My understanding was the key will still function for both encryption and decryption operations without setting trust or signing the imported key pair. So without trusting or signing the key on either platform it still works on AIX and still does not work on HPUX. Also the output was correctly copied from each platform for command list-key-details. It was just identical output.
The key pair did not originate from the AIX platform - it originated from IPSwitch WS_FTP pro.
I can successfully export a keypair generated on AIX and import into HPUX and use it for encryption and decryption operations. I just can't do it on HPUX using this open source key pair.
However, just to make sure the trust wasn't the issue I went ahead and followed your recommendation to set implicit trust and it still did not resolve the issue.
Here is the new output from list-key-details from HPUX and it now shows implicit trust and comlpete validity.
Key Details: ABCKEY <ABCKEY>
Key ID: 0x760B47BF (0x846E6F08760B47BF)
Type: RSA (v4) key pair
Size: 1024
Validity: Complete
Trust: Implicit (Axiomatic)
Created: 2012-08-29
Expires: Never
Status: Active
Cipher: Blowfish
Cipher: CAST5
Cipher: IDEA
Cipher: TripleDES
Hash: SHA-1
Hash: MD5
Hash: RIPEMD-160
Hash: Unknown 0x05
Compress: Zip (Absent)
Photo: No
Revocable: Yes
Token: No
Keyserver: Absent
Default: No
Wrapper: No
Prop Flags: Sign user IDs
Prop Flags: Sign messages
Prop Flags: PGP NetShare
Prop Flags: PGP WDE
Prop Flags: PGP ZIP
Prop Flags: PGP Messaging
Ksrv Flags: Absent
Feat Flags: Absent
Notations: None
Usage: Sign user IDs
Usage: Sign messages
Subkey ID: 0xD48CCB6E (0x3E6829F9D48CCB6E)
Type: RSA (v4) subkey pair
Size: 1024
Created: 2012-08-29
Expires: Never
Status: Active
Revocable: Yes
Token: No
X.509: No
Prop Flags: Encrypt communications
Prop Flags: Encrypt storage
Prop Flags: PGP NetShare
Prop Flags: PGP WDE
Prop Flags: PGP ZIP
Prop Flags: PGP Messaging
Notations: None
Usage: Encrypt communications
Usage: Encrypt storage
Usage: PGP NetShare
Usage: PGP WDE
Usage: PGP ZIP
Usage: PGP Messaging
ADK: None
Revoker: None
Thanks for your help - let me know if you have any more suggestions.