encryption - Open an encrypted file with specific user -

encryption - Open an encrypted file with specific user -

i need decrypt file without saving decrypted info of file on computer. explain. let's assume have encrypted file on file server (the encryption's algorithm irrelevant) when file triggered open event phone call next code:

public void fileopenning() { // "foo" can decrypt , see/change content of file if (environement.currentuser == "foo") { // display encrypted file user } else { // nothing, user can't open file. } }

now, want show user file without decrypt file itself, if so, has access file server able watch file, since decrypted (and can see, "foo" can decrypt , see content of file) alternative thought saving decrypted info in temporary file, still unsecure , complicated alter content of file 1 time again , save since need encrypt file again.. suggestions of how can handle it?

it sounds mean encrypted file (ef) somewhere on cloud server (cs), , have secure, dedicated server (ss), not in cloud, holds key. so:

user foo establishes ssl/tls connection ss , authenticates password or whatever.

user foo requests file.

ss makes sure user foo authorized access file.

ss retrieves ef cs , decrypts locally. (it doesn't matter whether ss decrypts ef in memory or stores plaintext on ss's disk, since have assume ss secure.)

ss transmits plaintext user foo. ssl/tls connection ensures no 1 can hear in.

of course, plaintext ends on machine user foo using. that's unavoidable. there may ways maintain in ram only, , not on disk, depending on how big , how it's beingness viewed.

is mean?

encryption