PEM TypeScript Library

• Author: Jonathan M. Wilbur <[email protected]>
• Copyright Year: 2019
• License: MIT License

Building

You can build this library by running npm run build.

The outputs will all be in dist.

• ./dist/pem.min.js is the entire PEM library for the web browser, which is minified.
• ./dist/index.js is the entire NodeJS library.

Library Usage

Decoding PEM Files

There are two methods in the PEMObject that are used for decoding PEM objects. The first, decode(), only decodes a single PEM object, which must start with the pre-encapsulation header and end with a post-encapsulation header. (Whitespace is trimmed, so it is fine if you have a trailing newline.)

const text : string =
`-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----`;
const pem : PEMObject = new PEMObject();
pem.decode(text);
console.log(pem.label === "CERTIFICATE"); // logs "true"
console.log(pem.data); // logs the Uint8Array of bytes decoded from the base-64 data

The second, parse(), is a static method that retrieves and decodes all of the PEM objects from a file. This is usually what you should use to decode PEM data, as it complies strictly to RFC 7468. This is important, because PEM files can contain explanatory text and/or whitespace before, between, or after objects.

const text : string =
`---OOSH, you thought this was a line? try again, bub.
-----BEGIN CERTIFICATE-----


MIICUTCCAfugAwIBAgIBADANBgkqhkiG9w0BAQQFADBXMQswCQYDVQQGEwJDTjEL
MAkGA1UECB
MCUE4xCzAJBgNVBAcTAkNOMQswCQYDVQQKEwJPTjELMAkGA1UECxMC
VU4xFDASBgNVBAMTC0hlcm9uZyBZYW5nMB4XDTA1MDcxNTIxMTk0N1oXDTA1MDgx
NDIxMTk0N1owVzELMAkGA1UEBhMCQ04xCzAJBgNVBAgTAlBOMQswCQYDVQQHEwJD
TjELMAkGA1UEChMCT04xCzAJBgNVBAsTAlVOMRQwEgYDVQQDEwtIZXJvbmcgWWFu
ZzBcMA0GCSqGSIb3DQEBAQUAA0sAMEgCQQCp5hnG7ogBhtlynpOS21cBewKE/B7j
V14qeyslnr26xZUsSVko36ZnhiaO/zbMOoRcKK9vEcgMtcLFuQTWDl3RAgMBAAGj
gbEwga4wHQYDVR0OBBYEFFXI70krXeQDxZ
gbaCQoR4jUDncEMH8GA1UdIwR4MHaA
FFXI70krXeQDxZgbaCQoR4jUDncEoVukWTBXMQswCQYDVQQGEwJDTjELMAkGA1UE
CBMCUE4xCzAJBgNVBAcTAkNOMQswCQYDVQQKEwJPTjELMAkGA1UECxMCVU4xFDAS
BgNVBAMTC0hlcm9uZyBZYW5nggEAMAwGA1UdEwQFMAMBAf8wDQYJKoZIhvcNAQEE
BQADQQA/ugzBrjjK9jcWnDVfGHlk3icNRq0oV7Ri32z/+HQX67aRfgZu7KWdI+Ju
Wm7DCfrPNGVwFWUQOmsPue9rZBgO
-----END CERTIFICATE-----
Explanatory text
-----BEGIN CERTIFICATE-----

MIICUTCCAfugAwIBAgIBADANBgkqhkiG9w0BAQQFADBXMQswCQYDVQQGEwJDTjEL
MAkGA1UECBMCUE4xCzAJBgNVBAcTAkNOMQswCQYDVQQKEwJPTjELMAkGA1UECxMC
VU4xFDASBgNVBAMTC0hlcm9uZyBZ
YW5nMB4XDTA1MDcxNTIxMTk0N1oXDTA1MDgx
NDIxMTk0N1owVzELMAkGA1UEBhMCQ04xCzAJBgNVBAgTAlBOMQswCQYDVQQHEwJD
TjELMAkGA1UEChMCT04xCzAJBgNVBAsTAlVOMRQwEgYDVQQDEwtIZXJvbmcgWWFu
ZzBcMA0GCSqGSIb3DQEBAQUAA0sAMEgCQQCp5hnG7ogBhtlynpOS21cBewKE/B7j
V14qeyslnr26xZUsSVko36ZnhiaO/zbMOoRcKK9vEcgMtcLFuQTWDl3RAgMBAAGj
gbEwga4wHQYDVR0OBBYEFFXI70krXeQDxZgbaCQoR4jUDncEMH8GA1UdIwR4MHaA
FFXI70krXeQDxZgbaCQoR4jUDncEoVukWTBXMQswCQYDVQQGEwJDTjELMAkGA1UE
CBMCUE4xCzAJBgNVBAcTA
kNOMQswCQYDVQQKEwJPTjELMAkGA1UECxMCVU4xFDAS
BgNVBAMTC0hlcm9uZyBZYW5nggEAMAwGA1UdEwQFMAMBAf8wDQYJKoZIhvcNAQEE
BQADQQA/ugzBrjjK9jcWnDVfGHlk3icNRq0oV7Ri32z/+HQX67aRfgZu7KWdI+Ju
Wm7DCfrPNGVwFWUQOmsPue9rZBgO
-----END CERTIFICATE-----

 GOTTA GO FASTT

`;
const pems : PEMObject[] = PEMObject.parse(text);
console.log(pems[0].label === "CERTIFICATE"); // logs "true"
console.log(pems[1].label === "CERTIFICATE"); // logs "true"
console.log(pems[0].data); // logs the Uint8Array of bytes decoded from the base-64 data

Encoding (Creating) PEM Files

Creating PEM files is simple: set the label, set the data, and access the encoded property, like so:

const pem : PEMObject = new PEMObject();
pem.label = "CERTIFICATE";
pem.data = new Uint8Array([ 0xFF, 0x00, 0xFF, 0x00 ]);
console.log(pem.encoded); // Logs the PEM encoded object

Validating PEM Files

You can validate PEM object labels like so:

const pem : PEMObject = new PEMObject();
pem.label = "CERTIFICATE";
console.log(pem.hasRFC7468CompliantLabel); // Logs "true"
pem.label = "BLORPIFICATE";
console.log(pem.hasRFC7468CompliantLabel); // Logs "false"

Hacking PEM Files

I don't know why you would want to do this, but every part of the PEM file is accessible as an accessor, like so:

const pem : PEMObject = new PEMObject();
pem.label = "CERTIFICATE";
pem.data = new Uint8Array([ 0xFF, 0x00, 0xFF, 0x00 ]);
console.log(pem.label); // Logs "CERTIFICATE"
console.log(pem.preEncapsulationBoundary); // Logs "-----BEGIN CERTIFICATE-----"
console.log(pem.postEncapsulationBoundary); // Logs "-----END CERTIFICATE-----"
console.log(pem.encapsulatedTextPortion); // Logs the base-64 encoding of pem.data

See Also

• RFC 7468