then it was only pure wallet.dat file or does it json-rpc can you lighten me up a bit,
To the best of my knowledge... it has always been a "wallet.dat" wallet file. The JSON-RPC stuff seems to have been first added around version 0.3.0, in early 2010 (February)... based on this commit in the old repo on sourceforge:
https://sourceforge.net/p/bitcoin/code/60/Passwords (wallet encryption) were added to Bitcoin-Qt in version 0.4.0 (released 23 September 2011):
https://bitcoin.org/en/release/v0.4.0Such a relief even if it is not the surest information but must have than all day searching with my brother google.