diff --git a/sros2/sros2/api/_utilities.py b/sros2/sros2/api/_utilities.py
index 0a0a5a82..eb382ad6 100644
--- a/sros2/sros2/api/_utilities.py
+++ b/sros2/sros2/api/_utilities.py
@@ -19,9 +19,9 @@
 
 from cryptography import x509
 from cryptography.hazmat.backends import default_backend as cryptography_backend
-from cryptography.hazmat.bindings.openssl.binding import Binding as SSLBinding
 from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives import smime
 from cryptography.hazmat.primitives.asymmetric import ec
 
 _DOMAIN_ID_ENV = 'ROS_DOMAIN_ID'
@@ -63,7 +63,13 @@ def create_smime_signed_file(cert_path, key_path, unsigned_file_path, signed_fil
 
     # Sign the contents, and write the result to the appropriate place
     with open(signed_file_path, 'wb') as f:
-        f.write(_sign_bytes(cert, private_key, content))
+        builder = smime.SMIMESignatureBuilder(
+            content).add_signer(
+                cert, private_key, hashes.SHA256()
+            )
+        f.write(builder.sign(
+            smime.SMIMEEncoding.PEM,
+            (smime.SMIMEOptions.Text, smime.SMIMEOptions.DetachedSignature)))
 
 
 def build_key_and_cert(subject_name, *, ca=False, ca_key=None, issuer_name=''):
@@ -130,42 +136,3 @@ def load_cert(cert_path):
     with open(cert_path, 'rb') as cert_file:
         return x509.load_pem_x509_certificate(
             cert_file.read(), cryptography_backend())
-
-
-def _sign_bytes(cert, key, byte_string):
-    # Using two flags here to get the output required:
-    #   - PKCS7_DETACHED: Use cleartext signing
-    #   - PKCS7_TEXT: Set the MIME headers for text/plain
-    flags = SSLBinding.lib.PKCS7_DETACHED
-    flags |= SSLBinding.lib.PKCS7_TEXT
-
-    # Convert the byte string into a buffer for SSL
-    bio_in = SSLBinding.lib.BIO_new_mem_buf(byte_string, len(byte_string))
-    try:
-        pkcs7 = SSLBinding.lib.PKCS7_sign(
-            cert._x509, key._evp_pkey, SSLBinding.ffi.NULL, bio_in, flags)
-    finally:
-        # Free the memory allocated for the buffer
-        SSLBinding.lib.BIO_free(bio_in)
-
-    # PKCS7_sign consumes the buffer; allocate a new one again to get it into the final document
-    bio_in = SSLBinding.lib.BIO_new_mem_buf(byte_string, len(byte_string))
-    try:
-        # Allocate a buffer for the output document
-        bio_out = SSLBinding.lib.BIO_new(SSLBinding.lib.BIO_s_mem())
-        try:
-            # Write the final document out to the buffer
-            SSLBinding.lib.SMIME_write_PKCS7(bio_out, pkcs7, bio_in, flags)
-
-            # Copy the output document back to python-managed memory
-            result_buffer = SSLBinding.ffi.new('char**')
-            buffer_length = SSLBinding.lib.BIO_get_mem_data(bio_out, result_buffer)
-            output = SSLBinding.ffi.buffer(result_buffer[0], buffer_length)[:]
-        finally:
-            # Free the memory required for the output buffer
-            SSLBinding.lib.BIO_free(bio_out)
-    finally:
-        # Free the memory allocated for the input buffer
-        SSLBinding.lib.BIO_free(bio_in)
-
-    return output