Certificates are often known as X.509 certificates, since X.509 is the standard that defines their context and layout. The commonest algorithms for creating public and private keys are RSA and DSA, and keys are often referred to as RSA keys or DSA keys. None of these, however, define the format of the file in which a certificate or key is held. There are many rival formats for these files. Some of the commonest standard formats are:
- DER. This format can contain private keys (RSA or DSA), public keys (RSA or DSA) and X.509 certificates. It is headerless. It is the default format for most browsers. A file can contain only one certificate. Optionally the certificate can be encrypted. The standard extension is .cer, but might be .der in some installations.
- PEM. This format can contain private keys (RSA or DSA), public keys (RSA or DSA) and X.509 certificates. It is the default format for OpenSSL. It stores the data in either ASN.1 or DER format, surrounded by ASCII headers, so is suitable for sending files as text between systems. A file can contain multiple certificates. The standard extension is .pem.
- PKCS #7. This is the Cryptographic Message Syntax Standard. A file can contain multiple certificates. Optionally they can be hashed. Optionally a certificate can be accompanied by a private key. As well as the original PKCS #7, there are three revisions: a, b, and c. The standard extensions for these four versions are .spc, .p7a, .p7b and .p7c respectively.
- PKCS #8. This format can contain private keys and encrypted private key information. It stores the data in base64 encoded data, usually using a DER or PEM structure which is then encrypted. The standard extension is .p8.
- PKCS #12. This is also known as PFX. This format can contain private keys (RSA or DSA), public keys (RSA or DSA) and X.509 certificates. It stores them in a binary format. The standard extension is .pfx or .p12.
FAQs
Certificates are data structures based on the ASN1 standard. They can be encoded in various formats: PEM (Privacy-Enhanced Mail): This is an ASCII format based on specific headers and footers (BEGIN/END) encoding the certificate in Base64 format.
What is the certificate format? ›
Certificates are data structures based on the ASN1 standard. They can be encoded in various formats: PEM (Privacy-Enhanced Mail): This is an ASCII format based on specific headers and footers (BEGIN/END) encoding the certificate in Base64 format.
What are .CRT and .key files? ›
crt and key files represent both parts of a certificate, key being the private key to the certificate and crt being the signed certificate. It's only one of the ways to generate certs, another way would be having both inside a pem file or another in a p12 container.
What are the three types of certificates? ›
There are three types of SSL Certificate available today; Extended Validation (EV SSL), Organization Validated (OV SSL) and Domain Validated (DV SSL).
What is the most common certificate format? ›
PEM is the most popular SSL certificate format and the one you'll likely encounter. The majority of CAs offer SSL certificates in PEM format with different certificate file extensions such as . pem, . crt, .
What is the most commonly used format for certificates? ›
Some of the commonest standard formats are:
- DER. This format can contain private keys (RSA or DSA), public keys (RSA or DSA) and X. ...
- PEM. This format can contain private keys (RSA or DSA), public keys (RSA or DSA) and X. ...
- PKCS #7. This is the Cryptographic Message Syntax Standard. ...
- PKCS #8. ...
- PKCS #12.
The most common format for public key certificates is defined by X. 509. Because X. 509 is very general, the format is further constrained by profiles defined for certain use cases, such as Public Key Infrastructure (X.
Are .cer and .crt the same? ›
CER and CRT are two common file extensions used for digital certificates. CER files contain encoded certificates in a binary DER format while CRT files contain Base64 encoded certificates in a text format. While CER and CRT files contain essentially the same certificate data, they use different encoding formats.
What is a .PEM and csr file? ›
A Certificate Signing Request (CSR) is also supplied in PEM format, which is converted from PKCS10 format. The name originated from the abbreviation Privacy-enhanced Electronic Mail (PEM), which was the standard for email security.
What format is a CRT file? ›
CRT = The CRT extension is used for certificates. The certificates may be encoded as binary DER or as ASCII PEM. The CER and CRT extensions are nearly synonymous. Most common among *nix systems.
PEM format
This is the most commonly used format for storing certificates. Most servers (such as Apache or nginx) use the private key and certificate in two separate test files. We often refer to PEM as "text format", because it is encoded in Base64.
How do I identify a certificate type? ›
To check an SSL certificate on any website, all you need to do is follow two simple steps.
- First, check if the URL of the website begins with HTTPS, where S indicates it has an SSL certificate.
- Second, click on the padlock icon on the address bar to check all the detailed information related to the certificate.
The certificates are akin to a driver's license or passport for the digital world. Common examples of PKI security today are SSL certificates on websites so that site visitors know they're sending information to the intended recipient, digital signatures, and authentication for Internet of Things devices.
What is a .PEM file? ›
Privacy Enhanced Mail (PEM) files are a type of Public Key Infrastructure (PKI) file used for keys and certificates. PEM, initially invented to make e-mail secure, is now an Internet security standard.
What format is a .cer file? ›
cer file is a binary or base64-encoded file, whereas a . pfx file is a binary file. Binary files store data in its raw binary format, while base64-encoded files convert binary data into ASCII text for easier transmission and storage in text-based environments.
Which standard is most widely used for certificates? ›
509 or EMV standard. One particularly common use for certificate authorities is to sign certificates used in HTTPS, the secure browsing protocol for the World Wide Web.
How to identify certificate format? ›
There are different formats of X. 509 certificates such as PEM, DER, PKCS#7 and PKCS#12. PEM and PKCS#7 formats use Base64 ASCII encoding while DER and PKCS#12 use binary encoding. The certificate files have different extensions based on the format and encoding they use.
What is a form of certificate? ›
Form of Certificate means with respect to a Class E Certificate, the form of such Security attached as an exhibit to the Certificate Purchase Agreement.
