Provided by: openssl_3.0.2-0ubuntu1.19_amd64 
NAME
openssl-glossary - An OpenSSL Glossary
DESCRIPTION
Algorithm
Cryptograpic primitives such as the SHA256 digest, or AES encryption are referred to in OpenSSL as
"algorithms". There can be more than one implementation for any given algorithm available for use.
crypto(7)
ASN.1, ASN1
ASN.1 ("Abstract Syntax Notation One") is a notation for describing abstract types and values. It is
defined in the ITU-T documents X.680 to X.683:
<https://www.itu.int/rec/T-REC-X.680>, <https://www.itu.int/rec/T-REC-X.681>,
<https://www.itu.int/rec/T-REC-X.682>, <https://www.itu.int/rec/T-REC-X.683>
Base Provider
An OpenSSL Provider that contains encoders and decoders for OpenSSL keys. All the algorithm
implementations in the Base Provider are also available in the Default Provider.
OSSL_PROVIDER-base(7)
Decoder
A decoder is a type of algorithm used for decoding keys and parameters from some external format such
as PEM or DER.
OSSL_DECODER_CTX_new_for_pkey(3)
Default Provider
An OpenSSL Provider that contains the most commmon OpenSSL algorithm implementations. It is loaded by
default if no other provider is available. All the algorithm implementations in the Base Provider are
also available in the Default Provider.
OSSL_PROVIDER-default(7)
DER ("Distinguished Encoding Rules")
DER is a binary encoding of data, structured according to an ASN.1 specification. This is a common
encoding used for cryptographic objects such as private and public keys, certificates, CRLs, ...
It is defined in ITU-T document X.690:
<https://www.itu.int/rec/T-REC-X.690>
Encoder
An encoder is a type of algorithm used for encoding keys and parameters to some external format such
as PEM or DER.
OSSL_ENCODER_CTX_new_for_pkey(3)
Explicit Fetching
Explicit Fetching is a type of Fetching (see Fetching). Explicit Fetching is where a function call is
made to obtain an algorithm object representing an implementation such as EVP_MD_fetch(3) or
EVP_CIPHER_fetch(3)
Fetching
Fetching is the process of looking through the available algorithm implementations, applying
selection criteria (via a property query string), and finally choosing the implementation that will
be used.
Also see Explicit Fetching and Implict Fetching.
crypto(7)
FIPS Provider
An OpenSSL Provider that contains OpenSSL algorithm implementations that have been validated
according to the FIPS 140-2 standard.
OSSL_PROVIDER-FIPS(7)
Implicit Fetching
Implicit Fetching is a type of Fetching (see Fetching). Implicit Fetching is where an algorithm
object with no associated implementation is used such as the return value from EVP_sha256(3) or
EVP_aes_128_cbc(3). With implicit fetching an implementation is fetched automatically using default
selection criteria the first time the algorithm is used.
Legacy Provider
An OpenSSL Provider that contains algorithm implementations that are considered insecure or are no
longer in common use.
OSSL_PROVIDER-legacy(7)
Library Context
A Library Context in OpenSSL is represented by the type OSSL_LIB_CTX. It can be thought of as a scope
within which configuration options apply. If an application does not explicitly create a library
context then the "default" one is used. Many OpenSSL functions can take a library context as an
argument. A NULL value can always be passed to indicate the default library context.
OSSL_LIB_CTX(3)
MSBLOB
MSBLOB is a Microsoft specific binary format for RSA and DSA keys, both private and public. This
form is never passphrase protected.
Null Provider
An OpenSSL Provider that contains no algorithm implementations. This can be useful to prevent the
default provider from being automatically loaded in a library context.
OSSL_PROVIDER-null(7)
Operation
An operation is a group of OpenSSL functions with a common purpose such as encryption, or digesting.
crypto(7)
PEM ("Privacy Enhanced Message")
PEM is a format used for encoding of binary content into a mail and ASCII friendly form. The content
is a series of base64-encoded lines, surrounded by begin/end markers each on their own line. For
example:
-----BEGIN PRIVATE KEY-----
MIICdg....
... bhTQ==
-----END PRIVATE KEY-----
Optional header line(s) may appear after the begin line, and their existence depends on the type of
object being written or read.
For all OpenSSL uses, the binary content is expected to be a DER encoded structure.
This is defined in IETF RFC 1421:
<https://tools.ietf.org/html/rfc1421>
PKCS#8
PKCS#8 is a specification of ASN.1 structures that OpenSSL uses for storing or transmitting any
private key in a key type agnostic manner. There are two structures worth noting for OpenSSL use,
one that contains the key data in unencrypted form (known as "PrivateKeyInfo") and an encrypted
wrapper structure (known as "EncryptedPrivateKeyInfo").
This is specified in RFC 5208:
<https://tools.ietf.org/html/rfc5208>
Property
A property is a way of classifying and selecting algorithm implementations. A property is a
key/value pair expressed as a string. For example all algorithm implementations in the default
provider have the property "provider=default". An algorithm implementation can have multiple
properties defined against it.
Also see Property Query String.
property(7)
Property Query String
A property query string is a string containing a sequence of properties that can be used to select an
algorithm implementation. For example the query string "provider=example,foo=bar" will select
algorithms from the "example" provider that have a "foo" property defined for them with a value of
"bar".
Property Query Strings are used during fetching. See Fetching.
property(7)
Provider
A provider in OpenSSL is a component that groups together algorithm implementations. Providers can
come from OpenSSL itself or from third parties.
provider(7)
PVK PVK is a Microsoft specific binary format for RSA and DSA private keys. This form may be passphrase
protected.
SubjectPublicKeyInfo
SubjectPublicKeyInfo is an ASN.1 structure that OpenSSL uses for storing and transmitting any public
key in a key type agnostic manner.
This is specified as part of the specification for certificates, RFC 5280:
<https://tools.ietf.org/html/rfc5280>
HISTORY
This glossary was added in OpenSSL 3.0.
COPYRIGHT
Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance
with the License. You can obtain a copy in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.
3.0.2 2025-02-05 OPENSSL-GLOSSARY(7SSL)