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-rw-r--r--src/cryptography/hazmat/primitives/asymmetric/utils.py7
1 files changed, 7 insertions, 0 deletions
diff --git a/src/cryptography/hazmat/primitives/asymmetric/utils.py b/src/cryptography/hazmat/primitives/asymmetric/utils.py
index 71f4ff8e..f04eb66e 100644
--- a/src/cryptography/hazmat/primitives/asymmetric/utils.py
+++ b/src/cryptography/hazmat/primitives/asymmetric/utils.py
@@ -4,6 +4,7 @@
from __future__ import absolute_import, division, print_function
+from pyasn1.codec.ber import eoo
from pyasn1.codec.der import decoder, encoder
from pyasn1.error import PyAsn1Error
from pyasn1.type import namedtype, univ
@@ -28,6 +29,12 @@ def decode_rfc6979_signature(signature):
raise ValueError(
"The signature contains bytes after the end of the ASN.1 sequence."
)
+ # pyasn1 can erroneously return this from top-level DER decoding.
+ # It's intended as a sentinel in recursive BER decoding, so it's
+ # returned even though an asn1Spec is provided.
+ if data == eoo.endOfOctets:
+ raise ValueError("Invalid signature data. Unable to decode ASN.1")
+
r = int(data.getComponentByName('r'))
s = int(data.getComponentByName('s'))
return (r, s)