Technique used in text analysis in a safe manner

A computer system used in text analysis, the computer system comprising:

• one or more computer processors;
• one or more computer readable storage media;
• and
• program instructions stored on the one or more computer readable storage media for execution by at least one of the one or more computer processors, the program instructions comprising:
• program instructions to replace a first character string in a logic, wherein the logic is a rule which analyzes input text and extracts additional information used for the text analysis, with a second character string which is different from the first character string, using a mapping between the first character string and the second character string, the first character string being a character or a combination of characters in the logic;
• program instructions to search for a first character string in a target document for the text analysis and replacing the first character string, if found, with the second character string, using the mapping;
• program instructions to send the logic after the replacement to a server computer;
• program instructions to send the target document after the replacement to the server computer;
• and
• program instructions to receive from the server computer a text analysis result for the target document after the replacement.