tfhe-rs/tfhe/docs/fhe-computation/operations/string-operations.md

String operations

This document details the string operations supported by TFHE-rs.

clear name	fhe name	first input type	second input type	third input type
eq	eq	FheAsciiString	FheAsciiString or ClearString
ne	ne	FheAsciiString	FheAsciiString or ClearString
le	le	FheAsciiString	FheAsciiString or ClearString
ge	ge	FheAsciiString	FheAsciiString or ClearString
lt	lt	FheAsciiString	FheAsciiString or ClearString
gt	gt	FheAsciiString	FheAsciiString or ClearString
len	len	FheAsciiString
is_empty	is_empty	FheAsciiString
eq_ignore_ascii_case	eq_ignore_case	FheAsciiString	FheAsciiString or ClearString
to_lowercase	to_lowercase	FheAsciiString
to_uppercase	to_uppercase	FheAsciiString
contains	contains	FheAsciiString	FheAsciiString or ClearString
ends_with	ends_with	FheAsciiString	FheAsciiString or ClearString
starts_with	starts_with	FheAsciiString	FheAsciiString or ClearString
find	find	FheAsciiString	FheAsciiString or ClearString
rfind	rfind	FheAsciiString	FheAsciiString or ClearString
strip_prefix	strip_prefix	FheAsciiString	FheAsciiString or ClearString
strip_suffix	strip_suffix	FheAsciiString	FheAsci---iString or ClearString
concat	concat	FheAsciiString	FheAsciiString
repeat	repeat	FheAsciiString	u16 or u32 or i32 or usize or (FheUint16, u16)
trim_end	trim_end	FheAsciiString
trim_start	trim_start	FheAsciiString
trim	trim	FheAsciiString
replace	replace	FheAsciiString	FheAsciiString
replacen	replacen	FheAsciiString	FheAsciiString or ClearString	u16 or u32 or i32 or usize or (FheUint16, u16)

The following example shows how to perform string operations:

use tfhe::prelude::*;
use tfhe::{
    generate_keys, set_server_key, ConfigBuilder, FheAsciiString,
};
    
fn main() -> Result<(), Box<dyn std::error::Error>> {
    
    let config = ConfigBuilder::default().build();
    let (client_key, server_key) = generate_keys(config);
    set_server_key(server_key);
    
    let string1 = FheAsciiString::try_encrypt("tfhe-RS", &client_key).unwrap();
    let string2 = FheAsciiString::try_encrypt("TFHE-rs", &client_key).unwrap();
    let is_eq = string1.eq_ignore_case(&string2);

    assert!(is_eq.decrypt(&client_key));

    Ok(())
}