As of PHP 5.0.0, you have the ability to choose between 64 bit RC2 encryption OR 128 bit RC2 encryption.
The new function description should now be:
bool openssl_pkcs7_encrypt ( string infile, string outfile, mixed recipcerts, array headers [, int flags] [,int cipher])
Where the int value of cipher is 0 or 1. 0 = 64 bit and 1 = 128 bit.