SSH vs SSL/TLS: Definitions & Differences of Communication Protocols
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<article id="post-4251" class="post-4251 post type-post status-publish format-standard has-post-thumbnail hentry category-ssl-certificate category-website-security tag-ssh-vs-ssl-tls tag-ssh-vs-tls-difference entry" morss_own_score="8.946954813359529" morss_score="16.765528308547907"> <p><span><a href="https://certera.com/blog/">Home</a> » <span>SSH vs SSL/TLS: Definitions & Differences of Communication Protocols</span></span></p> <h1>SSH vs SSL/TLS: Definitions & Differences of Communication Protocols</h1> <div><img decoding="async" src="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2012%2012'%3E%3C/svg%3E" title="1 Star"><img decoding="async" src="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2012%2012'%3E%3C/svg%3E" title="2 Stars"><img decoding="async" src="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2012%2012'%3E%3C/svg%3E" title="3 Stars"><img decoding="async" src="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2012%2012'%3E%3C/svg%3E" title="4 Stars"><img decoding="async" src="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2012%2012'%3E%3C/svg%3E" title="5 Stars"><strong>1</strong> votes, average: <strong>5.00</strong> out of 5)</div> <p><img decoding="async" src="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2016%2016'%3E%3C/svg%3E"> </p> <figure> <img decoding="async" src="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20960%20620'%3E%3C/svg%3E"></figure> <div class="entry-content" morss_own_score="5.406377759607523" morss_score="251.32820012537485"> <h2>What is SSL/TLS?</h2> <p>The first widely used protocol that was aimed to secure the Internet connections was SSL, which was created by Netscape in mid 1995.</p> <p>It uses both public key and <a href="https://certera.com/blog/symmetric-vs-asymmetric-encryption-detailed-guide/">symmetric key encryption</a> to generate a connection or channel that will help protect data passing between a client, for instance, a web browser, and a server, for instance, a website.</p> <p>That is why, after many successful years, SSL has been identified as containing a number of defects and is recognized as insecure to date. TLS, the next generation of SSL, was developed to rectify these security faults and improve the language’s strength.</p> <p><strong>Also Read:</strong> <a href="https://certera.com/blog/ssl-tls-timeline-history-of-ssl-tls-protocol-versions/">SSL/TLS Timeline: Evolution from SSL to TLS 1.3</a></p> <p>TLS was released in different versions, with the current ones being TLS 1.0, TLS 1.1, TLS 1.2, and TLS 1.3; each being more secure than the preceding one and performing better.</p> <p><a href="https://certera.com/blog/tls-1-3-everything-you-need-to-know/">TLS 1. 3</a> reveals better protection and efficiency in the handshake of devices between users, providing the best security for the PC operating systems.</p> <p>It not only encrypts data that is in transmission so that sensitive information cannot be intercepted by other parties, but also gives authentication, which assures that the server with which a client is communicating is authorized.</p> <p>This dual role of encryption and authentication is highly beneficial in preserving the security and reliability of Internet connections.</p> <p><strong>Also Read:</strong> <a href="https://certera.com/blog/what-is-ssl-tls-https/">WHAT IS SSL, TLS & HTTPS? [Explanation to Difference]</a></p> <h2>How does SSL/TLS Work?</h2> <h3>Establishing a Secure Connection (Handshake Process)</h3> <p>The basic idea of the <a href="https://certera.com/blog/ssl-tls-handshake-a-crucial-step-towards-secure-connections/">SSL/TLS handshake</a> is the key exchange between client and server, where they can have secure communication.</p> <p>It starts with the client sending the message ‘Client Hello’ to the server over the network, containing SSL/TLS version, list of all <a href="https://certera.com/blog/what-is-ssl-cipher-suite-and-how-it-works/">supported cipher suites</a> i.e., the cryptographic algorithms for encryption of data, and random numbers.</p> <p>The server replies with a ‘Server Hello’ which contains the SSL/TLS version that the server is using, the <a href="https://certera.com/blog/what-is-a-cipher-types-of-ciphers-in-cryptography/">identified cipher</a>, and another random number SAS. The server then conveys its digital certificate, that is, its public key, which is authenticated by a CA, to the client.</p> <p>If the selected cipher suite needs more parameters, then the server sends to the client a Server Key Exchange message. The client, in turn, computes the pre-master secret and encrypts it using the server’s public key, then sends it back to the server.</p> <p><strong>Also Read:</strong> <a href="https://certera.com/blog/common-ssl-tls-challenges-issues-attacks-to-exploits/">Common SSL/TLS Attacks: What SSL Prevents?</a></p> <p>This pre-master secret, together with the exchanged random numbers are used by both the client and the server to derive the symmetric session keys.</p> <p>Both the client and the server end the handshake with ‘Finished’ messages that are encrypted and signify that both sides have mutually developed a secure connection.