Abstract: A data string that includes potentially sensitive information, such as an account number for a payment card, may be evaluated to determine whether or not any portion of the data string encodes a known identifier of sensitive information, such as a known bank identification number (BIN). A fixed number of bytes of the data string may be analyzed using a trie algorithm, in which the value of a first byte is compared with the value of a corresponding first character of the known identifier. A second byte is then compared with a set of values of corresponding second characters, which accompany the first character of the known identifier. Then the value of a third byte of the data string is compared with a set of values of corresponding third values, which accompany the first and second characters of the known identifier. The use of a trie algorithm decreases the length of the search process by several orders of magnitude.