Thanks for the report and for the reproducer. I've tested it on 23.04
and got the following output:
BN_cmp(A, B): 0
BN_cmp(A, B): 0
IIUC the issue is therefore fixed.
** Changed in: openssl (Ubuntu)
Status: New => Fix Released
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https://bugs.launchpad.net/bugs/1734447
Title:
BN_cmp regards negative and positive zero as different numbers
Status in openssl package in Ubuntu:
Fix Released
Bug description:
"BN_cmp() returns -1 if a < b, 0 if a == b and 1 if a > b." (
https://wiki.openssl.org/index.php/Manual:BN_cmp(3) )
The libcrypto.a shipped with Ubuntu makes a distinction between a
negative 0 ("-0") and a positive zero ("0"). This means that
BN_cmp(-0, 0) returns -1 and BN_cmp(0, -0) returns 1. The latest
versions of OpenSSL (1.0.2m and 1.1.0g) both return 0 for both
comparisons, which is what you would expect.
lsb_release -rd:
Description: Ubuntu 16.04.3 LTS
Release: 16.04
Tested on both the 32 bit and 64 bit versions of this Ubuntu release.
Attached is a proof of concept.
The anomaly may also be caused by BN_dec2bn rather than BN_cmp.
The bug is unlikely to have direct security consequences, but may
cause unexpected behaviour in other applications that depend on this
widespread library.
Found with https://github.com/guidovranken/bignum-fuzzer
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