PEM

tags

Security

Summary #

Privacy-Enhanced Mail (PEM) is a de facto file format for storing and sending cryptography keys, certificates, and other data, based on a set of 1993 IETF standards defining “privacy-enhanced mail.” While the original standards were never broadly adopted and were supplanted by PGP(Pretty Good Privacy) and S/MIME(Secure/Multipurpose internet Mail Extensions), the textual encoding they defined became very popular. The PEM format was eventually formalized by the IETF in RFC 7468. wikipedia

• PEM (originally “Privacy Enhanced Mail”) is the most common format for X509 certificates, CSR, and cryptographic keys
• PEM files are usually seen with the extensions .crt, .pem, .cer, and .key (for private keys), but you may also see them with different extensions.

  openssl x509 -in CERTIFICATE.pem -text -noout
  openssl x509 -outform der -in CERTIFICATE.pem -out CERTIFICATE.der
  

Format #

—–BEGIN PRIVATE KEY—– base64 encoded data —–END PRIVATE KEY—–

—–BEGIN CERTIFICATE—– … base64 encoding of the DER encoded certificate with line endings and padding with equals signs … —–END CERTIFICATE—–

• Example

—–BEGIN EC PRIVATE KEY—– MIGNAgEAMBAGByqGSM49AgEGBSuBBAAKBHYwdAIBAQQglcjiAt/7M3uLon55OLAu EOdT1NZMUp8FXU0a37JgiJqgBwYFK4EEAAqhRANCAASwsT6+MbEUxY3pLU2brH4p TKBr57yNQnPRsJTYJ0gaKk1n0nkG6p6E9KxofEA1tyCzEv9B+GzD6FTGBb657H15 —–END EC PRIVATE KEY—– ref

PEM also defines a one-line header, consisting of —–BEGIN, a label, and —–, and a one-line footer, consisting of —–END, a label, and —–. The label determines the type of message encoded. Common labels include

• CERTIFICATE,

• CERTIFICATE REQUEST,

• PUBLIC KEY

• PRIVATE KEY and

• X509 CRL.

  related

Types of file extensions that store PEM format #

ref

1. “.csr”
2. “.pem”
3. “.key”