</p> <h3>Securing Data Transmission</h3> <p>This means that after the SSL/TLS connection handshake has been made and a secure connection has been attained, any content that is exchanged between the client and server goes through the session keys that were made during the handshake process.</p> <p>This assurance brings confidentiality, integrity, and authenticity of the data. Data that is exchanged between the client is encrypted with the session key before the exchange and transmission.</p> <p><strong>Also Read:</strong> <a href="https://certera.com/blog/how-to-fix-ssl-handshake-failed-error/">How to Fix the SSL Handshake Failed & Cloudflare 525 Error?</a></p> <p>The same key is used by the server to decrypt or encode the data that is received from or sent to the client and vice versa. The data is encrypted before it is sent to prevent any third party from intercepting the data and understanding it.</p> <p>Moreover, another security technique applied by SSL/TLS is Message Authentication Code (MAC), appended to each message; the receiving party checks the MAC in order to determine whether the received message has been tampered with or altered during transmission.</p> <p>This is done through the server’s certificates granted during the handshake process; the client also has the option of presenting a certificate for authentication, enhancing security.</p> <h3>Session Resumption</h3> <p>For a better throughput and low latency, SSL/TLS have built in session resumption, in which the client can connect to the server using session keys of the previous connection, thereby avoiding the initial handshaking.</p> <p>The server gives a session id upon connection startup, and the client saves this number and sends it in a future connection request to continue the session.</p> <p><strong>Also Read:</strong> <a href="https://certera.com/blog/what-is-2-way-ssl-how-does-it-work-one-way-vs-two-way-ssl-authentication/">What is 2-Way SSL? How does it Work? One-Way vs Two-Way SSL Authentication</a></p> <p>However, a server option is to create a session ticket is created to contain the session keys that may be stored by the client to be used when the client reestablishes the session with the server.</p> <p>As explained below, this session resumption feature greatly minimizes the computational cost as well as time for the setting up of connections, which are secure, further improving the efficiency of SSL/TLS.</p> <p><a href="https://certera.com/blog/what-is-ssh-secure-shell-how-does-the-ssh-protocol-work/">SSH (Secure Shell)</a> is a cryptographic network protocol that seeks to enable a user to secure access to and backup services that are provided over an insecure network.</p> <p>It works based on the client-server model in which the SSH client makes a connection to the SSH server, which in turn develops a secure communication channel for encrypting and authenticating data.</p> <p>Such encryption means that any information exchanged between the client and the server cannot be intercepted or even snooped on.</p> <p>SSH employs high levels of encryption and supports diverse approaches to authentication, such as password-based and public key, making it more secure and versatile.</p> <p><strong>Also Read:</strong> <a href="https://certera.com/blog/passwordless-ssh-the-future-of-secure-remote-access-and-automation/">Passwordless SSH: The Future of Secure Remote Access and Automation</a></p> <p>SSH is an incredibly powerful tool because it’s designed to provide secure remote access to systems, which is why it’s so popular with system administrators, developers, and IT professionals.</p> <p>SSH provides the ability to run commands remotely on a machine securely, transfer files securely through SCP and SFTP protocols, and act as a secure tunnel for other protocols and services through the use of port forwarding.</p> <p><strong>Also Read:</strong> <a href="https://certera.com/blog/https-vs-sftp-know-the-difference/">HTTPS Vs. SFTP: Differentiate Between the Two</a></p> <p>Thanks to this flexibility, SSH is used in various terms, such as server administration, automated deployment, and more secure communications in the enterprise, where data and operations are in transit in an encrypted manner.</p> <h2>How does SSH Work?</h2> <h3>Establishing the Connection</h3> <p>SSH is a cryptographic network connection protocol that incorporates secure channel operations through an insecure network. It starts when a client starts someone to connect to an SSH server.</p> <p>The server then sends back its public key, and the client can then check on the authenticity of the server. This public key is then inspected by the client against a local list of known host entities.</p> <p>In case the key is acknowledged, the connection is continued, and if the key is a new one, then the connection is usually confirmed by the user.</p> <p>This verification process aids in confirming the client is conversing with the right server, thereby eliminating <a href="https://certera.com/blog/man-in-the-middle-mitm-attacks-how-to-detect-and-prevent-it/">man-in-the-middle threats</a>.