Mastering the %SYSTEM.Encryption class
The InterSystems IRIS has excellent support for encryption, decryption and hashing operations. Inside the class %SYSTEM.Encryption (https://docs.intersystems.com/iris20212/csp/documatic/%25CSP.Documatic.c...) there are class methods for the main algorithms on the market.
IRIS Algorithms and Encrypt/Decrypt types
As you can see, the operations are based on keys and include 3 options:
 Symmetric Keys: the parts running encrypt and decrypt operations share the same secret key.
 Asymmetric Keys: the parts conducting encrypt and decrypt operations share the same secret key for encryption. However, for decryption, each partner has a private key. This key cannot be shared with other people, because it is an identity proof.
 Hash: used when you do not need to decrypt, but only encrypt.It is a common approach when it comes to storing user passwords.
Differences Between Symmetric and Asymmetric Encryption
 Symmetric encryption uses a single key that needs to be shared among the people who need to receive the message while asymmetric encryption uses a pair of public keys and a private key to encrypt and decrypt messages when communicating.
 Symmetric encryption is an old technique while asymmetric encryption is relatively new.
 Asymmetric encryption was introduced to complement the inherent problem of the need to share the key in a symmetric encryption model, eliminating the need to share the key by using a pair of publicprivate keys.
 Asymmetric encryption takes relatively more time than symmetric encryption.






























Source: https://www.ssl2buy.com/wiki/symmetricvsasymmetricencryptionwhataredifferences
Using the %SYSTEM.Encryption class to do Encrypt, Decrypt and Hash
To exercise IRIS support to Encrypt, Decrypt and Hash operations, go to https://github.com/yurimarx/cryptographysamples and follow these steps:
1. Clone/git pull the repo into any local directory
$ git clone https://github.com/yurimarx/cryptographysamples.git
2. Open a Docker terminal in this directory and run:
$ dockercompose build
3. Run the IRIS container:
$ dockercompose up d
4. Open IRIS Terminal:
$ dockercompose exec iris iris session iris U IRISAPP IRISAPP>
5. To do RSA Encrypt for asymmetric encryption execute this:
IRISAPP>Set ciphertext = ##class(dc.cryptosamples.Samples).DoRSAEncrypt("InterSystems") IRISAPP>Write ciphertext Ms/eR7pPmE39KBJu75EOYIxpFEd7qqoji61EfahJE1r9mGZX1NYuw5i2cPS5YwE3Aw6vPAeiEKXF rYW++WtzMeRIRdCMbLG9PrCHD3iQHfZobBnuzx/JMXVc6a4TssbY9gk7qJ5BmlqRTU8zNJiiVmd8 pCFpJgwKzKkNrIgaQn48EgnwblmVkxSFnF2jwXpBt/naNudBguFUBthef2wfULl4uY00aZzHHNxA bi15mzTdlSJu1vRtCQaEahng9ug7BZ6dyWCHOv74O/L5NEHI+jU+kHQeF2DJneE2yWNESzqhSECa ZbRjjxNxiRn/HVAKyZdAjkGQVKUkyG8vjnc3Jw==
6. To do RSA Decrypt for asymmetric decryption run this:
IRISAPP>Set plaintext = ##class(dc.cryptosamples.Samples).DoRSADecrypt(ciphertext) IRISAPP>Write plaintext InterSystems
7. To do AES CBC Encrypt for symmetric encryption perform this:
IRISAPP>Do ##class(dc.cryptosamples.Samples).DoAESCBCEncrypt("InterSystems") 8sGVUikDZaJF+Z9UljFVAA==
8. To do AES CBC Decrypt for symmetric encryption complete this:
IRISAPP>Do ##class(dc.cryptosamples.Samples).DoAESCBCDecrypt("8sGVUikDZaJF+Z9UljFVAA==") InterSystems
9. To do MD5 hash for an old hash approach conduct this:
IRISAPP>Do ##class(dc.cryptosamples.Samples).DoHash("InterSystems") rOs6HXfrnbEY5+JBdUJ8hw==
10. To do SHA hash for recommended hash approach follow this:
IRISAPP>Do ##class(dc.cryptosamples.Samples).DoSHAHash("InterSystems") +X0hDlyoViPlWOm/825KvN3rRKB5cTU5EQTDLvPWM+E=
11. To exit the terminal, do any of the following:
Enter HALT or H (not casesensitive)
About the source code
1. About the Symmetric key
In the Dockerfile, there was created an Environment key to be used as secret key on symmetric operations.
2. About the Asymmetric key
# to use with asymmetric encrypt/decrypt
RUN openssl req new x509 sha256 config examplecom.conf newkey rsa:2048 nodes keyout examplecom.key.pem days 365 out examplecom.cert.pem

In the Dockerfile were generated a private key and a public key to be used with asymmetric operations.
3. Symmetric Encrypt
The operation AES CBC Encrypt was used to encrypt texts.
Base64 Encode returns the results as a pretty/readable text to the user.
4. Symmetric Decrypt
The operation AES CBC Decrypt was used to decrypt texts.
Base64 Decode returns the encrypted text to a binary one, so it can be used to decrypt.
5. Asymmetric Encrypt
It is necessary to get the public key file content to encrypt with RSA.
The operation RSA Encrypt was used to encrypt texts.
6. Asymmetric Decrypt
It is necessary to get the private key file content to decrypt with RSA.
The operation RSA Decrypt was used to decrypt texts.
7. Hash text using MD5 (old approach)
The operation MD5 Hash will encrypt the text, and it will not be possible to decrypt it.
Hash using MD5 is not recommended for new projects because it is considered insecure. That is why it was replaced by SHA. The InterSystems IRIS supports SHA (our next example will demonstrate it).
8. Hash text using SHA (recommend approach)
We will use the SHA3 Hash method for this sample. According to InterSystems documentation, this method generates a hash using one of the U.S. Secure Hash Algorithms  3. (See Federal Information Processing Standards Publication 202 for more information.).
For the SHA method, it is possible to set the bit length used on a hash operation. The greater the number of bits, the more difficult it is to crack the hash. However, the hashing process slows down too. In this sample we used 256 bits. You can choose these options for bit length:
 224 (SHA224)
 256 (SHA256)
 384 (SHA384)
 512 (SHA512)
thank you for the time you spent to write this up!
Thanks!