Hi, I'm trying to create a CSR for an SMIME certificate for an email address with non-ASCII characters (localpart and domain), and I'm getting this error after entering äbç@être.org as the email address: 139749651649856:error:0D07A07C:asn1 encoding routines:ASN1_mbstring_ncopy:illegal characters:../crypto/asn1/a_mbstr.c:115: The error message is similar if the only non-ASCII characters are in the domain name, or if they are only in the localpart (only the leading number in the error message changes). It's just for testing purposes, and I'm only really interested in the domain part. I must be doing something wrong. How can I use non-ASCII (UTF8-encoded Unicode characters, LANG=en_AU.UTF-8)? It looks like it's expecting multi-byte strings (a_mbstr.c). My smime.cnf contains: [req] distinguished_name = req_distinguished_name [req_distinguished_name] countryName = Country Name (2 letter code) countryName_default = AU countryName_min = 2 countryName_max = 2 stateOrProvinceName = State or Province Name (full name) stateOrProvinceName_default = Some-State localityName = Locality Name (eg, city) 0.organizationName = Organization Name (eg, company) 0.organizationName_default = Internet Widgits Pty Ltd organizationalUnitName = Organizational Unit Name (eg, section) commonName = Common Name (e.g. server FQDN or YOUR name) commonName_max = 64 emailAddress = Email Address emailAddress_max = 64 [smime] basicConstraints = CA:FALSE keyUsage = nonRepudiation, digitalSignature, keyEncipherment subjectKeyIdentifier = hash authorityKeyIdentifier = keyid:always,issuer subjectAltName = email:copy extendedKeyUsage = emailProtection And the openssl commands were: OPENSSL_CONF=`pwd`/smime.cnf # Generate an RSA Private Key for the Certificate Authority openssl genrsa -aes256 -out ca.key 2048 # Create Self-Signed Certificate for the Certificate Authority openssl req -new -x509 -days 365 -key ca.key -out ca.crt # Generate an RSA Private Key for the Personal E-Mail Certificate openssl genrsa -aes256 -out smime_test_user.key 2048 # Create the Certificate Signing Request openssl req -new -key smime_test_user.key -out smime_test_user.csr The error happened during the command above. > openssl req -new -key smime_test_user.key -out smime_test_user.csr Enter pass phrase for smime_test_user.key: You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [AU]: State or Province Name (full name) [Some-State]: Locality Name (eg, city) []: Organization Name (eg, company) [Internet Widgits Pty Ltd]: Organizational Unit Name (eg, section) []: Common Name (e.g. server FQDN or YOUR name) []: Email Address []:äbç@être.org problems making Certificate Request 139749651649856:error:0D07A07C:asn1 encoding routines:ASN1_mbstring_ncopy:illegal characters:../crypto/asn1/a_mbstr.c:115: So I didn't get to the final command: # Sign the Certificate Using the Certificate Authority openssl x509 -req -days 365 -in smime_test_user.csr -CA ca.crt -CAkey ca.key -set_serial 1 -out smime_test_user.crt -addtrust emailProtection -addreject clientAuth -addreject serverAuth -trustout -extfile smime.cnf -extensions smime cheers, raf