How to create a single line x509 certificate that can be parsed by OpenSSL commandline tool

Question

I wanted to prepare a single line x509 Certificate string which can be parsed by OpenSSL command-line utility.

I created a private key using OpenSSL command-line utility,

openssl genrsa -out privatekey.pem 1024

And then created a public key,

openssl req -new -x509 -key privatekey.pem -out publickey.cer -days 1825

The contents of the certificate is,

$ openssl x509 -in publickey.cer
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

I then converted the newline symbols to \n using below awk command,

$ awk 'NF {sub(/\r/, ""); printf "%s\\n",$0;}' publickey.cer  | tee single_line_publickey.cer

The transformed certificate is,

But OpenSSL command line tool is failing to parse this single line certificate,

$ openssl x509 -in single_line_publickey.cer 
unable to load certificate
140671947637184:error:0909006C:PEM routines:get_name:no start line:../crypto/pem/pem_lib.c:745:Expecting: TRUSTED CERTIFICATE

Looks like it is not able to find the encapsulation boundaries -----BEGIN CERTIFICATE----- and -----END CERTIFICATE-----. From the RFC7468: Textual Encodings of PKIX, PKCS, and CMS Structures standard, I found that BEGIN CERTIFICATE and END CERTIFICATE labels needs to be separated by newline. Here looks like \n is not working. I tried \r\n to simulate CR+LF but still I had the same problem.

What I observed is the OpenSSL command-line tool is able to parse the certificate when I keep BEGIN CERTIFICATE and END CERTIFICATE labels in newlines. The certificate file is,

$ cat multi_line_publickey.cer
-----BEGIN CERTIFICATE-----
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
-----END CERTIFICATE-----

And the OpenSSL tool is able to parse it,

$ openssl x509 -in multi_line_publickey.cer -noout -subject
subject=C = AU, ST = Some-State, O = Internet Widgits Pty Ltd

But here I have three lines. How to prepare this certificate as one line in a way that OpenSSL Command Line utility can parse it?

I have a web front-end which takes only strings as input. I wanted the users to pass certificates through this front-end. The frontend then passes this single line certificate as a parameter to openstack heat stack creation. The front end has pretty basic Javascript support with very limited modules. — anoop.babu
Sounds like you should just transport the base64, then write the PEM header and footer yourself. — bartonjs

jww jww · Accepted Answer · 2019-10-06T03:50:11

I wanted to prepare a single line x509 Certificate string which can be parsed by OpenSSL command-line utility...

PEM encoding is detailed in RFC 1421, Privacy Enhancement for Internet Electronic Mail. Among the specifications, it says:

Encapsulation boundaries are on their own lines,
The message is Base64 encoded,
Lines are limited to 64 characters,
End-of-line is CR ('\r') and LF ('\n')

OpenSSL has never handled ill-formed certificates well. It has been that way as long as I can remember. A fair number of libraries don't handle EOL well. They choke on CRLF line endings as well.

In contrast, the OpenSSH file format RFC, RFC 4716, say an implementation must handle an eol that is CR, LF, or CRLF. The RFC also says certificates and keys should be written using native platform conventions, so you will see all three in the field.

How to create a single line x509 certificate that can be parsed by OpenSSL commandline tool

3 Answers