回目录 《公钥基础设施Public key infrastructure》
- Ensuring the contents of the document are encrypted such that the document is kept confidential.
- Ensuring the document is not altered during transmission.
- Since Alice does not know Bob, he has to somehow prove that the document is indeed sent by him.
- Ensuring Alice receives the document and that she cannot deny receiving it in future. PKI supports all the above four requirements with methods such as secure messaging, message digests, digital signatures, and non-repudiation services.
provides some degree of certainty that a given message has come from a legitimate source. Digital signature with private key
merely shows evidence that a message may have been altered. Over Distance: when communicate, hash function Over time: merkle tree Centralize integrity Decentralize integrity
is a concept, or a way, to ensure that the sender or receiver of a message cannot deny either sending or receiving such a message in future. One of the important audit checks for non-repudiation is a time stamp. The time stamp is an audit trail that provides information of the time the message is sent by the sender and the time the message is received by the receiver.
# 1.1 Secure messaging
To ensure that the document is protected from eavesdropping and not altered during the transmission, Bob will first encrypt the document using Alice’s public key. This ensures two things: one, that the document is encrypted, and two, only Alice can open it as the document requires the private key of Alice to open it. To summarize, encryption is accomplished using the public key of the receiver and the receiver decrypts with his or her private key. In this method, Bob could ensure that the document is encrypted and only the intended receiver (Alice) can open it. However, Bob cannot ensure whether the contents are altered (Integrity) during transmission by document encryption alone.
# 1.2 Message digest
In order to ensure that the document is not altered during transmission, Bob performs a hash function on the document. The hash value is a computational value based on the contents of the document. This hash value is known as the message digest. By performing the same hash function on the decrypted document the message, the digest can be obtained by Alice and she can compare it with the one sent by Bob to ensure that the contents are not altered. This process will ensure the integrity requirement.
# 1.3 Digital signature
https://en.wikipedia.org/wiki/Digital_signature In order to prove that the document is sent by Bob to Alice, Bob needs to use a digital signature. Using a digital signature means applying the sender’s private key to the message, or document, or to the message digest. This process is known as as signing. Only by using the sender’s public key can the message be decrypted.
Bob will encrypt the message digest with his private key to create a digital signature. In the scenario illustrated in the image above, Bob will encrypt the document using Alice’s public key and sign it using his digital signature. This ensures that Alice can verify that the document is sent by Bob, by verifying the digital signature (Bob’s private key) using Bob’s public key. Remember a private key and the corresponding public key are linked, albeit mathematically. Alice can also verify that the document is not altered by validating the message digest, and also can open the encrypted document using her private key. Message authentication is an authenticity verification procedure that facilitates the verification of the integrity of the message as well as the authenticity of the source from which the message is received.
# 1.4 Digital certificate
By digitally signing the document, Bob has assured that the document is sent by him to Alice. However, he has not yet proved that he is Bob. To prove this, Bob needs to use a digital certificate. A digital certificate is an electronic identity issued to a person, system, or an organization by a competent authority after verifying the credentials of the entity. A digital certificate is a public key that is unique for each entity. A certification authority issues digital certificates. In PKI, digital certificates are used for authenticity verification of an entity. An entity can be an individual, system, or an organization. An organization that is involved in issuing, distributing, and revoking digital certificates is known as a Certification Authority (CA). A CA acts as a notary by verifying an entity’s identity. One of the important PKI standards pertaining to digital certificates is X.509. It is a standard published by the International Telecommunication Union (ITU) that specifies the standard format for digital certificates. PKI also provides key exchange functionality that facilitates the secure exchange of public keys such that the authenticity of the parties can be verified.
# 2.1 Certificate authority or Self-signed with X.509
PGP VS X.509 http://world.std.com/~cme/html/web.html
# 2.2 WOT
# 2.3 PGP
How PGP works ? and how to make it Pretty Great Privacy OpenPGP Message Format: https://tools.ietf.org/html/rfc4880
How PGP works https://users.ece.cmu.edu/~adrian/630-f04/PGP-intro.html Explanation of the web of trust of PGP https://www.rubin.ch/pgp/weboftrust.en.html
Both when encrypting messages and when verifying signatures, it is critical that the public key used to send messages to someone or some entity actually does 'belong' to the intended recipient. Simply downloading a public key from somewhere is not a reliable assurance of that association; deliberate (or accidental) impersonation is possible. From its first version, PGP has always included provisions for distributing user's public keys in an 'identity certification ', which is also constructed cryptographically so that any tampering (or accidental garble) is readily detectable. However, merely making a certificate which is impossible to modify without being detected is insufficient; this can prevent corruption only after the certificate has been created, not before. Users must also ensure by some means that the public key in a certificate actually does belong to the person or entity claiming it. From its first release, PGP products have included an internal certificate 'vetting scheme' to assist with this, a trust model which has been called a web of trust. A given public key (or more specifically, information binding a user name to a key) may be digitally signed by a third party user to attest to the association between someone (actually a user name) and the key. There are several levels of confidence which can be included in such signatures. Although many programs read and write this information, few (if any) include this level of certification when calculating whether to trust a key.
