TLS (Transport Layer Security)
Two methods exist for mapping client certificates:
Tls şifrələməsini necə aça bilərəm
Last updated on: 2021-05-24
Authored by: David Fonseca
The article describes some registry setting information for the Windows® implementation of the Transport Layer Security (TLS) protocol and the Secure Sockets Layer (SSL) protocol through the Schannel Security Support Provider (SSP).
Note: Applies to Windows Server (Semi-Annual Channel), Windows Server 2019, Windows Server 2016, and Windows 10.
The following sections address specific registry setting parameters:
CertificateMappingMethods
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL
Two methods exist for mapping client certificates:
- One-to-one mappings: These mappings match individual client certificates to individual user accounts on a one-to-one basis. Each client certificate maps to a user account.
- Many-to-one mappings: These mappings match multiple certificates to a user account based on subfields in the client certificates.
Configuring this entry on your server each time a client presents a client certificate automatically associates that user with the appropriate Windows User Account.
Ciphers and cipher suites
To configure these records, you need the TLS cipher suite order, group policy MDM, or PowerShell®, and this article does not cover the configuration.
ClientCacheTime
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL
This entry controls the time that the operating system takes (in milliseconds) to expire client-side cache entries. If the value is 0 , it turns off the secure connection.
EnableOcspStaplingForSni
Online Certificate Status Protocol (OCSP) is a protocol used for obtaining the revocation status of an X.509 digital certificate during the TLS handshake. By activating this entry, the webserver can reduce its workload.
Registry path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL
Add the following key: “EnableOcspStaplingForSni”=dword:00000001
To disable, set the DWORD value to 0: “EnableOcspStaplingForSni”=dword:00000000
FIPSAlgorithmPolicy
Registry path: HKLM SYSTEM\CurrentControlSet\Control\LSA
The National Institute of Standards and Technology publicly announces Federal Information Processing (FIPS) standards developed for use in computer systems by non-military American government agencies and government contractors. Setting this entry controls FIPS compliance. The default is 0 .
Hashes
Configuring the cipher suite order should control TLS/SSL hash algorithms.
IssuerCacheSize
When the issuers do not map to an account, the server might attempt to map the same issuer name repeatedly, hundreds of times per second. You use this entry, which controls the size of the issuer cache, with issuer mapping. This registry entry specifies the cache size, and the default value is 100 .
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL
IssuerCacheTime
As IssuerCacheSize avoids multiply attempts to map the issuer to the server, you can limit the length of the cache timeout interval in milliseconds. The default value is 10 minutes.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL
KeyExchangeAlgorithm: Client RSA key sizes
This entry controls the client RSA key size.
Registry path: HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\KeyExchangeAlgorithms\PKCS
If you want to specify a minimum length for the RSA key, you should create a ClientMinKeyBitLength entry and assign the desired length. If you don’t create this entry, the default value is 1024 bits. However, if you specify a maximum length, create the ClientMaxKeyBitLength entry and change the desired value.
Note: Configuring the cipher suite order should control using key exchange algorithms.
KeyExchangeAlgorithm: Diffie-Hellman key sizes
This entry controls the Diffie-Hellman key sizes.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\KeyExchangeAlgorithms\Diffie-Hellman
Note that the extra entries to specify a value of the Diffie-Helman key are the same as the RSA key. If you want to specify a minimum supported range of Diffie-Helman key, you should create a ClientMinKeyBitLength entry and assign the desire bit length that you want. If you don’t create this entry, the default value is 1024 bits. If you specify a maximum support range, create the ClientMaxKeyBitLength entry and change the desired value. Finally, use the ServerMinKeyBitLength entry to specify the length for the TLS server default. If not, the default value is 2048.
Note: Configuring the cipher suite order should control using key exchange algorithms.
