PuTTY bug kbdint-instruction-ignored-2

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summary: SSH keyboard-interactive instructions to user are not displayed
class: bug: This is clearly an actual problem we want fixed.
difficulty: fun: Just needs tuits, and not many of them.
priority: high: This should be fixed in the next release.
absent-in: 0.70
present-in: 0.71
fixed-in: 64a9b3ed673a7a56b133d2d2a0be709adcb0f696 (0.72)

In the keyboard-interactive SSH authentication system, each INFO_REQUEST message contains a number of prompts each requesting a specific detail from the user, and may also contain an "instruction" string which acts as a heading for the whole group of prompts.

(For example, suppose a user is logging in using a hardware token which presents two separate values. Then the instruction string might say something like “Enter code XXXXX into your hardware token and enter the displayed information”, and then there might be two separate prompts following it asking for value #1 and value #2.)

In PuTTY 0.71, the instruction field was ignored, and never displayed to the user at all. This was an unintended side effect of code restructuring.

(See also kbdint-instruction-ignored, a bug in 0.60 in which the instruction field was ignored in the unusual case where it was the only thing in the packet – i.e. not accompanied by any actual prompts at all. This bug is a superset of that one: in 0.71, the instruction field is never printed, regardless of how sensible the rest of the packet looks.)

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(last revision of this bug record was at 2019-07-20 07:44:55 +0100)