Failures on ARM after upgrading libtommath

[karel-m]

After upgrading libtommath to the latest version (develop branch) there are more or less consinstent CPAN testers failing report from ARM architecture, namely:

• armv6l-linux
• arm64-freebsd
• aarch64-linux
• aarch64-freebsd

It seems to be an issue related to ARM; it does not seem to be compiler specific; other platforms (x86, x86_64) build fine even on different OS (linux, windows, freebds, openbsd).

For example:

• https://www.cpantesters.org/cpan/report/7b112218-4624-11f0-8860-ba8612798db0
• https://www.cpantesters.org/cpan/report/2dc34fd4-45bd-11f0-8f02-593d6e8775ea
• more https://fast2-matrix.cpantesters.org/?dist=CryptX%200.086_004
• or https://fast2-matrix.cpantesters.org/?dist=CryptX%200.086_003

Failing tests:

• t/pk_ecc.t
• t/pk_ecc_test_vectors_openssl.t

Unfortunatelly I do not have an ARM box available for debugging at the moment; but from the diagnostic output it seems that the failing operation is import of an ECC compressed public key which calls ecc_set_key >>> ltc_ecc_import_point (where some maths related magic takes place).

@sjaeckel are there any known issues reported for libtommath+ARM architecture?

• I am using this libtommath commit e823b0c34cea291bdb94d672731e1c1f08525557
• on top of that I have applied make c89 trick (great idea BTW)
• plus two small necessary tweaks - patched_s_mp_rand_platform.c + patched_tommath_c89.h

[sjaeckel]

@sjaeckel are there any known issues reported for libtommath+ARM architecture?

https://github.com/libtom/libtommath/actions/runs/15581985721/job/43879248481 says that mp_kronecker() and mp_sqrtmod_prime() (which uses mp_kronecker()) are broken on aarch64... CC @czurnieden

[sjaeckel]

OK, so it seems like char is per default unsigned on aarch64 ... I'll rewrite the commit message of libtom/libtommath@adc93b6 but that apparently fixes it ...

[sjaeckel]

Can you please verify whether this fixes the issue for you?

[karel-m]

Thank you for prompt reply.

I have released CryptX-0.086_005 with the proposed fix. In a few hours we should see reports on https://fast2-matrix.cpantesters.org/?dist=CryptX%200.086_005

[karel-m]

Looks good:

• aarch64-linux (gcc-13.2.0) https://www.cpantesters.org/cpan/report/bcf73fca-46b8-11f0-9731-5a536e8775ea
• arm64-freebsd (clang 19.1.7) https://www.cpantesters.org/cpan/report/9306ddfe-46ba-11f0-8749-0cfb6d8775ea

@sjaeckel Could you please commit the fix to librommath develop branch?

[sjaeckel]

@sjaeckel Could you please commit the fix to librommath develop branch?

done

[karel-m]

Thank you for your time