MaximumCacheSize
The cache elements can have different sizes. When you activate this entry, you set a maximum size cache. Setting the value to 0 disables the server-side session and avoids reconnection. Probably, by activating this entry, you get additional memory consumption on your server. The default value is 20,000 elements.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL
Messaging: fragment parsing
Each time a client tries to connect to a server with TLS and the connection is successful, the system stores a handshake message on the server. You can set a size limit for the storage of those messages. When you set the value to 0x0 , you can’t store handshake messages, which causes the TLS to fail. You can increase the maximum allowed size to 2^24-1 bytes.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Messaging
SendTrustedIssuerList
Use this entry only if you do not want to send any list of the trusted issuers to the client.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL
ServerCacheTime
Use this entry to set the time (in milliseconds) that the operating system takes to expire server-side cache entries.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL
A value of 0 disables the server-side session cache and prevents reconnection. Increasing ServerCacheTime above the default values causes Lsass.exe to consume memory. Each session cache element typically requires 2 to 4 KB of memory. Default server cache time is 10 hours.
If you disable the entry by default by using the DisabledByDefault entry and an SSPI app explicitly requests to use SSL, TLS, or DTLS, it might be negotiated.
SSL 2.0
This subkey controls the use of SSL 2.0.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols
To enable the SSL 2.0 protocol, create an Enabled entry (in the Client or Server subkey) and change the value to 1 . To disable it, change the value to 0 . To disable SSL 2.0 by default, create a DisabledByDefault entry and change the value to 1 .
SSL 3.0
This subkey controls the use of SSL 3.0.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols
To enable the SSL 3.0 protocol, create an Enabled entry (in the Client or Server subkey) and change the value to 1 . To disable it, change the value to 0 . To disable SSL 3.0 by default, create a DisabledByDefault entry and change the value to 1 .
TLS 1.0
This subkey controls the use of TLS 1.0.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols
To enable the TLS 1.0 protocol, create an Enabled entry (in the Client or Server subkey) and change the value to 1 . To disable it, change the DWORD value to 0 . To disable TLS 1.0 by default, create a DisabledByDefault entry and change the value to 1 .
TLS 1.1
This subkey controls the use of TLS 1.1.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols
To enable the TLS 1.1 protocol, create an Enabled entry (in the Client or Server subkey) and change the value to 1 . To disable it, change the value to 0 . To disable TLS 1.1 by default, create a DisabledByDefault entry and change the value to 1 .
TLS 1.2
This subkey controls the use of TLS 1.2.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols
To enable the TLS 1.2 protocol, create an Enabled entry (in the Client or Server subkey) and change the value to 1 . To disable it, change the value to 0. To disable TLS 1.2 by default, create a DisabledByDefault entry and change the value to 1 .
DTLS 1.0
This subkey controls the use of DTLS 1.0.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols
To enable the DTLS 1.0 protocol, create an Enabled entry (in the Client or Server subkey) and change the value to 1 . To disable it, change the value to 0 . To disable DTLS 1.0 by default, create a DisabledByDefault entry and change the value to 1 .
DTLS 1.2
This subkey controls the use of DTLS 1.2.
Registry path: HKLM SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols
To enable the DTLS 1.2 protocol, create an Enabled entry (in the Client or Server subkey) and change the value to 1 . To disable it, change the value to 0 . To disable DTLS 1.2 by default, create a DisabledByDefault entry and change the value to 1 .
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TLS (Transport Layer Security)
TLS (Transport Layer Security) is a cryptographic protocol for organizing secure communication on the Internet.
Content
- 2022
- Release of free TLS security certificates for Russian sites
- TLS version 1.3 with support for Russian encryption standards
- Free TLS certificates will ensure the availability of sites
2022
Release of free TLS security certificates for Russian sites
In Russia, an information infrastructure has been developed to maintain the trouble-free operation of Russian information resources. This was announced by the company FSAU Research Institute “Sunrise” on March 28, 2022. The information system of the National Certification Center created for this purpose provides the issuance of TLS certificates using both Russian and other cryptographic algorithms. Read more here.
TLS version 1.3 with support for Russian encryption standards
On March 14, 2022, the company Kryptonite”” announced that its specialists, together with employees of the company, CryptoCom”” completed the development of an open implementation of the TLS protocol version 1.3, which provides data protection using. the Russian cryptographic algorithms It is available as an extension for OpenSSL 1.1.1.
