The fullchain.pem we send as our client cert contains the AC14K_M
intermediate CA, which is SHA-1 signed. Samsung's OCF Root CA (trust
anchor) is also SHA-1 self-signed. OpenSSL 3.x SECLEVEL=2 rejects
SHA-1 in any certificate it touches — including our own outbound chain —
raising SSL_R_CA_MD_TOO_WEAK before the verify callback is reached.
Fix: call SSL_CTX_set_security_level(ctx, 1) before loading any certs.
Tries pyOpenSSL >= 24.0 ctx.set_security_level(), falls back to cffi,
then ctypes as a last resort. SECLEVEL=1 (80-bit minimum) allows SHA-1
while still enforcing meaningful key-strength constraints.
Marc Billow
027768f7d7