</p> <h3>Key Exchange and Session Encryption</h3> <p>After the identification of the server, the client and the server agree on a secret key to be used in the client-server communication processes.</p> <p>This is often done by employing the Diffie-Hellman key exchange technique, where both parties can create a secret key from the public channel.</p> <p><strong>Also Read:</strong> <a href="https://certera.com/blog/what-is-public-key-encryption-public-vs-private-key-encryption/">What Is Public Key Encryption? Public vs. Private Key Encryption</a></p> <p>In this process, the client and server create two pairs of keys, public and private, for any communication, and transmit the public keys between them.</p> <p>With the help of these keys and their own private keys, the client and the server can establish the shared secret, which in turn is used to build the session keys for the purpose of further encryption.</p> <p>This shared secret means that only the client and the server can decrypt the data passed between them through the session, thus making it confidential and integral.</p> <h3>User Authentication</h3> <p>After the creation of the secure channel, the client must prove the legitimacy of its presence to the server. Several types of authentication can be employed by SSH, and the two main types are Password and Public Key.</p> <p>In <a href="https://certera.com/blog/navigating-the-future-of-cybersecurity-with-zero-trust-and-passwordless-authentication/">password-based authentication</a>, the client has to send a password in an encrypted format back to the server.</p> <p>In public key authentication, the client employs a private key to encrypt data to form a digital sign which is then checked by the use of the public key from the client side from the server.</p> <p>This method is considered more secure than the use of passwords because, instead of using passwords that can be easily guessed or phished, it uses cryptographic keys.</p> <p>After the registration process, the client receives a confirmation of acceptance and is allowed to connect to the server and perform other operations provided by the server settings.</p> <h3>Data Transfer and Command Execution</h3> <p>If the client and the server are successfully authenticated, they can transfer data strictly between them.</p> <p>SSH employs the use of symmetric encryption, for instance, Advanced Encryption Standard (AES), to ensure that any data that is transmitted during the session cannot be accessed by anyone other than the sender and the intended recipient.</p> <p>Further, it affords integrity and authenticity through the message authentication code (MAC), making the possibility of alteration of the data sheet easily noticeable.</p> <p>The client can now perform operations on the server, such as running commands, moving files through SCP or SFTP, and forwarding ports to protect other forms of network traffic.</p> <h3>Session Termination</h3> <p>Upon completion of the session, the client sends a termination signal to the server to bring the session to an end. The transfer is complete; the server responds to the termination and terminates the connection.</p> <p>Finally, there is the destruction of session keys and any other information that is associated with the session by both parties.</p> <p>It is important to terminate the session properly so as to allow free release of resources, besides protecting possible session information from threats.</p> <h2>SSH vs SSL Key Difference</h2> <figure> <table> <tbody morss_own_score="3.0" morss_score="14.0"> <tr> <td><strong>Aspect</strong></td> <td><strong>SSH (Secure Shell)</strong></td> <td><strong>SSL/TLS (Secure Sockets Layer/Transport Layer Security)</strong></td> </tr> <tr> <td><strong>Purpose</strong></td> <td>Secure remote login and command execution.</td> <td>Secure communication over a computer network.</td> </tr> <tr> <td><strong>Primary Use Case</strong></td> <td>Remote administration of servers and network devices.</td> <td>Securing web traffic (HTTPS), email, and other protocols.</td> </tr> <tr> <td><strong>Port Number</strong></td> <td>Typically uses port 22.</td> <td>SSL uses port 443 (HTTPS) and 25/587 (SMTP), among others.</td> </tr> <tr> <td><strong>Encryption</strong></td> <td>Uses symmetric encryption for data transfer.</td> <td>Uses both asymmetric (during handshake) and symmetric encryption.</td> </tr> <tr> <td><strong>Authentication</strong></td> <td>Uses password-based, public key-based, or both.</td> <td>Uses digital certificates issued by Certificate Authorities (CAs).</td> </tr> <tr> <td><strong>Protocol Layers</strong></td> <td>Operates at the application layer.</td> <td>Operates at the transport layer.</td> </tr> <tr> <td><strong>Key Exchange</strong></td> <td>Supports various key exchange algorithms (e.g., Diffie-Hellman, ECDH).</td> <td>Uses a handshake protocol involving asymmetric key exchange.</td> </tr> <tr> <td><strong>Data Integrity</strong></td> <td>Ensures data integrity with MACs (Message Authentication Codes).</td> <td>Ensures data integrity with MACs and digital signatures.</td> </tr> <tr> <td><strong>Connection Establishment</strong></td> <td>Establishes a secure channel after authentication.</td> <td>Establishes a secure channel through a handshake process.