B4X

Blowfish OFB Output Feedback Mode Encryption

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Demonstrates how to encrypt using Blowfish OFB (Output Feedback) mode. B4X

'  This example assumes the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

Dim crypt As ChilkatCrypt2
crypt.Initialize("crypt")

'  Use "blowfish2" to produce correct results that match published blowfish test vectors.
crypt.CryptAlgorithm = "blowfish2"
'  Set the cipher mode to Output Feedback
crypt.CipherMode = "ofb"
crypt.KeyLength = 256

'  EncodingMode specifies the encoding of the output for
'  encryption, and the input for decryption.
'  It may be "hex", "url", "base64", "quoted-printable", or many other choices.
crypt.EncodingMode = "hex"

'  The block size of the blowfish algoirthm is 8 bytes, therefore the IV is 8 bytes.
Dim ivHex As String = "0001020304050607"
crypt.SetEncodedIV(ivHex, "hex")

'  The secret key must equal the size of the key.  For
'  256-bit encryption, the binary secret key is 32 bytes.
Dim keyHex As String = "603deb1015ca71be2b73aef0857d77811f352c073b6108d72d9810a30914dff4"
crypt.SetEncodedKey(keyHex, "hex")

'  Encrypt a string...
Dim encStr As String = crypt.EncryptStringENC("Emergencies have always been the pretext on which the safeguards of individual liberty have been eroded. -- Friedrich Hayek")
Log(encStr)

Dim decrypt As ChilkatCrypt2
decrypt.Initialize("decrypt")
decrypt.CryptAlgorithm = "blowfish2"
decrypt.CipherMode = "ofb"
decrypt.KeyLength = 256
decrypt.EncodingMode = "hex"
decrypt.SetEncodedIV(ivHex, "hex")
decrypt.SetEncodedKey(keyHex, "hex")

'  Now decrypt:
Dim decStr As String = decrypt.DecryptStringENC(encStr)
Log(decStr)