(Lianja) RSA Encrypt RSA/ECB/OAEPWithSHA1AndMGF1Padding

Demonstrates how to RSA encrypt using RSA/ECB/OAEPWithSHA1AndMGF1Padding. Also demonstrates RSA/ECB/OAEPWithSHA-256AndMGF1Padding. Both of these terms are from Java's JCE. Note: In this context, "ECB" doesn't actually mean anything. It's a symmetric cipher mode that doesn't apply (or make sense) in this context.

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

loRsa = createobject("CkRsa")

// First load a public key object with a public key.
// In this case, we'll load it from a file.
loPubkey = createobject("CkPublicKey")
llSuccess = loPubkey.LoadFromFile("qa_data/pem/rsa_public.pem")
if (llSuccess <> .T.) then
    ? loPubkey.LastErrorText
    release loRsa
    release loPubkey
    return
endif

// RSA encryption is limited to small amounts of data. The limit
// is typically a few hundred bytes and is based on the key size and
// padding (OAEP vs. PKCS1_5).  RSA encryption is typically used for
// encrypting hashes or symmetric (bulk encryption algorithm) secret keys.
lcPlainText = "Time is an illusion. Lunchtime doubly so."

// Import the public key to be used for encrypting.
llSuccess = loRsa.ImportPublicKeyObj(loPubkey)

// To get OAEP padding, set the OaepPadding property:
loRsa.OaepPadding = .T.

// To use SHA1 or SHA-256, set the OaepHash property
loRsa.OaepHash = "sha256"
// for SHA1 --
loRsa.OaepHash = "sha1"

// Indicate we'll want hex output
loRsa.EncodingMode = "hex"

// Encrypt..
llUsePrivateKey = .F.
lcEncryptedStr = loRsa.EncryptStringENC(lcPlainText,llUsePrivateKey)
? lcEncryptedStr

// -------------------------------------------------
// Now decrypt with the matching private key.
loRsa2 = createobject("CkRsa")

loPrivKey = createobject("CkPrivateKey")
llSuccess = loPrivKey.LoadEncryptedPem("qa_data/pem/rsa_passwd.pem","passwd")
if (llSuccess <> .T.) then
    ? loPrivKey.LastErrorText
    release loRsa
    release loPubkey
    release loRsa2
    release loPrivKey
    return
endif

llSuccess = loRsa2.ImportPrivateKeyObj(loPrivKey)

// Make sure we have the same settings used for encryption.
loRsa2.OaepPadding = .T.
loRsa2.EncodingMode = "hex"
loRsa2.OaepHash = "sha1"

lcOriginalStr = loRsa2.DecryptStringENC(lcEncryptedStr,.T.)

? lcOriginalStr


release loRsa
release loPubkey
release loRsa2
release loPrivKey