Signature Verification problem

[Howard Chan]

Dear all,   I'm experimenting with openssl and I have the following problem at hand:   I have this file which used sha1 hash algorithm to obtain it's message digest, and subsequently the digest was encrypted (signed) using RSA algorithm with a private key from a X.509 certificate.   Now, I have the original file, the signed message digest (from above), and I have the corresponding public key of the X.509 certificate.    My question is; what openssl commands can I use now to verify the signature of the signed message digest?   I have created the message digest of the original file already.  I now want to know "what can I do with the signed message digest so that I can decrypt it (verify) using the public key?"   After decrypting (verifying) it, am I supposed to get the same message digest which I created earlier from the original file?   Please help me out.  Thanks a million.   Best regards,   HC