This standard sets out the encryption algorithms, formats, composition and other features that programs must use to be OpenPGP-compliant. PGP encryption is used in a number of proprietary programs, such as the Symantec products mentioned above. The most prominent of these is Gpg4win , which is a free suite of encryption tools for Windows. PGP encryption relies on several major elements that you will need to get your head around in order to understand how it works.
The most important ones are symmetric-key cryptography, public-key cryptography , digital signatures and the web of trust. Symmetric-key cryptography involves using the same key to both encrypt and decrypt data. In PGP, a random, one-off key is generated, which is known as the session key. The session key encrypts the message , which is the bulk of the data that needs to be sent.
This type of encryption is relatively efficient, but it has a problem. How do you share the session key with your recipient? If you send it alongside your email, then anyone who intercepts the message can access the contents just as easily as your recipient. Without the key, your recipient will only see the ciphertext. PGP solves this problem with public-key cryptography , also known as asymmetric cryptography.
In this kind of encryption there are two keys: a public key and a private one. Each user has one of each. The public key of your potential correspondent can be found by searching through key servers or by asking the person directly. Public keys are used by the sender to encrypt data, but they cannot decrypt it. This is why public keys are freely handed out, but private keys need to be guarded carefully. If your private key is compromised by an attacker, it enables them to access all of your PGP encrypted emails.
Because public-key encryption is simply too inefficient. It would take too long and use a larger amount of computational resources. Since the body of the message usually contains the bulk of the data, PGP uses the more economical symmetric-key encryption for this. It reserves the lumbering public-key encryption for the session key, making the whole process more efficient. In this way, the message gets encrypted through more practical means, while public-key encryption is used to securely deliver the session key to your recipient.
Since only their private key can decrypt the session key, and the session key is needed to decrypt the message, the contents are secure from attackers. Our written signatures are frequently used to verify that we are who we say we are. They are far from foolproof, but they are still a useful way of preventing fraud. Digital signatures are similar, using public-key cryptography to authenticate that the data comes from the source it claims to and that it has not been tampered with. The process makes digital signatures essentially impossible to forge unless the private key has been compromised.
It all depends on what you are sending and why. If the message must be delivered intact and without alteration, then a digital signature will need to be used. If both are important, you should use them together. The plaintext of your message is fed through a hash function , which is an algorithm that transforms inputs into a fixed-size block of data, called a message digest. This encrypted message digest is what is known as the digital signature. In PGP encryption, the digital signature is sent alongside the message body which can either be encrypted or in plaintext.
When someone receives a digitally signed email, they can check its authenticity and integrity by using the public key of the sender. First, a hash function is used on the message that was received. This gives the message digest of the email in its current form. The next step is to calculate the original message digest from the digital signature that was sent. This gives the message digest exactly as it was when it was signed by the sender. If the message had been altered by even one character or punctuation mark, then the message digests will be completely different.
It may be an innocent mistake because the wrong public key has accidentally been used, but it could also be a fraudulent message or one that has been tampered with. How do you know that a public key actually belongs to the person who says it does? Thankfully, this was all thought of ahead of time and solutions were put in place. Otherwise, something so simple would completely undermine the whole system. To prevent this kind of activity, the web of trust was developed. The web of trust grew as a way of vetting that each PGP public key and user ID are really connected to the person or organization that they are said to represent.
The best part? It does it all without a central authority that can collapse or be corrupted. If you know a PGP user personally, you can confirm that their public key is linked to their actual identity. You can put your trust in them and digitally sign their certificate, which shows that at least one person vouches for their identity.
They can also do the same for you. If both of you meet one new PGP user each and digitally sign their certificates to verify their identities, you start to build a small network, where the four of you can trust the links between the public keys and identities, based on the trust each person has in others that they are linked to. Over time, this builds an interconnected web of trust , with lots of people vouching for each other with digital signatures that verify their ownership of a public key.
Sometimes it can be difficult for new users to find someone to sign their certificates and verify the relationship between themselves and their public key. This has been partially solved by key-signing parties , which are real-life meetups where users can assess whether keys belong to the person saying it does. There are different levels of trust, including full and partial.
Those that have many digital signatures on their certificates that represent full trust are seen as much more dependable than those with only a couple of partial-trust signatures. The web of trust allows users to assess for themselves whether they trust the digital certificate of a potential correspondent. If the message they want to send is extremely sensitive, they might decide that the risk is too great to send it to someone who only has partial trust. This is a common certificate standard that is also used for other purposes. The main difference between PGP certificates and X.
PGP certificates can be signed by certificate authorities as well, but X. In contrast to PGP certificates, which a user can make themselves, X. These certificates also only have a single digital signature from the issuer, as opposed to the many signatures that a PGP certificate can have from other users. PGP can also be used to encrypt your attachments.
There are a couple of ways to do this, but it will depend on your implementation. This prevents the leaking of metadata that occurs if each segment is encrypted separately. You want to get the message out to journalists, but you are terrified for your own safety.
What if the government finds out that you were the one who leaked the information and they send people after you? You eventually decide that releasing the information to the public is the right thing to do, but you want to do it in a way that protects you as much as possible. You search online and find a journalist who is renowned for this kind of work and always protects their sources.
You find it on their website or by searching a key-server. You type out the message:. Eric Young's crypto page and. SSL performance. TLS ssl, the next generation, transport layer security. FGInt rsa, elgamal, dsa, source. Crypto Systems Toolkit. CryptoLib info from Bell Labs. Microsoft's CryptoAPI. Rivest's RC6. Eric Young's libdes.
