Distributed tokenization using several substitution steps

A server, comprising:

• a non-transitory computer-readable storage medium storing executable instructions that, when executed, perform steps comprising:
• receiving a string of characters in a first character domain at the server;
• accessing, by the server, a first token table and a second token table, the first token table mapping each of a set of input values in the first character domain to a different token value comprising characters in the first character domain and characters in a second character domain different from the first character domain, the second token table mapping each of a set of input values in the first character domain to a different token value comprising characters in the second character domain;
• tokenizing, by the server, the accessed string of characters by replacing a first substring of the accessed string of characters with a first token value mapped to a value of the first substring by the first token table to form a first intermediate string of characters;
• tokenizing, by the server, a portion of the first intermediate string of characters comprising characters in the first character domain included in the first token value by replacing the portion of the first intermediate string of characters with a second token value mapped to a value of the portion of the first intermediate string of characters by the second token table to form a tokenized string of characters;
• and
• transmitting, by the server, the tokenized string of characters to a central server;
• and
• a hardware processor configured to execute the instructions.

A non-transitory computer-readable storage medium storing executable computer instructions that, when executed by a processor, cause the processor to perform steps comprising:

• receiving a string of characters in a first character domain at a local server;
• accessing, by the local server, a first token table and a second token table, the first token table mapping each of a set of input values in the first character domain to a different token value comprising characters in the first character domain and characters in a second character domain different from the first character domain, the second token table mapping each of a set of input values in the first character domain to a different token value comprising characters in the second character domain;
• tokenizing, by the local server, the accessed string of characters by replacing a first substring of the accessed string of characters with a first token value mapped to a value of the first substring by the first token table to form a first intermediate string of characters;
• tokenizing, by the local server, a portion of the first intermediate string of characters comprising characters in the first character domain included in the first token value by replacing the portion of the first intermediate string of characters with a second token value mapped to a value of the portion of the first intermediate string of characters by the second token table to form a tokenized string of characters;
• and
• transmitting, by the local server, the tokenized string of characters to a central server.