I'm using some code grabbed off the Interwebs that should work, but I'm getting an exception... got the .der files from my boss, so I assume they're valid, but perhaps not. Spacing and returns are odd here but normal on my machine.
C:\Users\Trevor Basden\Desktop\ImportKey>
java ImportKey AKMClientPrivKey.der AKM
ClientSignedCert.der password
Using keystore-file : C:\Users\Trevor Basden\Desktop\ImportKey\keyst2
HERE1
java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: I
OException : algid parse error, not a sequence
at sun.security.rsa.RSAKeyFactory.engineGeneratePrivate(Unknown Source)
at java.security.KeyFactory.generatePrivate(Unknown Source)
at ImportKey.main(ImportKey.java:257)
Caused by: java.security.InvalidKeyException: IOException : algid parse error, n
ot a sequence
at sun.security.pkcs.PKCS8Key.decode(Unknown Source)
at sun.security.pkcs.PKCS8Key.decode(Unknown Source)
at sun.security.rsa.RSAPrivateCrtKeyImpl.<init>(Unknown Source)
at sun.security.rsa.RSAPrivateCrtKeyImpl.newKey(Unknown Source)
at sun.security.rsa.RSAKeyFactory.generatePrivate(Unknown Source)
... 3 more