Techniques for presenting a key to a human across a human-machine interface include receiving key data that indicates a key to be input to a target process. The key is reversibly converted to a first human-language statement. The human language statement is designed so that multiple variations in the human-language statement due to common human errors can be correctly reversed to regenerate the key data. The common human-language statement is presented to a human user for use in the target process. After receiving input data that indicates a second human language statement based on human memory of the first human language statement, the second human language statement is corrected for common human language errors. The corrected second human language statement is then converted to second key data and sent to the target process. Thus multiple human inputs are accepted and correctly converted to the key for the target process.