</td> </tr> <tr> <td><strong>Use of Certificates</strong></td> <td>Does not rely on third-party certificates.</td> <td>Relies on third-party certificates from CAs for authentication.</td> </tr> <tr> <td><strong>Session Management</strong></td> <td>Sessions managed by user or system configuration.</td> <td>Sessions can be resumed to improve performance.</td> </tr> <tr> <td><strong>Common Algorithms</strong></td> <td>Uses algorithms like RSA, DSA, ECDSA for authentication.</td> <td>Uses algorithms like RSA, ECC for certificates; AES, ChaCha20 for encryption.</td> </tr> <tr> <td><strong>Typical Applications</strong></td> <td>SSH terminals, SCP (Secure Copy Protocol), SFTP (SSH File Transfer Protocol).</td> <td>HTTPS, FTPS, SMTPS, IMAPS, and other secure protocols.</td> </tr> <tr> <td><strong>Mutual Authentication</strong></td> <td>Often supports mutual authentication.</td> <td>Typically authenticates the server; client authentication is optional.</td> </tr> <tr> <td><strong>Session Resumption</strong></td> <td>Not typically used; sessions are established as needed.</td> <td>Supports session resumption to optimize performance.</td> </tr> </tbody> </table> </figure> <h2>Similarities Between SSH and SSL/TLS</h2> <h3>Encryption</h3> <p>SSH (Secure Shell) and SSL/TLS (Secure Sockets Layer/Transport Layer Security) are two technologies that all employ the use of encryption to secure data as it passes through a network.</p> <p>They use very powerful cryptographic techniques to ensure that messages passed cannot be decoded by anyone else other than the intended recipient.</p> <p>This encryption contains passwords, personal details, and financial information from unauthorized access while improving privacy.</p> <h3>Authentication</h3> <p>SSH and SSL/TLS include features for authentication to ensure that the end user and server are authentic. SSH normally implements public key authentication, where the client and server first exchange keys to gain each other’s trust.</p> <p>Likewise, SSL/TLS involves the use of <a href="https://certera.com/">trusted digital certificates by CA</a> to mutually authenticate the server, and at times, the client during the handshaking phase.</p> <p>This authentication process eliminates cases of impersonation so that everyone is sure that one is interacting with the right and authentic party.</p> <h3>Integrity</h3> <p>Both protocols are secured and guarantee integrity of data through the use of <a href="https://certera.com/blog/what-is-a-hash-function-in-cryptography/">cryptographic hash functions</a> and Message Authentication Codes (MACs).</p> <p>These techniques ensure that data being transmitted has not undergone any change in the process of transmission.</p> <p>This means that if any of the data is modified by the attacker, the hash or MAC at the receiving end will not match in case of an integrity breach. This feature is fundamental to ensuring the quality and validity of information shared through the system.</p> <h3>Secure Channels</h3> <p>SSH and SSL/TLS are used for secure communication over the network that may contain different threats and vulnerabilities. They develop a secure channel between a client and a server that data conveyed through this channel cannot be intercepted or modified.</p> <p>This secure channel is also crucial for various applications such as, remote access secure transfers, secure file transfer, and secure web browsing.</p> <h3>Versatility</h3> <p>The two protocols are highly flexible and can be implemented in a wide range of applications.</p> <p>SSH is widely applied for remote login securely, transferring files securely using SCP or SFTP, and even remotely executing commands on other servers in a secure way.</p> <p>But SSL/TLS is widely used to protect web connections (<a href="https://certera.com/blog/http-vs-https-the-technical-difference/">HTTP over SSL to HTTPS</a>), electronic mail (SMTP through SSL), instant messaging, and other Internet-related services.</p> <p>Due to their versatility, communication protocols can be considered as the basic elements of network protection at present.</p> <h2>Conclusion</h2> <p>Certera remains your steadfast ally, providing the relevant best solutions to overcome these challenges of hacking and compliance. The <a href="https://certera.com/">full range of web security solutions</a> offered ensures your organization gains the capability in the effective and efficiently protect your digital assets.</p> </div> <p><img decoding="async" src="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20132%20132'%3E%3C/svg%3E"></p> <h2> Janki Mehta</h2> <p> Janki Mehta is a passionate Cyber-Security Enthusiast who keenly monitors the latest developments in the Web/Cyber Security industry. She puts her knowledge into practice and helps web users by arming them with the necessary security measures to stay safe in the digital world.</p> </article><h2>What is SSL/TLS?</h2><p>The first widely used protocol that was aimed to secure the Internet connections was SSL, which was created by Netscape in mid 1995.</p><p>It uses both public key and <a href="https://certera.com/blog/symmetric-vs-asymmetric-encryption-detailed-guide/">symmetric key encryption</a> to generate a connection or channel that will help protect data passing between a client, for instance, a web browser, and a server, for instance, a website.