A large amount of files were encrypted by

    openssl enc -aes-256-cbc -pass pass:MYPASSWORD

Openssl should derive key+IV from passphrase. I'd like to know key+IV equivalent of that MYPASSWORD. Is that possible?

I know MYPASSWORD. I could decrypt and then re-encrypt with new known key+IV with:

    openssl enc -d -aes-256-cbc -pass pass:MYPASSWORD
    openssl enc -aes-256-cbc -K MYKEY -IV MYIV

But the problem is that the amount of data is quite large.