Certicoms excellent tutorial. RSA's elliptic curves cryptosystems and what are elliptic curves. ECC tutorial. Certicom ECC standards and X9. Rosing's book Implementing Elliptic Curve Cryptography sources. INRIA's break of 97 bit ecc. RFC random numbers. Ritter's randomness links and randomness tests. Wagner's page or netscape randomness. PGP 5. RSA paper Hardware based random number generation. FIPS has some rng tests too. Carmichael numbers.
STEL source. Secure Shell ssh and a FAQ and ssh Ylonen's ssh paper. Sun's secure RPC. RASP secure media. Secure Networks Ballista security scanner. Schumann Security Software single sign-on, role based access rbac. HP's ICF international cryptography framework. Bellcore's VRA exportable file encryption. CORBA security and spec. Microsoft's Proxy Server. Nmap scanner or here.
1.0 Things you should know about Thunderbird before you start
SecureOffice 3DES for office. YaHoo's firewall systems and firewall faq. The Firewall Report and a firewall products and review. DataComm's firewall performance and CMP's review of 6 firewalls and another comparison. CSI's firewall product analysis. Ranum's Thinking about Firewalls and a firewall tutorial. Ugate's firewall nat box or sonicwall or gnat box or SOHO or macsense xrouter. NIST site security and more firewall info and more info. SURF firewall paper and source. NEC's paper on firewalls and virtual private networks. Jain's vpn links papers, books.
Internet Week's vpn page. Network Computing's VPN review. Gong's enclave paper. PPTP specs. PPTP for linux and archives. Microsoft's Windows VPN. PPTP vulnerabilities and update and evaluation. NetFortress and DEC's altavista tunnel and network-alchemy. Datamation's VPN article. Bellcore smartcard and Litronics. IBM's cryptocards. Skipjack review. NIST's clipper chip info. Gutmann's X style guide. Sesame and Germany's SecuDE or here. Trusted Third Parties in Electronic Commerce. CIAC and bulletins. ESnet key dn. DoD's disa Multilevel Security program.
UK's itsec certification e0-e6. NIST's latest common criteria product certifcation. Multics page and info on timing channels. NACIC national counter intelligence. Network Encryption history and patents. GSA public key project. AES proposals and performance and source code and round1 comments. European's AES follow on nessie. Manhattan Cyber project. Timestep's IPsec whitepaper. NRL implementation of IPv6 security or here. DNS security and Internet draft. SNMP v3 security and Stalling's article and keychange. Clipper key escrow, and Fortezza Denning.
US crypto policy. The Risks of Key Recovery. Cylink's CyKey pdf key recovery. European govt's and key escrow. Sobirey's list of IDS systems. ICSA's ids buyer's guide.
How to encrypt email (Gmail, Outlook iOS, OSX, Android, Webmail)
NIDS faq. Data Comm's ids comparison slides and infoworld's review. UNM security group. Coast projects and their autonomous agents and their ids page. Deception Toolkit honeypot or honeypot or honeypot or touches. Defending a Computer System using Autonomous Agents. Forrest's computer immune systems for IDS. Ptacek's eluding network intrusion detection and vulnerabilities of IDS's. LBL's Paxson's bro and paper. CMU's ids info and statistical-based ids. TIS's stalker. ProWatch Secure or abirnet's sessionwall. En Garde's T-sight manual intrusion detection. Axent's Intruder Alert or MimeStar.
IDS tester replay tcpdump's. DARPA intrusion detection evaluation. CERT's intrusion detection check list and recovering from a root compromise. CERT incident stats and a paper. Mitre's cve common vulnerabilities. Yahoo's hacker news and SANS newsbites and securityfocus news.
NSA's cyber-attack and moonlight maze. CNN's cyber terror or here or here. DARPA's information survivability. Wired's cyberwar feb '98 issue. Open Computing cover story s and a Security Timeline and a survey. The Internet Threat. I-way security. ISS's vulnerability database. IP spoofing. IIS rds exploit. Ranum's Taxonomy of Network Attacks slides also here. Cisco's tracking packet floods using cisco routers. CERT's denial of service workshop pdf.
How to encrypt email (Gmail, Outlook iOS, OSX, Android, Webmail)
ICSA's info on ddos. Cisco info on distributed denial of service attacks. Stoll's Stalking the Wily Hacker. L0pht computer underground. US News hacker article June Wietse's guide-to-cracking and cracking software. Muffets crack Unix password cracker. NT password cracker l0phtcrack and re-setting NT passwords. AccessData cryptography and password recovery and more password recovery.
UC berkeley sniffer detection paper and a sniffer detect faq. En Garde's IP-watcher. Internet security diary. Muffet's WANhack doc and slides. X security and Unix security software rootkit,xkey.
- Pen Testing in AWS!
- Metalepsis in Popular Culture (Narratologia);
- What is PGP encryption and how does it work? | Comparitech.
- Der Brigant (German Edition)?
- The Extreme Life of the Sea.
- CS549: Cryptography and Network Security;
SyMark Unix security packages. MIME dangers. A Portrait of J. Random Hacker. Hacker'z Blood and underground archive and hacker's tools. Yahoo's hacker page. First Virtual's keyboard sniffer attack. TrendMicro's antivirus. CIAC's virus database. UNIX viruses and Bliss and scanner. Timing attack or Kocher's page and RSA's response. Bellcore's stress attacks on tamper proof devices and DES. Intel's HDCP high bandwidth data copy protection. PKZIP attack. RC brute force. Differential Cryptanalysis of Madryga. Kocher's differential power analysis smart cards.
Shor's Algorithms for Quantum Computation discrete logs and factoring. RC4 weak keys. Architectural considerations for cryptanalytic hardware. PBS's decoding nazi secrets. Netscape's security overview and data security. Mosaic's user authentication tutorial.