</p><p>That is why, after many successful years, SSL has been identified as containing a number of defects and is recognized as insecure to date. TLS, the next generation of SSL, was developed to rectify these security faults and improve the language’s strength.</p><p><strong>Also Read:</strong> <a href="https://certera.com/blog/ssl-tls-timeline-history-of-ssl-tls-protocol-versions/">SSL/TLS Timeline: Evolution from SSL to TLS 1.3</a></p><p>TLS was released in different versions, with the current ones being TLS 1.0, TLS 1.1, TLS 1.2, and TLS 1.3; each being more secure than the preceding one and performing better.</p><p><a href="https://certera.com/blog/tls-1-3-everything-you-need-to-know/">TLS 1. 3</a> reveals better protection and efficiency in the handshake of devices between users, providing the best security for the PC operating systems.</p><p>It not only encrypts data that is in transmission so that sensitive information cannot be intercepted by other parties, but also gives authentication, which assures that the server with which a client is communicating is authorized.</p><p>This dual role of encryption and authentication is highly beneficial in preserving the security and reliability of Internet connections.</p><p><strong>Also Read:</strong> <a href="https://certera.com/blog/what-is-ssl-tls-https/">WHAT IS SSL, TLS & HTTPS? [Explanation to Difference]</a></p><h2>How does SSL/TLS Work?</h2><h3>Establishing a Secure Connection (Handshake Process)</h3><p>The basic idea of the <a href="https://certera.com/blog/ssl-tls-handshake-a-crucial-step-towards-secure-connections/">SSL/TLS handshake</a> is the key exchange between client and server, where they can have secure communication.</p><p>It starts with the client sending the message ‘Client Hello’ to the server over the network, containing SSL/TLS version, list of all <a href="https://certera.com/blog/what-is-ssl-cipher-suite-and-how-it-works/">supported cipher suites</a> i.e., the cryptographic algorithms for encryption of data, and random numbers.</p><p>The server replies with a ‘Server Hello’ which contains the SSL/TLS version that the server is using, the <a href="https://certera.com/blog/what-is-a-cipher-types-of-ciphers-in-cryptography/">identified cipher</a>, and another random number SAS. The server then conveys its digital certificate, that is, its public key, which is authenticated by a CA, to the client.</p><p>If the selected cipher suite needs more parameters, then the server sends to the client a Server Key Exchange message. The client, in turn, computes the pre-master secret and encrypts it using the server’s public key, then sends it back to the server.</p><p><strong>Also Read:</strong> <a href="https://certera.com/blog/common-ssl-tls-challenges-issues-attacks-to-exploits/">Common SSL/TLS Attacks: What SSL Prevents?</a></p><p>This pre-master secret, together with the exchanged random numbers are used by both the client and the server to derive the symmetric session keys.</p><p>Both the client and the server end the handshake with ‘Finished’ messages that are encrypted and signify that both sides have mutually developed a secure connection.</p><h3>Securing Data Transmission</h3><p>This means that after the SSL/TLS connection handshake has been made and a secure connection has been attained, any content that is exchanged between the client and server goes through the session keys that were made during the handshake process.</p><p>This assurance brings confidentiality, integrity, and authenticity of the data. Data that is exchanged between the client is encrypted with the session key before the exchange and transmission.</p><p><strong>Also Read:</strong> <a href="https://certera.com/blog/how-to-fix-ssl-handshake-failed-error/">How to Fix the SSL Handshake Failed & Cloudflare 525 Error?</a></p><p>The same key is used by the server to decrypt or encode the data that is received from or sent to the client and vice versa. The data is encrypted before it is sent to prevent any third party from intercepting the data and understanding it.</p><p>Moreover, another security technique applied by SSL/TLS is Message Authentication Code (MAC), appended to each message; the receiving party checks the MAC in order to determine whether the received message has been tampered with or altered during transmission.</p><p>This is done through the server’s certificates granted during the handshake process; the client also has the option of presenting a certificate for authentication, enhancing security.</p><h3>Session Resumption</h3><p>For a better throughput and low latency, SSL/TLS have built in session resumption, in which the client can connect to the server using session keys of the previous connection, thereby avoiding the initial handshaking.</p><p>The server gives a session id upon connection startup, and the client saves this number and sends it in a future connection request to continue the session.