The TLS protocol is used in browsers, instant messengers, email clients, IP telephony and other applications to ensure the confidentiality of data transmitted over the Internet. Version 1.3 of this protocol is defined in the international standard RFC8446 and is quite “revolutionary.” Thanks to it, significant modifications have been made to the protocol to simultaneously strengthen security and improve its user characteristics.
TLS 1.3 allows you to use various algorithms for encryption, key distribution and digital signature. A specific set of cryptographic algorithms (cipher suites), supported by both sides, is set at the Handshake stage – negotiation of connection parameters.
The RFC8446 standard provides for the use of only foreign cryptographic algorithms in the protocol. In Russia, the expansion of RFC8446 is adopted – standard R 1323565.1.030-2020. Its main difference is the use of Russian cryptographic algorithms and support for other modes of protocol operation. The domestic standard defines 4 crypto sets, each of which uses the MGM mode (described in P 1323565.1.026) with its own unique parameters.
MGM mode belongs to the group of AEAD algorithms. It uses a multi-line mode with Galois authentication, which allows you to simultaneously process confidential data (content of network packets) and auxiliary technical (packet headers). The latter do not need to be encrypted, but they need to provide protection against modification (integrity) and verified compliance with encrypted fragments. In other words, MGM protects against unauthorized changes to metadata transmitted in plain text.
Earlier, the research and production company Kryptonit announced the creation of an open source implementation based on OpenSSL 1.1.1 of all current Russian encryption algorithms and modes of their use, including the MGM mode. The next step was to ensure that these algorithms could be used in the TLS 1.3 protocol.
The main mechanism for expanding the functionality of the OpenSSL library in versions 1.1.1 and earlier is the engine mechanism. A significant amount of Russian cryptographic algorithms is available in OpenSSL through the Gost Engine extension.
Specialists from Kryptonit and CryptoCom completed the following improvements to the Ghost Engine, as well as the source code of the OpenSSL library itself:
- added a public ephemeral key encoding algorithm in the key_share extension (in the Handshake step);
- added an algorithm for generating a common secret ECDHE value using the Diffie-Hellman protocol;
- the TLSTREE algorithm is implemented, which is used to generate keys for protecting records from the root key;
- the algorithm matching mechanism in the signature_algorithms extension has been improved (it required editing the OpenSSL code);
- the built-in test system has been improved.
At the final stage, according to the methodological recommendations of the TK26, the resulting implementation of the TLS 1.3 protocol was checked using control examples. Additionally, it was tested using the formal language of the primary specifications of cryptographic protocols. The developed implementation of the TLS 1.3 protocol is planned to be used at the cryptographic compatibility testing stand, also developed at Kryptonit NPK.
In parallel, for the current OpenSSL 3.0 branch, similar work is already underway to implement Russian encryption standards.
Free TLS certificates will ensure the availability of sites
On March 4, 2022 Ministry of Digital Science of the Russian Federation , they announced that in the near future regulatory acts would be adopted regulating the work of the National Certification Centre on the free issuance of TLS certificates Russian legal to persons. This will help users maintain safe access to sites that have had TLS revoked.
It will be possible to obtain a TLS certificate on the State Public services portal in a fully remote mode. All browsers and operating systems will have to support the operation of TLS certificates on the sites that receive them. It will be possible to see the full list of domains for which certificates have been issued on the State Public services portal.
See also
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What is TLS (Transport Layer Security)?
During the Internet’s early days, aspects such as data security weren’t nearly as important as they are today. Most communications were transmitted unencrypted between servers during these times. Much like postcards, any mailman was able to read their content.
The TLS protocol – also referred to as SSL/TLS – introduced encryption for transmitted contents. Following on from the above example, this is comparable to a sealed envelope which only the addressed recipient can open and read.
Contents
- What is TLS?
- How does TLS work?
- Advantages and disadvantages of TLS
- Areas of application for TLS
- Implementation of TLS
- Known TLS attacks
What is TLS?
The abbreviation TLS stands for Transport Layer Security. It was originally designated to run on top of transport protocols such as TCP/IP-Models. The TLS protocol essentially encrypts data transmissions online or between devices to ensure they are only accessed by the authorised recipients. The protocol’s predecessor was the well-known SSL (Secure Socket Layer) which is why TLS is often referred to as SSL/TLS to avoid confusion.
