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SHA1 Mesasge Digest Algorithm
This chapter provides tutorial notes and example codes on the SHA1 message digest algorithm. Topics include SHA1 algorithm overview; using SHA1 in Java, PHP, and Perl.
2016-11-05, 1492👍, 5💬

💬 2015-10-14 Herong: Yojana, information on key generation of Blowfish Algorithm can be found in Key Schedule (Sub-Keys Generation) Algorithm tutoria...

💬 2015-10-13 Yojana Yadav: Plz send me the detail of key generation of Blowfish Algorithm

💬 2013-06-28 Herong: Abbas, You are welcome!

💬 2013-06-26 abbas: thank you for sha-1 and it's so helpful

First 8336 Hex Digits of PI
This section provides first 8336 hex digits of constant PI, 3.1415927..., needed for Blowfish encryption algorithm.
2016-10-31, 4937👍, 8💬

💬 2016-10-31 Andres: cool

💬 2016-04-07 Tamas Losonczi: This is great

💬 2016-03-15 Bogdan: Thanks!

💬 2015-12-03 Herong: Sadi, we only need (18*32+4*256*32)/4=8336 hex digits for the Blowfish encryption algorithm. I have typos in my tutorials. I wil...

💬 2015-12-02 Sadi: Sorry, I meant "8336 and not 8366"... Also would you like to compare these with "http://hexpi.sourceforge.net/" as there are som...

(More comments ...)

"keytool" Importing CA's Own Certificate
This section provides a tutorial example on how to import CA's certificate generated by 'OpenSSL' into a 'keystore' file using 'keytool'
2016-10-20, 527👍, 2💬

💬 2016-10-20 Herong: Akhtar, AES256 encryption does not require any certificates. It requires a secret AES key, see Introduction to AES (Advanced Enc...

💬 2016-10-19 Akhtar: I have also a certificate file (.cer) .I did the same procedure to import in to mykey store and got .jks file but, now i want to...

What Is Block Cipher?
This section describes what is block cipher - An encryption scheme in which 'the clear text is broken up into blocks of fixed length, and encrypted one block at a time'.
2016-09-26, 308👍, 1💬

💬 2016-09-26 eva: soooooooo Amazing thank so much this site helping to learn about blowfish algorthm more

Blowfish Cipher Algorithm
This section describes the Blowfish cipher algorithm - A 16-round Feistel cipher with block size of 64 bits developed by Bruce Schneier in 1993.
2016-08-03, 673👍, 2💬

💬 2016-08-03 azi: fantastic

What Is PKCS5Padding?
This section describes what is PKCS5Padding - a schema to pad cleartext to be multiples of 8-byte blocks.
2016-06-16, 17280👍, 8💬

💬 2016-06-16 yo: hola pescado

💬 2016-04-04 ankit: this is me.

💬 2016-01-28 John: Herong, thanks a lot.

💬 2016-01-27 Herong: John, the schema of PKCS7Padding can be described as below: Pad the input at the trailing end with k−(l mod k) octets with the s...

💬 2016-01-24 John: For PKCS7Padding, what is the schema? I'm interested to what is after 0x0909090909090909099

(More comments ...)

"openssl pkcs8" Converting Keys to PKCS#8 Format
This section provides a tutorial example on how to convert a private key file from the traditional format into PKCS#8 format using the 'openssl pkcs8' command. Keys can still be encoded with DER or PEM with or without DES encryption in PKCS#8 format.
2016-04-12, 5355👍, 1💬

💬 2016-04-12 Nishant Desai: Does anyone knows any library by which i can execute openssl pkcs8 -topk8 -in openssl_key.pem -inform pem -out openssl_key_pk8_e...

Certificate X.509 Standard and DER/PEM Formats
This chapter provides tutorial notes and example codes on certificate content standard and file formats. Topics include X.509 standard for certificate content; DER encoding for certificate binary file format; PEM encoding for certificate text file format; exchanging certificates in DER and PEM forma...
2016-04-10, 130👍, 1💬

Summary - Migrating "keystore" Keys to "OpenSSL"
This section describes high level steps on how to migrate a private key generated in a JKS (Java KeyStore) file to an 'OpenSSL' key file. The key step is to convert a JKS file into a PKCS#12 file with 'keytool'.
2016-04-09, 102👍, 1💬

Cryptography Basic Concepts
This chapter describes some basic concepts of cryptography: what is cryptography, what is function and what is encryption.
2016-04-07, 2146👍, 4💬

💬 2016-02-03 dinesh: thanks

💬 2015-12-28 Herong: Malini, RSA is good example of cryptosystem. Read Introduction of RSA Algorithm for more information.

💬 2015-12-28 malini: need cryptosystem

Certificate in PEM Format
This section describes what is certificate PEM (Privacy Enhanced Mail) format - A format uses PEM idea to convert a certificate in DER format to a message of printable characters. The conversion uses the Base64 encoding.
2016-03-30, 3232👍, 2💬

💬 2016-03-30 Herong: Bcbin, why don't you post your question here? Maybe others can help you too. Or send me an email directly.

💬 2016-03-27 bcbin: my name is bcbin, my email is bcbin@yahoo.com. please connecting me. i need you help ):

Key Schedule (Sub-Keys Generation) Algorithm
This section describes the Blowfish Key Schedule (Sub-Keys Generation) algorithm. It uses the binary representation of the fractional portion of constant Pi - 3.1415927... as initial values.
2016-03-17, 1095👍, 2💬

💬 2016-03-17 Herong: Hi Yogita, Blowfish(T) function refers the Blowfish algorithm described in the previous tutorial: Blowfish Cipher Algorithm.

