DEA64decrypt and DEA64encrypt (String functions)

DEA64 encryption or decryption (String class)

[Introduced in Model 204 7.6]

DEA64decrypt and DEA64encrypt are synonyms for the String class function that applies the DEA (Data Encryption Algorithm) using a 64-bit symmetric key to decrypt or encrypt each 64-bit block of input text. For more details about how the algorithm works, see Data Encryption Standard.

The length of the returned string is the same as that of the object string.

DEA is a two-way cipher, so encrypting a string with a key and then decrypting the result of that encryption with the same key produces the original string. That is, the following assertion should always hold:

assert %string:dea64encrypt(%key):dea64decrypt(%key) eq %string

You can use DEA64decrypt to "document" that you are decrypting, and use DEA64encrypt to "document" that you are encrypting. You can use DEA64decrypt and DEA64encrypt interchangeably on the rest of this page.

Syntax

%outString = string:DEA64decrypt( key) Throws UnsupportedCrypto, InvalidCryptoKey, InvalidCryptoData

%outString = string:DEA64encrypt( key) Throws UnsupportedCrypto, InvalidCryptoKey, InvalidCryptoData

Syntax terms

%outString	A string variable to receive the encrypted or decrypted method object string. Its length is the same as string.
string	The string to which the method is applied. string must be a multiple of eight bytes in length; its maximum is 32768 bytes. It may be null.
key	An 8-byte (only) string variable whose value is used to encrypt or decrypt the method object, string.

Usage notes

• You are not prevented from creating confusion by encrypting with DEA64decrypt and decrypting with DEA64encrypt.
• The DEA64decrypt and DEA64encrypt functions are available as of Model 204 7.6.

Examples

In the following example, the output string from the DEA64encrypt method is converted to hex using the StringToHex function to reveal its non-displayable characters, then decrypted to return the original input string:

b %ls is longstring %string is longstring %key is string len 8 %string = 'onetwothreefour0onetwothreefour0' %key = '12345678' %ls = %string:dea64encrypt(%key) printText {~} is {%ls:stringTohex} printText {~} is: {%ls:dea64decrypt(%key)} end

The result is:

%ls:stringTohex is: A54138C10468C061567574F88567E221A54138C10468C061567574F88567E221 %ls:dea64decrypt(%key) is: onetwothreefour0onetwothreefour0

See also

• Additional DEA methods:
  • DEA64decrypt and DEA64encrypt (String functions)
  • DEA128decrypt and DEA128encrypt (String functions)
  • DEA192decrypt and DEA192encrypt (String functions)
  • DEA64CBCdecrypt and DEA64CBCencrypt (String functions)
  • DEA128CBCdecrypt and DEA128CBCencrypt (String functions)
  • DEA192CBCdecrypt and DEA192CBCencrypt (String functions)
• Additional two-way ciphers:
  • AES128decrypt and AES128encrypt (String functions)
  • AES192decrypt and AES192encrypt (String functions)
  • AES256decrypt and AES256encrypt (String functions)
  • AES128CBCdecrypt and AES128CBCencrypt (String functions)
  • AES192CBCdecrypt and AES192CBCencrypt (String functions)
  • AES256CBCdecrypt and AES256CBCencrypt (String functions)
  • RC4decrypt and RC4encrypt (String functions)
• String one-way ciphers:
  • MD5digest
  • SHAdigest
  • SHA224digest
  • SHA256digest

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