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Using SHA1 Message Digest in Java
This section provides a tutorial example on how to use SHA1 message digest algorithm in Java. The JDK JCE package offers the SHA1 algorithm through a generic message digest class, javax.security.MessageDigest.
2018-12-04, 14585👍, 11💬

💬 2018-12-04 Gowtham: Great & Layman Terms

💬 2018-09-12 Onkar D: very good summary about SHA1

💬 2018-09-11 abccc: dvcz

💬 2018-08-31 Munikumar: Great...

💬 2017-10-24 Siva: Thanks

(More comments ...)

Outdated: Visiting an "https" Web Site with Firefox 3
This section describes how Firefox 3 shows a lock icon when you visit an 'https' Web site to provide you more security related information.
2018-11-10, 114👍, 2💬

💬 2018-11-10 Herong: Falle, try to use whois.icann.org to get more information about that website.

💬 2018-11-10 Falle: Thanks for your help . I couldn't access full information about cardtopia.org a website that scammed me of apple gift cards wort...

What Is DER (Distinguished Encoding Rules) Encoding?
This section describes the DER (Distinguished Encoding Rules) - A binary format of encoding a data value of any data types including nested data structures.
2018-10-29, 7399👍, 4💬

💬 2018-10-29 Thanks!: meaningful comments.

💬 2017-03-15 noname: thanks

💬 2016-01-25 Dev: hello

Converting Secret Keys to and from Byte Arrays
This section provides a quick introduction of the SecretKeySpec class and the KeySpec interface. They can be used to convert secret keys into byte arrays to store them in external files.
2018-10-20, 5929👍, 3💬

💬 2018-10-20 Herong: Marco, I just did a Google translation on your comment: "I wonder what all this could be". Are you trying to ask a question?

💬 2018-10-16 Marco: mi chiedo che cosa potrebbe essere tutto questo

💬 2015-11-03 cpp: hello

PDF Printing Version: Cryptography Tutorials
Information on how to obtain the PDF version of this book for printing.
2018-10-20, 6084👍, 34💬

💬 2018-10-20 Herong: bachi, thanks for sharing your comment.

💬 2018-10-13 bachi: I like how you composed your content. I like how you explain the DES algorithm

💬 2018-09-12 aaa: thanks

💬 2018-01-21 ahmed: thanks for your sharing

💬 2017-08-18 yamai: how can I design a java program

(More comments ...)

Introduction to DES Algorithm
This chapter provides tutorial examples and notes about DES (Data Encryption Standard) algorithm. Topics include description of block cipher, DES encryption algorithm, Round Keys Generation, DES decryption algorithm.
2018-10-18, 291👍, 4💬

💬 2018-10-18 sam: harry please stop bullying me

"keytool" Exporting Certificates in DER and PEM
This section provides a tutorial example on how to export certificates in DER and PEM format using the 'keytool -exportcert' command.
2018-10-06, 20486👍, 4💬

💬 2018-10-06 Herong: Srinivas, what are those special characters? Are they appended to the keystore file or the certificate file?

💬 2018-09-25 Srinivas: After generating certificate, there are some special characters appended.

💬 2016-06-27 Herong: Mandar, can you double check your command? The error indicates you entered a wrong password.

💬 2016-06-23 Mandar: converting to der is sucessful. while converting to pem, I am getting below error. keytool error: java.io.IOException: Keystore ...

What Is DSA (Digital Signature Algorithm)?
This section describes the DSA (Digital Signature Algorithm) algorithm, which consists of 2 parts: generation of a pair of public key and private key; generation and verification of digital signature.
2018-08-29, 23712👍, 15💬

💬 2018-08-29 Shawn: Thanks for the detailed explanation.

💬 2017-10-29 Abi: Very informative

💬 2017-04-01 Herong: T, A double asterisk ** is the exponentiation operation that raise a base to a power.

💬 2017-03-27 t: What is "**"?

💬 2017-03-10 appalaraju: useful

(More comments ...)

DESSubkeysTest.java - DES Key Schedule Algorithm Illustration
This section provides a tutorial Java program, DESSubkeysTest.java, to illustrate how DES key schedule algorithm works.
2018-07-20, 491👍, 2💬

💬 2018-07-20 aqil: havr fun

"OpenSSL" Signing CSR Generated by "keytool"
This chapter provides tutorial notes and example codes on using 'OpenSSL' to act as CA (Certificate Authority). Topics include setting up 'OpenSSL' as CA; using 'keytool' to generate CA private key; using 'keytool' to generate CSR (Certificate Signing Request); using 'OpenSSL' to sign CSR, using 'ke...
2018-07-12, 144👍, 1💬

"openssl pkcs12" Merging Key with Certificate
This section provides a tutorial example on how to merge a private key and its self-signed certificate into a single PKCS#12 file, with can be then encoded as PEM and encrypted with DES.
2018-07-07, 146👍, 1💬

"keytool" Importing Certificates in DER and PEM
This section provides a tutorial example on how to use 'keytool' to import certificates in DER and PEM formats generated by 'OpenSSL' into 'keystore' files.
2018-06-28, 12989👍, 2💬

💬 2016-04-01 MM: Thank you, this is very helpful.

64-bit RSA Key Validated by RsaKeyValidator.java
This section provides a tutorial example on how a 64-bit RSA key is validated by RsaKeyValidator.java with 3 rounds of encryption and decryption tests.
2018-06-09, 228👍, 2💬

💬 2018-06-09 Herong: Adrian, you are welcome!