</p><p><strong>Also Read:</strong> <a href="https://certera.com/blog/what-is-2-way-ssl-how-does-it-work-one-way-vs-two-way-ssl-authentication/">What is 2-Way SSL? How does it Work? One-Way vs Two-Way SSL Authentication</a></p><p>However, a server option is to create a session ticket is created to contain the session keys that may be stored by the client to be used when the client reestablishes the session with the server.</p><p>As explained below, this session resumption feature greatly minimizes the computational cost as well as time for the setting up of connections, which are secure, further improving the efficiency of SSL/TLS.</p><p><a href="https://certera.com/blog/what-is-ssh-secure-shell-how-does-the-ssh-protocol-work/">SSH (Secure Shell)</a> is a cryptographic network protocol that seeks to enable a user to secure access to and backup services that are provided over an insecure network.</p><p>It works based on the client-server model in which the SSH client makes a connection to the SSH server, which in turn develops a secure communication channel for encrypting and authenticating data.</p><p>Such encryption means that any information exchanged between the client and the server cannot be intercepted or even snooped on.</p><p>SSH employs high levels of encryption and supports diverse approaches to authentication, such as password-based and public key, making it more secure and versatile.</p><p><strong>Also Read:</strong> <a href="https://certera.com/blog/passwordless-ssh-the-future-of-secure-remote-access-and-automation/">Passwordless SSH: The Future of Secure Remote Access and Automation</a></p><p>SSH is an incredibly powerful tool because it’s designed to provide secure remote access to systems, which is why it’s so popular with system administrators, developers, and IT professionals.</p><p>SSH provides the ability to run commands remotely on a machine securely, transfer files securely through SCP and SFTP protocols, and act as a secure tunnel for other protocols and services through the use of port forwarding.</p><p><strong>Also Read:</strong> <a href="https://certera.com/blog/https-vs-sftp-know-the-difference/">HTTPS Vs. SFTP: Differentiate Between the Two</a></p><p>Thanks to this flexibility, SSH is used in various terms, such as server administration, automated deployment, and more secure communications in the enterprise, where data and operations are in transit in an encrypted manner.</p><h2>How does SSH Work?</h2><h3>Establishing the Connection</h3><p>SSH is a cryptographic network connection protocol that incorporates secure channel operations through an insecure network. It starts when a client starts someone to connect to an SSH server.</p><p>The server then sends back its public key, and the client can then check on the authenticity of the server. This public key is then inspected by the client against a local list of known host entities.</p><p>In case the key is acknowledged, the connection is continued, and if the key is a new one, then the connection is usually confirmed by the user.</p><p>This verification process aids in confirming the client is conversing with the right server, thereby eliminating <a href="https://certera.com/blog/man-in-the-middle-mitm-attacks-how-to-detect-and-prevent-it/">man-in-the-middle threats</a>.</p><h3>Key Exchange and Session Encryption</h3><p>After the identification of the server, the client and the server agree on a secret key to be used in the client-server communication processes.</p><p>This is often done by employing the Diffie-Hellman key exchange technique, where both parties can create a secret key from the public channel.</p><p><strong>Also Read:</strong> <a href="https://certera.com/blog/what-is-public-key-encryption-public-vs-private-key-encryption/">What Is Public Key Encryption? Public vs. Private Key Encryption</a></p><p>In this process, the client and server create two pairs of keys, public and private, for any communication, and transmit the public keys between them.</p><p>With the help of these keys and their own private keys, the client and the server can establish the shared secret, which in turn is used to build the session keys for the purpose of further encryption.</p><p>This shared secret means that only the client and the server can decrypt the data passed between them through the session, thus making it confidential and integral.</p><h3>User Authentication</h3><p>After the creation of the secure channel, the client must prove the legitimacy of its presence to the server. Several types of authentication can be employed by SSH, and the two main types are Password and Public Key.</p><p>In <a href="https://certera.com/blog/navigating-the-future-of-cybersecurity-with-zero-trust-and-passwordless-authentication/">password-based authentication</a>, the client has to send a password in an encrypted format back to the server.</p><p>In public key authentication, the client employs a private key to encrypt data to form a digital sign which is then checked by the use of the public key from the client side from the server.</p><p>This method is considered more secure than the use of passwords because, instead of using passwords that can be easily guessed or phished, it uses cryptographic keys.</p><p>After the registration process, the client receives a confirmation of acceptance and is allowed to connect to the server and perform other operations provided by the server settings.