The problem: my favorite myproxy-logon command suddenly stopped working and I got the error barf below
Failed to receive credentials.
Error authenticating: GSS Major Status: Authentication Failed
GSS Minor Status Error Chain:
globus_gss_assist: Error during context initialization
globus_gsi_gssapi: Unable to verify remote side's credentials
globus_gsi_gssapi: Unable to verify remote side's credentials: Couldn't verify the remote certificate
OpenSSL Error: s3_pkt.c:1052: in library: SSL routines, function SSL3_READ_BYTES: sslv3 alert bad certificate SSL alert number 42
I tried the usual soluiton: made sure my certificates were correct in $HOME/.globus/certificates and /etc/grid-security/certificates but still got the error.
Solution: I had a proxy certificate from another (non-overlapping) Grid sitting around in the default X509 location (/tmp/x509up_nnn). I deleted this and myproxy-logon worked again. Apparently the myproxy-logon command tries to use this credential to authenticate to the MyProxy server. The errors are what you expect since MyProxy from Grid #1 doesn't trust the CA of Grid #2.
Delete the old credential and things should work again.