:
sig: The blinded signature to print.
Returns:
The produced string. On error, an Exception is thrown.
"""
_str = ffi.new("char *")
_str = lib.groupsig_blindsig_to_string(sig)
if _str == ffi.NULL:
raise Exception('Error converting blindsig to string.')
return ffi.string(_str).decode('utf8')
def message_to_base64(msg):
"""
Exports the given message object to a Base64 string.
Parameters:
msg: The message to export to a string.
Returns:
A Base64 string. On error, an Exception is thrown.
"""
_str = ffi.new("char *")
_str = lib.message_to_base64(msg)
if _str == ffi.NULL:
raise Exception('Error converting message to a Base64 string.')
return ffi.string(_str).decode('utf8')
def signature_to_string(sig):
"""
Returns a human readable string for the given group signature.
Parameters:
sig: The group signature.
Returns:
A human readable string. On error, an Exception is thrown.
"""
_str = ffi.new("char *")
_str = lib.groupsig_signature_to_string(sig)
if _str == ffi.NULL:
raise Exception('Error converting signature to string.')
return ffi.string(_str).decode('utf8')
def memkey_to_string(key):
"""
Returns a human readable string for the given member key.
Parameters:
key: The native member key data structure.
Returns:
A human readable string. On error, an Exception is thrown.
"""
_str = ffi.new("char *")
_str = lib.groupsig_mem_key_to_string(key)
if _str == ffi.NULL:
raise Exception('Error converting member key to string.')
return ffi.string(_str).decode('utf8')
def message_to_string(msg):
"""
Exports the given message object to a UTF-8 string. Use only for messages
that are ensured to be strings.
Parameters:
msg: The message to export to a string.
Returns:
A UTF-8 string. On error, an Exception is thrown.
"""
_str = ffi.new("char *")
_str = lib.message_to_string(msg)
if _str == ffi.NULL:
raise Exception('Error converting message to string.')
return ffi.string(_str).decode('utf8')