</p><h3>Data Transfer and Command Execution</h3><p>If the client and the server are successfully authenticated, they can transfer data strictly between them.</p><p>SSH employs the use of symmetric encryption, for instance, Advanced Encryption Standard (AES), to ensure that any data that is transmitted during the session cannot be accessed by anyone other than the sender and the intended recipient.</p><p>Further, it affords integrity and authenticity through the message authentication code (MAC), making the possibility of alteration of the data sheet easily noticeable.</p><p>The client can now perform operations on the server, such as running commands, moving files through SCP or SFTP, and forwarding ports to protect other forms of network traffic.</p><h3>Session Termination</h3><p>Upon completion of the session, the client sends a termination signal to the server to bring the session to an end. The transfer is complete; the server responds to the termination and terminates the connection.</p><p>Finally, there is the destruction of session keys and any other information that is associated with the session by both parties.</p><p>It is important to terminate the session properly so as to allow free release of resources, besides protecting possible session information from threats.</p><h2>SSH vs SSL Key Difference</h2><figure> <table> <tbody morss_own_score="3.0" morss_score="14.0"> <tr> <td><strong>Aspect</strong></td> <td><strong>SSH (Secure Shell)</strong></td> <td><strong>SSL/TLS (Secure Sockets Layer/Transport Layer Security)</strong></td> </tr> <tr> <td><strong>Purpose</strong></td> <td>Secure remote login and command execution.</td> <td>Secure communication over a computer network.</td> </tr> <tr> <td><strong>Primary Use Case</strong></td> <td>Remote administration of servers and network devices.</td> <td>Securing web traffic (HTTPS), email, and other protocols.</td> </tr> <tr> <td><strong>Port Number</strong></td> <td>Typically uses port 22.</td> <td>SSL uses port 443 (HTTPS) and 25/587 (SMTP), among others.</td> </tr> <tr> <td><strong>Encryption</strong></td> <td>Uses symmetric encryption for data transfer.</td> <td>Uses both asymmetric (during handshake) and symmetric encryption.</td> </tr> <tr> <td><strong>Authentication</strong></td> <td>Uses password-based, public key-based, or both.</td> <td>Uses digital certificates issued by Certificate Authorities (CAs).</td> </tr> <tr> <td><strong>Protocol Layers</strong></td> <td>Operates at the application layer.</td> <td>Operates at the transport layer.</td> </tr> <tr> <td><strong>Key Exchange</strong></td> <td>Supports various key exchange algorithms (e.g., Diffie-Hellman, ECDH).</td> <td>Uses a handshake protocol involving asymmetric key exchange.</td> </tr> <tr> <td><strong>Data Integrity</strong></td> <td>Ensures data integrity with MACs (Message Authentication Codes).</td> <td>Ensures data integrity with MACs and digital signatures.</td> </tr> <tr> <td><strong>Connection Establishment</strong></td> <td>Establishes a secure channel after authentication.</td> <td>Establishes a secure channel through a handshake process.</td> </tr> <tr> <td><strong>Use of Certificates</strong></td> <td>Does not rely on third-party certificates.</td> <td>Relies on third-party certificates from CAs for authentication.</td> </tr> <tr> <td><strong>Session Management</strong></td> <td>Sessions managed by user or system configuration.</td> <td>Sessions can be resumed to improve performance.</td> </tr> <tr> <td><strong>Common Algorithms</strong></td> <td>Uses algorithms like RSA, DSA, ECDSA for authentication.</td> <td>Uses algorithms like RSA, ECC for certificates; AES, ChaCha20 for encryption.</td> </tr> <tr> <td><strong>Typical Applications</strong></td> <td>SSH terminals, SCP (Secure Copy Protocol), SFTP (SSH File Transfer Protocol).</td> <td>HTTPS, FTPS, SMTPS, IMAPS, and other secure protocols.</td> </tr> <tr> <td><strong>Mutual Authentication</strong></td> <td>Often supports mutual authentication.</td> <td>Typically authenticates the server; client authentication is optional.</td> </tr> <tr> <td><strong>Session Resumption</strong></td> <td>Not typically used; sessions are established as needed.</td> <td>Supports session resumption to optimize performance.</td> </tr> </tbody> </table> </figure><h2>Similarities Between SSH and SSL/TLS</h2><h3>Encryption</h3><p>SSH (Secure Shell) and SSL/TLS (Secure Sockets Layer/Transport Layer Security) are two technologies that all employ the use of encryption to secure data as it passes through a network.</p><p>They use very powerful cryptographic techniques to ensure that messages passed cannot be decoded by anyone else other than the intended recipient.</p><p>This encryption contains passwords, personal details, and financial information from unauthorized access while improving privacy.</p><h3>Authentication</h3><p>SSH and SSL/TLS include features for authentication to ensure that the end user and server are authentic. SSH normally implements public key authentication, where the client and server first exchange keys to gain each other’s trust.