(Tcl) RSA Encrypt/Decrypt Bytes

See more RSA Examples

Demonstrates how to RSA encrypt and decrypt byte data.

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load ./chilkat.dll

# The RSA public key is used for encryption, and the private key for decryption.

# The public key's role is to make encryption accessible to anyone while ensuring that
# only the private key holder can decrypt the messages.
# The public key is designed to be widely distributed so anyone can use it to encrypt messages
# intended for the owner of the private key.

# Load our 2048-bit RSA public key.
set pubKey [new_CkPublicKey]

# In all Chilkat methods expecting a path, you pass either absolute or relative paths.
set success [CkPublicKey_LoadFromFile $pubKey "qa_data/rsaKeys/myTestRsaPublic.pem"]
if {$success == 0} then {
    puts [CkPublicKey_lastErrorText $pubKey]
    delete_CkPublicKey $pubKey
    exit
}

set rsa [new_CkRsa]

# Tell RSA to use the public key.
CkRsa_ImportPublicKeyObj $rsa $pubKey

# RSA encryption is for small amounts of data, on the order of 200 bytes or less.
# The maximum number of bytes that can be RSA encrypted depends
# on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
# For specific limits, see: RSA Encryption Maximum Number of Bytes

# A typical use for RSA is to encrypt symmetric encryption keys, such as an AES key.
set prng [new_CkPrng]

set keyBytes [new_CkByteData]

set success [CkPrng_GenRandomBytes $prng 32 $keyBytes]

set encBytes [new_CkByteData]

set success [CkRsa_EncryptBytes $rsa $keyBytes 0 $encBytes]

# ------------------------------------------------------------------------------------------------------------------------
# Let's decrypt, which requires the matching private key...

# Load the matching 2048-bit RSA private key.
set privKey [new_CkPrivateKey]

set password "secret"
set success [CkPrivateKey_LoadAnyFormatFile $privKey "qa_data/rsaKeys/myTestRsaPrivate.pem" $password]
if {$success == 0} then {
    puts [CkPrivateKey_lastErrorText $privKey]
    delete_CkPublicKey $pubKey
    delete_CkRsa $rsa
    delete_CkPrng $prng
    delete_CkByteData $keyBytes
    delete_CkByteData $encBytes
    delete_CkPrivateKey $privKey
    exit
}

# Tell the RSA object to use the private key.
CkRsa_ImportPrivateKeyObj $rsa $privKey

set decBytes [new_CkByteData]

set success [CkRsa_DecryptBytes $rsa $encBytes 1 $decBytes]
if {$success == 0} then {
    puts [CkRsa_lastErrorText $rsa]
    delete_CkPublicKey $pubKey
    delete_CkRsa $rsa
    delete_CkPrng $prng
    delete_CkByteData $keyBytes
    delete_CkByteData $encBytes
    delete_CkPrivateKey $privKey
    delete_CkByteData $decBytes
    exit
}

puts "Success."

delete_CkPublicKey $pubKey
delete_CkRsa $rsa
delete_CkPrng $prng
delete_CkByteData $keyBytes
delete_CkByteData $encBytes
delete_CkPrivateKey $privKey
delete_CkByteData $decBytes