💬 2016-03-16 YOGITA: what is the function blowfish(T) here? Send the pseudo code

Viewing Components of RSA Keys
This section provides a tutorial example on how to view different components of a pair of RSA private key and public key using the OpenSSL command line tool.
2016-03-14, 1630👍, 2💬

💬 2015-10-02 Herong: Looks like someone is testing Base64 encoding here :-)

💬 2015-10-01 1: CSENry/M1h2AhxGSxQluy4b1ynzBGWeO320C AwEAAQJAbQQn... IQCoo0AdFXm789FfHuB+mVIKNtBLTAQNaMuX z6lXl7Ib7Q==

Viewing Components of Certificate Signing Request
This section provides a tutorial example on how to view different components of a CSR (Certificate Signing Request) for your public key with OpenSSL.
2016-03-14, 587👍, 3💬

💬 2014-03-29 Herong: Hi Mike, Sorry for the inconvenience. HTML tags are supported, but they are limited to admin users only to reduce spamming and h...

💬 2014-03-23 Mike: Wow. What a waste of time trying to make a legible comment post. No instructions on how to get a paragraph break, include a angl...

💬 2014-03-23 Mike: You made a note in "Viewing Components of Certificate Signing Request" where you said, "The request is signed with my private ke...

Key Pair Sample Program - JcaKeyPair.java
This section provides a tutorial example on how to write simple program to generate a pair of private key and public key for the RSA or DSA algorithm.
2016-03-01, 835👍, 1💬

💬 2016-03-01 Shruti: thanks

Illustration of RSA Algorithm: p,q=7,19
This section provides a tutorial example to illustrate how RSA public key encryption algorithm works with 2 small prime numbers 7 and 19.
2016-02-29, 1109👍, 3💬

💬 2015-11-01 Herong: Jun, AES algorithm is added now, see Introduction to AES (Advanced Encryption Standard).

💬 2015-10-17 Herong: Jun, thank you for pointing out the mistake. I will correct it in the next version. AES will also be included.

💬 2015-10-16 jun: thanks a lot. your book makes everything clear for me except that I have not found a char for AES. By the way, I think "Generati...

RSA Implementation using java.math.BigInteger Class
This chapter provides tutorial notes and example codes on RSA implementation using Java BigInteger class. Topics include introduction of the java.math.BigInteger class; generating large probable prime numbers; generating RSA public key and private key; validating RSA keys; determining cleartext and ...
2016-02-29, 2638👍, 3💬

💬 2016-02-29 Herong: sah, is that an encoded comment?

💬 2016-02-28 sah: 7C4A8D09CA3762AF61E59520943DC26494F8 941B

💬 2014-02-06 Chinmayee: Searching for a book on RSAKey generation and got your link. Have not gone through the pdf yet. If find it good, will go for the...

DESCipherTest.java - DES Cipher Algorithm Illustration
This section provides a tutorial Java program, DESCipherTest.java, to illustrate how DES cipher algorithm works.
2016-01-24, 914👍, 1💬

💬 2016-01-24 Joe: Output

Steps of Using DES Algorithm in JDK JCE
This section describes how to use DES algorithm provided in the JDK JCE package. Steps include building a secret key object from key material; creating and initializing a cipher object.
2016-01-24, 725👍, 1💬

💬 2016-01-24 Joe: Very nice

What is ECB (Electronic CodeBook) Operation Mode?
This section describes what is ECB (Electronic CodeBook) Operation Mode - each plaintext block is encrypted independently without any input from other blocks.
2016-01-10, 2546👍, 2💬

💬 2016-01-10 Todd: Thanks!

Introduction to AES (Advanced Encryption Standard)
Tutorial notes and example codes on AES algorithms. Topics include introduction of AES (Advanced Encryption Standard); AES encryption algorithm; AES key schedule (round keys) algorithm and illustration example; MixColumns procedure algorithm; AES decryption algorithms.
2015-11-27, 257👍, 1💬

What is OFB (Output FeedBack) Operation Mode?
This section describes what is OFB (Output FeedBack) Operation Mode - each plaintext block is XORed with the current output block to be the ciphertext block. The current output block is the encrypted version of the previous output block.
2015-11-13, 1421👍, 2💬

💬 2015-11-13 Ashish: Hello world!

Generating New RSA Key Pairs
This section provides a tutorial example on how to generate a new pair of RSA priviate key and public key using the OpenSSL command line tool.
2015-11-03, 899👍, 1💬

💬 2015-11-03 Juli: Thanks

Validating a Certificate Path with OpenSSL
This section provides a tutorial example on how to perform validation of a certificate path with the 'openssl verify' command.
2015-10-14, 17216👍, 5💬

💬 2015-10-14 Herong: Karnan, if the issuer is a root CA, issuer certificate should be in your trusted certificate store. If the issuer is an intermed...

💬 2015-10-13 karnan: how to get issuer certificate

💬 2015-09-02 Liang: Thanks, Yang, This is a very helpful for understanding the basic concept of Crypto/SSL.

💬 2015-08-14 Chris: If you have to specify an intermediate as trusted, that means the intermediate is not qualified to be a signer.

💬 2015-08-12 Aleksandar Kostadinov: I see a strange thing: openssl verify -CApath . &lt;(cd /tmp ; cat server.pem intermediate.pem) That does not work if interm...

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