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The aim of this reorganisation is to make it easier to test all the ciphers in PuTTY in a uniform way. It was inconvenient that there were two separate vtable systems for the ciphers used in SSH-1 and SSH-2 with different functionality. Now there's only one type, called ssh_cipher. But really it's the old ssh2_cipher, just renamed: I haven't made any changes to the API on the SSH-2 side. Instead, I've removed ssh1_cipher completely, and adapted the SSH-1 BPP to use the SSH-2 style API. (The relevant differences are that ssh1_cipher encapsulated both the sending and receiving directions in one object - so now ssh1bpp has to make a separate cipher instance per direction - and that ssh1_cipher automatically initialised the IV to all zeroes, which ssh1bpp now has to do by hand.) The previous ssh1_cipher vtable for single-DES has been removed completely, because when converted into the new API it became identical to the SSH-2 single-DES vtable; so now there's just one vtable for DES-CBC which works in both protocols. The other two SSH-1 ciphers each had to stay separate, because 3DES is completely different between SSH-1 and SSH-2 (three layers of CBC structure versus one), and Blowfish varies in endianness and key length between the two. (Actually, while I'm here, I've only just noticed that the SSH-1 Blowfish cipher mis-describes itself in log messages as Blowfish-128. In fact it passes the whole of the input key buffer, which has length SSH1_SESSION_KEY_LENGTH == 32 bytes == 256 bits. So it's actually Blowfish-256, and has been all along!)