From Pretty Good To Great Enhancing PGP using Bitcoin and the Blockchain https://arxiv.org/abs/1508.04868 Bitcoin pgp?? https://bitcointalk.org/index.php?topic=186264.msg1929410#msg1929410 https://www.quora.com/What-are-the-main-benefits-of-using-blockchain-techs-Vs-PGP
# 2.4 Blockchain-based PKI
# 3.1 SSL/TLS
SSL is deprecated predecessor of TLS, latest version is TLS1.3 https://en.wikipedia.org/wiki/Transport_Layer_Security#Protocol_details Encryption is through the following Algorithm and Protocol Identification is guaranteed by CA
# 3.1.1 Public key cryptography
Public key cryptography (negotiating exchange symmetric master secret key) Rsa dsa ecdsa ecc Symmetric (Exchange message) Des … Hash function (Integrity) Md5 hmac
# 3.1.2 Certifications - X.509 cert - always related to CA party
a standard defining the format of public key certificates https://en.wikipedia.org/wiki/X.509
# 3.1.3 Algorithm for TLS whole flow
Step 1:Key exchange or key agreement algorithm Purpose: to negotiate and generate master secret key https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5551094/ 1. RSA 2. Diffie hellman Perfect Forward Secrecy https://www.youtube.com/watch?v=IkM3R-KDu44 3. ECC Step 2-Part 1: Cipher to exchange message with master secret key Step 2-Part 2: Data integrity
# 3.1.4 Protocol - Handshake
Tcp handshake => TLS/SSL Handshake A walk-through of a TCP handshake http://commandlinefanatic.com/cgi-bin/showarticle.cgi?article=art058 The TLS Handshake at a High Level http://commandlinefanatic.com/cgi-bin/showarticle.cgi?article=art057 A walk-through of an SSL handshake http://commandlinefanatic.com/cgi-bin/showarticle.cgi?article=art059 SSL Certificate Exchange https://commandlinefanatic.com/cgi-bin/showarticle.cgi?article=art061
# 3.2 Manager tools
# 3.2.1 Truststore
(as name suggest) is used to store certificates from trusted Certificate authorities(CA) which are used to verify certificate presented by Server in SSL Connection
# 3.2.2 Keystore
while keyStore is used to store private key and own identity certificate which program should present to other parties (Server or client) to verify its identity
https://en.wikipedia.org/wiki/Keystore Import a private key into a Java Key Store http://commandlinefanatic.com/cgi-bin/showarticle.cgi?article=art049 Import an encrypted private key into a Java KeyStore https://commandlinefanatic.com/cgi-bin/showarticle.cgi?article=art050 A Utility for Viewing Java Keystore Contents http://commandlinefanatic.com/cgi-bin/showarticle.cgi?article=art045
KEYSTORE vs private key vs certificate
Difference between trustStore vs keyStore in Java SSLRead more: http://www.java67.com/2012/12/difference-between-truststore-vs.html#ixzz5UBSznugK www.java67.com/2012/12/difference-between-truststore-vs.html
Manage keys, certificates and keystores https://www.ibm.com/support/knowledgecenter/en/SSCQGF_7.1.0/com.ibm.IBMDI.doc_7.1/adminguide36.htm
# 4. Use case
Encryption and decryption, digital signature, and key exchange are the three primary functions of a PKI.
