+ *) Hack to fix PKCS#7 decryption when used with some unorthodox RC2
+ handling. Most clients have the effective key size in bits equal to
+ the key length in bits: so a 40 bit RC2 key uses a 40 bit (5 byte) key.
+ A few however don't do this and instead use the size of the decrypted key
+ to determine the RC2 key length and the AlgorithmIdentifier to determine
+ the effective key length. In this case the effective key lenth can still
+ be 40 bits but the key length can be 168 bits for example. This is fixed
+ by manually forcing an RC2 key into the EVP_PKEY structure because the
+ EVP code can't currently handle unusual RC2 key sizes: it always assumes
+ the key length and effective key length are equal.
+ [Steve Henson]
+