💬 2018-06-09 Adrian: I needed in rush working 64-bit keys. You helped me a lot. Thanks! :D

Illustration of DSA Algorithm: p,q=7,3
This section provides a tutorial example to illustrate how DSA digital signature algorithm works with small prime modulus p=7 and prime divisor q=3.
2018-04-24, 2564👍, 5💬

💬 2016-03-22 Herong: Peter, I see the issue now. This example needs to be reviewed and updated. Thanks for the feedback.

💬 2016-03-21 peter winzell: x is not selected according to 0 < x < q

💬 2015-10-19 Herong: Hi Marian, do you have a question about this tutorial?

💬 2015-10-18 Marian: when q=3 x = 5 # selected: 0 < x < q

Introduction of DSA (Digital Signature Algorithm)
This chapter provides tutorial notes and example codes on DSA (Digital Signature Algorithm). Topics include introduction of DSA; illustration of DSA key generation, message signing and signature verification; proof of Digital Signature Algorithm.
2018-04-07, 2558👍, 11💬

💬 2018-04-07 Digital Signature Algorithm: Conclusions: DSA (Digital Signature Algorithm) uses public key and private key to generate and verify digital signatures. DSA pu...

💬 2018-04-07 Submit Your Comment: Please write meaningful comments. Thanks! ☺

💬 2018-04-07 world: hello

💬 2018-02-20 amit: hello

💬 2017-09-19 dasu: we r champion

Java Implementation of DES - Test Cases
This section provides two test cases for the Java implementation of DES algorithm, CipherDES.java.
2018-03-30, 165👍, 2💬

DES Key Schedule (Round Keys Generation) Algorithm
This section describes DES (Data Encryption Standard) algorithm - A 16-round Feistel cipher with block size of 64 bits.
2018-02-24, 8422👍, 13💬

💬 2018-02-24 Herong: hema, values in the pc-2 table are pre-defined by the algorithm. They are not calculated.

💬 2018-02-23 hema: i understood pc-1 table can you pls guide to calculate manually pc-2 table in des algorithm.

💬 2017-10-24 Herong: QuAI, you are right those bits are not used in the Permuted Choice 1 (PC1) table.

💬 2017-10-19 QuAl: And forget about bits 8, 16, ..., 64 of initial кey K! Those bits for parity check only (see FIPS 46-3)

💬 2017-06-15 Azaz: Not that much useful

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"OpenSSL" Generating CA's Private Key
This section provides a tutorial example on how to use OpenSSL to generate a RSA private key of 2048 bit long with OpenSSL. This key will be used as the CA's private key and must stored securely in a file with password protection.
2018-02-03, 769👍, 1💬

💬 2018-02-03 atomic.kidd: most Excellent Herong for this sharing of excellent Informations. Even the openssh documentation is not up to date nor as accura...

"openssl enc" Converting Keys from Binary to PEM
This section provides a tutorial example on how to convert a private and public key pair stored in binary PKCS#8 format into PEM (Privacy Enhanced Mail) format with the 'openssl enc' command.
2018-01-20, 534👍, 2💬

💬 2018-01-20 Herong: Dan, Thanks for comment. The "-inform" and "-outform" options are definitely better options. This tutorial will be updated.

💬 2018-01-17 Dan Lukes: openssl dsa understands binary key's format as well. Just claim it using option '-inform DER'. Moreover, 'openssl dsa -inform DE...

DES Decryption Algorithm
This section describes DES decryption algorithm - identical to the encryption algorithm step by step in the same order, only with the subkeys applied in the reverse order.
2018-01-20, 803👍, 2💬

💬 2017-12-16 Herong: deepak, is this a encrypted comment?

💬 2017-12-11 deepak: 9bc94bbaf6d380eb8f8c6548b2cf6343ccef 5978768e3d69b796d6ef0839172b

OpenSSL Introduction and Installation
This chapter provides tutorial notes and example codes on OpenSSL. Topics include introduction of OpenSSL; installing OpenSSL on Windows systems.
2017-12-24, 789👍, 4💬

💬 2016-11-28 musa: thanks

What Is SHA1 Message Digest Algorithm?
This section describes what is SHA1 (Secure Hash Algorithm 1) - a message digest algorithm which takes as input a message of arbitrary length and produces as output a 160-bit 'fingerprint'.
2017-12-09, 4540👍, 6💬

💬 2017-12-09 Herong: See the next tutorial: SHA1 Message Digest Algorithm Overview.

💬 2017-12-04 V: where can we find sha-1 formula ?

💬 2016-01-16 raza: i am raza see you latter

💬 2015-10-10 Herong: Ash, the next tutorial may help you understand better: SHA1 Message Digest Algorithm Overview

💬 2015-10-09 Ash: Please can u explain clearly..I dint understood

(More comments ...)

PHP Implementation of DES - mcrypt
This chapter provides tutorial examples and notes about PHP implementation of DES. Topics include introduction of mcrypt library; mcrypt encryption functions; DES encryption and decryption test program and test result.
2017-11-23, 1442👍, 3💬

💬 2016-01-02 sivaprakash: nice

How Secure Is RSA Algorithm?
This section discusses the security of RSA public key encryption algorithm. RSA private key is not 100% secure. But if the private key uses larger value of n = p*q, it will take a very long time to crack the private key.
2017-11-10, 623👍, 2💬

💬 2017-11-10 Anonymous: LOLZZZ

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