</p><p>Likewise, SSL/TLS involves the use of <a href="https://certera.com/">trusted digital certificates by CA</a> to mutually authenticate the server, and at times, the client during the handshaking phase.</p><p>This authentication process eliminates cases of impersonation so that everyone is sure that one is interacting with the right and authentic party.</p><h3>Integrity</h3><p>Both protocols are secured and guarantee integrity of data through the use of <a href="https://certera.com/blog/what-is-a-hash-function-in-cryptography/">cryptographic hash functions</a> and Message Authentication Codes (MACs).</p><p>These techniques ensure that data being transmitted has not undergone any change in the process of transmission.</p><p>This means that if any of the data is modified by the attacker, the hash or MAC at the receiving end will not match in case of an integrity breach. This feature is fundamental to ensuring the quality and validity of information shared through the system.</p><h3>Secure Channels</h3><p>SSH and SSL/TLS are used for secure communication over the network that may contain different threats and vulnerabilities. They develop a secure channel between a client and a server that data conveyed through this channel cannot be intercepted or modified.</p><p>This secure channel is also crucial for various applications such as, remote access secure transfers, secure file transfer, and secure web browsing.</p><h3>Versatility</h3><p>The two protocols are highly flexible and can be implemented in a wide range of applications.</p><p>SSH is widely applied for remote login securely, transferring files securely using SCP or SFTP, and even remotely executing commands on other servers in a secure way.</p><p>But SSL/TLS is widely used to protect web connections (<a href="https://certera.com/blog/http-vs-https-the-technical-difference/">HTTP over SSL to HTTPS</a>), electronic mail (SMTP through SSL), instant messaging, and other Internet-related services.</p><p>Due to their versatility, communication protocols can be considered as the basic elements of network protection at present.</p><h2>Conclusion</h2><p>Certera remains your steadfast ally, providing the relevant best solutions to overcome these challenges of hacking and compliance. The <a href="https://certera.com/">full range of web security solutions</a> offered ensures your organization gains the capability in the effective and efficiently protect your digital assets.</p><div class="spu-placeholder" style="display:none"></div><div class="addtoany_share_save_container addtoany_content addtoany_content_bottom"><div class="a2a_kit a2a_kit_size_20 addtoany_list" data-a2a-url="https://securityboulevard.com/2025/12/ssh-vs-ssl-tls-definitions-differences-of-communication-protocols/" data-a2a-title="SSH vs SSL/TLS: Definitions & Differences of Communication Protocols"><a class="a2a_button_twitter" href="https://www.addtoany.com/add_to/twitter?linkurl=https%3A%2F%2Fsecurityboulevard.com%2F2025%2F12%2Fssh-vs-ssl-tls-definitions-differences-of-communication-protocols%2F&linkname=SSH%20vs%20SSL%2FTLS%3A%20Definitions%20%26%20Differences%20of%20Communication%20Protocols" title="Twitter" rel="nofollow noopener" target="_blank"></a><a class="a2a_button_linkedin" href="https://www.addtoany.com/add_to/linkedin?linkurl=https%3A%2F%2Fsecurityboulevard.com%2F2025%2F12%2Fssh-vs-ssl-tls-definitions-differences-of-communication-protocols%2F&linkname=SSH%20vs%20SSL%2FTLS%3A%20Definitions%20%26%20Differences%20of%20Communication%20Protocols" title="LinkedIn" rel="nofollow noopener" target="_blank"></a><a class="a2a_button_facebook" href="https://www.addtoany.com/add_to/facebook?linkurl=https%3A%2F%2Fsecurityboulevard.com%2F2025%2F12%2Fssh-vs-ssl-tls-definitions-differences-of-communication-protocols%2F&linkname=SSH%20vs%20SSL%2FTLS%3A%20Definitions%20%26%20Differences%20of%20Communication%20Protocols" title="Facebook" rel="nofollow noopener" target="_blank"></a><a class="a2a_button_reddit" href="https://www.addtoany.com/add_to/reddit?linkurl=https%3A%2F%2Fsecurityboulevard.com%2F2025%2F12%2Fssh-vs-ssl-tls-definitions-differences-of-communication-protocols%2F&linkname=SSH%20vs%20SSL%2FTLS%3A%20Definitions%20%26%20Differences%20of%20Communication%20Protocols" title="Reddit" rel="nofollow noopener" target="_blank"></a><a class="a2a_button_email" href="https://www.addtoany.com/add_to/email?linkurl=https%3A%2F%2Fsecurityboulevard.com%2F2025%2F12%2Fssh-vs-ssl-tls-definitions-differences-of-communication-protocols%2F&linkname=SSH%20vs%20SSL%2FTLS%3A%20Definitions%20%26%20Differences%20of%20Communication%20Protocols" title="Email" rel="nofollow noopener" target="_blank"></a><a class="a2a_dd addtoany_share_save addtoany_share" href="https://www.addtoany.com/share"></a></div></div><p class="syndicated-attribution">*** This is a Security Bloggers Network syndicated blog from <a href="https://certera.com/blog/">EncryptedFence by Certera – Web &amp; Cyber Security Blog</a> authored by <a href="https://securityboulevard.com/author/0/" title="Read other posts by Janki Mehta">Janki Mehta</a>. Read the original post at: <a href="https://certera.com/blog/ssh-vs-ssl-tls-definitions-differences-of-communication-protocols/">https://certera.com/blog/ssh-vs-ssl-tls-definitions-differences-of-communication-protocols/</a> </p>