How does TLS work?
TLS encrypts data sent via the Internet and is normally implemented on top of TCP using symmetric cryptography.
Find out more about the different encryption methods in our dedicated article on the topic.
What may sound simple in theory, is quite complicated in reality. As part of the secure transmission process, the server has to share the access key with the client – before any communication is secured via TLS. You may be well-aware of the issue if you regularly send encrypted e-mail attachments: by encrypting an attachment, you need to share the password with the recipient, for example, via telephone.
The TLS protocol uses the following measures to solve this problem:
- If a client, such as a web browser, contacts the web server, it receives a certificate. This SSL certificate verifies that a sender is authentic and is not, for example, hiding behind a fraudulent identity.
- The client verifies the certificate and sends the server a randomly encrypted number with a public key to the server.
- The server produces a session key from this public key to encrypt the communication. Because the public key originates from the client, the server can be certain that the session key stems from the correct sender.
- The server then sends the encrypted session key to the client. The encryption is based on the Diffie Hellman key exchange method.
- Now, both parties are able to encrypt their data using the session key.
The reason why asymmetric encryption is only used for the session key (but not the encryption of the data streams themselves) is because of speed: asymmetric encryption is relatively slow and would delay the data communication.
Advantages and disadvantages of TLS
TLS is a relatively elegant solution to secure data transfer on the web because it doesn’t require parties to encrypt the content they exchange. Instead, it suffices for the transport only to be conducted via the TLS protocol, irrespective of the operating system or software applications used by the parties involved. All data streams are then automatically encrypted during transmission.
However, the added layer of security comes at the cost of speed because processes such as certification, and public and session key generation are computationally intensive.
Areas of application for TLS
TLS is universally deployable because it doesn’t rely on specific operating systems or applications. Accordingly, a variety of TLS-secured versions are available for various user protocols. The naming scheme is simple: the name of the protocol concludes on the letter “s” if the protocol communicates via TLS.
The most important area of application for TLS is the World Wide Web, or more accurately, the HTTP protocol. The encrypted version is called HTTPS.
Other frequent fields of application include:
- POP3S: collect e-mails from a server using the POP3 protocol
- IMAPS: synchronise inbox with server using the IMAP protocol
- SMTPS: send e-mails
- FTPS: file transfer via FTP protocol
- SIPS: Voice-over-IP calls via the SIP protocol
- IRCS: encrypted chats
OpenVPN, which is a free software for Virtual Private Networks (VPN), also uses a TLS protocol.
Implementation of TLS
Among the most important implementations of TLS are:
- OpenSSL – the most common implementation used by most HTTPS websites
- GnuTLS (Free Software Foundation)
- LibreSSL (OpenBSD)
- NSS (Network Security Services)
- BoringSSL (Google)
- Cryptlib (Peter Gutmann)
- Botan (BSD licence, Jack Lloyd)
- JSSE (Java Secure Socket Extension, Oracle)
- S2n (Amazon)
The list is not complete. For more information on the implementation of TLS, Wikipedia is an excellent source.
Known TLS attacks
However, TLS is not immune to attacks and data leaks. Some well-known points of attack and weak spots include:
- Programming errors: The Heartbleed Bug became famous for being a serious programming error in some of the earlier versions of OpenSSL. It was fixed in 2014.
- Weak encryption: As a consequence of export restrictions to cryptography in the US, exportable versions were developed. However, these were easier to crack than previous versions.
- Compression attacks: If HTTP compression is used instead of TLS compression, hackers are able to guess TLS -encrypted contents using dedicated techniques.
- The BEAST attack affected TLS version 1.0 and was disclosed in 2014. Current TLS versions are safe.
- The Padding Oracle attack was discovered in 2002 and remained a threat until SSL version 3.0. The current TLS version 1.3 is not affected.
At the same time, there have been attempts to avoid a fully secure TLS encryption in order for authorities to access encrypted communications, for example, to monitor the fraudulent activity of financial transactions. The European Telecommunications Standards Institute has been among the organisations at the forefront of creating defined breaking points in the protocol.
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