diff --git a/native/native_rust_library/src/crypto_tools.rs b/native/native_rust_library/src/crypto_tools.rs
--- a/native/native_rust_library/src/crypto_tools.rs
+++ b/native/native_rust_library/src/crypto_tools.rs
@@ -1,5 +1,9 @@
 use crate::ffi::DeviceType;
+use openssl::hash::MessageDigest;
+use openssl::pkey::PKey;
+use openssl::sign::Signer;
 use rand::distributions::{Alphanumeric, DistString};
+
 #[cfg(test)]
 use regex::Regex;
 
@@ -33,6 +37,16 @@
   Ok(format!("{}:{}", &prefix, &suffix))
 }
 
+pub fn sign_string_with_private_key(
+  private_key: &PKey<openssl::pkey::Private>,
+  string_to_be_signed: &str,
+) -> anyhow::Result<String> {
+  let mut signer = Signer::new(MessageDigest::sha256(), &private_key)?;
+  signer.update(string_to_be_signed.as_bytes())?;
+  let signature = signer.sign_to_vec()?;
+  Ok(base64::encode(signature))
+}
+
 #[cfg(test)]
 mod tests {
   use super::*;