# 4.1 Authenticate / Digital Signature
https://en.wikipedia.org/wiki/Digital_signature schnorr signature
Example: Securely install software with gnupg https://www.linuxbabe.com/security/verify-pgp-signature-software-downloads-linux https://medium.com/@lukedashjr/how-to-securely-install-bitcoin-9bfeca7d3b2a
JSON Web Token (JWT) Signing https://auth0.com/blog/json-web-token-signing-algorithms-overview/ https://stackoverflow.com/questions/38588319/understanding-rsa-signing-for-jwt
# 4.2 Https /SSL/ TLS
SSL Certificate Installation Instructions&Tutorials https://www.digicert.com/ssl-certificate-installation.htm How about move from installed server to a new server? SSL Certificate Export/Import Explained https://www.digicert.com/import-export-ssl-certificate.htm
With .NET IIS Using Microsoft IIS to generate CSR and Private Key(export from mmc,later when complete importing certificate, it also managed by mmc) https://docs.druva.com/Knowledge_Base/inSync/How_To/Using_Microsoft_IIS_to_generate_CSR_and_Private_Key Use pfx file when you export the cert&privatekey to another server https://www.digicert.com/ssl-support/pfx-import-export-iis-7.htm
With Java Keytool https client and https server Usually for web application, we generate private key stored in keystore, import to web server host, and get it signed by CA, get a cert file stored in truststore which contains public key and ca’s signature Use Keytool https://www.javacodegeeks.com/2013/06/java-security-tutorial-step-by-step-guide-to-create-ssl-connection-and-certificates.html Use Pure Java code(keytool shipped with jdk) Generate keystore and truststore https://www.pixelstech.net/article/1409966488-Different-types-of-keystore-in-Java----JKS Https client and https server demo https://www.pixelstech.net/article/1445603357-A-HTTPS-client-and-HTTPS-server-demo-in-Java
Self signed CA with openssl Play all parties: prvatekey-publickey pair => create csr with publickey => create ca => ca sign csr How to setup your own CA with OpenSSL https://gist.github.com/Soarez/9688998 On windows for iis https://medium.com/the-new-control-plane/generating-self-signed-certificates-on-windows-7812a600c2d8 https://medium.com/@tbusser/creating-a-browser-trusted-self-signed-ssl-certificate-2709ce43fd15 https://www.sslshopper.com/article-how-to-create-a-self-signed-certificate-in-iis-7.html
# 4.3 SSH
跟SSL的区别： SSL的公钥信息和身份信息（填的地区邮箱网址等）需要用x.509自签或者ca对证书进行签名（自签就是自己用自己的私钥签名，相当于我生成了一对公私钥，现在要对公钥认证，自己再拿着这个私钥签名，所以叫自签； 如果是ca签发，当然是ca机构用他们自己的私钥对请求认证的公钥进行签名）， 签名后生成证书，证书就包含了请求公证的公钥信息和身份信息以及ca的签名信息； 而SSH生成的公私钥不需要认证，都是放在机器的某个目录下如.ssh，然后将公钥拷贝到互信的其他机器的相应.ssh目录，这样几台机器之间就可以免密登录（需要加载私钥到内存中）;当然如果是比如github，则需要拷贝到github的设置中： Adding a new SSH key to your GitHub account
ls -al ~/.ssh ssh-keygen -t rsa -b 4096 -C "[email protected]" # start the ssh-agent in the background $ eval $(ssh-agent -s) ssh-add ~/.ssh/id_rsa
SSL presents public keys in the context of an X.509 certificate, which itself includes a lot of information about the principal identified by the public key as well as its own digital signature, signed by yet another keypair. SSH does not normally use certificates to contain public keys; instead, the identity associated with a public key is determined by its location in the file system (i.e. whose home directory it's installed in). SSL SSH
# 4.4 authroize&authentication
OAuth2.0 JWT https://jwt.io/
# 4.5 blockchain - ECC
# Generate curve parameters openssl ecparam -name secp521r1 -outform PEM -out secp521r1.pem # Generate the private key openssl ecparam -inform PEM -in secp521r1.pem -genkey -outform PEM -out private-key.pem # Convert private key to pkcs8 openssl pkcs8 -topk8 -nocrypt -inform PEM -in private-key.pem -outform PEM -out private-key-pkcs8.pem # Generate the certificate for the private key openssl req -new -x509 -key private-key-pkcs8.pem -outform PEM -out server.pem -days 365 # Sign the document ./xmlsectool.sh --sign --signatureAlgorithm 'http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha256' --inFile ../doc.xml --outFile ../sign.xml --key private-key-pkcs8.pem --certificate server.pem # Verify the signature ./xmlsectool.sh --verifySignature --certificate server.pem -inFile ../sign.xml
How Certificates Use Digital Signatures https://commandlinefanatic.com/cgi-bin/showarticle.cgi?article=art012
From symmentic to man in the middle attack https://ssd.eff.org/en/module/deep-dive-end-end-encryption-how-do-public-key-encryption-systems-work https://en.wikipedia.org/wiki/Man-in-the-middle_attack